California Building Standards Code
2025 California Mechanical Code (Title 24, Part 4)
Part 4 of Title 24 — HVAC, ventilation, exhaust and mechanical system requirements.
- Edition
- 2025
- Effective
- 2026-01-01
- Last ingested
- 2026-07-07
- Jurisdiction
- California
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2025 California Mechanical Code Converted from PDF using pymupdf4llm Source: 2025 California Mechanical Code.pdf Text ratio: 100.0% Conversion date: 2025-12-23 23:19:22 --- CALIFORNIA BUILDING STANDARDS COMMISSION CALIFORNIA 2025 MECHANICAL CODE CALIFORNIA CODE OF REGULATIONS I TITLE 24 PART 4 ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. Copyright© to 2024 UMC© Held by International Association of Plumbing…
301.7 OSHPD 1R . . . . . . . . . . . . . . . . . . . 51 ¶
301.7 OSHPD 1R . . . . . . . . . . . . . . . . . . . 51 302.0 Materials – Standards and Alternates . . . . . . . . . . . . . . . . . . . . 51 302.1 Minimum Standards . . . . . . . . . . . . 51 302.2 Alternate Materials and Methods of Construction Equivalency . . . . . . 51 302.3 Alternative Engineered Design. . . . 52 303.0 Installation . . . . . . . . . . . . . . . . . . . 52 303.1 Listed Appliances . . . . . . . . . . . . . . 52 303.2 Closet or Alcove Installations . . . . . 52 303.3 Unlisted Appliances . . . . . . . . . . . . 52 303.4 Anchorage of Appliances . . . . . . . . 52 303.5…
306.2 Building Automation Systems . . . . 56 ¶
306.2 Building Automation Systems . . . . 56 ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. TABLE OF CONTENTS 307.0 Labeling . . . . . . . . . . . . . . . . . . . . . 56 307.1 Fuel-Burning Appliances . . . . . . . . 56 307.2 Electric Heating Appliances . . . . . . 56 307.3 Heat Pump and Electric Cooling Appliances . . . . . . . . . . . . . . . . . . . 56 307.4 Absorption Units . . . . . . . . . . . . . . . 56 308.0 Improper Location. . . . . . . . . . . . . . 57 308.1 General. . . . . . . . . . . . . . . . . . . . . . 57…
311.5 California Energy Code ¶
311.5 California Energy Code Requirements for Residential Air Filtration . . . . . . . . . . . . . . . . . . 59 312.0 Plumbing Connections . . . . . . . . . . 59 312.1 General. . . . . . . . . . . . . . . . . . . . . . 59 313.0 Hangers, Supports, and Anchors . . 59 313.1 General. . . . . . . . . . . . . . . . . . . . . . 59 313.2 Material. . . . . . . . . . . . . . . . . . . . . . 59 313.3 Suspended Piping . . . . . . . . . . . . . 59 313.4 Alignment . . . . . . . . . . . . . . . . . . . . 59 313.5 Underground Installation . . . . . . . . 59 313.6 Hanger Rod Sizes . . . . . . . . . . . . . 59…
318.0 Scope . . . . . . . . . . . . . . . . . . . . . . . 60 ¶
318.0 Scope . . . . . . . . . . . . . . . . . . . . . . . 60
318.1 Applicability . . . . . . . . . . . . . . . . . . 60 ¶
318.1 Applicability . . . . . . . . . . . . . . . . . . 60
318.2 Services/Systems and Utilities . . . . 60 ¶
318.2 Services/Systems and Utilities . . . . 60
319.0 Steam and Hot-Water Systems . . . 60 ¶
319.0 Steam and Hot-Water Systems . . . 60
319.1 Requirements for Hospitals and ¶
319.1 Requirements for Hospitals and Optional Services Provided in Correctional Treatment Centers . . . 60
319.2 Requirements for Skilled ¶
319.2 Requirements for Skilled Nursing, Intermediate Care Facilities and Basic Services Provided in Correctional Treatment Centers . . . . . . . . . . . . . 61
320.0 Air Conditioning and ¶
320.0 Air Conditioning and Heating Systems . . . . . . . . . . . . . . 61
320.1 Requirements for Hospitals and ¶
320.1 Requirements for Hospitals and Optional Services Provided in Correctional Treatment Centers . . . 61
320.2 Requirements for Skilled ¶
320.2 Requirements for Skilled Nursing, Intermediate Care Facilities and Basic Services Provided in Correctional Treatment Centers . . . . . . . . . . . . . 61
320.3 Requirements for Outpatient ¶
320.3 Requirements for Outpatient Facilities and Licensed Clinics. . . . 61
320.4 Telephone and Technology ¶
320.4 Telephone and Technology Equipment Centers. . . . . . . . . . . . . 61
320.5 Psychiatric Services. . . . . . . . . . . . 61 ¶
320.5 Psychiatric Services. . . . . . . . . . . . 61
321.0 Essential Mechanical Provisions . . . 61 ¶
321.0 Essential Mechanical Provisions . . . 61
322.0 Sensitive Areas or Rooms . . . . . . . 62 ¶
322.0 Sensitive Areas or Rooms . . . . . . . 62 ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. TABLE OF CONTENTS
323.0 Mechanical Equipment ¶
323.0 Mechanical Equipment Schedules . . . . . . . . . . . . . . . . . . . 62
324.0 Diesel-Powered Emergency ¶
324.0 Diesel-Powered Emergency Generators . . . . . . . . . . . . . . . . . . . 62
325.0 Alternate Source of Power for ¶
325.0 Alternate Source of Power for Safe Temperatures. . . . . . . . . . . . . 62 Table 303.10.1 Reduction of Clearances with Specified Forms of Protection . . . . 63 Table 313.3 Hangers and Supports . . . . . . . . . . 65 CHAPTER 4 VENTILATION AIR . . . . . . . . . . . . 67 401.0 General. . . . . . . . . . . . . . . . . . . . . . 69 401.1 Applicability. . . . . . . . . . . . . . . . . . . 69 401.2 Indoor Swimming Pools . . . . . . . . . 69
401.3 Filters . . . . . . . . . . . . . . . . . . . . . . . 69 ¶
401.3 Filters . . . . . . . . . . . . . . . . . . . . . . . 69 402.0 Ventilation Air . . . . . . . . . . . . . . . . . 69 402.1 Occupiable Spaces. . . . . . . . . . . . . 69 402.2 Natural Ventilation Procedure. . . . . 70 Table Minimum Openable Areas: 402.2.1.6(A)(1) Single Openings . . . . . . . . . . . . . . . 71 Table Minimum Openable Areas: 402.2.1.6(A)(2) Two Vertically Spaced Openings . . . . . . . . . . . . . . 71 402.3 Mechanical Ventilation . . . . . . . . . . 71 402.4 Outdoor Air Intakes. . . . . . . . . . . . . 71 Table 402.4.1 Air Intake Minimum Separation Distance . . . . . . . .…
406.0 Evaporative Cooling System ¶
406.0 Evaporative Cooling System for Health Care Facilities . . . . . . . . 78
407.0 Ventilation System Details . . . . . . . 78 ¶
407.0 Ventilation System Details . . . . . . . 78
407.1 General. . . . . . . . . . . . . . . . . . . . . . 78 ¶
407.1 General. . . . . . . . . . . . . . . . . . . . . . 78
407.2 Outdoor Air Intakes and ¶
407.2 Outdoor Air Intakes and Exhaust Outlets . . . . . . . . . . . . . . . 78
407.3 Air Balance. . . . . . . . . . . . . . . . . . . 78 ¶
407.3 Air Balance. . . . . . . . . . . . . . . . . . . 78
407.4 Air Circulation . . . . . . . . . . . . . . . . . 78 ¶
407.4 Air Circulation . . . . . . . . . . . . . . . . . 78
407.5 Variable Air Volume . . . . . . . . . . . . 79 ¶
407.5 Variable Air Volume . . . . . . . . . . . . 79
407.6 Economizers. . . . . . . . . . . . . . . . . . 79 ¶
407.6 Economizers. . . . . . . . . . . . . . . . . . 79
407.7 Unoccupied Turndown. . . . . . . . . . 79 ¶
407.7 Unoccupied Turndown. . . . . . . . . . 79
407.8 Building Pressurization . . . . . . . . . 80 ¶
407.8 Building Pressurization . . . . . . . . . 80
408.0 Filters . . . . . . . . . . . . . . . . . . . . . . . 80 ¶
408.0 Filters . . . . . . . . . . . . . . . . . . . . . . . 80
408.1 General. . . . . . . . . . . . . . . . . . . . . . 80 ¶
408.1 General. . . . . . . . . . . . . . . . . . . . . . 80
408.2 Filters for Hospitals. . . . . . . . . . . . . 80 ¶
408.2 Filters for Hospitals. . . . . . . . . . . . . 80
408.3 Filters for Skilled Nursing ¶
408.3 Filters for Skilled Nursing Facilities, Intermediate Care Facilities, and Correctional Treatment Centers . . . . . . . . . . . . . 80
408.4 Filters for Outpatient Facilities . . . . 80 ¶
408.4 Filters for Outpatient Facilities . . . . 80
408.5 Filters for Recirculating ¶
408.5 Filters for Recirculating Room Units. . . . . . . . . . . . . . . . . . . 80
409.0 Ducts . . . . . . . . . . . . . . . . . . . . . . . 80 ¶
409.0 Ducts . . . . . . . . . . . . . . . . . . . . . . . 80
410.0 Laboratory Ventilating Systems ¶
410.0 Laboratory Ventilating Systems and Hoods . . . . . . . . . . . . . . . . . . . 80
410.1 Laboratory Ventilating Systems . . . 80 ¶
410.1 Laboratory Ventilating Systems . . . 80
410.2 Exhaust Hoods and ¶
410.2 Exhaust Hoods and Safety Cabinets . . . . . . . . . . . . . . . 80
410.3 Laboratory Fume Hoods . . . . . . . . 80 ¶
410.3 Laboratory Fume Hoods . . . . . . . . 80
411.0 Kitchen and Dining Areas . . . . . . . 81 ¶
411.0 Kitchen and Dining Areas . . . . . . . 81
412.0 Boiler, Mechanical, and ¶
412.0 Boiler, Mechanical, and Electrical Rooms . . . . . . . . . . . . . . 81
413.0 Odorous Rooms . . . . . . . . . . . . . . . 81 ¶
413.0 Odorous Rooms . . . . . . . . . . . . . . . 81
414.0 Airborne Infection Isolation ¶
414.0 Airborne Infection Isolation Rooms . . . . . . . . . . . . . . . . . . . . . . 81
414.1 Exhaust Systems . . . . . . . . . . . . . . 81 ¶
414.1 Exhaust Systems . . . . . . . . . . . . . . 81
414.2 Air Distribution . . . . . . . . . . . . . . . . 81 ¶
414.2 Air Distribution . . . . . . . . . . . . . . . . 81
415.0 Protective Environment Rooms . . . 82 ¶
415.0 Protective Environment Rooms . . . 82 ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. TABLE OF CONTENTS
415.1 Air Distribution . . . . . . . . . . . . . . . . 82 ¶
415.1 Air Distribution . . . . . . . . . . . . . . . . 82
416.0 Alarms – Airborne Infection ¶
416.0 Alarms – Airborne Infection Isolation Rooms and Protective Environment Rooms . . . . . . . . . . . . 82
417.0 Testing and Balancing Airborne ¶
417.0 Testing and Balancing Airborne Infection Isolation Rooms and Protective Environment Rooms . . . 82
418.0 Design Requirements for ¶
418.0 Design Requirements for Ethylene Oxide (ETO) Sterilization Areas. . . . . . . . . . . . . . 82
418.1 Air Changes . . . . . . . . . . . . . . . . . . 82 ¶
418.1 Air Changes . . . . . . . . . . . . . . . . . . 82
418.2 Exhaust Requirements . . . . . . . . . . 82 ¶
418.2 Exhaust Requirements . . . . . . . . . . 82
418.3 Ventilation Requirements . . . . . . . . 82 ¶
418.3 Ventilation Requirements . . . . . . . . 82
418.4 Gas Valves . . . . . . . . . . . . . . . . . . . 82 ¶
418.4 Gas Valves . . . . . . . . . . . . . . . . . . . 82
418.5 Alarm Systems . . . . . . . . . . . . . . . . 83 ¶
418.5 Alarm Systems . . . . . . . . . . . . . . . . 83
419.0 Neonatal Intensive Care Units . . . . 83 ¶
419.0 Neonatal Intensive Care Units . . . . 83
419.1 Formula Preparation Area . . . . . . . 83 ¶
419.1 Formula Preparation Area . . . . . . . 83
419.2 Treatment Area/Room . . . . . . . . . . 83 ¶
419.2 Treatment Area/Room . . . . . . . . . . 83 Table 4-A Pressure Relationship and Ventilation Requirements for General Acute Care Hospitals, Skilled Nursing Facilities, Intermediate Care Facilities, Outpatient Facilities, Licensed Clinics, Correctional Treatment Centers, and Acute Psychiatric Hospitals . . . . . . . . . . . 84 Table 4-B Filter Efficiencies for Central Ventilation and Air-Conditioning Systems In General Acute Care Hospitals, Outpatient Facilities, Licensed Clinics and Acute Psychiatric Hospitals . . . . . . . . . . . 91 Table 4-C Filter Efficiencies for Central Ventilation…
505.12 Pharmacies – Compounding ¶
505.12 Pharmacies – Compounding Area of Parenteral Solutions . . . . 103 506.0 Product-Conveying Ducts. . . . . . . 103 506.1 Materials . . . . . . . . . . . . . . . . . . . . 103 Table 505.9 Range of Minimum Duct Design Velocities. . . . . . . . . . . . . . . . . . . . 103 Table 506.2(1) Minimum Sheet Metal Thickness for Round Ducts . . . . . . . . . . . . . . 104 506.2 Construction . . . . . . . . . . . . . . . . . 105 Table 506.2(2) Minimum Sheet Metal Thickness for Rectangular Ducts. . . . . . . . . . 106 506.3 Penetrations . . . . . . . . . . . . . . . . . 106 506.4 Condensate . . . . .…
507.7 Pharmaceutical Compounding ¶
507.7 Pharmaceutical Compounding Exhaust Discharge . . . . . . . . . . . . 111 508.0 Type I Hoods . . . . . . . . . . . . . . . . 111 508.1 Where Required . . . . . . . . . . . . . . 111 508.2 Listed Type I Hood Assemblies . . 111 508.3 Construction of Type I Hoods . . . . 111 508.4 Supports . . . . . . . . . . . . . . . . . . . . 112 508.5 Hood Size . . . . . . . . . . . . . . . . . . . 112 Table 508.5.1.2 Extra-Heavy-Duty Cooking Appliance Airflow . . . . . . . . . . . . . 113 Table 508.5.1.3 Heavy-Duty Cooking Appliance Airflow. . . . . . . . . . . . . . . . . . . . . . 113 Table 508.5.1.4…
609.2 Air-Moving Systems and ¶
609.2 Air-Moving Systems and Smoke Detectors in Group I-2 Occupancies . . . . . . . . . . . . . . . . 144 CHAPTER 7 COMBUSTION AIR . . . . . . . . . . . 145 701.0 General. . . . . . . . . . . . . . . . . . . . . 147 701.1 Applicability. . . . . . . . . . . . . . . . . . 147 701.2 Pressure Difference . . . . . . . . . . . 147 701.3 Makeup Air . . . . . . . . . . . . . . . . . . 147 701.4 Indoor Combustion Air . . . . . . . . . 147 701.5 Indoor Opening Size and Location . . . . . . . . . . . . . . . . . . . . 147 701.6 Outdoor Combustion Air . . . . . . . . 147 701.7 Combination Indoor and…
1502.0 General. . . . . . . . . . . . . . . . . . . . . 339 ¶
1502.0 General. . . . . . . . . . . . . . . . . . . . . 339 CHAPTER 16 STATIONARY POWER PLANTS . . . . . . . . . . . . . . . . . . . . 341 1601.0 Stationary Fuel Cell Power Plants . . . . . . . . . . . . . . . . . . . . . . 343 1601.1 General. . . . . . . . . . . . . . . . . . . . . 343 1602.0 Stationary Gas Engines and Generators and Gas Turbines . . . 343 1602.1 Gas Engines . . . . . . . . . . . . . . . . . 343
1602.2 Liquid-Fueled Engines and ¶
1602.2 Liquid-Fueled Engines and Gas Turbines . . . . . . . . . . . . . . . . 343 1602.3 Stationary Engine Generators . . . 343 CHAPTER 17 GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS. . . . . . . 345 Part I General . . . . . . . . . . . . . . . . . . . . 347 1701.0 General. . . . . . . . . . . . . . . . . . . . . 347 1701.1 Applicability. . . . . . . . . . . . . . . . . . 347 1701.2 Construction Documents . . . . . . . 347 1701.3 Site Survey . . . . . . . . . . . . . . . . . . 347 1701.4 Used Materials . . . . . . . . . . . . . . . 347 1701.5 Contact with Building Material . . .…
104.2 Items (1) through (5) of this code. ¶
104.2 Items (1) through (5) of this code. (2) Changes, alterations, or repairs of a minor nature not affecting structural features, egress, sanitation, safety, or accessibility as determined by the enforcing agency. (3) Retroactive permits issued in accordance with Health and Safety Code Section 17958.12. Exemptions from permit requirements shall not be deemed to grant authorization for any work to be done in any manner in violation of other provisions of law or this code. 1.8.4.2 Fees. Subject to other provisions of law, the governing body of any city, county, or city and county may…
101.0 General. ¶
101.1 Title. This document shall be known as the “Uniform ¶
101.1 Title. This document shall be known as the “Uniform Mechanical Code,” may be cited as such, and will be referred to herein as “this code.”
101.2 Scope. The provisions of this code shall apply to the ¶
101.2 Scope. The provisions of this code shall apply to the erection, installation, alteration, repair, relocation, replacement, addition to, use, or maintenance of mechanical systems within this jurisdiction.
101.3 Purpose. ¶
101.3 Purpose. This code is an ordinance providing minimum requirements and standards for the protection of the public health, safety, and welfare.
101.4 Unconstitutional. ¶
101.4 Unconstitutional. Where a section, subsection, sentence, clause, or phrase of this code is, for a reason, held to be unconstitutional, such decision shall not affect the validity of the remaining portions of this code. The legislative body hereby declares that it would have passed this code, and each section, subsection, sentence, clause, or phrase thereof, irrespective of the fact that one or more sections, subsections, sentences, clauses, and phrases are declared unconstitutional.
101.5 Validity. ¶
101.5 Validity. Where a provision of this code, or the application thereof to a person or circumstance, is held invalid, the remainder of the code, or the application of such provision to other persons or circumstances, shall not be affected thereby.
102.0 Applicability. ¶
102.1 Conflicts Between Codes. Where the requirements ¶
102.1 Conflicts Between Codes. Where the requirements within the jurisdiction of this mechanical code conflict with the requirements of the plumbing code, the plumbing code shall prevail. In instances where this code, applicable standards, or the manufacturer’s installation instructions conflict, the more stringent provisions shall prevail. Where there is a conflict between a general requirement and a specific requirement, the specific requirement shall prevail. [OSHPD 1, 1R, 2, 3, 4 & 5] See Chapter 1, Division I, Section 1.1.7
102.2 Existing Installations. Mechanical systems lawfully ¶
102.2 Existing Installations. Mechanical systems lawfully in existence at the time of the adoption of this code shall be permitted to have their use, maintenance, or repair continued where the use, maintenance, or repair is in accordance with the original design and location and no hazard to life, health, or property has been created by such mechanical system.
102.3 Maintenance. Mechanical systems, materials, and ¶
102.3 Maintenance. Mechanical systems, materials, and appurtenances, both existing and new, of a premise under the Authority Having Jurisdiction shall be maintained in operating condition. Devices or safeguards required by this code shall be maintained in accordance with the code edition under which installed. The owner or the owner’s designated agent shall be responsible for maintenance of mechanical systems. To determine compliance with this subsection, the Authority Having Jurisdiction shall be permitted to cause a mechanical system to be reinspected. 102.3.1 Commercial HVAC Systems.…
102.4 Additions, Alterations, Renovations, or ¶
102.4 Additions, Alterations, Renovations, or Repairs. Additions, alterations, renovations, or repairs shall conform to that required for a new system without requiring the existing mechanical system to be in accordance with the requirements of this code. Additions, alterations, renovations, or repairs shall not cause an existing system to become unsafe, insanitary or overloaded. Additions, alterations, renovations, or repairs to existing mechanical system installations shall comply with the provisions for new construction, unless such deviations are found to be necessary and are first…
102.5 Health and Safety. ¶
102.5 Health and Safety. Where compliance with the provisions of this code fails to eliminate or alleviate a nuisance, or other dangerous or insanitary condition that involves health or safety hazards, the owner or the owner’s agent shall install such additional mechanical system facilities or shall make such repairs or alterations as ordered by the Authority Having Jurisdiction.
102.6 Changes in Building Occupancy. Mechanical ¶
102.6 Changes in Building Occupancy. Mechanical systems that are a part of a building or structure undergoing a change in use or occupancy, as defined in the building code, shall be in accordance with the requirements of this code that are applicable to the new use or occupancy.
102.7 Moved Structures. Parts of the mechanical system of ¶
102.7 Moved Structures. Parts of the mechanical system of a building and part thereof that is moved from one foundation to another, or from one location to another, shall be in accordance with the provisions of this code for new installations and completely tested as prescribed elsewhere in this section for new work, except that walls or floors need not be removed during such test where equivalent means of inspection acceptable to the Authority Having Jurisdiction are provided.
102.8 Appendices. The provisions in the appendices are ¶
102.8 Appendices. The provisions in the appendices are intended to supplement the requirements of this code and shall not be considered part of this code unless formally adopted as such. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. DIVISION II SCOPE AND ADMINISTRATION
103.0 Duties and Powers of the Authority Having ¶
103.0 Duties and Powers of the Authority Having Jurisdiction.
103.1 General. The Authority Having Jurisdiction shall be ¶
103.1 General. The Authority Having Jurisdiction shall be the Authority duly appointed to enforce this code. For such purposes, the Authority Having Jurisdiction shall have the powers of a law enforcement officer. The Authority Having Jurisdiction shall have the power to render interpretations of this code and to adopt and enforce rules and regulations supplemental to this code as deemed necessary in order to clarify the application of the provisions of this code. Such interpretations, rules, and regulations shall comply with the intent and purpose of this code. In accordance with the…
103.2 Liability. The Authority Having Jurisdiction charged ¶
103.2 Liability. The Authority Having Jurisdiction charged with the enforcement of this code, acting in good faith and without malice in the discharge of the Authority Having Jurisdiction’s duties, shall not thereby be rendered personally liable for damage that accrues to persons or property as a result of an act or by reason of an act or omission in the discharge of such duties. A suit brought against the Authority Having Jurisdiction or employee because of such act or omission performed in the enforcement of provisions of this code shall be defended by legal counsel provided by this…
103.3 Applications and Permits. The Authority Having ¶
103.3 Applications and Permits. The Authority Having Jurisdiction shall be permitted to require the submission of plans, specifications, drawings, and such other information in accordance with the Authority Having Jurisdiction, prior to the commencement of, and at a time during the progress of, work regulated by this code. The issuance of a permit upon construction documents shall not prevent the Authority Having Jurisdiction from thereafter requiring the correction of errors in said construction documents or from preventing construction operations being carried on thereunder where in…
103.4 Right of Entry. Where it is necessary to make an ¶
103.4 Right of Entry. Where it is necessary to make an inspection to enforce the provisions of this code, or where the Authority Having Jurisdiction has reasonable cause to believe that there exists in a building or upon a premises a condition or violation of this code that makes the building or premises unsafe, insanitary, dangerous, or hazardous, the Authority Having Jurisdiction shall be permitted to enter the building or premises at reasonable times to inspect or to perform the duties imposed upon the Authority Having Jurisdiction by this code, provided that where such building or…
104.0 Permits. ¶
104.1 Permits Required. It shall be unlawful for a person, ¶
104.1 Permits Required. It shall be unlawful for a person, firm, or corporation to make an installation, alteration, repair, replacement, or remodel a mechanical system regulated by this code except as permitted in Section 104.2, or to cause the same to be done without first obtaining a separate mechanical permit for each separate building or structure.
104.2 Exempt Work. A permit shall not be required for the ¶
104.2 Exempt Work. A permit shall not be required for the following: (1) A portable heating appliance, portable ventilating equipment, a portable cooling unit, or a portable evaporative cooler. (2) A closed system of steam, hot, or chilled water piping within heating or cooling equipment regulated by this code. (3) Replacement of a component part that does not alter its original approval and is in accordance with other applicable requirements of this code. (4) Refrigerating equipment that is part of the equipment for which a permit has been issued pursuant to the requirements of this code.…
104.3 Application for Permit. To obtain a permit, the ¶
104.3 Application for Permit. To obtain a permit, the applicant shall first file an application therefore in writing on a form furnished by the Authority Having Jurisdiction for that purpose. Such application shall: (1) Identify and describe the work to be covered by the permit for which application is made. 22 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. DIVISION II SCOPE AND ADMINISTRATION (2) Describe the land upon which the proposed work is to be done by legal description, street…
104.4 Permit Issuance. ¶
104.4 Permit Issuance. The application, construction documents, and other data filed by an applicant for a permit shall be reviewed by the Authority Having Jurisdiction. Such plans shall be permitted to be reviewed by other departments of this jurisdiction to verify compliance with applicable laws under their jurisdiction. Where the Authority Having Jurisdiction finds that the work described in an application for permit and the plans, specifications, and other data filed therewith are in accordance with the requirements of the code and other pertinent laws and ordinances and that the fees…
104.5 Fees. Fees shall be assessed in accordance with the ¶
104.5 Fees. Fees shall be assessed in accordance with the provisions of this section and as set forth in the fee schedule, Table 104.5. The fees are to be determined and adopted by this jurisdiction. 104.5.1 Work Commencing Before Permit Issuance. Where work for which a permit is required by this code has been commenced without first obtaining said permit, a special investigation shall be made before a permit is issued for such work. 104.5.2 Investigation Fees. An investigation fee, in addition to the permit fee, shall be collected whether or not a permit is then or subsequently issued. The…
105.0 Inspections and Testing. ¶
105.1 General. Mechanical systems for which a permit is ¶
105.1 General. Mechanical systems for which a permit is required by this code shall be inspected by the Authority Having Jurisdiction. No mechanical system or portion thereof shall be covered, concealed, or put into use until inspected and approved as prescribed in this code. Neither the Authority Having Jurisdiction nor the jurisdiction shall be liable for expense entailed in the removal or replacement of material required to permit inspection. Mechanical systems regulated by this code shall not be connected to the energy fuel supply lines until authorized by the Authority Having…
105.2 Required Inspections. New mechanical system ¶
105.2 Required Inspections. New mechanical system work and such portions of existing systems as affected by new work, or changes, shall be inspected by the Authority Having Jurisdiction to ensure compliance with the requirements of this code and to ensure that the installation and construction of the mechanical system are in accordance with approved plans. The Authority Having Jurisdiction shall make the following inspections and other such inspections as necessary. The permittee or the permittee’s authorized agent shall be responsible for the scheduling of such inspections as follows: (1)…
105.3 Testing of Systems. Mechanical systems shall be ¶
105.3 Testing of Systems. Mechanical systems shall be tested and approved in accordance with this code or the Authority Having Jurisdiction. Tests shall be conducted in the presence of the Authority Having Jurisdiction or the Authority Having Jurisdiction’s duly appointed representative. No test or inspection shall be required where a mechanical system, or part thereof, is set up for exhibition purposes and has no connection with water or an energy fuel supply. In cases where it would be impractical to provide the required water or air tests, or for minor installations and repairs, the…
105.4 Connection to Service Utilities. No person shall ¶
105.4 Connection to Service Utilities. No person shall make connections from a source of energy or fuel to a mechanical system or equipment regulated by this code and for which a permit is required until approved by the Authority Having Jurisdiction. The Authority Having Jurisdiction shall be permitted to authorize temporary connection of the mechanical system equipment to the source of energy or fuel for the purpose of testing the equipment.
106.0 Violations and Penalties. ¶
106.1 General. It shall be unlawful for a person, firm, or ¶
106.1 General. It shall be unlawful for a person, firm, or corporation to erect, construct, enlarge, alter, repair, move, improve, remove, convert, demolish, equip, use, or maintain a mechanical system or permit the same to be done in violation of this code.
106.2 Notices of Correction or Violation. Notices of ¶
106.2 Notices of Correction or Violation. Notices of correction or violation shall be written by the Authority Having Jurisdiction and shall be permitted to be posted at the site of the work or mailed or delivered to the permittee or their authorized representative. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. DIVISION II SCOPE AND ADMINISTRATION Refusal, failure, or neglect to comply with such notice or order within 10 days of receipt thereof, shall be considered a violation of this code and shall be subject to the…
106.3 Penalties. A person, firm, or corporation violating a ¶
106.3 Penalties. A person, firm, or corporation violating a provision of this code shall be deemed guilty of a misdemeanor, and upon conviction thereof, shall be punishable by a fine, imprisonment, or both set forth by the governing laws of the jurisdiction. Each separate day or a portion thereof, during which a violation of this code occurs or continues, shall be deemed to constitute a separate offense.
106.4 Stop Orders. Where work is being done contrary to ¶
106.4 Stop Orders. Where work is being done contrary to the provisions of this code, the Authority Having Jurisdiction shall be permitted to order the work stopped by notice in writing served on persons engaged in the doing or causing such work to be done, and such persons shall forthwith stop work until authorized by the Authority Having Jurisdiction to proceed with the work.
106.5 Authority to Disconnect Utilities in Emergen- ¶
106.5 Authority to Disconnect Utilities in Emergen- cies. The Authority Having Jurisdiction shall have the authority to disconnect a mechanical system to a building, structure, or equipment regulated by this code in case of emergency where necessary to eliminate an immediate hazard to life or property.
106.6 Authority to Condemn. ¶
106.6 Authority to Condemn. Where the Authority Having Jurisdiction ascertains that a mechanical system or portion thereof, regulated by this code, has become hazardous to life, health, or property, or has become insanitary, the Authority Having Jurisdiction shall order in writing that such mechanical system either be removed or placed in a safe or sanitary condition. The order shall fix a reasonable time limit for compliance. No person shall use or maintain a defective mechanical system after receiving such notice. Where such mechanical system is to be disconnected, written notice shall be…
107.0 Board of Appeals. ¶
107.1 General. In order to hear and decide appeals of orders, ¶
107.1 General. In order to hear and decide appeals of orders, decisions, or determinations made by the Authority Having Jurisdiction relative to the application and interpretations of this code, there shall be and is hereby created a Board of Appeals consisting of members who are qualified by experience and training to pass upon matters pertaining to mechanical system design, construction, and maintenance and the public health aspects of mechanical systems and who are not employees of the jurisdiction. The Authority Having Jurisdiction shall be an ex-officio member and shall act as secretary…
107.2 Limitations of Authority. The Board of Appeals ¶
107.2 Limitations of Authority. The Board of Appeals shall have no authority relative to interpretation of the administrative provisions of this code, nor shall the board be empowered to waive requirements of this code. 26 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. DIVISION II SCOPE AND ADMINISTRATION TABLE 104.5 MECHANICAL PERMIT FEES Permit Issuance 1. For the issuance of each…
201.0 General. ¶
201.1 Applicability. ¶
201.1 Applicability. For the purpose of this code, the following terms have the meanings indicated in this chapter. No attempt is made to define ordinary words, which are used in accordance with their established dictionary meanings, except where a word has been used loosely, and it is necessary to define its meaning as used in this code to avoid misunderstanding.
202.0 Definition of Terms. ¶
202.1 General. ¶
202.1 General. The definitions of terms are arranged alphabetically according to the first word of the term.
203.0 – A – ¶
203.0 – A – Absorption Unit. An absorption refrigeration system that has been factory-assembled and tested prior to its installation. Accepted Engineering Practice. That which conforms to technical or scientific-based principles, test, or standards that are accepted by the engineering profession. Access Panel. A closure device used to cover an opening into a duct, an enclosure, equipment, or an appurtenance. [NFPA 96:3.3.1] Accessible. Where applied to a device, appliance, or equipment, “accessible” means having access thereto, but which first may require the removal of an access panel, door,…
204.0 – B – ¶
204.0 – B – Backflow. The flow of water or other liquids, mixtures, or substances into the distributing pipes of a potable supply of water from sources other than its intended source. Baffle Plate. An object placed in or near an appliance to change the direction or retard the flow of air, air-fuel mixtures, or flue gases. [NFPA 96:3.3.8] Boiler. A closed vessel used for heating water or liquid, or for generating steam or vapor by direct application of heat from combustible fuels or electricity. Boiler, Automatic. A boiler equipped with certain controls and limit devices. Boiler,…
205.0 – C – ¶
205.0 – C – CAS Number. The Chemical Abstract System registry number. Central Heating Plant or Heating Plant. Environmental heating equipment installed in a manner to supply heat by means of ducts or pipes to areas other than the room or space in which the equipment is located. Certified. A formally stated recognition and approval of an acceptable level of competency, acceptable to the Authority Having Jurisdiction. [NFPA 96:3.3.10] Certified Person. A person trained and certified by the equipment manufacturer, or by a recognized organization through a formal certification program for the…
206.0 – D – ¶
206.0 – D – Damper. A valve or plate for controlling draft or the flow of gases, including air. [NFPA 211:3.3.52] Ceiling Radiation Damper. A listed device installed in a ceiling membrane of a fire-resistance-rated floorceiling or roof-ceiling assembly to automatically limit the radiative heat transfer through an air inlet/outlet opening. [NFPA 5000:3.3.140.1] Combination Fire/Smoke Damper. An automaticclosing metal assembly consisting of one or more louvers, blades, slats, or vanes that closes upon detection of heat or smoke as to restrict the passage of flame and smoke. Corridor Damper. An…
208.0 – F – ¶
208.0 – F – Fabrication Area (Fab Area). An area within a Group H Occupancy semiconductor fabrication facility and related research and development areas in that there are processes involving hazardous production materials. Such areas are allowed to include ancillary rooms or areas such as dressing rooms and offices that are directly related to the fab area processes. Factory-Built Grease Duct Enclosures. A listed factory-built grease duct system evaluated as an enclosure system for reduced clearances to combustibles and as an alternative to a duct with its fire-rated enclosure. [NFPA…
207.0 – E – ¶
207.0 – E – Easily Accessible. See Accessible, Readily . Effective Ground-Fault Current Path. An intentionally constructed, low impedance electrically conductive path designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system to the electrical supply source and that facilitates the operation of the overcurrent protective device or ground-fault detectors. [NFPA 54:3.3.33] Electric Duct Heaters. A heater located in the airstream of a forced-air system where the air-moving unit is not provided as an integral part of the equipment. ),…
209.0 – G – ¶
209.0 – G – Galvanized Steel. A steel that has been coated with a thin layer of zinc for corrosion protection; conforming to the requirements of ASTM A653/A653M Standard Specification for Steel Sheet, Zinc-Coat (Galvanized) or Zinc-Iron Alloy- Coat (Galvanized) by the Hot Dip Process . Gas. A substance used as fuel, such as natural, liquefied petroleum (LP-Gas), and mixtures of these gases, with gas-air mixtures within the flammable range. Fuel Gas. Natural, manufactured, liquefied petroleum, or a mixture of these. Flue Gas. Products of combustion with excess air in appliance flues or heat…
210.0 – H – ¶
210.0 – H – Hangers. See Supports. Hazardous Location. An area or space where combustible dust, ignitable fibers, flammable liquids, volatile liquids, gases, vapors, or mixtures are or may be present in the air in quantities sufficient to produce explosive or ignitable mix tures. Hazardous Process Piping (HPP). A process material piping or tubing conveying a liquid or gas that has a degreeof-hazard rating in health, flammability, or reactivity of Class 3 or 4, as ranked by the fire code. Health Facilities. [OSHPD 1, 1R, 2, 3, 4, 5 & 6] Build- ings specified within the statutory authority of…
211.0 – I – ¶
211.0 – I – Immediately Dangerous to Life and Health (IDLH). A concentration of airborne contaminant’s, normally expressed in parts per million (ppm) or milligrams per cubic meter (mg/m [3] ), that represents the maximum level from which one is capable of escaping within 30 minutes without escapeimpairing symptoms or irreversible health effects. This level is established by the National Institute of Occupational Safety and Health (NIOSH). » Heating System. A warm air heating plant consisting of a heat exchanger enclosed in a casing, from which the heated air is distributed through ducts to…
212.0 – J – ¶
212.0 – J – Joint, Brazed. A joint obtained by joining of metal parts with alloys that melt at temperatures exceeding 840°F (449°C) but less than the melting temperature of the parts being joined. Joint, Compression. A multipiece joint with cup-shaped threaded nuts that, when tightened, compress tapered sleeves so that they form a tight joint on the periphery of the tubing they connect. Joint, Flanged. One made by bolting together a pair of flanged ends. Joint, Flared. A metal-to-metal compression joint in which a conical spread is made on the end of a tube that is compressed by a flare nut…
213.0 – K – ¶
214.0 – L – ¶
214.0 – L – Labeled. Equipment or materials bearing a label of a listing agency (accredited conformity assessment body). See Listed (Third Party Certified). [HCD 1 & HCD 2] “Labeled” means equipment or materials to which has been attached a label, symbol or other identifying mark of an organization, approved by the Department, that maintains a periodic inspection program of production of labeled products, instal- lations, equipment, or materials and by whose labeling the manufacturer indicates compliance with appropriate stan- dards or performance in a specified manner. LEL (Lower Explosive…
215.0 – M – ¶
215.0 – M – Machinery. The refrigeration equipment forming a part of the refrigeration system, including, but not limited to, the following: compressors, condensers, liquid receivers, evaporators, and connecting piping. Machinery Room. [SFM] Machinery Room is a room in which a refrigeration system is permanently installed and operated but not including evaporators located in a cold stor- age room, refrigerator box, air-cooled space or other enclosed space. Closets solely contained within, and opening only into, a room shall not be considered machinery rooms, but shall be considered a part of…
216.0 – N – ¶
216.0 – N – Natural Ventilation. Ventilation provided by thermal, wind, or diffusion effects through doors, windows, or other intentional openings in the building. [ASHRAE 62.1:3] Noncombustible Material. As applied to building construction material, means a material that in the form in which it is used is either one of the following: (1) A material that, in the form in which it is used and under the conditions anticipated, will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat. Materials that are reported as passing ASTM E136 are considered…
217.0 – O – ¶
217.0 – O – Occupancy. The purpose for which a building or part thereof is used or intended to be used. Occupancy, Nontransient. Occupancy of a dwelling unit or sleeping unit for more than 30 days. [ASHRAE 62.1:3] Occupancy Classification. Classifications are defined in the building code. [HCD 1, HCD 2 & SFM] Whenever the term “Building Code” is used in this code, it shall mean the California Building Code, Title 24, Part 2. Occupational Exposure Limit (OEL). The timeweighted average (TWA) concentration for a normal 8-hour workday and a 40-hour workweek to which nearly all workers can be…
218.0 – P – ¶
218.0 – P – PE. Polyethylene. PE-AL-PE. Polyethylene-aluminum-polyethylene. PE-RT. Polyethylene of raised temperature. PEL (Permissible Exposure Limit). The time-weighted average concentration [set by the U.S. Occupational Safety and Health Administration (OSHA)] for a normal 8-hour workday and a 40-hour workweek to which nearly all workers can be repeatedly exposed without adverse effect. Chemical manufacturers publish similar recommendations [e.g., acceptable exposure level (AEL), industrial exposure limit (IEL), or occupational exposure limit (OEL), depending on the company], generally for…
219.0 – Q – ¶
219.0 – Q – Qualified. A competent and capable person or company that has met the requirements and training for a given field acceptable to the Authority Having Jurisdiction. Quick-Disconnect Device, Fuel Gas. A hand-operated device that provides a means for connecting and disconnecting an appliance or an appliance connector to a gas supply and that is equipped with an automatic means to shut off the gas supply when the device is disconnected. [NFPA 54:3.3.27.3]
220.0 – R – ¶
220.0 – R – Radiant Room Heater. A room heater designed to transfer heat primarily by direct radiation. [NFPA 211:3.3.88.2.2] Receiver, Liquid. A vessel permanently connected to a refrigeration system by inlet and outlet pipes for storage of liquid. Recirculating Systems. Systems for control of smoke or grease-laden vapors from commercial cooking equipment that do not exhaust to the outside. [NFPA 96:3.3.41] Reclaimed Refrigerants. Refrigerants reprocessed to the same specifications as new refrigerants by any means, including distillation. Such refrigerants have been chemically analyzed to…
221.0 – S – ¶
221.0 – S – Seam, Welded. See Joint, Welded. Secondary Filtration. Fume incinerators, thermal recovery units, air pollution control devices or other filtration media installed in ducts or hoods located in the path of travel of exhaust products after the initial filtration. Self-Contained. Having all essential working parts, except energy and control connections, so contained in a case or framework that they do not depend on appliances or fastenings outside of the machine. Service Corridor. A fully enclosed passage used for transporting hazardous production materials and purposes other than…
222.0 – T – ¶
222.0 – T – Termination, Duct. The final or intended end portion of a duct system that is designed and functions to fulfill the obligations of the system in a satisfactory manner. [NFPA 96:3.3.19] Testing Agency. [HCD 1 & HCD 2] See “Approved Test- ing Agency.” Thermal Highway. A collection one or more GeoMicroDistricts that acts as an energy transport system and supplies or accepts energy from multiple GeoMicroDistricts, individual buildings, or other sources. Also known as convective circulation circuit. Thermal Recovery Unit. A device or series of devices whose purpose is to reclaim only…
223.0 – U – ¶
223.0 – U – UMC. [HCD 1, HCD 2, OSHPD 1, 1R, 2, 3, 4, 5 & 6] The most recent edition of Uniform Mechanical Code published by the International Association of Plumbing and Mechanical Officials. Unconditioned Space. An area, room, or space not being heated or cooled by any equipment. Unit Heater. A heating appliance designed for nonresidential space heating and equipped with an integral means for circulation of air. 46 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. DEFINITIONS Vented Appliance…
225.0 – W – ¶
225.0 – W – Wall Heater. See Vented Wall Furnace. Warm Air Furnace. An environmental heating appliance designed or arranged to discharge heated air through any duct or ducts. This definition shall not include a unit heater. » » » Unusually Tight Construction. Construction where: (1) Walls and ceilings exposed to the outdoors have a continuous water vapor retarder with a rating of 1 perm or less with openings gasketed or sealed. (2) Weatherstripping is on openable windows and doors. (3) Caulking or sealants are applied to areas such as joints around window and door frames, between sole plates…
224.0 – V – ¶
224.0 – V – Vacuum. A pressure less than that exerted by the atmosphere. Valve, Pressure-Relief. A pressure-actuated valve held closed by a spring or other means and designed to automatically relieve pressure in excess of its setting. Valve, Stop. A device in a piping system to shut off the flow of the fluid. Valve, Three-Way-Type Stop. A manually operated valve with one inlet that alternately can stop flow to either of two outlets. Valves, Companion or Block. Pairs of mating stop valves valving off sections of refrigeration systems and arranged so that these sections may be joined before…
226.0 – X – ¶
227.0 – Y – ¶
228.0 – Z – ¶
228.0 – Z – Zeotropic. Blends comprising multiple components of different volatilities that, when used in refrigeration cycles, change volumetric composition and saturation temperatures as they evaporate (boil) or condense at constant pressure. [ASHRAE 34:3] Zone. [OSHPD 1, 2, 3, 4 & 5] A space or group of spaces within a building for which the heating, or cooling require- ments are sufficiently similar that desired conditions can be maintained throughout by a single controlling device. 48 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or…
301.0 General. ¶
301.1 Applicability. ¶
301.1 Applicability. This chapter covers general requirements for heating, ventilating, air-conditioning, refrigeration, miscellaneous heat-producing, and energy-utilizing equipment or appliances. Such equipment or appliances shall comply with the requirements of this code.
301.2 Approval. Equipment or appliance shall be approved ¶
301.2 Approval. Equipment or appliance shall be approved by the Authority Having Jurisdiction for safe use or comply with applicable nationally recognized standards as evidenced by the listing and label of an approved agency. A list of accepted standards is included in Chapter 18. Defective materials or parts shall be replaced in such a manner as not to invalidate an approval.
301.3 Design of Equipment. The installer or contractor ¶
301.3 Design of Equipment. The installer or contractor shall furnish satisfactory evidence that the appliance is constructed in accordance with the requirements of this code. The permanently attached label of an approved agency shall be permitted to be accepted as such evidence.
301.4 Electrical Connections. For equipment regulated ¶
301.4 Electrical Connections. For equipment regulated by this code: (1) Equipment requiring electrical connections of more than 50 volts shall have a positive means of disconnect adjacent to and in sight from the equipment served. Exception: Other power disconnect means shall be acceptable where in accordance with the California Elec- trical Code . (2) A 120 volt receptacle shall be located within 25 feet (7620 mm) of the equipment for service and maintenance purposes. The receptacle outlet shall be on the supply side of the disconnect switch. The receptacle need not be located on the same…
301.5 Oil-Burning Appliances. The tank, piping, and ¶
301.5 Oil-Burning Appliances. The tank, piping, and valves for appliances burning oil shall be installed in accordance with the requirements of NFPA 31.
301.6 Personnel Protection. ¶
301.6 Personnel Protection. A metal guard shall be provided around exposed flywheels, fans, pulleys, belts, and moving machinery that are portions of a heating, ventilating, or refrigerating system.
301.7 OSHPD 1R. [OSHPD 1R] For OSHPD 1R, refer to ¶
301.7 OSHPD 1R. [OSHPD 1R] For OSHPD 1R, refer to Section 309 of California Existing Building Code for general requirements.
302.0 Materials – Standards and Alternates. ¶
302.0 Materials – Standards and Alternates.
302.1 Minimum Standards. Listed pipe, pipe fittings, ¶
302.1 Minimum Standards. Listed pipe, pipe fittings, appliances, appurtenances, equipment, materials, and devices used in a mechanical system shall be listed (third-party certified) by a listing agency (accredited conformity assessment body) as complying with the approved applicable recognized standards referenced in this code, and shall be free from defects. Unless otherwise provided for in this code, materials, appurtenances, or devices used or entering into the construction of mechanical systems, or parts thereof, shall be submitted to the Authority Having Jurisdiction for approval prior…
302.2 Alternate Materials and Methods of Construc- ¶
302.2 Alternate Materials and Methods of Construc- tion Equivalency. Nothing in this code is intended to pre ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GENERAL REGULATIONS vent the use of systems, methods, or devices of equivalent or superior quality, strength, fire resistance, effectiveness, durability, and safety over those prescribed by this code. Technical documentation shall be submitted to the Authority Having Jurisdiction to demonstrate equivalency. The Authority Having Jurisdiction shall have the authority to…
302.3 Alternative Engineered Design. An alternative ¶
302.3 Alternative Engineered Design. An alternative engineered design shall comply with the intent of the provisions of this code and shall provide an equivalent level of quality, strength, effectiveness, fire resistance, durability, and safety. Material, equipment, or components shall be designed and installed in accordance with the manufacturer’s installa tion instructions. 302.3.1 Permit Application. The registered design professional shall indicate on the design documents that the mechanical system, or parts thereof, is an alternative engineered design so that it is noted on the…
303.0 Installation. ¶
303.1 Listed Appliances. The installation of equipment ¶
303.1 Listed Appliances. The installation of equipment and appliances regulated by this code shall be in accordance with the conditions of the listing, the manufacturer’s installation instructions and this code. The manufacturer’s instal lation and operating instructions shall be attached to the appliance. Clearances of listed equipment and appliances from combustible materials shall be as specified in the listing or on the rating plate.
303.2 Closet or Alcove Installations. [Not adopted ¶
303.2 Closet or Alcove Installations. [Not adopted for OSHPD 1, 1R, 2, 3, 4 & 5] Central heating furnaces and boilers installed in closets or alcoves shall be listed for such installation. Central heating furnaces not listed for closet or alcove installation shall be installed in a room or space having a volume not less than 12 times the total volume of the furnace. Central heating boilers not listed for closet or alcove installation shall be installed in a room or space having a volume 16 times the volume of the boiler. Where the ceiling height of the room or space exceeds 8 feet (2438 mm),…
303.3 Unlisted Appliances. ¶
303.3 Unlisted Appliances. Except as otherwise permitted in this code, unlisted equipment and appliances shall be approved by the Authority Having Jurisdiction prior to being installed. Unlisted equipment and appliances shall be installed in accordance with the manufacturer’s installation instruc tions and with clearances from combustible materials in accordance with Section 303.10 or Section 303.10.1.
303.4 Anchorage of Appliances. Appliances designed to ¶
303.4 Anchorage of Appliances. Appliances designed to be fixed in position shall be securely fastened in place in 52 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GENERAL REGULATIONS accordance with the manufacturer’s installation instructions. Supports for appliances shall be designed and constructed to sustain vertical and horizontal loads within the stress limita tions specified in the building code.
303.5 Restraining Device. Movement of appliances with ¶
303.5 Restraining Device. Movement of appliances with casters shall be limited by a restraining device installed in accordance with the connector and appliance manufacturer’s installation instructions. [NFPA 54:9.6.1.4]
303.6 Identification of Equipment. Where more than one ¶
303.6 Identification of Equipment. Where more than one heating, cooling, ventilating, or refrigerating system is installed on the roof of a building or within a building, it shall be permanently identified as to the area or space served by the equipment.
303.7 Liquefied Petroleum Gas (LP-Gas) Facilities. ¶
303.7 Liquefied Petroleum Gas (LP-Gas) Facilities. Containers, container valves regulating equipment, and appurtenances for the storage and supply of liquefied petroleum gas (LP-Gas) shall be installed in accordance with NFPA 58 and the California Fire Code . 303.7.1 Liquefied Petroleum Gas (LP-Gas) Appli- ances. [HCD 1 & HCD 2] Liquefied petroleum gas- burning appliances shall not be installed in a pit, basement, or similar location where heavier-than-air gas might collect. Appliances so fueled shall not be installed in an above-grade under-floor space or basement unless such location is…
303.8 Appliances on Roofs. Appliances on roofs shall be ¶
303.8 Appliances on Roofs. Appliances on roofs shall be designed or enclosed so as to withstand climatic conditions in the area in which they are installed. Where enclosures are provided, each enclosure shall permit easy entry and movement, shall be of reasonable height, and shall have at least a 30 inch (762 mm) clearance between the entire service access panel(s) of the appliance and the wall of the enclosure. [NFPA 54:9.4.1.1] 303.8.1 Load Capacity. Roofs on which appliances are to be installed shall be capable of supporting the additional load or shall be reinforced to support the…
303.9 Avoiding Strain on Gas Piping. Appliances shall ¶
303.9 Avoiding Strain on Gas Piping. Appliances shall be supported and connected to the piping so as not to exert undue strain on the connections. [NFPA 54:9.1.16]
303.10 Clearance to Combustible Materials. ¶
303.10 Clearance to Combustible Materials. Appliances and their vent connectors shall be installed with clearances from combustible material so their operation does not create a hazard to persons or property. Minimum clearances between combustible walls and the back and sides of various conventional types of appliances and their vent connectors are specified in Chapter 8 and Chapter 9, or NFPA 211. [NFPA 54:9.2.2] Where not provided in this code, listed and unlisted equipment or appliances shall be installed to maintain the required clearances for servicing and to combustible construction in…
303.11 Installation in Commercial Garages. ¶
303.11 Installation in Commercial Garages. Appliances installed in commercial garages shall be in accordance with Section 303.11.1 through Section 303.11.2. 303.11.1 Parking Structures. Appliances installed in enclosed, basement, and underground parking structures shall be installed in accordance with NFPA 88A. [NFPA 54:9.1.11.1] 303.11.2 Repair Garages. Appliances installed in repair garages shall be installed in accordance with NFPA 30A. [NFPA 54:9.1.11.2]
303.12 Installation in Aircraft Hangars. ¶
303.12 Installation in Aircraft Hangars. Heaters in aircraft hangars shall be installed in accordance with NFPA 409. [NFPA 54:9.1.12]
304.0 Accessibility for Service. ¶
304.1 General. All appliances shall be located with respect ¶
304.1 General. All appliances shall be located with respect to building construction and other equipment so as to permit access for repair or replacement of the appliance. Clearance shall be maintained to permit removal of the appliance; cleaning of heating surfaces; the replacement of filters, blowers, motors, burners, controls, and vent connections; the lubrication of moving parts where necessary; the adjustment and cleaning of burners and pilots; and the proper functioning of explosion vents, if provided. For attic installation, the passageway and servicing area adjacent to the appliance…
304.2 Sloped Roof. Where equipment or appliances that ¶
304.2 Sloped Roof. Where equipment or appliances that require service are installed on a roof having a slope of 4 units vertical in 12 units horizontal (33 percent slope) or more, a level platform of not less than 30 inches by 30 inches (762 mm by 762 mm) shall be provided at the service side of the equipment or appliance.
304.3 Access to Appliances on Roofs. Appliances ¶
304.3 Access to Appliances on Roofs. Appliances located on roofs or other elevated locations shall be accessible. [NFPA 54:9.4.3.1] 304.3.1 Access from the Inside. Buildings of more than 15 feet (4572 mm) in height shall have an inside means of access to the roof unless other means acceptable to the Authority Having Jurisdiction are used. [NFPA 54:9.4.3.2] 304.3.1.1 Access Type. The inside means of access shall be a permanent or foldaway inside stairway or ladder, terminating in an enclosure, scuttle, or trapdoor. Such scuttles or trapdoors shall be at least 22 inches by 24 inches (559 mm by…
304.4 Appliances in Attics and Under-Floor Spaces. ¶
304.4 Appliances in Attics and Under-Floor Spaces. An attic or under-floor space in which an appliance is installed shall be accessible through an opening and passageway larger than the largest component of the appliance, and not less than 22 inches by 30 inches (559 mm by 762 mm). {NFPA 54:9.5.1} 304.4.1 Length of Passageway. Where the height of the passageway is less than 6 feet (1829 mm), the distance from the passageway access to the appliance shall not exceed 20 feet (6096 mm) measured along the centerline of the passageway. [NFPA 54:9.5.1.1] Where the height of the passageway is 6 feet…
305.0 Location. ¶
305.1 Installation in Residential Garages. Appliances ¶
305.1 Installation in Residential Garages. Appliances in residential garages and in adjacent spaces that open to the garage and are not part of the living space of a dwelling unit shall be installed so that all heating elements, switches, burners, and burner-ignition devices are located not less than 18 inches (457 mm) above the floor. Exception: Listed flammable vapor ignition resistant (FVIR) appliances. {NFPA 54:9.1.10.1} 305.1.1 Physical Damage. Appliances installed in garages, warehouses, or other areas subject to mechanical damage shall be guarded against such damage by being installed…
305.2 Pit Location. Where excavation is necessary to install ¶
305.2 Pit Location. Where excavation is necessary to install an appliance, the depth shall extend not less than 6 inches (152 mm) below and 12 inches (305 mm) on all sides of the appliance, except on the service side, which shall have 30 inches (762 mm). Where the depth of the excavation for either the appliance or passageway exceeds 12 inches (305 mm), walls shall be lined with concrete or masonry 4 inches (102 mm) above the adjoining ground level. Exception: [HCD 1 & HCD 2] Liquefied petroleum gas (LP-Gas) appliances as described in Section 303.7.1.
305.3 Flood Hazard Areas. For buildings located in flood ¶
305.3 Flood Hazard Areas. For buildings located in flood hazard areas, heating, ventilating, air-conditioning, refrigeration, miscellaneous heat-producing, and energy-utilizing equipment and appliances shall be elevated at or above the elevation in accordance with the building code for utilities and attendant equipment or the elevation of the lowest floor, whichever is higher. Exception: Equipment and appliances shall be permitted to be located below the elevation in accordance with the build ing code for utilities and attendant equipment or the elevation of the lowest floor, whichever is…
305.4 Elevator Shaft. Unless required for the functionality ¶
305.4 Elevator Shaft. Unless required for the functionality and safety of the elevator system, mechanical systems shall not be located in an elevator shaft.
305.5 Drainage Pan. Where a water heater is located in an ¶
305.5 Drainage Pan. Where a water heater is located in an attic, in or on an attic ceiling assembly, floor-ceiling assembly, floor-subfloor assembly or where damage results from a leaking water heater, a watertight pan of corrosion-resistant materials shall be installed beneath the water heater in accordance with the following: (1) The drainage pan shall be provided with not less than [3] ⁄ 4 of an inch (20 mm) diameter drain to an approved location. The terminating end of the drainpipe shall be readily visible. (2) The drainage pan shall be not less than 1 [1] ⁄ 2 inches (38 mm) in depth.…
305.6 Outdoor Locations. Appliances installed in outdoor ¶
305.6 Outdoor Locations. Appliances installed in outdoor locations shall be in accordance with the following: (1) Listed for outdoor installation. (2) Provided with approved protection from the outdoor elements that can affect the operation, durability, or safety of such appliances and in accordance with the manufacturer’s installation instructions. (3) Outdoor cooking appliances shall comply with Section 922.0.
306.0 Automatic Control Devices. ¶
306.1 General. Heating appliances shall be equipped with ¶
306.1 General. Heating appliances shall be equipped with a listed device or devices that will shut off the fuel supply to the main burner or burners in the event of pilot or ignition failure. Liquefied petroleum gas-air-burning heating appli ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GENERAL REGULATIONS ances shall be equipped with a listed automatic device or devices that will shut off the flow of gas to the pilot in the event of ignition failure. Exception: The listed shutoff devices shall not be required on range or…
306.2 Building Automation Systems. [OSHPD 1] ¶
306.2 Building Automation Systems. [OSHPD 1] Building automation systems shall provide for localized con- trol in the event of network failure. This capability shall be specified in the construction documentation.
307.0 Labeling. ¶
307.1 Fuel-Burning Appliances. Fuel-burning heating ¶
307.1 Fuel-Burning Appliances. Fuel-burning heating appliances shall bear a permanent and legible factory-applied nameplate on which shall appear: (1) The name or trademark of the manufacturer. (2) The approved fuel input rating of the appliance, expressed in Btu/h (kW). (3) The model number or equivalent. (4) The serial number. (5) Instructions for the lighting, operation, and shutdown of the appliance. (6) The type of fuel approved for use with the appliance. (7) The symbol of an approved agency certifying compliance of the equipment with recognized standards. (8) Required clearances from…
307.2 Electric Heating Appliances. Electric heating ¶
307.2 Electric Heating Appliances. Electric heating appliances shall bear a permanent and legible factory-applied nameplate on which shall appear: (1) The name or trademark of the manufacturer. (2) The model number or equivalent. (3) The serial number. (4) The electrical rating in volts, amperes (or watts), and, for other than single phase, the number of phases. (5) The output rating in Btu/h (kW). (6) The electrical rating in volts, amperes, or watts of each field-replaceable electrical component. (7) The symbol of an approved agency certifying compliance of equipment with recognized…
307.3 Heat Pump and Electric Cooling Appliances. ¶
307.3 Heat Pump and Electric Cooling Appliances. Heat pumps and electric cooling appliances shall bear a permanent and legible factory-applied nameplate on which shall appear: (1) The name or trademark of the manufacturer. (2) The model number or equivalent. (3) The serial number. (4) The amount of refrigerant. (5) The refrigerant designation. (6) The factory test pressures or pressures applied. (7) The electrical rating in volts, amperes, and, for other than single phase, the number of phases. (8) The output rating in Btu/h (kW). (9) The electrical rating in volts, amperes, or watts of each…
307.4 Absorption Units. ¶
307.4 Absorption Units. Absorption units shall bear a permanent and legible factory-applied nameplate on which shall appear: (1) The name or trademark of the manufacturer. (2) The model number or equivalent. (3) The serial number. (4) The amount of refrigerant. (5) The refrigerant designation. (6) Hourly rating in Btu/h (kW). (7) The type of fuel approved for use with the unit. (8) Cooling capacity Btu/h (kW). (9) Required clearances from combustible surfaces on which or adjacent to which it is permitted to be mounted. (10)The symbol of an approved agency certifying compliance of the…
308.0 Improper Location. ¶
308.1 General. Piping or equipment shall not be so located as ¶
308.1 General. Piping or equipment shall not be so located as to interfere with the normal use thereof or with the normal operation and use of windows, doors, or other required facilities.
309.0 Workmanship. ¶
309.1 Engineering Practices. Design, construction, and ¶
309.1 Engineering Practices. Design, construction, and workmanship shall comply with accepted engineering practices and shall be of such character as to secure the results sought to be obtained by this code.
309.2 Concealing Imperfections. It shall be unlawful to ¶
309.2 Concealing Imperfections. It shall be unlawful to conceal cracks, holes, or other imperfections in materials by welding, brazing, or soldering, by using therein or thereon paint, wax, tar, solvent cement, other leak-sealing or repair agent.
309.3 Installation Practices. Mechanical systems shall ¶
309.3 Installation Practices. Mechanical systems shall be installed in a manner that is in accordance with this code, applicable standards, and the manufacturer’s installation instructions. All mechanical systems shall be in accordance with construction documents approved by the Authority Having Jurisdiction.
310.0 Condensate Wastes and Control. ¶
310.0 Condensate Wastes and Control.
310.1 Condensate Disposal. ¶
310.1 Condensate Disposal. Condensate from air washers, air-cooling coils, condensing appliances, and the overflow from evaporative coolers and similar water-supplied equipment or similar air-conditioning equipment shall be collected and discharged to an approved plumbing fixture or disposal area. Where discharged into the drainage system, equipment shall drain by means of an indirect waste pipe. The waste pipe shall have a slope of not less than [1] ⁄ 8 inch per foot (10.4 mm/m) or 1 percent slope and shall be of approved corrosion-resistant material not smaller than the outlet size in…
310.2 Condensate Control. Where any equipment or ¶
310.2 Condensate Control. Where any equipment or appliance is installed in a space where damage is capable of resulting from condensate overflow, a drain line shall be provided and shall be drained in accordance with Section 310.1. An additional protection method for condensate overflow shall be provided in accordance with one of the following: (1) A water level detecting device that will shut off the equipment or appliance in the event the primary drain is EQUIPMENT CAPACITY IN<brTONS OF REFRIGERATIONMINIMUM CONDENSATE<brPIPE DIAMETER<br(inches) ------ <br<brUp to 203⁄4 <br<br21 – 401…
310.3 Condensate Waste Pipe Material and Sizing. ¶
310.3 Condensate Waste Pipe Material and Sizing. Condensate waste pipes from air-cooling coils shall be sized in accordance with the equipment capacity as specified in Table 310.3. The material of the piping shall comply with the pressure and temperature rating of the appliance or equipment, and shall be approved for use with the liquid being discharged. TABLE 310.3 MINIMUM CONDENSATE PIPE SIZE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GENERAL REGULATIONS Condensate drain sizing for other slopes or other conditions…
310.4 Appliance Condensate Drains. Condensate drain ¶
310.4 Appliance Condensate Drains. Condensate drain lines from individual condensing appliances shall be sized as required by the manufacturer’s instructions. Condensate drain lines serving more than one appliance connecting to a common indirect waste pipe shall have the connections to the indirect waste pipe protected by a sanitary waste valve complying with ASME A112.18.8, condensate trap complying with IAPMO IGC 196, or trap with a trap primer.
310.5 Point of Discharge. Air-conditioning condensate ¶
310.5 Point of Discharge. Air-conditioning condensate waste pipes shall connect indirectly to the drainage system through an air gap or air break to trapped and vented receptors, dry wells, mop sinks, leach pits, or the tailpiece of plumbing fixtures. An individual condensate drain shall be trapped in accordance with the appliance manufacturer’s instructions or in accordance with Section 310.4.
310.6 Condensate Waste from Air-Conditioning ¶
310.6 Condensate Waste from Air-Conditioning Coils. Where the condensate waste from air-conditioning coils discharges by direct connection to a lavatory tailpiece or to an approved accessible inlet on a bathtub overflow, the connection shall be located in the area controlled by the same person controlling the air-conditioned space.
310.7 Female Plastic Connections. Female plastic ¶
310.7 Female Plastic Connections. Female plastic screwed fittings shall be used with plastic male fittings and plastic male threads. Female plastic threaded connections shall not be allowed to be used when threaded onto a male metallic connection.
311.0 Heating or Cooling Air System. ¶
311.0 Heating or Cooling Air System.
311.1 Source. ¶
311.1 Source. A heating or cooling air system shall be provided with return air, outside air, or both. A heating or cooling air system regulated by this code and designed to replace required ventilation shall be arranged to discharge into a conditioned space not less than the amount of outside air specified in Chapter 4.
311.2 Air Filters. Air filters shall be installed in a heating, ¶
311.2 Air Filters. Air filters shall be installed in a heating, cooling, or makeup air system. Media-type air filters shall comply with UL 900. Electrostatic and high efficiency particulate filters shall comply with Section 935.0. Exceptions: (1) Air filters used in systems serving single guest rooms or dwelling units shall not be required to be listed. (2) Air filters used in listed appliances and in accordance with the manufacturer’s instructions. 311.2.1 Minimum Filtration. In mechanically ventilated buildings, occupied areas of the building shall be provided with air filtration media for…
311.3 Prohibited Sources. ¶
311.3 Prohibited Sources. Outside or return air for a heating or cooling air system shall not be taken from the following locations: (1) Less than the separation distances to vents required by Section 802.6.1 and Section 802.8. (2) Less than the separation distances required by Section 402.4. (3) A hazardous or insanitary location, or a refrigeration machinery room as defined in this code. (4) An area, the volume of which is less than 25 percent of the entire volume served by such system, unless there is a permanent opening to an area the volume of which is equal to 25 percent of the entire…
311.4 Return-Air Limitations. Return air from one ¶
311.4 Return-Air Limitations. Return air from one dwelling unit shall not discharge into another dwelling unit through the heating or cooling air system. 58 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GENERAL REGULATIONS
311.5 California Energy Code Requirements for Res- ¶
311.5 California Energy Code Requirements for Res- idential Air Filtration. In mechanically ventilated residen- tial buildings, air filters shall be provided to clean outdoor air and return air prior to its delivery to occupied spaces where specified in California Energy Code Sections 150.0(m)12 and 160.2(b). The air filters shall comply with California Energy Code requirements for labeling, ventilation system design and installation, air filter efficacy, and air filter pressure drop.
312.0 Plumbing Connections. ¶
312.1 General. ¶
312.1 General. Water supply, sanitary drainage, and backflow protection shall be in accordance with the California Plumbing Code .
313.0 Hangers, Supports, and Anchors. ¶
313.0 Hangers, Supports, and Anchors.
313.1 General. ¶
313.1 General. Piping, tubing, appliances, and appurtenances shall be supported in accordance with this code, the manufacturer’s installation instructions, and in accordance with the Authority Having Jurisdiction. Seismic restraints shall be in accordance with the building code.
313.2 Material. Hangers, supports, and anchors shall be of ¶
313.2 Material. Hangers, supports, and anchors shall be of sufficient strength to support the weight of the pipe or tubing and its contents. Piping or tubing shall be isolated from incompatible materials.
313.3 Suspended Piping. Suspended piping or tubing ¶
313.3 Suspended Piping. Suspended piping or tubing shall be supported at intervals not to exceed those shown in Table 313.3.
313.4 Alignment. Piping or tubing shall be supported in ¶
313.4 Alignment. Piping or tubing shall be supported in such a manner as to maintain its alignment and prevent sagging.
313.5 Underground Installation. Piping or tubing in the ¶
313.5 Underground Installation. Piping or tubing in the ground shall be laid on a firm bed for its entire length; where other support is otherwise provided, it shall be approved in accordance with Section 302.0.
313.6 Hanger Rod Sizes. Hanger rod sizes shall be not ¶
313.6 Hanger Rod Sizes. Hanger rod sizes shall be not smaller than those shown in Table 313.6. TABLE 313.6 HANGER ROD SIZES PIPE AND TUBE SIZE<br(inches)ROD SIZES<br(inches) ------ <br1⁄2 - 43⁄8 <br5 - 81⁄2 <br10 - 125⁄8 For SI units: 1 inch = 25.4 mm
313.7 Gas Piping. Gas piping shall be supported by metal ¶
313.7 Gas Piping. Gas piping shall be supported by metal straps or hooks at intervals not to exceed those shown in Table 1310.3.5.1.
314.0 Balancing. ¶
314.1 General. Heating, ventilating, and air-conditioning ¶
314.1 General. Heating, ventilating, and air-conditioning systems (including hydronic systems) shall be balanced in accordance with one of the following methods: TABLE 313.6 HANGER ROD SIZES (1) AABC National Standards for Total System Balance (2) ACCA Manual B (3) ASHRAE 111 (4) NEBB Procedural Standards for Testing Adjusting Balancing of Environmental Systems (5) SMACNA HVAC Systems Testing, Adjusting, and Balancing
315.0 Louvers in Hurricane Prone Regions. ¶
315.0 Louvers in Hurricane Prone Regions.
315.1 General. Louvers located in areas within hurricane ¶
315.1 General. Louvers located in areas within hurricane prone regions that are within 1 mile (2 km) of the coastal mean high water line where the basic wind speed is 110 miles per hour (mi/h) (49.2 m/s) or more; or portions of hurricane-prone regions where the basic wind speed is 120 mi/h (53.6 m/s) or more; or Hawaii, shall be tested in accordance with Section 315.1.1 and Section 315.1.2. 315.1.1 Testing. Louvers that protect air intake or exhaust openings shall be tested in accordance with AMCA 550 for resistance to wind-driven rain. 315.1.2 Impact Resistance Test. Upon request by the…
316.0 Protection of Piping, Tubing, Materials, and ¶
316.0 Protection of Piping, Tubing, Materials, and Structures.
316.1 General. Piping or tubing passing under or through ¶
316.1 General. Piping or tubing passing under or through walls shall be protected from breakage. Piping passing through or under cinders or other corrosive materials shall be protected from external corrosion in an approved manner. Approved provisions shall be made for expansion of hot water piping. Voids around piping or tubing passing through concrete floors on the ground shall be sealed.
316.2 Installation. Piping or tubing shall be installed so that ¶
316.2 Installation. Piping or tubing shall be installed so that the piping, tubing, or connections will not be subject to undue strains or stresses, and provisions shall be made for expansion, contraction, and structural settlement. No piping or tubing, unless designed and listed for such use, shall be directly embedded in concrete or masonry. No structural member shall be seriously weakened or impaired by cutting, notching, or otherwise as defined in the California Building Code or California Residential Code .
316.3 Corrosion, Erosion, and Mechanical Damage. ¶
316.3 Corrosion, Erosion, and Mechanical Damage. Piping or tubing subject to corrosion, erosion, or mechanical damage shall be protected in an approved manner.
316.4 Protectively Coated Pipe. Protectively coated pipe ¶
316.4 Protectively Coated Pipe. Protectively coated pipe or tubing shall be inspected and tested, and a visible void, damage, or imperfection to the pipe coating shall be repaired in an approved manner.
316.5 Fire-Resistant Construction. Piping, tubing, and ¶
316.5 Fire-Resistant Construction. Piping, tubing, and duct system penetrations of fire-resistance-rated walls, parti For SI units: 1 inch = 25.4 mm ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GENERAL REGULATIONS tions, floors, floor/ceiling assemblies, roof/ceiling assemblies, or shaft enclosures shall be protected in accordance with the requirements of the California Building Code or California Residential Code .
316.6 Steel Nail Plates. Plastic piping or tubing, copper ¶
316.6 Steel Nail Plates. Plastic piping or tubing, copper or copper alloy piping or tubing, and ducts penetrating framing members to within 1 inch (25.4 mm) of the exposed framing shall be protected by steel nail plates not less than No. 18 gauge (0.0478 inches) (1.2141 mm) in thickness. The steel nail plate shall extend along the framing member not less than 1 [1] ⁄ 2 inches (38 mm) beyond the outside diameter of the pipe or tubing. Fuel gas piping shall be protected in accordance with Section 1310.4.3.
316.7 Sleeves. Sleeves shall be provided to protect piping ¶
316.7 Sleeves. Sleeves shall be provided to protect piping through concrete and masonry walls and concrete floors. Exception: Sleeves shall not be required where openings are drilled or bored. 316.7.1 Building Loads. Piping or tubing through concrete or masonry walls shall not be subject to a load from building construction. 316.7.2 Exterior Walls. In exterior walls, annular space between sleeves and pipes or tubing shall be sealed and made watertight, as approved by the Authority Having Jurisdiction. A penetration through fire-resistive construction shall be in accordance with Section 316.5.
316.8 Firewalls. A pipe sleeve through a firewall shall have ¶
316.8 Firewalls. A pipe sleeve through a firewall shall have the space around the pipe or tubing completely sealed with an approved fire-resistive material in accordance with other codes.
316.9 Structural Members. ¶
316.9 Structural Members. A structural member weakened or impaired by cutting, notching, or otherwise shall be reinforced, repaired, or replaced so as to be left in a safe structural condition in accordance with the requirements of the California Building Code or California Residential Code .
316.10 Rodentproofing. ¶
316.10 Rodentproofing. Mechanical system shall be constructed in such a manner as to restrict rodents or vermin from entering a building by following the ductwork from the outside into the building.
316.11 Metal Collars. In or on buildings where openings ¶
316.11 Metal Collars. In or on buildings where openings have been made in walls, floors, or ceilings for the passage of ductwork or pipes, such openings shall be closed and protected by the installation of approved metal collars securely fastened to the adjoining structure.
317.0 Trenching, Excavation, and Backfill. ¶
317.0 Trenching, Excavation, and Backfill.
317.1 Trenches. Trenches deeper than the footings of a ¶
317.1 Trenches. Trenches deeper than the footings of a building or structure, and paralleling the same, shall be located not less than 45 degrees (0.79 rad) from the bottom exterior edge of the footing, or as approved in accordance with Section 302.0.
317.2 Tunneling and Driving. Tunneling and driving shall ¶
317.2 Tunneling and Driving. Tunneling and driving shall be permitted to be done in yards, courts, or driveways of a building site. Where sufficient depth is available to permit, tunnels shall be permitted to be used between open-cut trenches. Tunnels shall have a clear height of 2 feet (610 mm) above the pipe and shall be limited in length to one-half the depth of the trench, with a maximum length of 8 feet (2438 mm). Where pipes are driven, the drive pipe shall be not less than one size larger than the pipe to be laid.
317.3 Open Trenches. Excavations required to be made for ¶
317.3 Open Trenches. Excavations required to be made for the installation of a mechanical system or part thereof, within the walls of a building, shall be open trench work and shall be kept open until it has been inspected, tested, and accepted.
317.4 Excavations. ¶
317.4 Excavations. Excavations shall be completely backfilled as soon after inspection as practicable. Precaution shall be taken to ensure compactness of backfill around piping without damage to such piping. Trenches shall be backfilled in thin layers to 12 inches (305 mm) above the top of the piping with clean earth, which shall not contain stones, boulders, cinderfill, frozen earth, construction debris, or other materials that will damage or break the piping or cause corrosive action. Mechanical devices such as bulldozers, graders, etc., shall be permitted to then be used to complete…
318.0 Scope. ¶
318.1 Applicability. This part is applicable to health facil- ¶
318.1 Applicability. This part is applicable to health facil- ities regulated by OSHPD. Note: This section has no corresponding provisions in the UMC. For the scope and authority of each state agency, refer to Chapter 1.
318.2 Services/Systems and Utilities. Refer to Section ¶
318.2 Services/Systems and Utilities. Refer to Section 1224.4.1, 1225.2.1 and 1228.4.1.1 of the California Building Code.
319.0 Steam and Hot-Water Systems. ¶
319.0 Steam and Hot-Water Systems.
319.1 Requirements for Hospitals and Optional Serv- ¶
319.1 Requirements for Hospitals and Optional Serv- ices Provided in Correctional Treatment Centers. [OSHPD 1, 1R, 4 & 5] 319.1.1 Boilers shall have the capacity, based upon the rest ratings published by the Hydronics Institute or another acceptable national standard to supply the nor- mal operating requirements of all connected systems and equipment. 319.1.2 A minimum of two boilers shall be provided. The arrangement of boilers shall be based on the capacity and capability of a boiler or boilers to operate all sys- tems during-periods of breakdown or maintenance of any one boiler. 319.1.3…
319.2 Requirements for Skilled Nursing, Intermedi- ¶
319.2 Requirements for Skilled Nursing, Intermedi- ate Care Facilities and Basic Services Provided in Correctional Treatment Centers. [OSHPD 2 & 4] 319.2.1 Boilers, if provided, shall accommodate Section 319.1. 319.2.2 Two or more interconnected water heaters are an acceptable means to provide two sources of heat for hot water (See Section 319.1.5).
320.0 Air Conditioning and Heating Systems. ¶
320.0 Air Conditioning and Heating Systems.
320.1 Requirements for Hospitals and Optional Serv- ¶
320.1 Requirements for Hospitals and Optional Serv- ices Provided in Correctional Treatment Centers. [OSHPD 1, 1R, 4 & 5] 320.1.1 The systems shall be designed to provide the temperatures and relative humidity for sensitive areas or rooms shown in Table 4-A. When outdoor humidity and internal moisture sources are not sufficient to meet the requirements of sensitive areas or rooms in Table 4-A, humidification shall be provided by means of the health- care facility air-handling systems. Temperature shall be individually controlled for each operating and delivery room. Burn unit patient rooms…
320.2 Requirements for Skilled Nursing, Intermedi- ¶
320.2 Requirements for Skilled Nursing, Intermedi- ate Care Facilities and Basic Services Provided in Correctional Treatment Centers. [OSHPD 2 & 4] 320.2.1 Systems shall accommodate the provisions of Sections 320.1.2 through 320.1.3. 320.2.2 Where air conditioning is provided, the system shall be thermostatically controlled in one or more zones.
320.3 Requirements for Outpatient Facilities and ¶
320.3 Requirements for Outpatient Facilities and Licensed Clinics. [OSHPD 3] 320.3.1 The system shall be designed to provide the tem- perature and humidities for sensitive areas for rooms shown in Table 4-A.
320.4 Telephone and Technology Equipment Centers. ¶
320.4 Telephone and Technology Equipment Centers. [OSHPD 1 & 4] Where telecommunications service entrance rooms, technology equipment centers, or technology distribu- tion rooms are provided in accordance with Section 1224.5 of the California Building Code, the following requirements shall apply: 320.4.1 Power for HVAC systems serving the room(s) shall be supplied by the Equipment Branch pursuant to the California Electrical Code. Where redundant systems are provided, only one shall be required to be supplied by the Equipment Branch. 320.4.2 Mechanical equipment or fixtures that are not…
320.5 Psychiatric Services. [OSHPD 1, 1R, 2, 4 & 5] For ¶
320.5 Psychiatric Services. [OSHPD 1, 1R, 2, 4 & 5] For projects associated with provision of psychiatric services in acute psychiatric hospitals, general acute-care hospitals, and special treatment program service units in skilled nursing facilities, psychiatric, seclusion, and holding-patient rooms shall be designed with security diffusers, grilles, and registers.
321.0 Essential Mechanical Provisions. [OSHPD 1, 2, ¶
321.0 Essential Mechanical Provisions. [OSHPD 1, 2, 3 (Surgical Clinics only) 4 & 5] During periods of power outages essential electrical power shall be provided for the following equipment:
321.1 (Does not apply to OSHPD 3 surgical clinic.) All heat- ¶
321.1 (Does not apply to OSHPD 3 surgical clinic.) All heat- ing equipment and fans necessary to maintain a minimum temperature of 60°F (15.6°) in patient areas which are not specified in Section 322.0.
321.2 All heating equipment and fans necessary to maintain ¶
321.2 All heating equipment and fans necessary to maintain the minimum temperatures listed in Table 4-A for sensitive areas specified in Section 322.0.
321.3 Cooling equipment necessary to maintain temperature ¶
321.3 Cooling equipment necessary to maintain temperature and humidity listed in Table 4-A for a minimum of one oper- ating room and other spaces as identified in the functional program. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GENERAL REGULATIONS
321.4 Equipment necessary for humidification of the areas ¶
321.4 Equipment necessary for humidification of the areas listed in Section 322.0.
321.5 All supply, return, and exhaust fans required to maintain ¶
321.5 All supply, return, and exhaust fans required to maintain the positive and negative air balances as required in Table 4-A .
321.6 All control components, control systems and fire and ¶
321.6 All control components, control systems and fire and smoke dampers necessary for the normal operation of equip- ment required to have essential electrical power.
321.7 Alarms for airborne infection isolation rooms and pro- ¶
321.7 Alarms for airborne infection isolation rooms and pro- tective environment rooms.
322.0 Sensitive Areas or Rooms. [OSHPD 1, 2, 3 (Sur- ¶
322.0 Sensitive Areas or Rooms. [OSHPD 1, 2, 3 (Sur- gical Clinics) 4 & 5] The following are sensitive areas or rooms: (1) Operating room (2) Hybrid operating room (3) Cesarean operating room (4) Delivery room (5) Surgical Cystoscopy (6) Class 3 imaging (7) Cardiac catheterization lab (8) Trauma/cardiac room (9) Post-anesthesia care unit (10)Intensive care (11) Newborn intensive-care nursery unit (12)Newborn nursery (13)Burn unit (14)Protective Environment Room (15)Procedure room (16)Class 2 imaging (17)Gastrointestinal endoscopy procedure room
322.1 The following conditions shall be met for sensitive ¶
322.1 The following conditions shall be met for sensitive areas or rooms: (1) Thermostats and humidistats shall be either locally reset- table and of the non-locking type or remotely resettable and of the locking type. (2) Systems shall be capable of maintaining the rooms within the temperature range in Table 4-A during normal oper- ation. Lower or higher temperature shall be permitted when patients’ comfort and/or medical conditions require those conditions. (3) The humidity ranges listed in Table 4-A are the minimum and maximum limits where control is specifically needed. (4) Types of…
323.0 Mechanical Equipment Schedules. [OSHPD 1, ¶
323.0 Mechanical Equipment Schedules. [OSHPD 1, 1R, 2, 4 & 5] Mechanical equipment schedules in the con- struction documents shall clearly indicate which equipment will be powered by essential power and which equipment includes the appropriate special seismic certifications.
324.0 Diesel-Powered Emergency Generators. ¶
324.0 Diesel-Powered Emergency Generators. [OSHPD 1, 1R, 2, 3, 4 & 5] The minimum horizontal sepa- ration distance between diesel-powered emergency electrical generator exhaust outlets and operable doors, windows and intake openings shall be 30 feet (9144 mm). The minimum horizontal distance from the generator exhaust to a property line shall be 15 feet (4572 mm) or per the requirements of the Authority Having Jurisdiction, whichever is greater.
325.0 Alternate Source of Power for Safe Tempera- ¶
325.0 Alternate Source of Power for Safe Tempera- tures. [OSHPD 2] Mechanical equipment required to main- tain a safe temperature for residents shall be powered by an alternate source of power per California Electrical Code Sec- tion 517.1. The safe temperature shall be between 71°F to 81°F (21.6°C to 27.2°C). 62 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GENERAL REGULATIONS TABLE 303.10.1 REDUCTION OF CLEARANCES WITH SPECIFIED FORMS OF PROTECTION [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]…
401.0 General. ¶
401.1 Applicability. This chapter contains requirements for ¶
401.1 Applicability. This chapter contains requirements for ventilation air supply, exhaust, and makeup air requirements for occupiable spaces within a building. [OSHPD 1, 1R, 2, 3, 4 & 5] See Sections 406.0 through 419.0. [SFM] Air filters shall comply with all requirements of Part 12, Title 24, Chap- ter 12-71, SFM Standard 12-71-1. Spaces within buildings, except those within a dwelling unit in residential occupancies where occupants are nontransient, shall comply with Section 402.0 through Section 404.0. Requirements for ventilation air rate for dwelling units in residential occupancies,…
401.2 Indoor Swimming Pools. The design of ventilation ¶
401.2 Indoor Swimming Pools. The design of ventilation systems serving an indoor aquatic facility (natatorium) shall comply with the Uniform Swimming Pool, Spa and Hot Tub Code (USPSHTC).
401.3 Filters. [BSC-CG & DSA-SS] In mechanically ven- ¶
401.3 Filters. [BSC-CG & DSA-SS] In mechanically ven- tilated buildings, provide regularly occupied areas of the building with air filtration media for outside and return air that provides at least a Minimum Efficiency Reporting Value (MERV) of 13. MERV 13 filters shall be installed prior to occupancy, and recommendations for maintenance with fil- ters of the same value shall be included in the operation and maintenance manual in compliance with Chapter 5, Division 5.5 of the California Green Building Standards Code (CAL- Green). Exception: Existing mechanical equipment. 401.3.1 Labeling.…
402.0 Ventilation Air. ¶
402.1 Occupiable Spaces. Occupiable spaces listed in ¶
402.1 Occupiable Spaces. Occupiable spaces listed in Table 402.1 shall be designed to have ventilation (outdoor) air for occupants in accordance with this chapter. [DSA-SS] Ven- tilation air requirements for occupancies regulated by the California Energy Commission are found in the California Energy Code. [CEC] Ventilation air requirements for occupancies regu- lated by the California Energy Commission and found in the California Energy Code supersede those of the California Mechanical Code. [OSHPD 1, 2, 3, 4 & 5] Health care spaces shall meet the ventilation requirements found in Table 4-A.…
402.2 Natural Ventilation Procedure. [Not permitted ¶
402.2 Natural Ventilation Procedure. [Not permitted for OSHPD 1, 2, 3, 4 & 5] Natural ventilation systems shall comply with the requirements of either Section 402.2.1 through Section 402.2.1.6(A) or Section 402.2.2. Designers shall provide interior air barriers, insulation, or other means that separate naturally ventilated spaces from mechanically cooled spaces to prevent high-dew-point outdoor air from coming into contact with mechanically cooled surfaces. [ASHRAE 62.1:6.4] 402.2.1 Prescriptive Compliance Path. Any zone designed for natural ventilation shall include a mechanical ventilation…
402.3 Mechanical Ventilation. [Not permitted for ¶
402.3 Mechanical Ventilation. [Not permitted for OSHPD 1, 2, 3, 4 & 5] Where natural ventilation is not permitted by this section or the California Building Standards Code, mechanical ventilation systems shall be designed, constructed, and installed to provide a method of supply air and either return air or exhaust air, or both, as applicable. Mechan Col1TABLE 402.2.1.6(A)(2) MINIMUM OPENABLE AREAS: TWO VERTICALLY SPACED OPENINGS [ASHRAE 62.1: TABLE 6-6]Col3Col4Col5Col6Col7 --------------------- Vbz/Az ≤<br(CFM/ft2)TOTAL OPENABLE AREAS IN ZONE AS A<brPERCENTAGE OFAzTOTAL OPENABLE AREAS IN…
402.4 Outdoor Air Intakes. Ventilation system outdoor ¶
402.4 Outdoor Air Intakes. Ventilation system outdoor air intakes shall be designed in accordance with Section 402.4.1 through Section 402.4.5. [ASHRAE 62.1:5.5] 402.4.1 Location. Outdoor air intakes (including openings that are required as part of a natural ventilation system) shall be located such that the shortest distance from the intake to any specific potential outdoor contaminant source listed in Table 402.4.1 shall be equal to or greater than the following: (1) The separation distance in Table 402.4.1 or (2) The calculation methods in ASHRAE 62.1 Normative Appendix B and shall comply…
403.0 Ventilation Rates. [Not permitted for OSHPD 1, ¶
403.0 Ventilation Rates. [Not permitted for OSHPD 1, 2, 3, 4 & 5 spaces listed in Table 4-A]
403.1 General. The design outdoor air intake flow rate for ¶
403.1 General. The design outdoor air intake flow rate for a ventilation system shall be determined in accordance with Section 403.2 through Section 403.10. 72 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. VENTILATION AIR
403.2 Zone Calculations. Ventilation zone parameters ¶
403.2 Zone Calculations. Ventilation zone parameters shall be determined in accordance with Section 403.2.1 through Section 403.2.3 for ventilation zones served by the ventilation system, except that the ventilation rates from ASHRAE/ASHE 170 shall be used for the occupancy categories, as applicable. [ASHRAE 62.1:6.2.1] 403.2.1 Breathing Zone Outdoor Airflow. The outdoor airflow required in the breathing zone ( Vbz ) of the occupiable space or spaces in a ventilation zone shall be not less than the value determined in accordance with Equation 403.2.1. Vbz = Rp•Pz + Ra• Az (Equation 403.2.1)…
403.3 Single-Zone Systems. For ventilation systems ¶
403.3 Single-Zone Systems. For ventilation systems where one or more air handlers supply a mixture of outdoor air and recirculated air to only one ventilation zone, the outdoor air intake flow ( Vot ) shall be determined in accordance with Equation 403.3. [ASHRAE 62.1:6.2.2] Vot = Voz (Equation 403.3)
403.4 One Hundred Percent Outdoor Air Systems. ¶
403.4 One Hundred Percent Outdoor Air Systems. For ventilation systems where one or more air handlers supply only outdoor air to one or more ventilation zones, the outdoor air intake flow ( Vot ) shall be determined in accordance with Equation 403.4. [ASHRAE 62.1:6.2.3] Vot = ∑ all zones Voz (Equation 403.4)
403.5 Multiple-Zone Recirculating Systems. ¶
403.5 Multiple-Zone Recirculating Systems. For ventilation systems where one or more air handlers supply a mixture of outdoor air and recirculated air to more than one ventilation zone, the outdoor air intake flow ( Vot ) shall be determined in accordance with Section 403.5.1 through Section 403.5.2. [ASHRAE 62.1:6.2.4] 403.5.1 Uncorrected Outdoor Air Intake. The uncorrected outdoor air intake ( Vou ) flow shall be determined in accordance with Equation 403.5.1. [ASHRAE 62.1:6.2.4.1] (Equation 403.5.1) Vou = D ∑ all zones ( Rp•Pz ) + ∑ all zones ( Ra•Az ) 403.5.1.1 Occupant Diversity. The…
403.6 Design for Varying Operating Conditions. ¶
403.6 Design for Varying Operating Conditions. Ventilation systems shall be designed to be capable of providing not less than the minimum ventilation rates required in the breathing zone where the zones served by the system are occupied, including all full- and part-load conditions. The minimum outdoor air intake flow shall be permitted to be less than the design value at part-load conditions. [ASHRAE 62.1:6.2.5 – 6.2.5.1] 403.6.1 Short-Term Conditions. Where it is known that peak occupancy will be of short duration, ventilation will be varied or interrupted for a short period of time, or…
403.7 Exhaust Ventilation. ¶
403.7 Exhaust Ventilation. Exhaust airflow shall be provided in accordance with the requirements in Table 403.7. Exhaust makeup air shall be permitted to be a combination of outdoor air, recirculated air, and transfer air. 403.7.1 Parking Garages. Exhaust rate for parking garages shall be in accordance with Table 403.7. Exhaust rate shall not be required for enclosed parking garages having a floor area of 1000 square feet (92.9 m [2] ) or less and used for the storage of 5 or less vehicles. 403.7.2 Enclosed Parking Garages. Mechanical ventilation systems for enclosed parking garages shall…
403.8 Dynamic Reset. The system shall be permitted to be ¶
403.8 Dynamic Reset. The system shall be permitted to be designed to reset the outdoor air intake flow ( Vot ), the space or ventilation zone airflow ( Voz ) as operating conditions change, or both. [ASHRAE 62.1:6.2.6]
403.9 Air Classification and Recirculation. Air shall be ¶
403.9 Air Classification and Recirculation. Air shall be classified as shown in Table 402.1, Table 403.7, or Table 403.9, and its recirculation shall be limited in accordance with Section 403.9.1 through Section 403.9.4. {ASHRAE 62.1:5.18} Recirculated air shall not be taken from prohibited locations in accordance with Section 311.3. Air (return, transfer, or exhaust air) leaving each space or location shall be designated at an expected air-quality classification not less than that shown in Table 402.1, Table 403.7, or Table 403.9 or as approved by the Authority Having Jurisdiction. Air…
403.10 Air Balance. All mechanical ventilation systems ¶
403.10 Air Balance. All mechanical ventilation systems shall be tested, balanced, and operated to demonstrate that the installation and performance of the systems are in accordance with the design intent. All testing and balancing shall be performed by a technician certified by the Associated Air Balance Council (AABC), the National Environmental Balancing Bureau (NEBB), the Testing, Adjusting and Balancing Bureau (TABB), or other equivalent approved agencies. Exception: For single family residential, compliance with Section 403.10 shall not be required. ), Copyright © 2025 IAPMO, and may not…
404.0 Alternative Procedure for Multiple-Zone Sys- ¶
404.0 Alternative Procedure for Multiple-Zone Sys- tems Ventilation Efficiency.
404.1 System Ventilation Efficiency. ¶
404.1 System Ventilation Efficiency. The system ventilation efficiency shall equal the lowest zone ventilation efficiency among the ventilation zones served by the air handler in accordance with Equation 404.1. [ASHRAE 62.1:A1.3] This section presents an alternative procedure for calculating the system ventilation efficiency ( Ev ) for multiple zone recirculating systems that shall be used when Section 403.5.1.3 is not used. Ev = minimum ( Evz ) (Equation 404.1)
404.2 Average Outdoor Air Fraction. ¶
404.2 Average Outdoor Air Fraction. The average outdoor air fraction ( X s) for the ventilation system shall be determined in accordance with Equation 404.2. Xs =Vou / Vps (Equation 404.2) Where the uncorrected outdoor air intake ( Vou ) is determined in accordance with Section 403.5.1, and the system primary airflow ( Vps ) shall be determined at the condition analyzed. [ASHRAE 62.1:A1.1]
404.3 Zone Ventilation Efficiency. The zone ventilation ¶
404.3 Zone Ventilation Efficiency. The zone ventilation efficiency ( Evz ) shall be determined in accordance with Section 404.3.1 or Section 404.3.2. [ASHRAE 62.1:A1.2] 404.3.1 Single Supply Systems. For single supply systems, where all of the air supplied to each ventilation zone is a mixture of outdoor air and system-level recirculated air, zone ventilation efficiency ( Evz ) shall be determined in accordance with Equation 404.3.1(1). Examples of single supply systems include constant-volume reheat, single-duct VAV, single-fan dual-duct, and multizone-systems. Evz = 1+ Xs – Zpz [Equation…
405.0 Ventilation for Residential Occupancies. ¶
405.0 Ventilation for Residential Occupancies.
405.1 General. ¶
405.1 General. Rooms or occupied spaces within residential occupancies, where the occupants are nontransient, shall be designed to have mechanical ventilation and exhaust air in accordance with Section 405.2 through Section 405.5. 405.1.1 Natural Ventilation. Where approved by the Authority Having Jurisdiction, natural ventilation shall be permitted for Climate Zone 1, Climate Zone 2, or for thermally conditioned buildings for less than 876 hours per year.
405.2 Ventilation Air Rate. ¶
405.2 Ventilation Air Rate. The required mechanical ventilation outdoor air rate ( Qtot ) shall be as calculated in accordance with Equation 405.2. Exception: For existing buildings and where permitted by the Authority Having Jurisdiction, the total mechanical ventilation ( Qtot ) is not required where Qtot is calculated to be less than 15 ft [3] /min (7.08 L/s). Qtot = 0.03 Afloor + 7.5 ( Nbr + 1) (Equation 405.2) Where: Qtot = Total required ventilation outdoor air rate, CFM (L/s) Afloor = Floor area, ft [2] (m [2] ) Nbr = Number of bedrooms more than 1 For SI Units: 1 square foot = 0.0929…
405.3 Bathroom Exhaust. A mechanical exhaust directly ¶
405.3 Bathroom Exhaust. A mechanical exhaust directly to the outdoors shall be provided in each room containing a bathtub, shower, or tub/shower combination. The fan shall run intermittently (on demand) or continuously. A readily accessible manual control designed to be operated as needed or an automatic control shall be provided for intermittent operations. [HCD 1 & HCD 2] Each bathroom shall also be mechanically ventilated in accordance with Division 4.5 of the California Green Building Standards Code (CALGreen). 405.3.1 Exhaust Rate. The exhaust rate shall be not less than 50 ft [3] /min…
405.4 Kitchen Exhaust. A mechanical exhaust system that ¶
405.4 Kitchen Exhaust. A mechanical exhaust system that discharges directly to the outdoors shall be provided in each kitchen. The fan shall run intermittently (on demand) or continuously. A readily accessible manual control designed to be operated as needed or an automatic control shall be provided for intermittent operations. Exception: Recirculating systems installed in accordance with Section 516.0 and the manufacturer’s installation instructions. 405.4.1 Exhaust Rate. For intermittent-controlled operations, the exhaust rate shall be not less than 100 ft [3] /min (47.2 L/s) for range…
405.5 Ventilation Openings. Occupiable spaces shall be ¶
405.5 Ventilation Openings. Occupiable spaces shall be provided with a readily accessible ventilation opening openable to the outdoors. The opening shall be not less than 5 square feet (0.464 m [2] ) or 4 percent of the occupied floor area. The openable area shall be based on free, unobstructed area through the opening. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. VENTILATION AIR
406.0 Evaporative Cooling System for Health Care ¶
406.0 Evaporative Cooling System for Health Care Facilities. [OSHPD 1, 2, 3, 4 & 5] Direct evaporative cool- ing systems where the air directly contacts the wetted surface or spray shall be limited in health facilities to nonpatient areas such as laundry rooms, and boiler or machinery rooms. Similar rooms with high heating-producing equipment will be consid- ered when specifically approved by the enforcing agency. The evaporative pads shall be a synthetic type. Filters shall be required in accordance with Tables 4-B and 4-C except utility rooms, i.e.: boiler or machinery rooms.
407.0 Ventilation System Details. [OSHPD 1, 1R, 2, 3, 4 ¶
407.0 Ventilation System Details. [OSHPD 1, 1R, 2, 3, 4 & 5]
407.1 General. ¶
407.1 General. 407.1.1 All supply-air, return air, and exhaust-air sys- tems shall be mechanically operated and such systems for areas listed in Table 4-A shall be operated continu- ously. Natural ventilation through windows or other openings such as louvers will be considered as supple- mental to the required mechanical ventilation systems. Exceptions: (1) Natural ventilation shall not be used in airborne infection isolation rooms and protective environment rooms. (2) Unoccupied turndown shall be permitted in accor- dance with Section 407.7. 407.1.2 Fans serving exhaust systems shall be…
407.2 Outdoor Air Intakes and Exhaust Outlets. ¶
407.2 Outdoor Air Intakes and Exhaust Outlets. 407.2.1 Outdoor Air Intakes. Outdoor air intakes shall be located at least 25 feet (7.62 m) from exhaust outlets of ventilating systems, combustion equipment stacks, med- ical-surgical vacuum systems, cooling towers, and areas that may collect vehicular exhaust or other noxious fumes. Plumbing vents shall be located in relation to out- door air intakes per California Plumbing Code. The bot- tom of outdoor air intakes shall be located as high as practicable, but not less than 10 feet (3048 mm) above ground level. If installed above the roof, they…
407.3 Air Balance. ¶
407.3 Air Balance. 407.3.1 The ventilation systems shall be designed and balanced to provide the general air balance relationship to adjacent areas, shown in Table 4-A. The ventilation systems shall be balanced in accordance with the latest edition of standards published by the Associated Air Bal- ance Council (AABC), the National Environmental Bal- ancing Bureau (NEBB), or the Testing, Adjusting and Balancing Bureau (TABB). Air balance tolerancing val- ues shall not result in noncompliance of the minimum required pressurization per Table 4-A.
407.4 Air Circulation. ¶
407.4 Air Circulation. 407.4.1 Design of the ventilation system shall provide air movement that is generally from clean to less clean areas. 407.4.1.1 All air distribution devices and supply air outlets shall meet the requirements of ASHRAE 170, Section 6.7.2 and Table 6-2. 407.4.1.2 Supply outlets and return and exhaust air inlets shall be located to prevent short-circuiting. 407.4.1.3 Air supplied to operating rooms, cesarean operating rooms, cardiac catheterization labs, sur- gical cystoscopy rooms, delivery rooms, and class 3 imaging shall be delivered by a primary supply dif- fuser array…
414.0 and 415.0. ¶
414.0 and 415.0. 407.4.2 Corridors shall not be used to convey supply, return, transfer or exhaust air to or from any room per the California Building Code. Exceptions: (1) Use of a corridor as a source of makeup air for exhaust systems in rooms that open directly onto such corridors is permitted where allowed by the Califor- nia Building Code. The corridor air balance shall be equal based on the total net transfer air to or from the corridor. (2) Air transfer caused by pressure differentials in rooms required to have a positive or negative air balance by Table 4-A. 407.4.3 No space above a…
407.5 Variable Air Volume. ¶
407.5 Variable Air Volume. 407.5.1 Variable Air Volume Systems (VAV). Variable air volume systems subjecting the patient to a fluctuating air movement are not acceptable for airborne infection isolation rooms, protective environment rooms or those critically sensitive areas listed in Section 322.0. For non- sensitive areas, variable air volume systems meeting the following criteria can be considered: 407.5.1.1 The VAV system shall comply with code requirements for outside air, total air, and pressure relationship through the full range of operation from minimum to maximum. 407.5.1.2 The…
407.6 Economizers. ¶
407.6 Economizers. 407.6.1 Systems with economizers shall include modu- lating relief and/or return fans to ensure compliance with the pressure requirements of spaces listed in Table 4-A.
407.7 Unoccupied Turndown. ¶
407.7 Unoccupied Turndown. 407.7.1 Where indicated with a “yes” in the Unoccupied turndown column of Table 4-A, the number of air changes shall be permitted to be reduced. The following condi- tions shall be met: (1) The number of air changes may be reduced to 25 per- cent of the indicated value in Table 4-A for pressur- ized spaces when the room is unoccupied. (2) The number of air changes per hour indicated is reestablished whenever the space is occupied. (3) The pressure relationship with surrounding rooms is maintained when the air changes per hour are reduced. (4) All operating, class 3…
408.3 Filters for Skilled Nursing Facilities, Intermedi- ¶
408.3 Filters for Skilled Nursing Facilities, Intermedi- ate Care Facilities, and Correctional Treatment Centers. 408.3.1 The air ventilation systems for skilled nursing facilities, intermediate care facilities and correctional treatment centers shall have filter bank efficiencies as listed in Table 4-C. 408.3.2 Airborne infection isolation rooms, protective environment rooms, and sensitive areas in correctional treatment centers shall comply with Section 408.2.
408.4 Filters for Outpatient Facilities. ¶
408.4 Filters for Outpatient Facilities. 408.4.1 The air ventilation systems for outpatient facil- ities shall have filter bank efficiencies as listed in Table 4-B.
408.5 Filters for Recirculating Room Units. ¶
408.5 Filters for Recirculating Room Units. 408.5.1 Filters for recirculating room units shall comply with Section 407.4.5. Where Table 4-A does not permit air recirculated by means of room units, room units with filtration per Table 4-B are permitted.
409.0 Ducts. [OSHPD 1, 1R, 2, 3, 4 & 5] ¶
409.0 Ducts. [OSHPD 1, 1R, 2, 3, 4 & 5]
409.1 Ducts which penetrate construction, intended for X- ¶
409.1 Ducts which penetrate construction, intended for X- ray or other radiation protection, shall not impair the effec- tiveness of the protection.
409.2 Duct linings and their use shall meet the requirements ¶
409.2 Duct linings and their use shall meet the requirements of Chapter 6, California Mechanical Code.
409.3 The anchorage and supporting structural elements for ¶
409.3 The anchorage and supporting structural elements for airducts shall be designed to withstand the lateral forces as required by the California Building Code, Title 24, Part 2.
410.0 Laboratory Ventilating Systems and Hoods. ¶
410.0 Laboratory Ventilating Systems and Hoods. [OSHPD 1, 1R, 2, 3, 4 & 5]
410.1 Laboratory Ventilating Systems. Laboratory ven- ¶
410.1 Laboratory Ventilating Systems. Laboratory ven- tilating systems shall comply with NFPA 99, as required by Section 1224.4.6.4 of the California Building Code.
410.2 Exhaust Hoods and Safety Cabinets. Hoods and ¶
410.2 Exhaust Hoods and Safety Cabinets. Hoods and safety cabinets may be used for normal exhaust of a space pro- vided minimum air change rates are maintained. If air change standards in Table 4-A do not provide sufficient air for proper operation of exhaust hoods and safety cabinets (when in use), supplementary makeup air (filtered and preheated) shall be provided around these units to maintain the required airflow direction and exhaust velocity. Makeup systems for hoods shall be arranged to minimize “short circuiting” of air and to avoid reduction in air velocity at the point of…
410.3 Laboratory Fume Hoods. Laboratory fume hoods ¶
410.3 Laboratory Fume Hoods. Laboratory fume hoods shall meet the following standards: 410.3.1 General Standard. Average face velocity shall be at least 75 feet per minute (0.38 meters per sec- ond). Exhaust system shall be separate from the build- ing exhaust system. Exhaust fan shall be located at the discharge end of the system. Exhaust duct system shall be of noncombustible corrosion-resistant material as required to meet the planned usage of the hood. < < <
407.8 Building Pressurization. ¶
407.8 Building Pressurization. 407.8.1 The outdoor air intake design for air handling systems shall be set to maintain the intake air rate to equal or exceed the building exhaust under all conditions including variable air volume and unoccupied turndown.
408.0 Filters. [OSHPD 1, 1R, 2, 3, 4 & 5] ¶
408.0 Filters. [OSHPD 1, 1R, 2, 3, 4 & 5]
408.1 General. Filter efficiencies shall be certified by the ¶
408.1 General. Filter efficiencies shall be certified by the manufacturer and shall be based on ASHRAE 52.2 Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size when specifically set forth in these standards. 408.1.1 A filter gauge shall be installed across each fil- ter bank serving central air systems. The gauge shall be red lined or a filter alarm light installed to signal when the recommended maximum static pressure drop has been reached. 408.1.2 Central air-handling systems are defined as any unit requiring duct work on the supply or inlet…
408.2 Filters for Hospitals. ¶
408.2 Filters for Hospitals. 408.2.1 All air-ventilation systems shall comply with code requirements of this section and shall have filter bank efficiencies as listed in Table 4-B. 80 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. VENTILATION AIR 410.3.2 Special Standards for Use with Strong Oxidants. Fume hoods and their associated equipment in the air stream intended for use with perchloric acid and other strong oxidants shall be constructed of stainless steel or other material consistent…
411.0 Kitchen and Dining Areas. [OSHPD 1, 2, 3, 4 & 5] ¶
411.0 Kitchen and Dining Areas. [OSHPD 1, 2, 3, 4 & 5]
411.1 The air from dining areas may be used to ventilate the ¶
411.1 The air from dining areas may be used to ventilate the food preparation areas only after it has passed through a fil- ter with at least an 80 percent average efficiency based on ASHRAE 52.2 or a minimum efficiency reporting value (MERV) of 13, based on ASHRAE 52.2. Exception: For skilled nursing facilities, intermediate care facilities and correctional treatment centers, the air from dining area may be used to ventilate food preparation areas only after it has passed through a filter with a 50 percent average effi- ciency based on ASHRAE 52.2 or a minimum efficiency report- ing value…
412.0 Boiler, Mechanical, and Electrical Rooms. ¶
412.0 Boiler, Mechanical, and Electrical Rooms. [OSHPD 1, 2, 3, 4 & 5]
412.1 Boiler, heater and electrical equipment rooms shall be ¶
412.1 Boiler, heater and electrical equipment rooms shall be provided with outdoor air so as to maintain combustion rates of equipment and temperatures in the rooms and in adjoining areas as rated in this chapter.
412.2 Floor surfaces in occupied spaces above such rooms ¶
412.2 Floor surfaces in occupied spaces above such rooms should not exceed a temperature of 85°F (29.4°C), and suit- able insulation may be required.
413.0 Odorous Rooms. [OSHPD 1, 2, 3, 4 & 5] ¶
413.0 Odorous Rooms. [OSHPD 1, 2, 3, 4 & 5]
413.1 Rooms in areas where excessive heat or moisture is ¶
413.1 Rooms in areas where excessive heat or moisture is generated, where objectional odors or dust are present, or where flammable or toxic gases may accumulate, which are used by health facility personnel or patients, shall be pro- vided with exhaust ventilation to change the air a minimum of ten times per hour.
413.2 Kitchen, morgues and laundries located inside a hos- ¶
413.2 Kitchen, morgues and laundries located inside a hos- pital building or skilled nursing facility in which patients are accommodated, or treated, shall be ventilated with exhaust systems which will provide a minimum of ten air changes per hour and prevent odors from entering patient areas.
414.0 Airborne Infection Isolation Rooms. [OSHPD ¶
414.0 Airborne Infection Isolation Rooms. [OSHPD 1, 2, 3, 4 & 5]
414.1 Exhaust Systems. A separate, dedicated exhaust ¶
414.1 Exhaust Systems. A separate, dedicated exhaust system shall be provided for airborne infection isolation rooms. The dedicated system may serve more than one air- borne infection isolation room, adjoining toilet room and anteroom. The exhaust ducts shall be identified by appro- priate labeling with the words "Caution Airborne Infection Isolation Rooms Exhaust" or similar terminology. Such labeling shall be in a manner which is not readily removable and shall appear on the exhaust duct at intervals of not more than 20 feet (6096 mm) and at least once near each room and each story…
414.2 Air Distribution. The supply outlets and exhaust ¶
414.2 Air Distribution. The supply outlets and exhaust inlets shall be located to provide airflow patterns that pre- vent stagnation of the air and eliminate short circuiting of the supply to the exhaust, and minimize exposure of health care workers to airborne infectious particles. Supply-air outlets shall be located at or near the ceiling and at the end of the ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. VENTILATION AIR airborne infection isolation room which is opposite the head of the bed. Exhaust registers shall be…
415.0 Protective Environment Rooms. [OSHPD 1, 2, 3, ¶
415.0 Protective Environment Rooms. [OSHPD 1, 2, 3, 4 & 5]
415.1 Air Distribution. The supply outlets and exhaust and ¶
415.1 Air Distribution. The supply outlets and exhaust and return inlets shall be located to provide airflow patterns that prevent stagnation of the air and eliminate short circuiting of the supply to the exhaust or return. Supply air shall be deliv- ered at or near the ceiling and near the patient's bed. All exhaust or return registers shall be located near the entrance to the protective environment room and not less than 3 inches (76 mm) nor more than 8 inches (203 mm) above the finished floor. Exception: For correctional treatment centers, the location and design of the supply outlets and…
416.0 Alarms – Airborne Infection Isolation Rooms ¶
416.0 Alarms – Airborne Infection Isolation Rooms and Protective Environment Rooms. [OSHPD 1, 2, 3, 4 & 5]
416.1 An alarm system which is based on static pressure con- ¶
416.1 An alarm system which is based on static pressure con- trol, volumetric control, or directional flow measurement shall be provided for each isolation room. The alarm system shall consist of a display monitor located on the corridor wall near the door to the room and a visual and audible alarm which annunciates at the room and at a nurses' station or other suit- able location that will provide responsible surveillance. A time delay shall be provided to allow for routine openings of doors. The alarm shall annunciate when the supply, return, or exhaust fans are interrupted or when the…
416.2 Other acceptable alarm systems will be allowed when ¶
416.2 Other acceptable alarm systems will be allowed when designs are specifically approved by the enforcing agency.
416.3 [OSHPD 4] For correctional treatment centers, the ¶
416.3 [OSHPD 4] For correctional treatment centers, the alarm system shall not create false alarms or security haz- ards.
416.4 Prior to acceptance of the rooms, the alarm system ¶
416.4 Prior to acceptance of the rooms, the alarm system shall be tested and operated to demonstrate to the owner or designated representative that the installation and perform- ance of the system conforms to design intent.
417.0 Testing and Balancing Airborne Infection Isola- ¶
417.0 Testing and Balancing Airborne Infection Isola- tion Rooms and Protective Environment Rooms. [OSHPD 1, 2, 3, 4 & 5] Prior to acceptance of the rooms, all mechanical systems shall be tested, balanced, and operated to demonstrate to the owner or designated representative that the installation and performance of the systems conform to design intent. All testing and balancing shall be performed by a qualified independent agency certified by the Associated Air Balance Council (AABC): the National Environmental Bal- ancing Bureau (NEBB); or the Testing, Adjusting and Bal- ancing Bureau…
418.0 Design Requirements for Ethylene Oxide (ETO) ¶
418.0 Design Requirements for Ethylene Oxide (ETO) Sterilization Areas. [OSHPD 1, 1R, 2, 3, 4 & 5]
418.1 Air Changes. The ETO sterilization equipment room ¶
418.1 Air Changes. The ETO sterilization equipment room shall be provided with minimum air changes per hour per Table 4-A and be maintained at a negative air balance.
418.2 Exhaust Requirements. ¶
418.2 Exhaust Requirements. 418.2.1 All air from the ETO sterilizer equipment room shall be exhausted to the outside by a dedicated system or other approved method. 418.2.2 The exhaust fan for the dedicated system shall be located at the discharge point of the system and identified as ETO Equipment Room Exhaust. 418.2.3 Discharge Point. The discharge point shall be a minimum of 25 feet (7620 mm) away from any outside intake, operable window or personnel passage.
418.3 Ventilation Requirements. ¶
418.3 Ventilation Requirements. 418.3.1 Aeration Units. The aeration units shall be ven- tilated through a nonrecirculating dedicated ventilation exhaust system. 418.3.2 Capture Box. When the drain is not located in the ETO sterilizer equipment room, ventilation is required by a capture box. 418.3.3 Cylinder Change. When not located in the ETO sterilizer equipment room, exhaust during cylinder change is required by installing a hood that is part of a dedicated ventilation exhaust system, positioned no more than 1 foot (305 mm) above or behind the point where the change of cylinders takes…
418.4 Gas Valves. Installation of gas line hand valves at the ¶
418.4 Gas Valves. Installation of gas line hand valves at the connection to the supply cylinders are required to minimize leakage during cylinder change. 82 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. VENTILATION AIR
418.5 Alarm Systems. An Audible and visual alarm system ¶
418.5 Alarm Systems. An Audible and visual alarm system shall be installed to alert sterilizer operating personnel if the air flow falls below design cubic feet per minute (L/s).
419.0 Neonatal Intensive Care Units. [OSHPD 1] ¶
419.0 Neonatal Intensive Care Units. [OSHPD 1]
419.1 Formula Preparation Area. Air shall be supplied ¶
419.1 Formula Preparation Area. Air shall be supplied over the formulation preparation area by group E, nonaspi- rating supply diffusers. Air shall be returned or exhausted by registers located not less than 3 inches (76 mm) nor more than 8 inches (203 mm) above the finished floor in the cleanup area.
419.2 Treatment Area/Room. Air shall be supplied over ¶
419.2 Treatment Area/Room. Air shall be supplied over the treatment surface by group E, nonaspirating supply dif- fusers. Air shall be returned or exhausted by registers located not less than 3 inches (76 mm) nor more than 8 inches (203 mm) above the finished floor, adjacent to the treatment sur- face. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. VENTILATION AIR TABLE 4-A PRESSURE RELATIONSHIP AND VENTILATION REQUIREMENTS FOR GENERAL ACUTE CARE HOSPITALS, SKILLED NURSING FACILITIES, INTERMEDIATE CARE FACILITIES,…
503.0 Motors, Fans, and Filters. ¶
503.1 General. Motors and fans shall be sized to provide ¶
503.1 General. Motors and fans shall be sized to provide the required air movement. Motors in areas that contain flammable vapors or dusts shall be of a type approved for such environments. A manually operated remote control installed at an approved location shall be provided to shut off fans or blowers in flammable vapor or dust systems. Equipment used in operations that generate explosive or flammable vapors, fumes, or dusts shall be interlocked with the ventilation system so that the equipment cannot be operated unless the ventilation fans are in operation. Motors for fans used to convey…
503.2 Fans. ¶
503.2 Fans. Parts of fans in contact with explosive or flammable vapors, fumes, or dusts shall be of nonferrous or nonsparking materials, or their casing shall be lined or constructed of such material. Where the size and hardness of materials passing through a fan are capable of producing a spark, both the fan, and the casing shall be of nonsparking materials. Where fans are required to be spark-resistant, their bearings shall not be within the airstream, and parts of the fan shall be grounded. Fans in systems handling materials that are likely to clog the blades, and fans in buffing or…
504.0 Environmental Air Ducts. ¶
504.1 General. Where not specified in this chapter, exhaust ¶
504.1 General. Where not specified in this chapter, exhaust ducts shall be constructed and installed in accordance with Chapter 6 and shall be airtight as approved by the Authority Having Jurisdiction. Environmental air ducts that have an alternate function as a part of an approved smoke control sys « »
501.0 General. ¶
501.1 Applicability. This chapter includes requirements for ¶
501.1 Applicability. This chapter includes requirements for environmental air ducts, product-conveying systems, and commercial hoods and kitchen ventilation. Part I addresses environmental air ducts and product conveying systems. Part II addresses commercial hoods and kitchen ventilation.
502.0 Termination. ¶
502.1 Exhaust Opening Protection. Exhaust openings ¶
502.1 Exhaust Opening Protection. Exhaust openings terminating to the outdoors shall be covered with a corrosionresistant screen having not less than [1] ⁄ 4 of an inch (6.4 mm) openings, and shall have not more than [1] ⁄ 2 of an inch (12.7 mm) openings. Exception: Clothes dryers.
502.2 Termination of Exhaust Ducts. Exhaust ducts ¶
502.2 Termination of Exhaust Ducts. Exhaust ducts shall terminate in accordance with Section 502.2.1 through Section 502.2.4. Classes of air shall be as defined in Section 203.0 and classified in Section 403.9. 502.2.1 Environmental, Class 1, and Class 2 Air Ducts. Environmental, Class 1, and Class 2 air duct exhaust shall terminate not less than 3 feet (914 mm) from a property line, 10 feet (3048 mm) above a public way, 3 feet (914 mm) from openings into the building and the minimum separation distance from ventilation system outdoor air intakes determined in accordance with Section 402.4.1.…
504.2 Independent Exhaust Systems. ¶
504.2 Independent Exhaust Systems. Single or combined mechanical exhaust systems for environmental air shall be independent of other exhaust systems. Combined exhaust systems shall operate at negative pressure and shall terminate in accordance with Section 502.2.1. Clothes dryer exhaust systems shall be independent of all other exhaust systems except where permitted in Section 504.4.4.
504.3 Domestic Cooking Exhaust Equipment. ¶
504.3 Domestic Cooking Exhaust Equipment. Domestic cooking exhaust equipment shall comply with the following requirements, as applicable: (1) The fan for overhead range hoods and downdraft exhaust equipment not integral with the cooking appliance shall comply with UL 507. (2) Overhead range hoods and downdraft exhaust equipment with integral fans shall comply with UL 507. (3) Domestic cooking appliances with integral downdraft exhaust equipment shall comply with UL 858 or CSA/ANSI Z21.1/CSA 1.1. (4) Microwave ovens with integral exhaust for installation over the cooking surface shall comply…
504.4 Clothes Dryers. A clothes dryer exhaust duct shall ¶
504.4 Clothes Dryers. A clothes dryer exhaust duct shall not be connected to a vent connector, gas vent, chimney, and shall not terminate into a crawl space, attic, or other concealed space. Exhaust ducts shall not be assembled with screws or other fastening means that extend into the duct and that are capable of catching lint, and that reduce the efficiency of the exhaust system. Exhaust ducts shall be constructed of rigid metallic material. Transition ducts used to connect the dryer to the exhaust duct shall be listed and labeled in accordance with UL 2158A, or installed in accordance with…
504.5 Heat Recovery Ventilation (HRV) and Energy ¶
504.5 Heat Recovery Ventilation (HRV) and Energy Recovery Ventilation (ERV) Systems. Heat recovery ventilators (HRV) and energy recovery ventilators (ERV) shall be installed in accordance with their listings and comply with the appliance manufacturer’s installation instructions. Non-ducted heat recovery ventilators shall comply with UL 1815. Ducted heat recovery ventilators shall comply with UL 1812. Heat recovery ventilator and energy recovery ventilator ducts shall comply with Chapter 6.
505.0 Product-Conveying Systems. ¶
505.1 General. A mechanical ventilation or exhaust system ¶
505.1 General. A mechanical ventilation or exhaust system shall be installed to control, capture, and remove emissions generated from product use or handling where required in accordance with the building code or fire code and where such emissions result in a hazard to life or property. The design of the system shall be such that the emissions are confined to the area in which they are generated by air currents, hoods, or enclosures and shall be exhausted by a duct system to a safe location or treated by removing contaminants. Ducts conveying explosives or flammable vapors, fumes, or dusts…
505.2 Incompatible Materials. Incompatible materials ¶
505.2 Incompatible Materials. Incompatible materials shall not be conveyed in the same system. [NFPA 91:4.2.2]
505.3 Flammability Limit. ¶
505.3 Flammability Limit. Unless the circumstances stipulated in Section 505.3.1, Section 505.3.2, or Section 505.3.3 exist, in systems conveying flammable vapors, gases, or mists, the concentration shall not exceed 25 percent of the lower flammability limit (LFL). [NFPA 91:4.2.3] 505.3.1 Higher Concentrations. Higher concentrations shall be permitted if the exhaust system is designed and protected in accordance with NFPA 69, using one or more of the following techniques: (1) Combustible concentration reduction (2) Oxidant concentration reduction (3) Deflagration suppression (4) Deflagration…
505.4 Air-Moving Devices. Air-moving devices shall be ¶
505.4 Air-Moving Devices. Air-moving devices shall be sized to establish the velocity required to capture, control, and convey materials through the exhaust system. [NFPA 91:4.2.5]
505.5 Generating Flames, Sparks, or Hot Materials. ¶
505.5 Generating Flames, Sparks, or Hot Materials. Operations generating flames, sparks, or hot material such as from grinding wheels and welding shall not be manifolded into any exhaust system that air conveys flammable or combustible materials. [NFPA 91:4.2.6]
505.6 Fire Dampers. Fire dampers shall be permitted to be ¶
505.6 Fire Dampers. Fire dampers shall be permitted to be installed in exhaust systems in accordance with the following: (1) Where ducts pass through fire barriers (2) Where a collection system installed on the end of the system is protected with an automatic extinguishing system (3) Where the duct system is protected with an automatic extinguishing system (4) Where ducts have been listed with interrupters (5) Where necessary to facilitate the control of smoke pursuant to the applicable NFPA standards [NFPA 91:4.2.9] 505.6.1 Prohibited. Fire dampers shall not be installed if the material…
505.7 Fire Detection, Smoke Control, and Alarm Sys- ¶
505.7 Fire Detection, Smoke Control, and Alarm Sys- tems. Unless the circumstances stipulated in Section 505.7.1 or Section 505.7.2 exist, fire detection and alarm systems shall not be interlocked to shut down air-moving devices. [NFPA 91:4.2.14] 505.7.1 Automatic Extinguishing System. Where shutdown is necessary for the effective operation of an automatic extinguishing system, it shall be permitted to interlock fire detection and alarm systems to shut down air-moving devices. [NFPA 91:4.2.14.1] 505.7.2 Shut Down Permitted. Where a documented risk analysis acceptable to the Authority Having…
505.8 Product-Conveying Duct Classifications. ¶
505.8 Product-Conveying Duct Classifications. Product-conveying ducts shall be classified according to their use, as follows: Class 1 - Ducts conveying nonabrasives, such as smoke, spray, mists, fogs, noncorrosive fumes and gases, light fine dusts, or powders. Class 2 - Ducts conveying moderately abrasive particulate in light concentrations, such as sawdust and grain dust, and buffing and polishing dust. Class 3 - Ducts conveying Class 2 materials in high concentrations and highly abrasive materials in low concentrations, such as manganese, steel chips, and coke. Class 4 - Ducts conveying…
505.9 Minimum Velocities and Circulation. ¶
505.9 Minimum Velocities and Circulation. The velocity and circulation of air in work areas shall be such that contaminant’s are captured by an airstream at the area where the emissions are generated and conveyed into a product-conveying duct system. Mixtures within work areas where contaminants are generated shall be diluted to be accordance with Section 505.3 with air that does not contain other contaminants. The velocity of air within the duct shall be not less than set forth in Table 505.9. Systems conveying particulate matter shall be designed by employing the constant velocity method.…
505.10 Makeup Air. ¶
505.10 Makeup Air. Makeup air shall be provided to replenish air exhausted by the ventilation system. Makeup air 102 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. EXHAUST SYSTEMS intakes shall be located so as to avoid recirculation of con taminated air within enclosures.
505.11 Hoods and Enclosures. Hoods and enclosures shall ¶
505.11 Hoods and Enclosures. Hoods and enclosures shall be used where contaminants originate in a concentrated area. The design of the hood or enclosure shall be such that air currents created by the exhaust systems will capture the contaminants and transport them directly to the exhaust duct. The volume of air shall be sufficient to dilute explosive or flammable vapors, fumes, or dusts in accordance with Section 505.3. Hoods of steel shall have a base metal thickness not less than 0.027 of an inch (0.686 mm) (No. 22 gauge) for Class 1 and Class 5 metal duct systems; 0.033 of an inch (0.838…
505.12 Pharmacies – Compounding Area of Par- ¶
505.12 Pharmacies – Compounding Area of Par- enteral Solutions. [CA – Board of Pharmacy] The pharmacy shall have a designated area for the preparation of sterile products for dispensing which shall be ventilated in a manner not interfering with laminar air flow. Note: For additional pharmacy building standard require- ments, see Chapter 12, California Building Code. 505.12.1 P harmacies – Laminar Flow Biological Safety Cabinet. [CA – Board of Pharmacy] In all pharmacies preparing parenteral cytotoxic agents, all com- pounding shall be conducted within a certified Class II Type A or Class II…
506.0 Product-Conveying Ducts. ¶
506.1 Materials. Materials used in product-conveying duct ¶
506.1 Materials. Materials used in product-conveying duct systems shall be suitable for the intended use and shall be of rigid sheet metal. Exceptions: (1) Asbestos-cement, concrete, clay, or ceramic materials shall be permitted to be used where it is shown that these materials will be equivalent to metal ducts installed in accordance with this chapter. (2) Ducts serving a Class 5 system shall be permitted to be constructed of approved nonmetallic material where the corrosive characteristics of the material being conveyed make a metal system unsuitable and where the mixture being conveyed is…
506.2 Construction. Ducts used for conveying products ¶
506.2 Construction. Ducts used for conveying products shall be airtight construction as approved by the Authority Having Jurisdiction, and shall not have openings other than those required for operation and maintenance of the system. Ducts constructed of steel shall comply with Table 506.2(1) or Table 506.2(2). Exceptions: (1) Class 1 product-conveying ducts that operate at less than 4 inches water column (0.9 kPa) negative pressure and con vey noncorrosive, nonflammable and nonexplosive materials at temperatures not exceeding 250°F (121°C) shall be permitted to be constructed in accordance…
506.3 Penetrations. Exhaust ducts shall not pass through ¶
506.3 Penetrations. Exhaust ducts shall not pass through fire walls. {NFPA 91:4.2.11} 506.3.1 Fire Barriers. Exhaust ducts passing through a fire barrier having a fire resistance rating of 2 hours or greater shall meet one of the following specifications: (1) Wrapped or encased with listed or approved materials having a fire resistance rating equal to the fire barrier for 10 feet (3048 mm) of the duct on each side of the fire barrier including duct supports within this span. (2) Constructed of materials and supports having a minimum fire resistance rating equal to the fire barrier. (3)…
506.4 Condensate. ¶
506.4 Condensate. Joints in duct construction shall be liquidtight when the conveying system contains condensable vapors or liquids in suspension. [NFPA 91:4.3.6.1] 506.4.1 Drainage. Provisions shall be made for drainage of condensate at low points in the duct. [NFPA 91:4.3.6.2]
506.5 Fittings. Fittings in Class 2, 3, and 4 systems shall be ¶
506.5 Fittings. Fittings in Class 2, 3, and 4 systems shall be not less than two gauges thicker than the thickness required for straight runs. Flexible metallic duct shall be permitted to be used for connecting ductwork to vibrating equipment. Duct systems subject to wide temperature fluctuations shall be provided with expansion joints. Branches shall connect to main ducts at the large end of transitions at an angle not exceeding 45 degrees (0.79 rad). Except for ducts used to convey noncorrosive vapors with no particulate, accessible cleanouts shall be provided at 10 foot (3048 mm) intervals…
506.6 Explosion Venting. Ducts conveying explosive dusts ¶
506.6 Explosion Venting. Ducts conveying explosive dusts shall have explosion vents, openings protected by anti-flashback swing valves, or rupture diaphragms. Openings to relieve explosive forces shall be located outside the building. Where relief devices cannot provide sufficient pressure relief, ductwork shall be designed to withstand an internal pressure of not less than 100 pounds-force per square inch (psi) (689 kPa). Where a room or building contains a dust explosion hazard that is external to protected equipment, as defined in NFPA 654, such areas shall be provided with deflagration…
506.7 Supports. ¶
506.7 Supports. Supports shall be of noncombustible materials, and the spacing shall not exceed 12 feet (3658 mm) for 8 inch (203 mm) ducts and 20 feet (6096 mm) for larger ducts.
506.8 Fire Protection. Sprinklers or other fire-protection ¶
506.8 Fire Protection. Sprinklers or other fire-protection devices shall be installed within ducts having a cross-sectional dimension exceeding 10 inches (254 mm) where the duct conveys flammable vapors or fumes. Sprinklers shall be installed at 12 foot (3658 mm) intervals in horizontal ducts and at changes in direction. In vertical runs, sprinklers shall be installed at the top and at alternate floor levels. 506.8.1 Loads. Duct supports shall be designed to carry the weight of the duct half filled with material. Where sprinkler protection is provided or cleaning of the duct will be…
506.9 Protection from Physical Damage. Ducts and ¶
506.9 Protection from Physical Damage. Ducts and exhaust equipment installed in locations where they are subject to physical damage shall be protected by guards.
506.10 Duct Clearances. Unless the conditions stipulated ¶
506.10 Duct Clearances. Unless the conditions stipulated in Section 506.10.1 or Section 506.10.2 exist, all duct systems and system components shall have a clearance of at least 6 inches (152 mm) from stored combustible materials, and not less than [1] ⁄ 2 of an inch (13 mm) clearance from combustible construction. [NFPA 91:4.7.1] 506.10.1 Protection Provided. Where stored combustible material or combustible construction is protected from ductwork by the use of materials or products listed for protection purposes, clearance shall be maintained in accordance with those listings. [NFPA…
506.11 Clearance Reduction Methods. ¶
506.11 Clearance Reduction Methods. It shall be permitted to protect stored combustible material or combustible construction from ductwork in accordance with Table 506.11 and Section 506.11.1 through Section 506.11.6. In no case shall the clearance between the duct and the combustible surface be reduced below that allowed in Table 506.11. [NFPA 91:4.7.4, 4.7.4.1] 506.11.1 Spacers and Ties. Spacers and ties for protection materials shall be of noncombustible material and shall not be installed on the duct side of the protection system. [NFPA 91:4.7.4.2] 506.11.2 Wool Batts Insulation. Mineral…
507.0 General Requirements. ¶
507.1 Exhaust Systems. Exhaust systems serving Type I ¶
507.1 Exhaust Systems. Exhaust systems serving Type I hoods shall comply with Section 507.2 through Section 518.0. Exhaust systems serving Type II hoods shall comply with Section 519.0.
507.2 Type I Hood Exhaust System Requirements. ¶
507.2 Type I Hood Exhaust System Requirements. Cooking equipment used in processes producing smoke or grease-laden vapors shall be equipped with an exhaust system that complies with all the equipment and performance requirements of this chapter. [NFPA 96:4.1.1] All such equipment and its performance shall be maintained in accordance with the requirements of this chapter during all periods of operation of the cooking equipment. [NFPA 96:4.1.2] The following equipment shall be kept in working condition: (1) Cooking equipment (2) Hoods (3) Ducts (if applicable) (4) Fans (5) Fire-extinguishing…
507.3 Listed Devices. Penetrations shall be sealed with ¶
507.3 Listed Devices. Penetrations shall be sealed with listed devices in accordance with the requirements of Section 507.3.1. 507.3.1 Penetration. Devices that require penetration of a Type I hood or grease duct, such as pipe and conduit penetration fittings and fasteners, shall be listed in accordance with UL 710 or UL 1978. Seams, joints, and penetrations of the hood enclosure shall comply with Section 508.3.2. Seams, joints, and penetrations of the ductwork shall comply with Section 510.5.3.
507.4 Clearance. Where enclosures are not required, hoods, ¶
507.4 Clearance. Where enclosures are not required, hoods, grease removal devices, exhaust fans, and ducts shall have a clearance of at least 18 inches (457 mm) to combustible material, 3 inches (76 mm) to limited-combustible material, and 0 inches (0 mm) to noncombustible material. [NFPA 96:4.2.1] 507.4.1 Listed. Where a hood, duct, or grease removal device is listed for clearances less than those required in Section 507.4, the listing requirements shall be permitted. [NFPA 96:4.2.2] 507.4.2 Clearance Reduction. Where a clearance reduction system consisting of 0.013 of an inch (0.33 mm) (28…
507.5 Drawings. For cooking operations in buildings, a ¶
507.5 Drawings. For cooking operations in buildings, a drawing(s) of the exhaust system installation along with 110 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. EXHAUST SYSTEMS copies of operating instructions for subassemblies and components used in the exhaust system, including electrical schematics, shall be kept on the premises and made available on request to the Authority Having Jurisdiction and maintenance persons. [NFPA 96:4.6.4]
507.6 Notification of Change. ¶
507.6 Notification of Change. If required by the Authority Having Jurisdiction, notification in writing shall be given of any alteration, replacement, or relocation of any exhaust or extinguishing system or part thereof or cooking equipment. [NFPA 96:4.7] Satisfaction shall be provided to the Authority Having Jurisdiction that the complete exhaust system as addressed in this chapter is installed and operable in accordance with the approved design and the manufacturer’s installation instructions.
507.7 Pharmaceutical Compounding Exhaust Dis- ¶
507.7 Pharmaceutical Compounding Exhaust Dis- charge. [OSHPD 1, 2, 3, 4 & 5] Exhaust discharge from fans serving the compounding suite shall extend at least 7 feet (2134 mm) above the roof and discharge vertically upward. Self-draining stacks or equivalent shall be used for rain pro- tection. Rain caps which divert the exhaust toward the roof shall be prohibited.
508.0 Type I Hoods. ¶
508.1 Where Required. Type I hoods shall be installed at ¶
508.1 Where Required. Type I hoods shall be installed at or above commercial-type deep-fat fryers, broilers, grills, hottop ranges, ovens, barbecues, rotisseries, and similar equipment that emits comparable amounts of smoke or grease in a food-processing establishment. For the purpose of this section, a food-processing establishment shall include a building or portion thereof used for the processing of food, but shall not include a dwelling unit. Exceptions: (1) A Type I hood shall not be required for cooking appliances that comply with UL 197 for reduced emissions where the grease discharge…
508.2 Listed Type I Hood Assemblies. Listed hood ¶
508.2 Listed Type I Hood Assemblies. Listed hood assemblies shall be installed in accordance with the terms of their listing and the manufacturer’s instructions. Listed hood assemblies shall be tested in accordance with UL 710 or equivalent. {NFPA 96:5.4.1, 5.4.2} 508.2.1 Listed Ultraviolet Hoods. Listed ultraviolet hoods shall be installed and maintained in accordance with the terms of their listing and the manufacturer’s instructions. Duct systems connected to ultraviolet hoods shall comply with Section 510.0. Ultraviolet hoods shall be tested and listed in accordance with UL 710. {NFPA…
508.3 Construction of Type I Hoods. The hood or that ¶
508.3 Construction of Type I Hoods. The hood or that portion of a primary collection means designed for collecting cooking vapors and residues shall be constructed of and be supported by steel not less than 0.048 of an inch (1.219 mm) (No. 18 MSG), in thickness, stainless steel not less than 0.036 of an inch (0.914 mm) (No. 20 MSG) in thickness, or other approved material of equivalent strength and fire and corrosion resistance. [NFPA 96:5.1.1] Exception: Listed exhaust hoods. 508.3.1 Grease Vapor. Wall-mounted exhaust hood assemblies shall be tight fitting against the back wall so as to not…
508.4 Supports. Hoods shall be secured in place to resist ¶
508.4 Supports. Hoods shall be secured in place to resist the lateral loads [OSHPD 1, 1R, 2, 4 & 5] given in the California Building Code, Title 24, Part 2 by noncombustible supports. The supports shall be capable of supporting the expected weight of the hood plus 800 pounds (362.9 kg).
508.5 Hood Size. Hoods shall be sized in accordance with ¶
508.5 Hood Size. Hoods shall be sized in accordance with the airflow capacity in accordance with Section 508.5.1.1 and installed to provide for the removal of heat, and capture and removal of grease-laden vapors in accordance with Section 511.2.2. 508.5.1 Canopy Size and Location. For canopy type commercial cooking hoods, the inside edge thereof shall overhang or extend a horizontal distance of not less than 6 inches (152 mm) beyond the edge of the cooking surface on open sides, and the vertical distance between the lip of the hood and the cooking surface shall not exceed 4 feet (1219 mm).…
508.6 Solid-Fuel Hood Assemblies. Where solid-fuel ¶
508.6 Solid-Fuel Hood Assemblies. Where solid-fuel cooking equipment is to be used, the solid-fuel hood assembly shall be in accordance with Section 517.0.
508.7 Exhaust Outlets. An exhaust outlet within an ¶
508.7 Exhaust Outlets. An exhaust outlet within an unlisted hood shall be located so as to optimize the capture of particulate matter. Each outlet shall serve not more than a 12 foot (3658 mm) section of an unlisted hood.
509.0 Grease Removal Devices in Hoods. ¶
509.0 Grease Removal Devices in Hoods.
509.1 Grease Removal Devices. Listed grease filters or ¶
509.1 Grease Removal Devices. Listed grease filters or other listed grease removal devices intended for use with commercial cooking operations shall be provided. Listed grease filters and grease removal devices that are removable but not an integral component of a specific listed exhaust hood shall be listed in accordance with UL 1046 and shall be designated on the filter. {NFPA 96:6.1.1, 6.1.2} 509.1.1 Grease Filters, Mesh-Type. Mesh filters shall not be used unless evaluated as an integral part of a listed exhaust hood or listed in conjunction with a primary filter in accordance with UL…
509.2 Installation. The distance between the grease removal ¶
509.2 Installation. The distance between the grease removal device and the cooking surface shall be as great as possible but not less than 18 inches (457 mm). [NFPA 96:6.2.1.1] 509.2.1 Vertical Distance. Where grease removal devices are used in conjunction with solid fuel or solid fueltype broilers, including gas or electrically heated charbroilers, a minimum vertical distance of 4 feet (1219 mm) shall be maintained between the lower edge of the grease removal device and the cooking surface. [NFPA 96:6.2.1.2] Exceptions: (1) For cooking equipment without exposed flame and where flue gases…
509.3 Solid-Fuel Grease Removal Devices. Where ¶
509.3 Solid-Fuel Grease Removal Devices. Where solid-fuel cooking equipment is provided with grease removal devices, these devices shall be in accordance with Section 517.0.
510.0 Exhaust Duct Systems. ¶
510.1 General. Ducts shall not pass through fire walls. ¶
510.1 General. Ducts shall not pass through fire walls. [NFPA 96:7.1.1] 510.1.1 Fire Hazards. All ducts shall lead directly to the exterior of the building, so as not to unduly increase any fire hazard. [NFPA 96:7.1.2] 510.1.2 Interconnection. Duct systems shall not be interconnected with any other building ventilation or exhaust system. [NFPA 96:7.1.3] 510.1.3 Duct Installation. All ducts shall be installed with a minimum slope of ¼ inch per linear foot (20.8 mm/m) on horizontal runs up to 75 feet (22 860 mm) and a minimum slope of 1 inch per linear foot (83.2 mm/m) on horizontal runs…
510.2 Clearance. Clearance between ducts and combustible ¶
510.2 Clearance. Clearance between ducts and combustible materials shall be provided in accordance with the requirements of Section 507.4 through Section 507.4.3.3. [NFPA 96:7.2]
510.3 Openings. Openings shall be provided at the sides or ¶
510.3 Openings. Openings shall be provided at the sides or at the top of the duct, whichever is more accessible, and at changes of direction. Openings shall be protected by approved access constructed and installed in accordance with the requirements of Section 510.3.7. [NFPA 96:7.3.1, 7.3.2] Exception: Openings shall not be required in portions of the duct that are accessible from the duct entry or discharge. [NFPA 96:7.3.3] 510.3.1 Access Panel. For hoods with dampers in the exhaust or supply collar, an access panel for cleaning and inspection shall be provided in the duct or the hood…
510.4 Listed Grease Ducts. Listed grease ducts shall be ¶
510.4 Listed Grease Ducts. Listed grease ducts shall be installed in accordance with the terms of the listing and the manufacturer’s instructions. [NFPA 96:7.1.8] 510.4.1 Factory-Built Grease Ducts. Factory-built grease ducts in accordance with UL 1978 shall be permitted to incorporate non-welded joints in accordance with their listings.
510.5 Other Grease Ducts. ¶
510.5 Other Grease Ducts. Other grease ducts shall comply with the requirements of Section 510.5.1 through Section 510.5.5. [NFPA 96:7.5] 510.5.1 Materials. Ducts shall be constructed of and supported by carbon steel not less than 0.060 of an inch (1.524 mm) (No. 16 MSG) in thickness or stainless steel not less than 0.048 of an inch (1.219 mm) (No. 18 MSG) in thickness. [NFPA 96:7.5.1.1] 510.5.2 Factory-Built Grease Ducts. Factory-built grease ducts listed in accordance with UL 1978 shall be permitted to use materials in accordance with their listing. {NFPA 96:7.5.1.2} 510.5.3 Installation.…
510.6 Exterior Installations. For cooking operations in ¶
510.6 Exterior Installations. For cooking operations in buildings, the exterior portion of the ductwork shall be vertical wherever possible and shall be installed and supported on the exterior of a building. Bolts, screws, rivets, and other mechanical fasteners shall not penetrate duct walls. Clearance of ducts shall comply with Section 507.4 through Section 507.4.3.3. [NFPA 96:7.6.1, 7.6.3, 7.6.4] ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. EXHAUST SYSTEMS 510.6.1 Weather Protection. All ducts shall be protected on the…
510.7 Interior Installations. In all buildings more than one ¶
510.7 Interior Installations. In all buildings more than one story in height and in one-story buildings where the roof-ceiling assembly is required to have a fire resistance rating, the ducts shall be enclosed in a continuous enclosure extending from the lowest fire-rated ceiling or floor above the hood, through any concealed spaces, to or through the roof, to maintain the integrity of the fire separations required by the applicable building code provisions. The enclosure shall be sealed around the duct at the point of penetration of the first firerated barrier after the hood, to maintain the…
510.8 Underground Installations. Grease ducts installed ¶
510.8 Underground Installations. Grease ducts installed underground shall be approved for underground installation. The material of the grease duct shall be corrosion-resistant and shall comply with Section 510.5.1. 510.8.1 Grease Receptacle. The grease duct shall be sloped to drain the grease back to an approved grease collection device. A grease collection device shall be located at the base of the vertical riser. 510.8.2 Cleanouts. For horizontal installations, cleanouts for cleaning and maintenance shall be provided 118 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may…
510.9 Termination of Type I Hood Exhaust System. ¶
510.9 Termination of Type I Hood Exhaust System. The exhaust system shall terminate as follows: (1) Outside the building with a fan or duct. (2) Through the roof or to the roof from outside, as in Section 510.9.1, or through a wall, as in Section 510.9.2. [NFPA 96:7.8.1] 510.9.1 Rooftop Terminations. Rooftop terminations shall be arranged with or provided with the following: (1) A minimum of 10 feet (3048 mm) of horizontal clearance from the outlet to adjacent buildings, property lines, and air intakes. (2) A minimum of 5 feet (1524 mm) of horizontal clearance from the outlet (fan housing) to…
510.10 Solid-Fuel Duct Systems. ¶
510.10 Solid-Fuel Duct Systems. Where solid-fuel cooking equipment is to be vented, the duct system shall be in accordance with Section 517.0. For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm Notes: 1. Fresh air intake (FAI) applies to an air intake, including an operable door or window. 2. Example: (a) FAIs 1 and 5 are on the same plane of exhaust or lower: 10 feet (3048 mm) min. between closest edges. (b) FAIs 2, 3, and 4 are above plane of exhaust fan: 10 feet + 0.25 feet (3048 mm + 76 mm) per degree between closest edges. FIGURE 510.9.2 EXHAUST TERMINATION DISTANCE FROM FRESH AIR INTAKE…
511.0 Air Movement. ¶
511.1 Exhaust Fans for Commercial Cooking Opera- ¶
511.1 Exhaust Fans for Commercial Cooking Opera- tions. Exhaust fans shall be installed in accordance with Section 511.1.1 through Section 511.1.6. Exhaust fans shall comply with UL 705 and be installed in accordance with the manufacturer’s installation instructions. 511.1.1 Upblast Fans. Upblast fans with motors surrounded by the airstream shall be hinged and supplied with flexible weatherproof electrical cable, and service hold-open retainers. Installation shall conform to the requirements of Section 510.9. Upblast fans shall have a drain directed to a readily accessible and visible grease…
511.2 Airflow. The air velocity through a duct shall be not ¶
511.2 Airflow. The air velocity through a duct shall be not less than 500 feet per minute (ft/min) (2.54 m/s) and not exceed 2500 ft/min (12.7 m/s). 511.2.1 Exceptions. Transition duct sections that do not exceed 3 feet (914 mm) in length and do not contain grease traps shall be permitted to be connected to hoods For SI units: 1 inch = 25.4 mm, °C = (°F-32)/1.8 FIGURE 511.1.2(1) TYPICAL SECTION OF DUCT-TO-FAN CONNECTION-BUTT JOINT METHOD [NFPA 96: FIGURE 8.1.3.2(a)] For SI units: 1 inch = 25.4 mm, °C = (°F-32)/1.8 FIGURE 511.1.2(2) TYPICAL SECTION OF DUCT-TO-FAN CONNECTION-OVERLAPPING METHOD…
511.3 Makeup Air. The makeup air quantity shall prevent ¶
511.3 Makeup Air. The makeup air quantity shall prevent negative pressures in the commercial cooking area(s) from exceeding 0.02 inch water column (0.005 kPa). Where the fire-extinguishing system activates, makeup air supplied internally to a hood shall be shut off. For compensating hoods, where a Type I or Type II hood has an internal discharge of makeup air, the makeup air flow shall not exceed 10 percent of the exhaust airflow, the exhaust airflow shall be the net exhaust from the hood in accordance with Section 508.5.1.2 through Section 508.5.1.5. The total hood exhaust shall be…
511.4 Common Duct (Manifold) Systems. Master ¶
511.4 Common Duct (Manifold) Systems. Master kitchen exhaust ducts that serve multiple tenants shall include provision to bleed air from outdoors or from adjacent spaces into the master exhaust duct where required to maintain the necessary minimum air velocity in the master exhaust duct. [NFPA 96:8.4.1] 511.4.1 Connections. Bleed air ducts shall connect to the top or side of the master exhaust duct. [NFPA 96:8.4.2] 511.4.2 Fire Damper. The bleed-air duct shall have a fire damper at least 12 inches (305 mm) from the exhaust duct connection. [NFPA 96:8.4.3] 511.4.3 Construction and Clearance.…
511.5 Solid-Fuel Air Movement Requirements. Where ¶
511.5 Solid-Fuel Air Movement Requirements. Where solid-fuel cooking equipment is used, exhaust and replacement air also shall be in accordance with Section 517.0.
512.0 Auxiliary Equipment. ¶
512.1 Dampers. Dampers shall not be installed in exhaust ¶
512.1 Dampers. Dampers shall not be installed in exhaust ducts or exhaust duct systems. [NFPA 96:9.1.1] 512.1.1 Use. Where specifically listed for such use or where required as part of a listed device or system, dampers in exhaust ducts or exhaust duct systems shall be permitted. [NFPA 96:9.1.2]
512.2 Electrical Equipment. Wiring systems of any type ¶
512.2 Electrical Equipment. Wiring systems of any type shall not be installed in ducts. [NFPA 96:9.2.1] 512.2.1 Device Installation in Ducts. Motors, lights, and other electrical devices shall be permitted to be installed in ducts or hoods or to be located in the path of travel of exhaust products only where specifically listed for such use. [NFPA 96:9.2.2] 122 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. EXHAUST SYSTEMS 512.2.2 Lighting Units. Lighting units on hoods shall not be located…
512.3 Other Equipment. ¶
512.3 Other Equipment. Fume incinerators, thermal recovery units, air pollution control devices, or other devices shall be permitted to be installed in ducts or hoods or to be located in the path of travel of exhaust products where specifically listed for such use. [NFPA 96:9.3.1] 512.3.1 Access Required. Equipment shall have space provided to all access panels or doors for the safe removal and servicing of control devices, such as filters, electrostatic precipitator cells, and odor control media beds, and for cleaning of the equipment housing. [NFPA 96:9.3.1.3] 512.3.2 Downgrading.…
512.4 Solid-Fuel Auxiliary Equipment. Where solid fuel ¶
512.4 Solid-Fuel Auxiliary Equipment. Where solid fuel cooking comprises a part of a cooking operation, additional provisions, and equipment as described in Section 517.0 shall be used where required.
513.0 Fire-Extinguishing Equipment. ¶
513.1 General. ¶
513.1 General. Fire-extinguishing equipment for the protection of grease removal devices, hood exhaust plenums, and exhaust duct systems shall be provided. [NFPA 96:10.1.1] 513.1.1 Devices in Exhaust Ducts. Fume incinerators, thermal recovery units, air pollution control devices, or other devices installed in the exhaust duct, shall be protected by an automatic fire-extinguishing system. [NFPA 96:10.1.3] 513.1.2 Protection. Cooking equipment that produces grease-laden vapors and that might be a source of ignition of grease in the hood, grease removal device, or duct shall be protected by…
513.2 Types of Equipment. Fire-extinguishing equipment ¶
513.2 Types of Equipment. Fire-extinguishing equipment shall include both automatic fire-extinguishing systems as primary protection and portable fire extinguishers as secondary backup. [NFPA 96:10.2.1] 513.2.1 Identification. A placard shall be conspicuously placed near each Class K extinguisher that states that the fire protection system shall be activated prior to using the fire extinguisher. [NFPA 96:10.2.2] 513.2.2 Standard. Commercial cooking equipment that produce grease laden vapors shall be provided with a Type I Hood, in accordance with this Code, and an auto- matic fire…
513.3 Simultaneous Operation. Fixed pipe extinguishing ¶
513.3 Simultaneous Operation. Fixed pipe extinguishing systems in a single hazard area shall be arranged for simultaneous automatic operation upon actuation of any one of the systems. [NFPA 96:10.3.1] 513.3.1 Hoods. Hoods installed end to end, back to back, or both, or sharing a common ductwork, not exceeding 75 feet (22 860 mm) in distance from the farthest hood, and having a grease producing appliance(s) located under one or more of the hoods, shall be considered a single hazard area requiring simultaneous automatic fire protection in all hoods and ducts. [NFPA 96:10.3.1.1] 513.3.1.1 Common…
513.4 Fuel and Electric Power Shutoff. Upon actuation of ¶
513.4 Fuel and Electric Power Shutoff. Upon actuation of any fire-extinguishing system for a cooking operation, all sources of fuel and electric power that produce heat to all equipment protected by the system shall automatically shut off. [NFPA 96:10.4.1] Exception: Solid-fuel cooking operations. 513.4.1 Steam. Steam supplied from an external source shall not be required to automatically shut off. [NFPA 96:10.4.2] 513.4.2 Protection Not Required. Gas appliances not requiring protection but located under the same ventilation equipment where protected appliances are located, shall also be…
513.5 Manual Actuation. ¶
513.5 Manual Actuation. All systems shall have both automatic and manual methods of actuation. At least one manual actuation device shall be located in a means of egress or at a location acceptable to the Authority Having Jurisdiction. The manual actuation device shall clearly identify the hazard protected and be provided with instructions for its use. Manual actuation devices shall be provided with a guard where required by the Authority Having Jurisdiction. An automatic sprinkler system shall not require a method – of manual actuation. {NFPA 96:10.5.1 10.5.2}
513.6 System Annunciation. ¶
513.6 System Annunciation. Upon actuation of an automatic fire-extinguishing system, an audible alarm or visual indicator shall be provided to show that the system has actuated. [NFPA 96:10.6.1] 513.6.1 Signaling. Where a fire alarm signaling system is serving the occupancy where the extinguishing system is located, the actuation of the automatic fire-extinguishing system shall actuate the fire alarm signaling system in accordance with the requirements of NFPA 72. [NFPA 96:10.6.2]
513.7 Special Design and Application. Hoods containing ¶
513.7 Special Design and Application. Hoods containing automatic fire-extinguishing systems are protected areas; therefore, these hoods shall not be considered obstructions to overhead sprinkler systems and shall not require floor additional sprinkler coverage underneath. [NFPA 96:10.7.1]
513.8 Review and Certification. Where required, complete ¶
513.8 Review and Certification. Where required, complete drawings of the system installation, including the hood(s), exhaust duct(s), and appliances, along with the interface of the fire-extinguishing system detectors, piping, nozzles, fuel and electric power shutoff devices, agent storage container(s), and manual actuation device(s), shall be submitted to the Authority Having Jurisdiction. [NFPA 96:10.8.1]
513.9 Installation Requirements. Installation of systems ¶
513.9 Installation Requirements. Installation of systems shall be performed only by persons properly trained and qualified to install the specific system being provided. The installer shall provide certification to the Authority Having Jurisdiction that the installation is in agreement with the terms of the listing and the manufacturer’s instructions and/or approved design. [NFPA 96:10.8.2.1, 10.8.2.2]
513.10 Portable Fire Extinguishers. ¶
513.10 Portable Fire Extinguishers. Portable fire extinguishers shall be selected and installed in kitchen cooking areas in accordance with Chapter 3, Title 19 California Code of Reg- ulations and shall be specifically listed for such use. Class K fire extinguishers shall be provided for cooking appliance hazards that involve combustible cooking media (vegetable oils and animal oils and fats). [NFPA 96:10.9.1, 10.9.2] 513.10.1 Other Fire Extinguishers. Portable fire extinguishers shall be provided for other hazards in kitchen areas and shall be selected and installed in accordance with…
513.11 Maintenance. Portable fire extinguishers shall be ¶
513.11 Maintenance. Portable fire extinguishers shall be maintained in accordance with NFPA 10. [NFPA 96:10.9.5] 513.11.1 Permitted Use. Portable fire extinguishers listed specifically for use in the kitchen cooking areas shall also be permitted. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. EXHAUST SYSTEMS
513.12 Solid-Fuel Fire-Extinguishing Equipment. ¶
513.12 Solid-Fuel Fire-Extinguishing Equipment. Where solid-fuel cooking equipment is served by fire extinguishing equipment, the provisions of Section 517.0 shall apply .
514.0 Procedures for the Use, Inspection, Testing, and ¶
514.0 Procedures for the Use, Inspection, Testing, and Maintenance of Equipment.
514.1 Operating Procedures. Exhaust systems shall be ¶
514.1 Operating Procedures. Exhaust systems shall be operated whenever cooking equipment is turned on. [NFPA 96:12.1.1] 514.1.1 Filters. Filter-equipped exhaust systems shall not be operated with filters removed. [NFPA 96:12.1.2] 514.1.2 Openings. Openings provided for replacing air exhausted through ventilating equipment shall not be restricted by covers, dampers, or any other means that would reduce the operating efficiency of the exhaust system. [NFPA 96:12.1.3] 514.1.3 Posting of Instructions. Instructions for manually operating the fire-extinguishing system shall be posted conspicuously…
514.2 Inspection, Testing, and Maintenance. ¶
514.2 Inspection, Testing, and Maintenance. Maintenance of the fire-extinguishing systems and listed exhaust hoods containing a constant or fire-activated water system that is listed to extinguish a fire in the grease removal devices, hood exhaust plenums, and exhaust ducts shall be made by properly trained, qualified, and certified person(s) acceptable to the Authority Having Jurisdiction at least every 6 months. [NFPA 96:12.2.1] 514.2.1 Requirements. All actuation and control components, including remote manual pull stations, mechanical and electrical devices, detectors, and actuators,…
514.3 Inspection for Grease Buildup. The entire exhaust ¶
514.3 Inspection for Grease Buildup. The entire exhaust system shall be inspected for grease buildup by a properly trained, qualified, and certified person(s) acceptable to the Authority Having Jurisdiction and in accordance with Table 514.3. [NFPA 96:12.4] TABLE 514.3 SCHEDULE OF INSPECTION FOR GREASE BUILDUP [NFPA 96: TABLE 12.4] TYPE OR VOLUME OF COOKINGINSPECTION ------ Systems serving solid fuel cooking operations.Monthly <br <br<brSystems serving high-volume cooking opera-<brtions.1Quarterly <br <brSystems serving moderate-volume cooking oper-<brations.Semiannually <br<brSystems serving…
514.4 Cleaning of Exhaust Systems. If, upon inspection, ¶
514.4 Cleaning of Exhaust Systems. If, upon inspection, the exhaust system is found to be contaminated with deposits from grease-laden vapors, the contaminated portions of the exhaust system shall be cleaned by a properly trained, qualified, and certified person(s) acceptable to the Authority Having Jurisdiction. [NFPA 96:12.6.1] 514.4.1 Measurement System. A measurement system of deposition shall be established to trigger a need to clean when the exhaust system is inspected at the frequencies in Table 514.3. [NFPA 96:12.6.1.1] 514.4.1.1 Combustible Contaminants. Hoods, grease removal…
514.5 Cooking Equipment Maintenance. Inspection and ¶
514.5 Cooking Equipment Maintenance. Inspection and servicing of the cooking equipment shall be made at least annually by properly trained and qualified persons. [NFPA 96:12.7.1] 514.5.1 Cleaning. Cooking equipment that collects grease below the surface, behind the equipment, or in cooking equipment flue gas exhaust, such as griddles, deep-fat fryers, or charbroilers, shall be inspected and, if found with grease accumulation, cleaned by a properly trained, qualified, and certified person(s) acceptable to the Authority Having Jurisdiction. [NFPA 96:12.7.2]
515.0 Minimum Safety Requirements for Cooking ¶
515.0 Minimum Safety Requirements for Cooking Equipment.
515.1 Cooking Equipment. Cooking equipment shall be ¶
515.1 Cooking Equipment. Cooking equipment shall be approved based on one of the following criteria: (1) Listings by a testing laboratory. (2) Test data acceptable to the Authority Having Jurisdiction. [NFPA 96:13.1.1] 515.1.1 Installation. All listed appliances shall be installed in accordance with the terms of their listings and the manufacturer’s instructions. Solid fuel used for flavoring within a gas-operated appliance shall be in a solid fuel holder (smoker box) that is listed with the equipment. [NFPA 96:13.1.2.1, 13.1.2.1.1] ), Copyright © 2025 IAPMO, and may not be used for any other…
515.2 Operating Controls. Deep-fat fryers shall be equipped ¶
515.2 Operating Controls. Deep-fat fryers shall be equipped with a separate high-limit control in addition to the adjustable operating control (thermostat) to shut off fuel or energy when the fat temperature reaches 475°F (246°C) at 1 inch (25.4 mm) below the surface. [NFPA 96:13.2]
516.0 Recirculating Systems. ¶
516.1 General Requirements. ¶
516.1 General Requirements. Recirculating systems containing or for use with appliances used in processes producing smoke or grease-laden vapors shall be equipped with components complying with the following: (1) The clearance requirements of Section 507.4 through Section 507.4.3.3. (2) A hood complying with the requirements of Section 508.0. (3) Grease removal devices complying with Section 509.0. (4) The air movement requirements of Section 511.2.1 and Section 511.2.2. (5) Auxiliary equipment (such as particulate and odor removal devices) complying with Section 512.0. (6) Fire-extinguishing…
516.2 Design Restrictions. All recirculating systems shall ¶
516.2 Design Restrictions. All recirculating systems shall comply with the requirements of Section 516.2.1 through Section 516.2.9. [NFPA 96:14.2] 516.2.1 Gas/Electrically Fueled Cooking Appli- ances. Only gas-fueled or electrically fueled cooking appliances shall be used. Listed gas-fueled equipment designed for use with specific recirculating systems shall have the flue outlets connected in the intended manner. Gas-fueled appliances shall have a minimum 18 inches (457 mm) clearance from the flue outlet to the filter inlet in accordance with Section 509.2.2 through Section 509.2.2.3 and…
516.3 Interlocks. The recirculating system shall be provided ¶
516.3 Interlocks. The recirculating system shall be provided with interlocks of all critical components and operations as indicated in Section 516.3.1 through Section 516.3.3.1 such that, if any of these interlocks are interrupted, the cooking appliance will not be able to operate. [NFPA 96:14.3.1] 516.3.1 Airflow Sections. All closure panels encompassing airflow sections shall have interlocks to ensure that the panels are in place and fully sealed. [NFPA 96:14.3.2] 516.3.2 Filter Component. Each filter component (grease and odor) shall have an interlock to prove the component is in place.…
516.4 Location and Application Restrictions. The ¶
516.4 Location and Application Restrictions. The location of recirculating systems shall be approved by the Authority Having Jurisdiction. Items to be reviewed in the fire risk assessment shall include, but not be limited to, life safety, combustibility of surroundings, proximity to air vents, and total fuel load. [NFPA 96:14.4.1 – 14.4.2]
516.5 Additional Fire Safety Requirements. ¶
516.5 Additional Fire Safety Requirements. In addition to the appliance nozzle(s), a recirculating system shall be listed with the appropriate fire protection for grease filters, grease filtration, odor filtration units, and ductwork, where applicable. [NFPA 96:14.5.1] 516.5.1 Installation Downstream. In addition to any other fire-extinguishing system actuation device, there shall be a fire-extinguishing system actuation device installed downstream of any ESP. [NFPA 96:14.5.2] 516.5.2 Locations. The requirements of Section 513.6 shall also apply to recirculating system locations. [NFPA…
516.6 Use and Maintenance. ¶
516.6 Use and Maintenance. Automatic or manual covers on cooking appliances, especially fryers, shall not inter fere with the application of the fire suppression system. [NFPA 96:14.6.1] 516.6.1 Manufacturer’s Instructions. All filters shall be cleaned or replaced in accordance with the manufacturer’s instructions. [NFPA 96:14.6.2] 516.6.2 Cleaning Schedule. All ESPs shall be cleaned a minimum of once per week and according to the manufacturer’s cleaning instructions. [NFPA 96:14.6.3] 516.6.3 Hood Plenum and Blower Section Clean- ing Schedule. The entire hood plenum and the blower section…
517.0 Solid-Fuel Cooking Operations. ¶
517.0 Solid-Fuel Cooking Operations.
517.1 Venting Application. ¶
517.1 Venting Application. Venting requirements of solidfuel cooking operations shall be determined in accordance with Section 517.1.1 through Section 517.1.6. [NFPA 96:15.1] 517.1.1 Natural Draft. Where solid-fuel cooking equipment is required by the manufacturer to have a natural draft, the vent shall comply with Section 517.4. [NFPA 96:15.1.1] 517.1.2 System Compliance. Where the solid-fuel cooking equipment has a self-contained top, is the appliance to be vented in an isolated space (except for a single water heater with its own separate vent), has a separate makeup air system, and is…
517.2 Location of Appliances. For cooking operations in ¶
517.2 Location of Appliances. For cooking operations in buildings, every appliance shall be located with respect to building construction and other equipment so as to permit access to the appliance. [NFPA 96:15.2.1] 517.2.1 Prohibited Location. Solid-fuel cooking appliances shall not be installed in confined spaces. [NFPA 96:15.2.2] Exception: Solid-fuel cooking appliances listed for installation in confined spaces such as alcoves shall be installed in accordance with the terms of the listing and the manufacturer’s instructions. [NFPA 96:15.2.3] 517.2.2 Flammable Vapors. Solid-fuel cooking…
517.3 Hoods for Solid-Fuel Cooking. Hoods shall be sized ¶
517.3 Hoods for Solid-Fuel Cooking. Hoods shall be sized and located in a manner capable of capturing and containing all the effluent discharging from the appliances. The hood and its exhaust system shall comply with the requirements of Section 508.0 through Section 513.0. [NFPA 96:15.3.1, 15.3.2] 517.3.1 Separation. Except as permitted in Section 517.3.1.1, exhaust systems serving solid-fuel cooking equipment in buildings, including gas or electrically operated equipment, shall be separate from all other exhaust systems. [NFPA 96:15.3.3] Exception: Cooking equipment not requiring automatic…
517.4 Exhaust Systems for Solid-Fuel Cooking. Where ¶
517.4 Exhaust Systems for Solid-Fuel Cooking. Where a hood is not required, in buildings where the duct system is three stories or less in height, a duct complying with Section 510.0 shall be provided. [NFPA 96:15.4] 517.4.1 Hood. If a hood is used in buildings where the duct system is three stories or less in height, the duct system shall comply with Section 510.0. [NFPA 96:15.4.1] 517.4.2 Building Exceeding Four Stories. A listed or approved grease duct system that is four stories in height or greater shall be provided for solid-fuel cooking exhaust systems. [NFPA 96:15.4.2] 517.4.3…
517.5 Grease Removal Devices for Solid-Fuel Cook- ¶
517.5 Grease Removal Devices for Solid-Fuel Cook- ing. Grease removal devices shall be constructed of steel or stainless steel or be approved for solid-fuel cooking. [NFPA 96:15.5.1] 517.5.1 Spark Arrester Devices. If airborne sparks and embers can be generated by the solid fuel cooking operation, spark arrester devices shall be used prior to using the grease removal device, to minimize the entrance of these sparks and embers into the grease removal device and into the hood and the duct system. [NFPA 96:15.5.2] 517.5.2 Filters. Filters shall be a minimum of 4 feet (1219 mm) above the…
517.6 Air Movement for Solid-Fuel Cooking. Exhaust ¶
517.6 Air Movement for Solid-Fuel Cooking. Exhaust system requirements shall comply with Section 511.0 for hooded operation or shall be installed in accordance with the manufacturer’s recommendations for unhooded applications. [NFPA 96:15.6.1] 130 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. EXHAUST SYSTEMS 517.6.1 Replacement Air. A replacement or makeup air system shall be provided to ensure a positive supply of replacement air at all times during cooking operations. [NFPA 96:15.6.2]…
517.7 Fire-Extinguishing Equipment for Solid-Fuel ¶
517.7 Fire-Extinguishing Equipment for Solid-Fuel Cooking. Solid-fuel cooking appliances that produce greaseladen vapors shall be protected by listed fire-extinguishing equipment. Exception: Where acceptable to the Authority Having Jurisdiction, solid-fuel cooking appliances constructed of solid masonry or reinforced Portland or refractory cement concrete and vented in accordance with NFPA 211 shall not require fixed automatic fire-extinguishing equipment. [NFPA 96:15.7.1, 15.7.2] 517.7.1 Grease Removal Devices, Hoods, and Duct Systems. Listed fire-extinguishing equipment shall be provided…
517.8 Other Safety Requirements. ¶
517.8 Other Safety Requirements. Metal-fabricated solidfuel cooking appliances shall be listed for the application where produced in practical quantities or shall be approved by the Authority Having Jurisdiction. Where listed, metal-fabricated solid fuel cooking appliances shall be installed in accordance with the terms of their listings and with the applicable requirements of this chapter. [NFPA 96:15.9.4.1, 15.9.4.2] 517.8.1 Site-Built Solid Fuel Cooking Appliances. Site-built solid-fuel cooking appliances shall be submitted for approval to the Authority Having Jurisdiction before being…
518.0 Downdraft Appliances. ¶
518.1 General. Downdraft appliance ventilation system ¶
518.1 General. Downdraft appliance ventilation system containing or for use with appliances used in processes pro ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. EXHAUST SYSTEMS ducing smoke or grease-laden vapors shall be equipped with components complying with the following: (1) The clearance requirements of Section 507.4 through Section 507.4.3.3. (2) The primary collection means designed for collecting cooking vapors and residues complying with the requirements of Section 508.0. (3) Grease removal devices complying with…
518.2 Ventilation System. ¶
518.2 Ventilation System. The downdraft appliance ventilation system shall be capable of capturing and containing all the effluent discharge from the appliance(s) it is serving. [NFPA 96:16.1.2]
518.3 Fire-Extinguishing Equipment. ¶
518.3 Fire-Extinguishing Equipment. For fire-extinguishing equipment on downdraft appliance ventilation systems, the following shall apply: (1) Cooking surface, duct, and plenum protection shall be provided. (2) At least one fusible link or heat detector shall be installed within each exhaust duct opening in accordance with the manufacturer’s listing. (3) A fusible link or heat detector shall be provided for each protected cooking appliance located in the plenum area of that appliance or in accordance with the extinguishing system manufacturer’s listing. (4) A manual actuation device shall be…
518.4 Airflow Switch or Transducer. An airflow switch or ¶
518.4 Airflow Switch or Transducer. An airflow switch or transducer shall be provided after the last filter component to ensure that a minimum airflow is maintained. [NFPA 96:16.3.1] 518.4.1 Interlocks. The airflow switch or transducer shall open the interlock circuit when the airflow falls 25 percent below the system’s normal operating flow or less than 10 percent its listed minimum rating, whichever is lower. [NFPA 96:16.3.2] 518.4.2 Manual Reset. The airflow switch or transducer shall be a manual reset device or circuit. [NFPA 96:16.3.3]
518.5 Surface Materials. Any surface located directly ¶
518.5 Surface Materials. Any surface located directly above the cooking appliance shall be of noncombustible or limited-combustible materials. [NFPA 96:16.4]
519.0 Type II Hood Exhaust System Requirements. ¶
519.0 Type II Hood Exhaust System Requirements.
519.1 Where Required. Type II hoods shall be installed ¶
519.1 Where Required. Type II hoods shall be installed above equipment and dishwashers that generate steam, heat, or products of combustion, and where grease or smoke is not present. Exceptions: (1) Dishwashing machines connected to a Type II duct system and exhausted directly to the outdoors. (2) Dishwashing machines with a self-contained condensing system listed in accordance with UL 921 and installed in a space where the HVAC system has been engineered to accommodate the latent and sensible heat load emitted from such appliances as approved by the Authority Having Jurisdiction. Such…
519.2 Construction of Type II Hoods. Type II hoods ¶
519.2 Construction of Type II Hoods. Type II hoods constructed of steel shall be not less than 0.024 of an inch (0.61 mm) (No. 24 gauge). Hoods constructed of copper shall be of copper sheets weighing not less than 0.17 ounces per square inch (oz/in [2] ) (7.47 kg/m [2] ). Joints and seams shall be substantially tight. Solder shall not be used except for sealing a joint or seam.
519.3 Type II Hood Exhaust System Net Airflow. The ¶
519.3 Type II Hood Exhaust System Net Airflow. The net airflow for Type II hoods shall be in accordance with Section 508.5.1.5 for light-duty cooking appliances. The net airflow for Type II hoods serving dishwashing appliances shall comply with Section 519.3.1. 519.3.1 Dishwashing Appliances. The net airflow for Type II hoods used for dishwashing equipment shall be not less than 200 cubic feet per minute (0.094 m [3] /s) per linear foot (m) of hood length.
519.4 Type II Exhaust Duct Systems. Ducts and ¶
519.4 Type II Exhaust Duct Systems. Ducts and plenums serving Type II hoods shall be constructed of rigid metallic materials in accordance with Chapter 6. Duct bracing and supports shall comply with Chapter 6. Ducts subject to positive pressure shall be adequately sealed.
519.5 Termination of Type II Hood Exhaust System. ¶
519.5 Termination of Type II Hood Exhaust System. The exhaust system shall terminate in accordance with Section 502.2.2. Rooftop terminations shall be directed away « 132 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. EXHAUST SYSTEMS from roof surfaces within 40 inches (1016 mm). The discharge outlet of moisture conveying exhaust ducts, such as dishwasher exhaust ducts, shall not terminate over a public way or over an area where condensate or vapor could create a nuisance or hazard.
519.6 Makeup Air. Makeup air shall be provided in accordance with Section 511.3. ¶
519.6 Makeup Air. Makeup air shall be provided in accordance with Section 511.3.
519.7 Independent Exhaust Duct System. Single or ¶
519.7 Independent Exhaust Duct System. Single or combined Type II exhaust systems shall be independent of all other exhaust systems. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. 134 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE CHAPTER 6 – DUCT SYSTEMS (Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency…
601.0 General. ¶
601.1 Applicability. Ducts and plenums that are portions of ¶
601.1 Applicability. Ducts and plenums that are portions of a heating, cooling, ventilation, or exhaust system shall comply with the requirements of this chapter, Chapter 5 for exhaust ducts, and Chapter 7 for combustion air ducts.
601.2 Sizing Requirements. Duct systems shall be sized ¶
601.2 Sizing Requirements. Duct systems shall be sized in accordance with applicable standards in Chapter 18 or by other approved methods. Exception: Residential duct systems shall be sized in accordance with ACCA Manual D, ACCA Manual Zr, as applicable, or by other approved methods. 601.2.1 California Energy Code Residential Return Duct Sizing Requirements. California Energy Code Tables 150.0-B and 150.0-C specify return duct sizing requirements for single return and multiple return duct systems, respectively, that are applicable as an alternative to confirming system airflow via field…
602.0 Material. ¶
602.1 General. ¶
602.1 General. Materials used for duct systems shall comply with Section 602.2 through Section 602.7 as applicable. Exception: [OSHPD 1, 1R, 2, 3, 4 & 5] See Section 407.4.2. [Not permitted for OSHPD 1, 1R, 2, 3, 4 & 5] Concealed building spaces or independent construction within buildings shall be permitted to be used as ducts or plenums. Gypsum board shall not be used for positive pressure ducts. Exception: In healthcare facilities, concealed spaces shall not be permitted to be used as ducts or plenums.
602.2 Combustibles Within Ducts or Plenums. ¶
602.2 Combustibles Within Ducts or Plenums. Materials exposed within ducts or plenums shall be noncombustible or shall have a flame spread index not to exceed 25 and a smoke-developed index not to exceed 50, where tested as a composite product in accordance with ASTM E84 or UL 723. Plastic piping installed in plenums shall be tested in accordance with all requirements of ASTM E84 or UL 723. Mounting methods, supports and sample sizes of materials for testing that are not specified in ASTM E84 or UL 723 shall be prohibited. Exceptions: (1) Return-air and outside-air ducts, plenums, or…
602.3 Tall Wood (Mass Timber) Buildings. ¶
602.3 Tall Wood (Mass Timber) Buildings. Duct systems installed in tall wood (mass timber) buildings shall comply with the following: (1) Be designed by a registered design professional in accordance with this code and the building code. (2) Be designed to accommodate expansion, contraction, and differential movement between parts of a tall wood (mass timber) building in accordance with Section 316.2. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. DUCT SYSTEMS » » » » » » » »
602.4 Metallic. Ducts, plenums, or fittings of metal shall ¶
602.4 Metallic. Ducts, plenums, or fittings of metal shall comply with SMACNA HVAC Duct Construction Standards – Metal and Flexible. Flexible metallic ducts shall comply with UL 181.
602.5 Nonmetallic Ducts. Nonmetallic ducts shall comply ¶
602.5 Nonmetallic Ducts. Nonmetallic ducts shall comply with Section 602.5.1, Section 602.5.2, Section 602.5.3, Section 602.5.4, or Section 602.5.5. 602.5.1 Phenolic. Phenolic duct, plenum, or fitting material shall comply with UL 181. Ducts, plenums, or fittings of phenolic shall be constructed in accordance with SMACNA Phenolic Duct Construction Standards or the conditions of its listing. 602.5.2 Gypsum. Where gypsum products are exposed in ducts or plenums, the air temperature shall be restricted to a range from 50°F (10°C) to 125°F (52°C), and moisture content shall be controlled so that…
602.6 Vibration Isolators. Vibration isolation connectors ¶
602.6 Vibration Isolators. Vibration isolation connectors installed between mechanical equipment and metal ducts (or casings) shall be made of an approved material and shall not exceed 10 inches (254 mm) in length.
602.7 Corridors. Corridors shall not be used to convey air to ¶
602.7 Corridors. Corridors shall not be used to convey air to or from rooms where the corridor is required to be of fire-resistive construction in accordance with the building code except where permitted by the building code. Corridors shall not serve as supply, return, exhaust, relief, or ventilation air ducts.
603.0 Installation of Ducts. ¶
603.1 General. Air ducts shall be installed in accordance ¶
603.1 General. Air ducts shall be installed in accordance with this chapter and the installation instructions. 603.1.1 Pressure Classification. The pressure classification of ducts shall be not less than the design operating pressure of the air distribution in which the duct is utilized. All ducts regardless of pressure classification(s) shall be sealed to Seal Class A. 603.1.2 Air Temperature. The temperature of the air to be conveyed in a duct shall not exceed 250°F (121°C). 603.1.3 Protection. Air ducts, other than plastic ducts, shall be installed with not less than 4 inches (102 mm) of…
603.2 Under-Floor or Crawl Space. Air ducts installed ¶
603.2 Under-Floor or Crawl Space. Air ducts installed under a floor in a crawl space shall be installed in accordance with the following: (1) Shall not prevent access to an area of the crawl space. (2) Where it is required to move under ducts for access to areas of the crawl space, a vertical clearance of not less than 18 inches (457 mm) shall be provided.
603.3 Metal Ducts. Ducts shall be supported at each change ¶
603.3 Metal Ducts. Ducts shall be supported at each change of direction and in accordance with SMACNA HVAC Duct Construction Standards – Metal and Flexible. Riser ducts shall be held in place by means of metal straps or angles and channels to secure the riser to the structure. Ducts shall be installed in a building with clearances that will retain the full thickness of fireproofing on structural members.
603.4 Flexible Air Ducts. Flexible air ducts shall comply ¶
603.4 Flexible Air Ducts. Flexible air ducts shall comply with UL 181, and shall be installed in accordance with the manufacturer’s installation instructions and SMACNA HVAC Duct Construction Standards – Metal and Flexible. Flexible air duct installations shall comply with the following: (1) Ducts shall be installed using the minimum required length to make the connection. (2) Horizontal duct runs shall be supported at not more than 4 feet (1219 mm) intervals. (3) Vertical risers shall be supported at not more than 6 feet (1829 mm) intervals. (4) Sag between support hangers shall not exceed…
603.5 Plastic Ducts. Plastic air ducts and fittings shall be ¶
603.5 Plastic Ducts. Plastic air ducts and fittings shall be permitted where installed underground and listed for such use.
603.6 Protection of Ducts. Ducts installed in locations ¶
603.6 Protection of Ducts. Ducts installed in locations where they are exposed to mechanical damage by vehicles or from other causes shall be protected by approved barriers. 603.6.1 Weather Protection. Ducts installed on the exterior of the building shall be protected against the ele ments.
603.7 Support of Ducts. Ducts shall be supported in ¶
603.7 Support of Ducts. Ducts shall be supported in accordance with the manufacturer’s installation instructions; and Section 603.7.1, Section 603.7.2 or Section 603.7.3. 603.7.1 Metal Ducts. Ducts shall be supported at each change of direction and in accordance with SMACNA HVAC Duct Construction Standards – Metal and Flexible. Riser ducts shall be held in place by means of metal straps or angles and channels to secure the riser to the structure. 603.7.1.1 Rectangular Ducts. Supports for rectangular ducts shall be installed on two opposite sides of each duct and shall be riveted, bolted, or…
603.8 Protection Against Flood Damage. ¶
603.8 Protection Against Flood Damage. In flood hazard areas, ducts shall be located above the elevation required by the building code for utilities and attendant equipment or the elevation of the lowest floor, whichever is higher, or shall be designed and constructed to prevent water from entering or accumulating within the ducts during floods up to such elevation. Where the ducts are located below that elevation, the ducts shall be capable of resisting hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy, during the occurrence of flooding to such elevation.
603.9 Joints and Seams of Ducts. Joints and seams for ¶
603.9 Joints and Seams of Ducts. Joints and seams for duct systems shall comply with SMACNA HVAC Duct Construction Standards – Metal and Flexible, SMACNA Round Industrial Duct Construction Standards, or SMACNA Rectangular Industrial Duct Construction Standards, as applicable. Joints of duct systems shall be made substantially airtight by means of tapes, mastics, gasketing, or other means. All ducts shall be sealed to Seal Class A. Crimp joints for round ducts shall have a contact lap of not less than 1 [1] ⁄ 2 inches (38 mm) and shall be mechanically fastened by means of not less than three…
603.10 Cross Contamination. Exhaust ducts that convey ¶
603.10 Cross Contamination. Exhaust ducts that convey Class 4 air shall be negatively pressurized relative to ducts, plenums, or occupiable spaces through which the ducts pass. Exhaust ducts under positive pressure that convey Class 2 or Class 3 air shall not extend into or pass through ducts, plenums, or occupiable spaces other than the space from which the exhaust air is drawn.
603.11 Underground Installation. ¶
603.11 Underground Installation. Ducts installed underground shall be approved for the installation and shall have a slope of not less than [1] ⁄ 8 inch per foot (10.4 mm/m) back to the main riser. Ducts, plenums, and fittings shall be permitted to be constructed of concrete, clay, or ceramics where installed in the ground or in a concrete slab, provided the joints are sealed and duct is secured in accordance with SMACNA HVAC Duct Construction Standards – Metal and Flexible. Metal ducts where installed in or under a concrete slab shall be encased in not less than 2 inches (51 mm) of concrete,…
603.12 Air Dispersion Systems. ¶
603.12 Air Dispersion Systems. Where installed, air dispersion systems shall be completely in exposed locations in duct systems under positive pressure, and not pass through or penetrate fire-resistant-rated construction. Air dispersion systems shall be listed and labeled in accordance with UL 2518.
603.13 Clearances. Duct clearances shall be in accordance ¶
603.13 Clearances. Duct clearances shall be in accordance with Section 603.13.1 through Section 603.13.6. 603.13.1 General. Duct clearances to combustible construction shall be in accordance with the listing and the manufacturer’s installation instructions. 603.13.2 Supply Air Ducts to Listed Furnaces. Supply air ducts connecting to listed central heating furnaces shall have the same minimum clearance to combustibles as required for the furnace supply plenum for a distance of not less than 3 feet (914 mm) from the supply plenum. Clearance shall not be required beyond the 3 feet (914 mm)…
604.0 Furnace Plenums and Air Ducts Used in Fuel- ¶
604.0 Furnace Plenums and Air Ducts Used in Fuel- Gas Appliances.
604.1 Furnace Plenums and Air Ducts. Furnace plenums ¶
604.1 Furnace Plenums and Air Ducts. Furnace plenums and air ducts shall be installed in accordance with this Chapter, and NFPA 90A or NFPA 90B. {NFPA 54:10.3.8.1}
604.2 Supplied as a Part of Furnace. A furnace plenum ¶
604.2 Supplied as a Part of Furnace. A furnace plenum supplied as a part of a furnace shall be installed in accordance with the manufacturer’s instructions. [NFPA 54:10.3.8.2]
604.3 Not Supplied with the Furnace. Where a furnace ¶
604.3 Not Supplied with the Furnace. Where a furnace plenum is not supplied with the furnace, any fabrication and installation instructions provided by the manufacturer shall be followed. The method of connecting supply and return ducts shall facilitate proper circulation of air. [NFPA 54:10.3.8.3]
604.4 Return Air. Where a furnace is installed so supply ¶
604.4 Return Air. Where a furnace is installed so supply ducts carry air circulated by the furnace to areas outside the space containing the furnace, the return air shall also be handled by a duct(s) sealed to the furnace casing and terminating outside the space containing the furnace. Return air shall not be taken from the mechanical room containing the furnace. [NFPA 54:10.3.8.4]
605.0 Insulation of Ducts. ¶
605.1 General. Air ducts conveying air at temperatures ¶
605.1 General. Air ducts conveying air at temperatures exceeding 140°F (60°C) shall be insulated to maintain an insulation surface temperature of not more than 140°F (60°C). Insulation material on the exterior of ducts shall be legibly printed with the name of the manufacturer, the thermal resistance (R) value at installed thickness, flame-spread index, and smoke developed index of the composite material. Internal duct liners and insulation shall be installed in accordance with SMACNA HVAC Duct Construction Standards – Metal and Flexible. [OSHPD 1, 1R, 2, 3, 4 & 5] Cold air ducts shall be…
605.2 [OSHPD 1, 3 (Surgical Clinics), 4 & 5] Thermal ¶
605.2 [OSHPD 1, 3 (Surgical Clinics), 4 & 5] Thermal acoustical lining materials shall not be installed within ducts, terminal boxes, sound traps, and other in-duct systems serving areas such as operating, cesarean operating rooms, delivery rooms, class 3 imaging, hybrid operating rooms, post anesthe- sia care units, cystoscopy, cardiac catheterization labs, nurs- eries, intensive care units, newborn intensive care units, protective environment rooms and airborne infection isolation rooms unless filters with 90 percent average efficiency based on ASHRAE Standard 52.2 or minimum efficiency…
605.3 [OSHPD 1, 2, 4 & 5] Thermal or acoustical lining ¶
605.3 [OSHPD 1, 2, 4 & 5] Thermal or acoustical lining materials shall not be installed within ducts which are down- stream of the 99.97 percent high-efficiency particulate air (HEPA) filter required in Section 408.2.1 for protective envi- ronment rooms. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. DUCT SYSTEMS
606.0 Smoke Dampers, Fire Dampers, and Ceiling ¶
606.0 Smoke Dampers, Fire Dampers, and Ceiling Dampers.
606.1 Smoke Dampers. Smoke dampers shall comply ¶
606.1 Smoke Dampers. Smoke dampers shall comply with UL 555S, and shall be installed in accordance with the manufacturer’s installation instructions where required by the California Building Code or California Residential Code .
606.2 Fire Dampers. Fire dampers shall comply with UL ¶
606.2 Fire Dampers. Fire dampers shall comply with UL 555, and shall be installed in accordance with the manufacturer’s installation instructions where required by the building code. Fire dampers shall have been tested for closure under airflow conditions and shall be labeled for both maximum airflow permitted and direction of flow. Where more than one damper is installed at a point in a single air path, the entire airflow shall be assumed to be passing through the smallest damper area. Ductwork shall be connected to damper sleeves or assemblies in accordance with the fire damper…
606.3 Ceiling Radiation Dampers. Ceiling radiation ¶
606.3 Ceiling Radiation Dampers. Ceiling radiation dampers shall comply with UL 555C or shall be tested as part of a fire-resistance-rated floor-ceiling or roof-ceiling assembly in accordance with ASTM E119 or UL 263, and shall be installed in accordance with the manufacturer’s installation instructions in the fire-resistive ceiling membrane of floorceiling and roof-ceiling assemblies where required by the building code. Fire dampers not meeting the temperature limitation of ceiling radiation dampers shall not be used as a substitute.
606.4 Combination Fire/Smoke Dampers. ¶
606.4 Combination Fire/Smoke Dampers. Combination fire/smoke dampers shall comply with UL 555 and UL 555S and the requirements in Section 606.1 and Section 606.2. 606.4.1 When the automatic activation of a smoke damper or a combination smoke-fire damper occurs, the HVAC system serving such dampers shall immediately shut down. Exceptions: (1) HVAC systems that are part of an engineered smoke evacuation system. (2) Where the automatic activation causes all the smoke dampers and combination smoke-fire dampers to close in the enclosed space having a common atmos- phere where openings are required…
606.5 Corridor Dampers. Corridor dampers shall comply ¶
606.5 Corridor Dampers. Corridor dampers shall comply with the requirements of combination fire/smoke dampers in Section 606.4.
606.6 Periodic Testing and Inspection. Testing and ¶
606.6 Periodic Testing and Inspection. Testing and inspection of dampers shall be in accordance with the following: (1) Smoke dampers shall be tested in accordance with NFPA 105. (2) Fire dampers shall be tested in accordance with NFPA 80. (3) Combination fire/smoke dampers shall be tested in accordance with NFPA 80 and NFPA 105.
606.7 Multiple Arrangements. Where size requires the ¶
606.7 Multiple Arrangements. Where size requires the use of multiple dampers, each damper shall be listed for use in multiple arrangements and installed in accordance with the manufacturer’s installation instructions.
606.8 Access and Identification. Fire and smoke ¶
606.8 Access and Identification. Fire and smoke dampers shall be provided with an approved means of access large enough to allow inspection and maintenance of the damper and its operating parts. The access shall not affect the integrity of the fire-resistance-rated assembly. The access openings shall not reduce the fire-resistance rating of the assembly. Access shall not require the use of tools. Access doors in ducts shall be tight fitting and approved for the required duct construction. Access points shall be permanently identified on the exterior by a label with letters not less than [1] ⁄…
606.9 Freedom from Interference. Dampers shall be ¶
606.9 Freedom from Interference. Dampers shall be installed in a manner to ensure positive closing or opening as required by function. Interior liners or insulation shall be held back from portions of a damper, its sleeve, or adjoining duct that would interfere with the damper’s proper operation. Exterior materials shall be installed so as to not interfere with the operation or maintenance of external operating devices needed for the function of the damper.
606.10 Temperature Classification of Operating Ele- ¶
606.10 Temperature Classification of Operating Ele- ments. Fusible links, thermal sensors, and pneumatic or electric operators shall have a temperature rating or classification as in accordance with the building code.
607.0 Ventilating Ceilings. ¶
607.1 General. Perforated ceilings shall be permitted to be ¶
607.1 General. Perforated ceilings shall be permitted to be used for air supply within the limitations of this section. Exit corridors, where required to be of fire-resistive construction by the California Building Code, shall not have ventilating ceilings. 607.1.1 [OSHPD 1, 1R, 2, 3, 4 & 5] Ventilating ceil- ings are not permitted in health facilities.
607.2 Requirements. Ventilating ceilings shall comply ¶
607.2 Requirements. Ventilating ceilings shall comply with the following: (1) Suspended ventilating ceiling material shall have a Class 1 flame spread classification on both sides, determined in accordance with the building code. Suspended ventilating ceiling supports shall be of noncombustible materials. (2) Luminaires recessed into ventilating ceilings shall be of a type approved for that purpose. « « « « 142 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. DUCT SYSTEMS
608.0 Use of Under-Floor Space as Supply Plenum ¶
608.0 Use of Under-Floor Space as Supply Plenum for Dwelling Units.
608.1 General. An under-floor space shall be permitted to ¶
608.1 General. An under-floor space shall be permitted to be used as a supply plenum.
608.2 Dwelling Units. The use of under-floor space shall ¶
608.2 Dwelling Units. The use of under-floor space shall be limited to dwelling units not more than two stories in height. Except for the floor immediately above the underfloor plenum, supply ducts shall be provided extending from the plenum to registers on other floor levels. Exception: In flood hazard areas, under-floor spaces shall not be used as supply plenums unless the flood opening requirements in the building code are met.
608.3 Enclosed. Such spaces shall be cleaned of all loose ¶
608.3 Enclosed. Such spaces shall be cleaned of all loose combustible scrap material and shall be tightly enclosed.
608.4 Flammable Materials. The enclosing material of ¶
608.4 Flammable Materials. The enclosing material of the under-floor space, including the sidewall insulation, shall be not more flammable than 1 inch (25.4 mm) (nominal) wood boards (flame-spread index of 200). Installation of foam plastics is regulated by the building code.
608.5 Access. Access shall be through an opening in the ¶
608.5 Access. Access shall be through an opening in the floor and shall be not less than 24 inches by 24 inches (610 mm by 610 mm).
608.6 Automatic Control. A furnace supplying warm air ¶
608.6 Automatic Control. A furnace supplying warm air to under-floor space shall be equipped with an automatic control that will start the air-circulating fan where the air in the furnace bonnet reaches a temperature not exceeding 150°F (66°C). Such control shall be one that cannot be set to exceed 150°F (66°C).
608.7 Temperature Limit. A furnace supplying warm air to ¶
608.7 Temperature Limit. A furnace supplying warm air to such space shall be equipped with an approved temperature limit control that will limit outlet air temperature to 200°F (93°C).
608.8 Noncombustible Receptacle. A noncombustible ¶
608.8 Noncombustible Receptacle. A noncombustible receptacle shall be placed below each floor opening into the air chamber, and such receptacle shall comply with Section 608.8.1 through Section 608.8.3. 608.8.1 Location. The receptacle shall be securely suspended from the floor members and shall be not more than 18 inches (457 mm) below the floor opening. 608.8.2 Area. The area of the receptacle shall extend 3 inches (76 mm) beyond the opening on all sides. 608.8.3 Perimeter. The perimeter of the receptacle shall have a vertical lip not less than 1 inch (25.4 mm) high at the open sides where…
608.9 Floor Registers. Floor registers shall be designed ¶
608.9 Floor Registers. Floor registers shall be designed for easy removal in order to give access for cleaning the receptacles.
608.10 Exterior Wall and Interior Stud Partitions. ¶
608.10 Exterior Wall and Interior Stud Partitions. Exterior walls and interior stud partitions shall be fire blocked at the floor.
608.11 Wall Register. Each wall register shall be connected ¶
608.11 Wall Register. Each wall register shall be connected to the air chamber by a register box or boot.
608.12 Distance from Combustible. A duct complying ¶
608.12 Distance from Combustible. A duct complying with Section 602.0 shall extend from the furnace supply outlet not less than 6 inches (152 mm) below combustible framing.
608.13 Vapor Barrier. The entire ground surface of the ¶
608.13 Vapor Barrier. The entire ground surface of the under-floor space shall be covered with a vapor barrier having a thickness not less than 4 mils (0.1 mm) and a flamespread index of not more than 200.
608.14 Prohibited. Fuel gas lines and plumbing waste ¶
608.14 Prohibited. Fuel gas lines and plumbing waste cleanouts shall not be located within the space.
609.0 Automatic Shutoffs. ¶
609.1 Air-Moving Systems and Smoke Detectors. ¶
609.1 Air-Moving Systems and Smoke Detectors. Air-moving systems supplying air in excess of 2000 cubic feet per minute (ft [3] /min) (0.9439 m [3] /s) to enclosed spaces within buildings shall be equipped with an automatic shutoff. Automatic shutoff shall be accomplished by interrupting the power source of the air-moving equipment upon detection of smoke in the main supply-air duct downstream of both the fan and filters served by such equipment. Exceptions: (1) Where all portions of the building served by air-moving equipment returning air in excess of 2,000 cubic feet per minute (ft [3]…
609.2 Air-Moving Systems and Smoke Detectors in ¶
609.2 Air-Moving Systems and Smoke Detectors in Group I-2 Occupancies. In Group I-2 occupancies, air- moving systems returning air in excess of 2,000 cubic feet per minute (ft [3] /min) (0.9439 m [3] /s) from enclosed spaces within buildings shall be equipped with an automatic shutoff. Auto- matic shutoff shall be accomplished by interrupting the power source of the air-moving equipment upon detection of smoke in the return air duct or plenum upstream of any filters, exhaust air connections, outside air connections, or decont- amination equipment and appliances. Group I-2 occupancies having…
701.0 General. ¶
701.1 Applicability. Air for combustion, ventilation, and ¶
701.1 Applicability. Air for combustion, ventilation, and dilution of flue gases for appliances installed in buildings shall be obtained by application of one of the methods covered in Section 701.4 through Section 701.9.3. Where the requirements of Section 701.4 are not met, outdoor air shall be introduced in accordance with methods covered in Section 701.6 through Section 701.9.3. Exceptions: (1) This provision shall not apply to direct vent appliances. (2) Type 1 clothes dryers that are provided with makeup air in accordance with Section 504.4.1. [NFPA 54:9.3.1.1] 701.1.1 Other Types of…
701.2 Pressure Difference. Where used, a draft hood or a ¶
701.2 Pressure Difference. Where used, a draft hood or a barometric draft regulator shall be installed in the same room or enclosure as the appliance served so as to prevent any difference in pressure between the hood or regulator and the combustion air supply. [NFPA 54:9.3.1.4]
701.3 Makeup Air. Where exhaust fans, clothes dryers, and ¶
701.3 Makeup Air. Where exhaust fans, clothes dryers, and kitchen ventilation systems interfere with the operation of appliances, makeup air shall be provided. [NFPA 54:9.3.1.5]
701.4 Indoor Combustion Air. The required volume of ¶
701.4 Indoor Combustion Air. The required volume of indoor air shall be determined in accordance with the method in Section 701.4.1 or Section 701.4.2 except that where the air infiltration rate is known to be less than 0.40 ACH (air change per hour), the method in Section 701.4.2 shall be used. The total required volume shall be the sum of the required volume calculated for appliances located within the space. Rooms communicating directly with the space in which the appliances are installed through openings not furnished with doors, and through combustion air openings sized and located in…
701.5 Indoor Opening Size and Location. Openings ¶
701.5 Indoor Opening Size and Location. Openings used to connect indoor spaces shall be sized and located in accordance with the following: (1) Combining spaces on the same story. Each opening shall have a minimum free area of 1 square inch per 1000 Btu/h (0.002 m [2] /kW) of the total input rating of all appliances in the space, but not less than 100 square inches (0.065 m [2] ). One permanent opening shall commence within 12 inches (305 mm) of the top of the enclosure and one permanent opening shall commence within 12 inches (305 mm) of the bottom of the enclosure (see Figure 701.5). The…
701.6 Outdoor Combustion Air. Outdoor combustion air ¶
701.6 Outdoor Combustion Air. Outdoor combustion air shall be provided through opening(s) to the outdoors in accor ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. COMBUSTION AIR dance with the methods in Section 701.6.1 or Section 701.6.2. The minimum dimension of air openings shall not be less than FIGURE 701.5 ALL COMBUSTION AIR FROM ADJACENT INDOOR SPACES THROUGH INDOOR COMBUSTION AIR OPENINGS [NFPA 54: FIGURE A.9.3.2.3(1)] 701.6.1 Two Permanent Openings Method. Two permanent openings, one commencing within 12 inches (305…
701.7 Combination Indoor and Outdoor Combustion ¶
701.7 Combination Indoor and Outdoor Combustion Air. The use of a combination of indoor and outdoor com bustion air shall be in accordance with Section 701.7.1 through Section 701.7.3. [NFPA 54:9.3.4] (see Appendix F for example calculations) FIGURE 701.6.1(1) ALL COMBUSTION AIR FROM OUTDOORS – INLET AIR FROM VENTILATED CRAWL SPACE AND OUTLET AIR TO VENTILATED ATTIC [NFPA 54: FIGURE A.9.3.3.1(1)(a)] FIGURE 701.6.1(2) ALL COMBUSTION AIR FROM OUTDOORS THROUGH VENTILATED ATTIC [NFPA 54: FIGURE A.9.3.3.1(1)(b)] 148 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for…
701.8 Engineered Installations. Engineered combustion ¶
701.8 Engineered Installations. Engineered combustion air installations shall provide an adequate supply of combustion, ventilation, and dilution air determined using engineering methods. [NFPA 54:9.3.5]
701.9 Mechanical Combustion Air Supply. Where all ¶
701.9 Mechanical Combustion Air Supply. Where all combustion air is provided by a mechanical air supply system, the combustion air shall be supplied from outdoors at the minimum rate of not less than 0.35 cubic feet per minute per 1000 Btu/h [0.034 (m [3] /min)/kW] for all appliances located within the space. [NFPA 54:9.3.6] 701.9.1 Exhaust Fans. Where exhaust fans are installed, additional air shall be provided to replace the exhausted air. [NFPA 54:9.3.6.1] 701.9.2 Interlock. Each of the appliances served shall be interlocked to the mechanical air supply system to prevent main burner…
701.10 Louvers, Grilles, and Screens. The required size ¶
701.10 Louvers, Grilles, and Screens. The required size of openings for combustion, ventilation, and dilution air shall be based on the net free area of each opening. Where the free area through a design of louver, grille, or screen is known, it shall be used in calculating the size opening required to provide the free area specified. Where the louver and grille design and free area are not known, it shall be assumed that wood louvers have 25 percent free area and metal louvers and grilles have 75 percent free area. Nonmotorized louvers and grilles shall be fixed in the open position. [NFPA…
701.11 Combustion Air Ducts. Combustion air ducts shall ¶
701.11 Combustion Air Ducts. Combustion air ducts shall comply with the following [NFPA 54:9.3.8]: (1) Ducts shall be constructed of galvanized steel or a material having equivalent corrosion resistance, strength, and rigidity. Exception: Within dwellings units, unobstructed stud and joist spaces shall not be prohibited from conveying combustion air, provided that not more than one fireblock is removed. [NFPA 54:9.3.8.1] (2) Ducts shall terminate in an unobstructed space, allowing free movement of combustion air to the appliances. [NFPA 54:9.3.8.2] (3) Ducts shall serve a single space. [NFPA…
701.12 Dampers Prohibited. Combustion air ducts or ¶
701.12 Dampers Prohibited. Combustion air ducts or plenums shall not be installed so as to require openings in or penetrations through construction where fire dampers are required. Manually operated dampers shall not be installed in combustion air openings. With prior approval, power-actuated movable louvers admitting combustion air shall be permitted to be used and, where installed, shall be electrically interlocked with the main burner fuel-supply valve so as to prevent fuel delivery unless the louvers are in the fully open position.
702.0 Extra Device or Attachment. ¶
702.1 General. No device or attachment shall be installed ¶
702.1 General. No device or attachment shall be installed on any appliance that could in any way impair the combustion of gas. [NFPA 54:9.1.15] 150 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE CHAPTER 8 – CHIMNEYS AND VENTS (Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.) Adopting…
801.0 General. ¶
801.1 Applicability. The requirements of this chapter shall ¶
801.1 Applicability. The requirements of this chapter shall govern the venting of fuel-burning appliances.
801.2 Venting of Gas Appliances. Low-heat and ¶
801.2 Venting of Gas Appliances. Low-heat and medium-heat gas appliances shall be vented in accordance with this chapter. Other gas appliances shall be vented in accordance with NFPA 211 or other applicable standards.
801.3 Appliances Fueled by Other Fuels. Appliances ¶
801.3 Appliances Fueled by Other Fuels. Appliances fueled by fuels other than gas shall be vented in accordance with NFPA 211 and the appliance manufacturer’s instructions.
802.0 Venting of Appliances. ¶
802.1 Listing. ¶
802.1 Listing. Type B and Type B-W gas vents shall comply with UL 441, Type L gas vents shall comply with UL 641. 802.1.1 Installation. Listed chimneys and vents shall be installed in accordance with this chapter and the manufacturer’s installation instructions. [NFPA 54:12.2.1] 802.1.2 Prohibited Discharge. Appliance vents shall not discharge into a space enclosed by screens having openings less than [1] ⁄ 4 of an inch (6.4 mm) mesh.
802.2 Connection to Venting Systems. ¶
802.2 Connection to Venting Systems. Except as permitted in Section 802.2.1 through Section 802.2.7, all appliances shall be connected to venting systems. [NFPA 54:12.3.1] 802.2.1 Appliances Not Required to be Vented. The following appliances shall not be required to be vented: (1) Listed ranges. (2) Built-in domestic cooking units listed and marked for optional venting. (3) Listed hot plates. (4) Listed Type 1 clothes dryers exhausted in accordance with Section 504.4. (5) A single listed booster-type (automatic instantaneous) water heater, when designed and used solely for the sanitizing…
802.3 Minimum Safe Performance. Venting systems shall ¶
802.3 Minimum Safe Performance. Venting systems shall be designed and constructed to convey all flue and vent gases to the outdoors. [NFPA 54:12.1] 802.3.1 Appliance Draft Requirements. A venting system shall satisfy the draft requirements of the appliance in accordance with the manufacturer’s instructions. [NFPA 54:12.4.1] 802.3.2 Appliance Venting Requirements. Appliances required to be vented shall be connected to a vent ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. CHIMNEYS AND VENTS ing system designed and installed…
802.4 Type of Venting System to be Used. The type of ¶
802.4 Type of Venting System to be Used. The type of venting system to be used shall be in accordance with Table 802.4. [NFPA 54:12.5.1] 802.4.1 Plastic Piping. Where plastic piping is used to vent an appliance, the appliance shall be listed for use with such venting materials and the appliance manufacturer’s installation instructions shall identify the specific plastic piping material. The plastic pipe venting materials shall be labeled in accordance with the product standards specified by the appliance manufacturer or shall be listed and labeled in accordance with UL 1738. [NFPA 54:12.5.2]…
802.5 Masonry, Metal, and Factory-Built Chimneys. ¶
802.5 Masonry, Metal, and Factory-Built Chimneys. Chimneys shall be installed in accordance with Section 802.5.1 through Section 802.5.3. 802.5.1 Factory-Built Chimneys. Factory-built chimneys shall be listed in accordance with UL 103, UL 959, or UL 2561. Factory-built chimneys used to vent appliances that operate at positive vent pressure shall be listed for such application. [NFPA 54:12.6.1.1] 802.5.1.1 Decorative Shrouds. Decorative shrouds addressed in Section 802.5.4.3 shall comply with UL 103 for factory-built residential chimneys, UL 127 for factory-built fireplaces, or UL 1482 for…
802.6 Gas Vents. The installation of gas vents shall meet ¶
802.6 Gas Vents. The installation of gas vents shall meet the following requirements: (1) Gas vents shall be installed in accordance with the manufacturer’s installation instructions. (2) A Type B-W gas vent shall have a listed capacity not less than that of the listed vented wall furnace to which it is connected. (3) Gas vents installed within masonry chimneys shall be installed in accordance with the manufacturer’s installation instructions. Gas vents installed within masonry chimneys shall be identified with a permanent label installed at the point where the vent enters the chimney. The…
802.7 Single-Wall Metal Pipe. Single-wall metal pipe shall ¶
802.7 Single-Wall Metal Pipe. Single-wall metal pipe shall be constructed of galvanized sheet steel not less than 0.0304 of an inch (0.7722 mm) thick or of other approved, noncombustible, corrosion-resistant material. [NFPA 54:12.8.1] 802.7.1 Cold Climate. Uninsulated single-wall metal pipe shall not be used outdoors for venting appliances in regions where the 99 percent winter design temperature is below 32°F (0°C). [NFPA 54:12.8.2] 802.7.2 Termination. The termination of single-wall metal pipe shall meet the following requirements: (1) Single-wall metal pipe shall terminate at least 5 feet…
802.8 Through-the-Wall Vent Termination. ¶
802.8 Through-the-Wall Vent Termination. Throughthe-wall vent termination shall be in accordance with Section 802.8.1 through Section 802.8.3. 802.8.1 Clearance for Through-the-Wall Vent Ter- mination. The clearance for through-the-wall direct vent and non-direct vent terminals shall be in accordance with Table 802.8.1 and Figure 802.8.1. Exception: The clearances in Table 802.8.1 shall not apply to the combustion air intake of a direct vent appliance. [NFPA 54:12.9.1] 802.8.2 Annular Spaces. Where vents, including those for direct vent appliances or combustion air intake pipes, penetrate…
802.9 Condensation Drain. Provision shall be made to ¶
802.9 Condensation Drain. Provision shall be made to collect and dispose of condensate from venting systems serving Category II and Category IV appliances and noncategorized condensing appliances. [NFPA 54:12.10.1] 802.9.1 Installation. Drains for condensate shall be installed in accordance with the appliance and vent manufacturers’ installation instructions. [NFPA 54:12.10.2]
802.10 Vent Connectors for Category I Appliances. ¶
802.10 Vent Connectors for Category I Appliances. A vent connector shall be used to connect an appliance to a gas vent, chimney, or single-wall metal pipe, except where the gas vent, chimney, or single-wall metal pipe is directly connected to the appliance. [NFPA 54:12.11.1] 802.10.1 Materials. A vent connector shall be made of noncombustible, corrosion-resistant material capable of « « TABLE 802.7.3.3 CLEARANCE FOR CONNECTORS [NFPA 54: TABLE 12.8.4.4]Col2Col3Col4Col5 --------------- MINIMUM DISTANCE FROM COMBUSTIBLE MATERIAL (inches)MINIMUM DISTANCE FROM COMBUSTIBLE MATERIAL (inches)MINIMUM…
802.11 Vent Connectors for Category II, Category III, ¶
802.11 Vent Connectors for Category II, Category III, and Category IV Appliances. The vent connectors for Category II, Category III, and Category IV appliances shall be in accordance with Section 802.4 through Section 802.4.3. [NFPA 54:12.12]
802.12 Appliances Requiring Draft Hoods. Vented ¶
802.12 Appliances Requiring Draft Hoods. Vented appliances shall be installed with draft hoods. Exception: Dual oven-type combination ranges; direct vent appliances; fan-assisted combustion system appliances; appli » » » » 802.10.3.1 Height of Connector. Where two or more vent connectors enter a common vent, chimney flue, or single-wall metal pipe, the smaller connector shall enter at the highest level consistent with the available headroom or clearance to combustible material. [NFPA 54:12.11.4.2] 802.10.3.2 Pressure. Vent connectors serving Category I appliances shall not be connected to any…
802.13 Manually Operated Dampers. ¶
802.13 Manually Operated Dampers. A manually operated damper shall not be placed in any appliance vent connector. Fixed baffles and balancing baffles shall not be classified as manually operated dampers. Balancing baffles shall be mechanically locked in the desired position before placing the appliance in service. Balancing baffles shall be listed in accordance with UL 378. [NFPA 54:12.14.1 – 12.14.3]
802.14 Automatically Operated Vent Dampers. An ¶
802.14 Automatically Operated Vent Dampers. An automatically operated vent damper shall be listed. [NFPA 54:12.15] 802.14.1 Listing. Automatically operated vent dampers for oil-fired appliances shall comply with UL 17. The automatic damper control shall comply with UL 378.
802.15 Obstruction of Flow. Devices that retard the flow ¶
802.15 Obstruction of Flow. Devices that retard the flow of vent gases shall not be installed in a vent connector, chimney, or vent. The following shall not be considered as obstructions: (1) Draft regulators and safety controls specifically listed for installation in venting systems and installed in accordance with the manufacturer’s installation instructions. (2) Approved draft regulators and safety controls designed and installed in accordance with engineering methods. (3) Listed heat reclaimers and automatically operated vent dampers installed in accordance with the manufacturers’…
803.0 Sizing of Category I Venting Systems. ¶
803.0 Sizing of Category I Venting Systems.
803.1 Additional Requirements to Single Appliance ¶
803.1 Additional Requirements to Single Appliance Vent. Venting Table 803.1.2(1) through Table 803.1.2(6) shall not be used where obstructions are installed in the venting system. The installation of vents serving listed appliances with vent dampers shall be in accordance with the appliance manufacturer’s instructions or in accordance with the following: (1) The maximum capacity of the vent system shall be determined using the “NAT Max” column. (2) The minimum capacity shall be determined as though the appliance were a fan-assisted appliance, using the “FAN Min” column to determine the…
803.2 Additional Requirements to Multiple-Appliance ¶
803.2 Additional Requirements to Multiple-Appliance Vent. Venting Table 803.2(1) through Table 803.2(9) shall not be used where obstructions are installed in the venting system. The installation of vents serving listed appliances with vent dampers shall be in accordance with the appliance manufacturer’s instructions, or in accordance with the following: (1) The maximum capacity of the vent connector shall be determined using the NAT Max column. (2) The maximum capacity of the vertical vent or chimney shall be determined using the FAN + NAT column when the second appliance is a fan-assisted…
901.0 General. ¶
901.1 Applicability. This chapter addresses requirements for ¶
901.1 Applicability. This chapter addresses requirements for the design, construction, and installation of specific appliances. In addition to the requirements of this chapter, appliances shall comply with the general requirements of Chapter 3.
902.0 General. ¶
902.1 Nonindustrial Appliances. ¶
902.1 Nonindustrial Appliances. This chapter is applicable primarily to nonindustrial-type appliances and installations and, unless specifically indicated, does not apply to industrial-type appliances and installations. Listed appliances shall be installed in accordance with their listing and the manufacturer’s installation instructions or, as elsewhere specified in this chapter, as applicable to the appliance. Unlisted appliances shall be installed as specified in this part as applicable to the appliances.
902.2 Combustion Air from Bedroom or Bathroom. ¶
902.2 Combustion Air from Bedroom or Bathroom. Appliances shall not be installed so their combustion, ventilation, and dilution air are obtained only from a bedroom or bathroom unless the bedroom or bathroom has the required volume in accordance with Section 701.4. [NFPA 54:10.1.2] [OSHPD 1, 1R, 2, 4 & 5] Warm air furnaces shall not be installed under openable windows on exterior walls.
902.3 Added or Converted Appliances. ¶
902.3 Added or Converted Appliances. When additional or replacement appliances or equipment is installed or an appliance is converted to gas from another fuel, the location in which the appliances or equipment is to be operated shall be checked to verify the following: (1) Air for combustion and ventilation is provided where required, in accordance with the provisions of Section 701.0. Where existing facilities are not adequate, they shall be upgraded to meet Section 701.0 specifications. (2) The installation components and appliances meet the clearances to combustible material provisions of…
902.4 Type of Gas(es). The appliance shall be connected to ¶
902.4 Type of Gas(es). The appliance shall be connected to the fuel gas for which it was designed. No attempt shall be made to convert the appliance from the gas specified on the rating plate for use with a different gas without consulting the installation instructions, the serving gas supplier, or the appliance manufacturer for complete instructions. Listed appliances shall not be converted unless permitted by and in accordance with the manufacturer’s installation instructions. [NFPA 54:9.1.3]
902.5 Safety Shutoff Devices for Unlisted LP-Gas ¶
902.5 Safety Shutoff Devices for Unlisted LP-Gas Appliances Used Indoors. Unlisted appliances for use with undiluted LP-Gases and installed indoors, except attended laboratory equipment, shall be equipped with safety shutoff devices of the complete shutoff type. [NFPA 54:9.1.4]
902.6 Fuel Input Rate. The fuel input rate to the appliance ¶
902.6 Fuel Input Rate. The fuel input rate to the appliance shall not be increased or decreased in violation of the approved rating at the altitude where it is being used.
902.7 Use of Air or Oxygen Under Pressure. Where air ¶
902.7 Use of Air or Oxygen Under Pressure. Where air or oxygen under pressure is used in connection with the gas supply, effective means such as a back pressure regulator and relief valve shall be provided to prevent air or oxygen from passing back into the gas piping. Where oxygen is used, installation shall be in accordance with NFPA 51. [NFPA 54:9.1.5]
902.8 Appliance Support. Appliances and equipment ¶
902.8 Appliance Support. Appliances and equipment shall be furnished either with load-distributing bases or with a sufficient number of supports to prevent damage to either the building structure or the appliance and the equipment. [NFPA 54:9.1.8.1] 902.8.1 Structural Capacity. At the locations selected for installation of appliances and equipment, the dynamic and static load-carrying capacities of the building structure shall be checked to determine whether they are adequate to carry the additional loads. The appliances and equipment shall be supported and shall be connected to the piping so…
902.9 Flammable Vapors. Appliances shall not be ¶
902.9 Flammable Vapors. Appliances shall not be installed in areas where the open use, handling, or dispensing of flammable liquids occurs, unless the design, operation, or installation reduces the potential of ignition of the flammable vapors. Appliances installed in compliance with Section 305.1 through Section 305.1.2, Section 303.11, or Section 303.12 shall be considered to comply with the intent of this provision. [NFPA 54:9.1.9]
902.10 Solid-Fuel-Burning Appliances. ¶
902.10 Solid-Fuel-Burning Appliances. Unless otherwise specified, solid-fuel-burning appliances shall be installed in accordance with NFPA 211 and the manufacturer’s instal lation instructions.
902.11 Combination of Appliances and Equipment. ¶
902.11 Combination of Appliances and Equipment. Any combination of appliances, equipment, attachments, or devices used together in any manner shall comply with the standards that apply to the individual appliance and equipment. [NFPA 54:9.1.19]
902.12 Protection of Gas Appliances from Fumes or ¶
902.12 Protection of Gas Appliances from Fumes or Gases Other than Products of Combustion. Nondirect-vent appliances installed in beauty shops, barber shops, or other facilities where chemicals that generate corrosive or flammable products such as aerosol sprays are routinely used shall be located in a mechanical room separate or partitioned off from other areas with provisions for combustion and dilution air from outdoors. Direct vent appliances in such facilities shall be in accordance with the appliance manufacturer’s installation instructions. [NFPA 54:9.1.6.2] ), Copyright © 2025 IAPMO,…
903.3 Packaged Terminal Air Conditioners. Packaged ¶
903.3 Packaged Terminal Air Conditioners. Packaged terminal air conditioners and heat pumps shall comply with UL 484 or UL 60335-2-40, and shall be installed in accordance with the manufacturer’s installation instructions.
904.0 Central Heating Boilers and Furnaces. ¶
904.0 Central Heating Boilers and Furnaces.
904.1 Application. Central heating furnaces and boilers ¶
904.1 Application. Central heating furnaces and boilers shall be listed in accordance with the following: (1) Central heating furnaces and boilers having input ratings up to and including 400 000 Btu/hr (117 kW) shall be listed in accordance with the following as applicable: (a) Furnaces listed in accordance with CSA/ANSI Z21.47/CSA 2.3. ~~»~~ »
902.13 Process Air. In addition to air needed for combus ¶
902.13 Process Air. In addition to air needed for combus tion in commercial or industrial processes, process air shall be provided as required for cooling of appliances, equipment, or material; for controlling dew point, heating, drying, oxidation, dilution, safety exhaust, odor control, and air for compressors; and for comfort and proper working conditions for personnel. [NFPA 54:9.1.7]
902.14 Gas Appliance Pressure Regulators. Where the ¶
902.14 Gas Appliance Pressure Regulators. Where the gas supply pressure is higher than that at which the appliance is designed to operate or varies beyond the design pressure limits of the appliance, a gas appliance pressure regulator listed in accordance with CSA/ANSI Z21.18/CSA 6.3 shall be installed. [NFPA 54:9.1.17]
902.15 Bleed Lines for Diaphragm-Type Valves. Bleed ¶
902.15 Bleed Lines for Diaphragm-Type Valves. Bleed lines shall comply with the following requirements: (1) Diaphragm-type valves shall be equipped to convey bleed gas to the outdoors or into the combustion chamber adjacent to a continuous pilot. (2) In the case of bleed lines leading outdoors, means shall be employed to prevent water from entering this piping and also to prevent blockage of vents by insects and foreign matter. (3) Bleed lines shall not terminate in the appliance flue or exhaust system. (4) In the case of bleed lines entering the combustion chamber, the bleed line shall be…
903.0 Air-Conditioning Appliances. ¶
903.1 Electric Air Conditioners. Electric air conditioning ¶
903.1 Electric Air Conditioners. Electric air conditioning systems designed for permanent installation shall comply with UL 1995 or UL 60335-2-40.
903.2 Gas-Fired Air Conditioners and Heat Pumps. ¶
903.2 Gas-Fired Air Conditioners and Heat Pumps. Gas-fired air conditioners shall comply with Section 903.2.1 through Section 903.2.7. 903.2.1 Application. Gas-fired air conditioners and heat pumps shall be listed in accordance with ANSI Z21.40.1/CGA 2.91 or ANSI Z21.40.2/CGA 2.92. [NFPA 54:10.2.1] 903.2.2 Independent Gas Piping. Gas piping serving heating appliances shall be permitted to also serve cooling appliances where heating and cooling appliances cannot be operated simultaneously. [NFPA 54:10.2.2] 200 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for…
904.4 Assembly and Installation. A central heating ¶
904.4 Assembly and Installation. A central heating boiler or furnace shall be installed in accordance with the manufacturer’s instructions in one of the following manners: (1) On a floor of noncombustible construction with noncombustible flooring and surface finish and with no combustible material against the underside thereof. (2) On fire-resistive slabs or arches having no combustible material against the underside thereof. Exceptions: (1) Appliances listed for installation on a combustible floor. (2) Installation on a floor protected in an approved manner. [NFPA 54:10.3.4] 904.4.1…
904.2 Location. Central heating furnace and low-pressure ¶
904.2 Location. Central heating furnace and low-pressure boiler installations in bedrooms or bathrooms shall comply with one of the following: (1) Central heating furnaces and low-pressure boilers shall be permitted to be installed in a closet located in the bedroom or bathroom, provided the closet is equipped with a listed, gasketed door assembly, and a listed self-closing device. The self-closing door assembly shall comply with the requirements of Section 904.2.1. The door assembly shall be installed with a threshold and bottom door seal and shall comply with the requirements of Section…
904.3 Clearance. ¶
904.3 Clearance. Central heating furnaces and low-pressure boilers shall be provided with clearances in accordance with Section 904.3.1 through Section 904.3.7. 904.3.1 Listed Units. Listed central heating furnaces and low-pressure boilers shall be installed with clearances in accordance with the terms of their listings and the manufacturer’s installation instructions. {NFPA 54:10.3.3.1} 904.3.2 Unlisted Units. Unlisted central heating furnaces and low-pressure boilers shall be installed with clearances from combustible material not less than those specified in Table 904.3.2. [NFPA…
904.5 Temperature or Pressure Limiting Devices. ¶
904.5 Temperature or Pressure Limiting Devices. Steam and hot water boilers, respectively, shall be provided with approved automatic limiting devices for shutting down the burner(s) to prevent boiler steam pressure or boiler water temperature from exceeding the maximum allowable working pressure or temperature. Safety limit controls shall not be used as operating controls. [NFPA 54:10.3.5]
904.6 Low-Water Cutoff. ¶
904.6 Low-Water Cutoff. All water boilers and steam boilers shall be provided with an automatic means to shut off the fuel supply to the burner(s) if the boiler water level drops below the lowest safe water line. In lieu of the low-water cutoff, water tube or coil-type boilers that require forced circulation to prevent overheating and failure shall have an approved flow sensing device arranged to shut down the boiler when the flow rate is inadequate to protect the boiler against overheating. [NFPA 54:10.3.6]
904.7 Steam Safety and Pressure Relief Valves. Steam ¶
904.7 Steam Safety and Pressure Relief Valves. Steam and hot water boilers shall be equipped, respectively, with listed or approved steam safety or pressure relief valves of appropriate discharge capacity and conforming with ASME requirements. A shutoff valve shall not be placed between the relief valve and the boiler or on discharge pipes between such valves and the atmosphere. [NFPA 54:10.3.7] 904.7.1 Discharge. Relief valves shall be piped to discharge near the floor. [NFPA 54:10.3.7.1] 904.7.2 Size. The entire discharged piping shall be at least the same size as the relief valve discharge…
904.8 Refrigeration Coils. ¶
904.8 Refrigeration Coils. The installation of refrigeration coils shall comply with the following requirements: (1) A refrigeration coil shall not be installed in conjunction with a forced air furnace where circulation of cooled air is provided by the furnace blower, unless the blower has sufficient capacity to overcome the external static pressure resistance imposed by the duct system and refrigeration coil at the air flow rate for heating or cooling, whichever is greater. (2) Furnaces shall not be located upstream from refrigeration coils, unless the refrigeration coil is designed or…
904.9 Cooling Units Used with Heating Boilers. ¶
904.9 Cooling Units Used with Heating Boilers. Boilers, where used in conjunction with refrigeration systems, shall be installed so that the chilled medium is piped in parallel with the heating boiler with appropriate valves to prevent the chilled medium from entering the heating boiler. [NFPA 54:10.3.10.1] 904.9.1 Exposed to Refrigerated Air Circulation. Where hot water heating boilers are connected to heating coils located in air-handling units where they can be exposed to refrigerated air circulation, such boiler piping systems shall be equipped with flow control valves or other automatic…
904.10 Furnace (Upright and Horizontal). ¶
904.10 Furnace (Upright and Horizontal). Upright furnaces shall be permitted to be installed in an attic, furred, or under-floor space exceeding 5 feet (1524 mm) in height, provided the required listings and furnace and duct clearances « « « TABLE 904.3.2 CLEARANCES TO COMBUSTIBLE MATERIAL FOR UNLISTED FURNACES AND BOILERS [NFPA 54: TABLE 10.3.3.2]Col2Col3Col4Col5Col6Col7 --------------------- MINIMUM CLEARANCE<br(inches)MINIMUM CLEARANCE<br(inches)MINIMUM CLEARANCE<br(inches)MINIMUM CLEARANCE<br(inches)MINIMUM CLEARANCE<br(inches)MINIMUM CLEARANCE<br(inches)MINIMUM CLEARANCE<br(inches)…
905.7 Duct Furnaces Used with Refrigeration Sys- ¶
905.7 Duct Furnaces Used with Refrigeration Sys- tems. A duct furnace shall not be installed in conjunction with a refrigeration coil where circulation of cooled air is provided by the blower. Exception: Where the blower has sufficient capacity to overcome the external static resistance imposed by the duct system, the furnace, and the cooling coil and the air throughput necessary for heating or cooling, whichever is greater. [NFPA 54:10.9.7.1] 905.7.1 In Conjunction with Cooling Appliances. Duct furnaces used in conjunction with cooling appliances shall be installed in parallel with or on the…
905.8 Installation in Commercial Garages and Aircraft ¶
905.8 Installation in Commercial Garages and Aircraft Hangars. Duct furnaces installed in garages for more than three motor vehicles or in aircraft hangars shall be installed in accordance with Section 303.11 and Section 303.12. [NFPA 54:10.9.8]
905.9 Electric Duct Heaters. Electric duct heaters installed ¶
905.9 Electric Duct Heaters. Electric duct heaters installed within an air duct shall be listed and labeled in accordance with UL 1996 and designed for the maximum air temperature. The duct heater and fan shall be interlocked such that the electric duct heater operates when the fan is operating. 905.9.1 Installation. Duct heaters shall be installed in accordance with the manufacturer’s installation instructions, and shall not create a hazard to persons or property. Where installed 4 feet (1219 mm) or less from a heat pump or air conditioner, the duct heater shall be listed for such…
906.0 Floor Furnaces. ¶
906.1 Application. ¶
906.1 Application. Floor furnaces shall be listed in accordance with ANSI Z21.86/CSA 2.32. [NFPA 54:10.10.1] » » » » » » » » » are observed. Horizontal furnaces shall be permitted to be installed in an attic, furred, or under-floor space, provided the required listings and furnace and duct clearances are observed.
904.11 Solid-Fuel-Fired Furnaces. ¶
904.11 Solid-Fuel-Fired Furnaces. Factory-built solidfuel-fired furnaces shall comply with UL 391 and shall be installed in accordance with the manufacturer’s installation instructions.
904.12 Oil-Fired Central Furnaces. ¶
904.12 Oil-Fired Central Furnaces. Oil-fired central furnaces shall comply with UL 727 and shall be installed in accordance with the manufacturer’s installation instructions.
904.13 Commercial or Industrial Gas Heaters. ¶
904.13 Commercial or Industrial Gas Heaters. Commercial or industrial gas-fired heaters shall comply with UL 795 and shall be installed in accordance with the manufac turer’s installation instructions.
904.14 Electric Central Furnaces. ¶
904.14 Electric Central Furnaces. Electric central heating furnaces shall comply with UL 1995 or UL 60335-2-40 and shall be installed in accordance with the manufacturer’s installation instructions.
905.0 Duct Furnaces. ¶
905.1 Application. Duct furnaces with inputs of 10 ¶
905.1 Application. Duct furnaces with inputs of 10 MBtu/hr (2931 kW) or less shall be listed in accordance with ANSI Z83.8/CSA 2.6. [NFPA 54:10.9.1]
905.2 Clearances. The installation of duct furnaces shall ¶
905.2 Clearances. The installation of duct furnaces shall comply with the following clearance requirements: (1) Listed duct furnaces shall be installed with clearances of not less than 6 inches (152 mm) between adjacent walls, ceilings, and floors of combustible material and the furnace draft hood. Furnaces listed for installation at lesser clearances shall be installed in accordance with their list ings and the manufacturer’s installation instructions. In no case shall the clearance be such as to interfere with combustion air and accessibility. (2) Unlisted duct furnaces shall be installed…
905.3 Installation of Duct Furnaces. Duct furnaces shall ¶
905.3 Installation of Duct Furnaces. Duct furnaces shall be installed in accordance with the manufacturer’s instruc tions. [NFPA 54:10.9.3]
905.4 Access Panels. The ducts connected to duct fur ¶
905.4 Access Panels. The ducts connected to duct fur naces shall have removable access panels on both the upstream and downstream sides of the furnace. [NFPA 54:10.9.4]
905.5 Location of Draft Hoods and Controls. The con ¶
905.5 Location of Draft Hoods and Controls. The con trols, combustion air inlet, and draft hoods for duct furnaces shall be located outside the ducts. The draft hood shall be located in the same enclosure from which combustion air is taken. [NFPA 54:10.9.5]
905.6 Circulating Air. Where a duct furnace is installed so ¶
905.6 Circulating Air. Where a duct furnace is installed so that supply ducts carry air circulated by the furnace to areas outside the space containing the furnace, the return air shall « « ~~«~~ « « « « ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. INSTALLATION OF SPECIFIC APPLIANCES » » ~~»~~ » » » » »
906.2 Installation. The installation of floor furnaces shall ¶
906.2 Installation. The installation of floor furnaces shall comply with the following requirements: (1) Listed floor furnaces shall be installed in accordance with their listing and the manufacturer’s installation instructions. (2) Unlisted floor furnaces shall not be installed on combustible floors. (3) Thermostats controlling floor furnaces shall not be located in a room or space that is capable of being separated from the room or space in which the register of the floor furnace is located. {NFPA 54:10.10.1}
906.3 Temperature Limit Controls. ¶
906.3 Temperature Limit Controls. Automatically operated floor furnaces shall be equipped with temperature limit controls. [NFPA 54:10.10.3]
906.4 Combustion and Circulating Air. Combustion and ¶
906.4 Combustion and Circulating Air. Combustion and circulating air shall be provided in accordance with Section 701.0. [NFPA 54:10.10.4]
906.5 Placement. The following provisions apply to furnaces that serve one story: ¶
906.5 Placement. The following provisions apply to furnaces that serve one story: (1) Floors. Floor furnaces shall not be installed in the floor of any doorway, stairway landing, aisle, or passageway of any enclosure, public or private, or in an exitway from any such room or space. (2) Walls and Corners. The register of a floor furnace with a horizontal warm air outlet shall not be placed closer than 6 inches (152 mm) from the nearest wall. A distance of at least 18 inches (457 mm) from two adjoining sides of the floor furnace register to walls shall be provided to eliminate the necessity of…
906.6 Bracing. The space provided for the furnace shall be ¶
906.6 Bracing. The space provided for the furnace shall be framed with doubled joists and with headers not lighter than the joists. [NFPA 54:10.10.6]
906.7 Support. ¶
906.7 Support. Means shall be provided to support the furnace when the floor register is removed. [NFPA 54:10.10.7]
906.8 Clearance. The lowest portion of the floor furnace ¶
906.8 Clearance. The lowest portion of the floor furnace shall have at least a 6 inch (152 mm) clearance from the general ground level. A reduced clearance to a minimum of 2 inches (51 mm) shall be permitted, provided the lower 6 inches (152 mm) portion of the floor furnace is sealed by the manufacturer to prevent entrance of water. Where these clearances are not present, the ground below and to the sides shall be excavated to form a “basin-like” pit under the furnace so that the required clearance is provided beneath the lowest portion of the furnace. A 12 inch (305 mm) clearance shall be…
906.9 Access. The space in which any floor furnace is ¶
906.9 Access. The space in which any floor furnace is installed shall be accessible by an opening in the foundation not less than 24 inches by 18 inches (610 mm by 457 mm) or by a trapdoor not less than 24 inches by 24 inches (610 mm by 610 mm) in any cross-section thereof, and a passageway not less than 24 inches by 18 inches (610 mm by 457 mm) in any cross-section thereof. [NFPA 54:10.10.9]
906.10 Seepage Pan. Where the excavation exceeds 12 ¶
906.10 Seepage Pan. Where the excavation exceeds 12 inches (305 mm) in depth or water seepage is likely to collect, a watertight copper pan, concrete pit, or other suitable material shall be used, unless adequate drainage is provided or the appliance is sealed by the manufacturer to meet this condition. A copper pan shall be made of not less than 16 ounces per square foot (oz/ft [2] ) (4.9 kg/m [2] ) sheet copper. The pan shall be anchored in place so as to prevent floating, and the walls shall extend at least 4 inches (102 mm) above the ground level with at least a 6 inches (152 mm)…
906.11 Wind Protection. Floor furnaces shall be protected, ¶
906.11 Wind Protection. Floor furnaces shall be protected, where necessary, against severe wind conditions. [NFPA 54:10.10.11]
906.12 Upper Floor Installations. Floor furnaces shall ¶
906.12 Upper Floor Installations. Floor furnaces shall be permitted to be installed in an upper floor, provided the furnace assembly projects below into a utility room, closet, garage, or similar nonhabitable space. In such installations, the floor furnace shall be enclosed completely (entirely separated from the nonhabitable space) with means for air intake to meet the provisions of Section 701.0, with access for servicing, minimum furnace clearances of 6 inches (152 mm) to all sides and bottom, and with the enclosure constructed of Portland cement plaster or metal lath or other…
906.13 First Floor Installation. Floor furnaces installed in ¶
906.13 First Floor Installation. Floor furnaces installed in the first or ground floors of buildings shall not be required to be enclosed unless the basements of these buildings have been converted to apartments or sleeping quarters, in which case the floor furnace shall be enclosed as specified for upper floor installations and shall project into a nonhabitable space. [NFPA 54:10.10.13]
906.14 Oil-Fired Floor Furnaces. Oil-fired floor furnaces ¶
906.14 Oil-Fired Floor Furnaces. Oil-fired floor furnaces shall comply with UL 729 and installed in accordance with the manufacturer’s installation instructions.
907.0 Wall Furnaces. ¶
907.1 Application. ¶
907.1 Application. Wall furnaces shall be listed in accordance with ANSI Z21.86/CSA 2.32. [NFPA 54:10.25.1]
907.2 Installation. Wall furnaces shall be installed in accor ¶
907.2 Installation. Wall furnaces shall be installed in accor dance with the manufacturer’s installation instructions. Wall furnaces installed in or attached to combustible material shall be listed for such installation. [NFPA 54:10.25.2.1] 907.2.1 Vented Wall Furnaces. Vented wall furnaces connected to a Type B-W gas vent system listed only for a single story shall be installed only in single-story buildings or the top story of multistory buildings. Vented wall furnaces connected to a Type B-W gas vent system listed for installation in multistory buildings shall be permitted to be installed…
907.4 Combustion and Circulating Air. Combustion and ¶
907.4 Combustion and Circulating Air. Combustion and circulating air shall be provided in accordance with Section 701.0. [NFPA 54:10.25.4]
907.5 Oil-Fired Wall Furnaces. Oil-fired wall furnaces ¶
907.5 Oil-Fired Wall Furnaces. Oil-fired wall furnaces shall comply with UL 730 and installed in accordance with the manufacturer’s installation instructions.
908.0 Clothes Dryers. ¶
908.1 Application. ¶
908.1 Application. Clothes dryers shall be listed in accordance with ANSI Z21.5.1/CSA 7.1 for Type I clothes dryers or ANSI Z21.5.2/CSA 7.2 for Type II clothes dryers. [NFPA 54:10.4.1]
908.2 Electric Clothes Dryers. Commercial electric ¶
908.2 Electric Clothes Dryers. Commercial electric clothes dryers shall comply with UL 1240 and installed in accordance with the manufacturer’s installation instructions. Residential and coin-operated electric clothes dryers shall comply with UL 2158 and installed in accordance with the manufacturer’s installation instructions.
908.3 Gas-Fired Clothes Dryers. ¶
908.3 Gas-Fired Clothes Dryers. Gas-fired clothes dryers shall comply with Section 908.3.1 through Section 908.3.3. 908.3.1 Clearance. The installation of clothes dryers shall comply with the following requirements: (1) Listed Type 1 clothes dryers shall be installed with a clearance of not less than 6 inches (152 mm) from adjacent combustible material. Clothes dryers listed for installation at reduced clearances shall be installed in accordance with their listing and the manufacturer’s installation instructions. Type 1 clothes dryers installed in closets shall be listed for such…
909.0 Conversion Burners. ¶
909.1 General. Installation of conversion burners shall con ¶
909.1 General. Installation of conversion burners shall con form to CSA Z21.8. [NFPA 54:10.5] » » » » shall be permitted to be an integral part of the vented wall furnace, as illustrated in Figure 907.2.1. The stud space in which the vented wall furnace is installed shall be ventilated at the first ceiling level by installation of the ceiling plate spacers furnished with the gas vent. Firestop spacers shall be installed at each subsequent ceiling or floor level penetrated by the vent. [NFPA 54:10.25.2.2] 907.2.2 Direct Vent Wall Furnaces. Direct vent wall furnaces shall be installed with the…
907.3 Location. Wall furnaces shall be located so as not to ¶
907.3 Location. Wall furnaces shall be located so as not to cause a hazard to walls, floors, curtains, furniture, or doors. Wall furnaces installed between bathrooms and adjoining rooms shall not circulate air from bathrooms to other parts of the building. [NFPA 54:10.25.3] ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. INSTALLATION OF SPECIFIC APPLIANCES « » » » » ~~»~~ »»
910.0 Burner Assemblies. ¶
910.1 Oil Burners. Oil burners shall comply with UL 296 ¶
910.1 Oil Burners. Oil burners shall comply with UL 296 and installed in accordance with the manufacturer’s installa tion instructions.
910.2 Gas Burners. Commercial gas burners shall comply ¶
910.2 Gas Burners. Commercial gas burners shall comply with UL 295 and installed in accordance with the manufac turer’s installation instructions.
911.0 Decorative Appliances for Installation in ¶
911.0 Decorative Appliances for Installation in Vented Fireplaces.
911.1 Application. Decorative appliances for installation in ¶
911.1 Application. Decorative appliances for installation in vented fireplaces shall be listed in accordance with ANSI Z21.60/CSA 2.26. [NFPA 54:10.6.1]
911.2 Prohibited Installations. Decorative appliances for ¶
911.2 Prohibited Installations. Decorative appliances for installation in vented fireplaces shall not be installed in bathrooms or bedrooms unless the bedroom or bathroom has the required volume in accordance with Section 701.4. [NFPA 54:10.6.2] [OSHPD 1, 1R, 2, 4 & 5] A vented decorative appliance shall not be located in any hospital, skilled nursing facility, intermediate care facility, or correctional treatment center.
911.3 Installation. A decorative appliance for installation ¶
911.3 Installation. A decorative appliance for installation in a vented fireplace shall be installed only in a vented fireplace having a working chimney flue and constructed of noncombustible materials. These appliances shall not be thermostatically controlled. [NFPA 54:10.6.3] 911.3.1 Listed Decorative Appliance. A listed decorative appliance for installation in a vented fireplace shall be installed in accordance with its listing and the manufacturer’s installation instructions. {NFPA 54:10.6.3.1} 911.3.2 Reserved
911.4 Fireplace Screens. A fireplace screen shall be ¶
911.4 Fireplace Screens. A fireplace screen shall be installed with a decorative appliance for installation in a vented fireplace. [NFPA 54:10.6.4]
912.0 Gas Fireplaces, Vented. ¶
912.1 Application. Vented gas fireplaces shall be listed in ¶
912.1 Application. Vented gas fireplaces shall be listed in accordance with ANSI Z21.50/CSA 2.22. [NFPA 54:10.7.1]
912.2 Reserved ¶
912.3 Installation. The installation of vented gas fireplaces ¶
912.3 Installation. The installation of vented gas fireplaces shall comply with the following requirements: (1) [HCD 1 & HCD 2] Any newly installed gas fireplace shall be a direct-vent sealed-combustion type. (2) Vented gas fireplaces shall be installed in accordance with their listing and the manufacturer’s installation instructions and where installed in or attached to com bustible material shall be specifically listed for such installation. (3) Panels, grilles, and access doors that are required to be removed for normal servicing operations shall not be attached to the building. (4) Direct…
912.4 Combustion and Circulating Air. Combustion and ¶
912.4 Combustion and Circulating Air. Combustion and circulating air shall be provided in accordance with Section 701.0. [NFPA 54:10.7.4]
913.0 Factory-Built Fireplaces and Fireplace Stoves. ¶
913.0 Factory-Built Fireplaces and Fireplace Stoves.
913.1 Factory-Built Fireplaces. Factory-built fireplaces ¶
913.1 Factory-Built Fireplaces. Factory-built fireplaces shall comply with UL 127 and installed in accordance with the manufacturer’s installation instructions. {NFPA 211:11.1.1} 913.1.1 Gasketed Fireplace Doors. A gasketed fireplace door shall not be installed on a factory-built fireplace, except where the fireplace system has been tested in accordance with UL 127.
913.2 Fireplace Stoves. Fireplace stoves shall comply ¶
913.2 Fireplace Stoves. Fireplace stoves shall comply with UL 737 and installed in accordance with the manufac turer’s installation instructions.
913.3 Fireplace Accessories. Heat exchangers, glass ¶
913.3 Fireplace Accessories. Heat exchangers, glass doors assemblies, combustion air vents, and termination caps shall comply with UL 907 and installed in accordance with the manufacturer’s installation instructions.
914.0 Non-Recirculating Direct Gas-Fired Industrial ¶
914.0 Non-Recirculating Direct Gas-Fired Industrial Air Heaters.
914.1 Application. ¶
914.1 Application. Direct gas-fired heating and forced ventilation appliances for commercial and industrial applications shall be listed in accordance with the following standards as applicable: (1) ANSI Z83.4/CSA 3.7. (2) ANSI Z83.18. [NFPA 54:10.8.1]
914.2 Prohibited Installations. Direct gas-fired heating ¶
914.2 Prohibited Installations. Direct gas-fired heating and forced ventilation appliances shall not serve any area containing sleeping quarters. Non-recirculating direct gas-fired heating and forced ventilation appliances shall not recirculate room air. Recirculating direct gas-fired industrial air heaters shall not recirculate room air in buildings that contain flammable solids, liquids, or gases; explosive materials; or substances that can become toxic when exposed to flame or heat. [NFPA 54:10.8.2.1 – 10.8.2.3]
914.3 Installation. ¶
914.3 Installation. Direct gas-fired heating and forced ventilation appliances shall be installed in accordance with the manufacturer’s instructions. [NFPA 54:10.8.3.1] 914.3.1 Fresh Air Ventilation. Direct gas-fired heating and forced ventilation appliances shall be permitted to provide fresh air ventilation. [NFPA 54:10.8.3.2] 914.3.2 Access Required. Direct gas-fired heating and forced ventilation appliances shall be provided with access for removal of burners; for replacement of motors, controls, filters, and other working parts; and for adjustment and lubrication of parts requiring…
914.4 Clearance from Combustible Materials. Direct ¶
914.4 Clearance from Combustible Materials. Direct gas-fired heating and forced ventilation appliances shall be installed with a clearance from combustible materials of not less than that shown on the rating plate and the manufacturer’s instructions. [NFPA 54:10.8.4]
914.5 Air Supply. The air supply to direct gas-fired heating ¶
914.5 Air Supply. The air supply to direct gas-fired heating and forced ventilation appliances shall be in accordance with Section 914.5.1 through Section 914.5.3. [NFPA 54:10.8.5] 914.5.1 Non-Recirculating Systems. All air to the non-recirculating direct gas-fired heating and forced ventilation appliance shall be ducted directly from outdoors. [NFPA 54:10.8.5.1] 914.5.2 Recirculating Systems. Ventilation air to the recirculating direct gas-fired heating and forced ventilation appliance shall be ducted directly from outdoors. Air in excess of the minimum ventilation air specified on the…
914.6 Atmospheric Vents, Gas Reliefs, or Bleeds. ¶
914.6 Atmospheric Vents, Gas Reliefs, or Bleeds. Direct gas-fired heating and forced ventilation appliances with valve train components equipped with atmospheric vents, gas reliefs, or bleeds shall have their vent lines, gas reliefs, or bleeds lead to a safe point outdoors. Means shall be employed on these lines to prevent water from entering and to prevent blockage from insects and foreign matter. An atmospheric vent line shall not be required to be provided on a valve train component equipped with a listed vent limiter. [NFPA 54:10.8.6]
914.7 Relief Openings. The design of the installation shall ¶
914.7 Relief Openings. The design of the installation shall include adequate provisions to permit the direct gas-fired heating and forced ventilation appliances to operate at their rated airflow without overpressurizing the space served by the heater by taking into account the structure’s designed infiltration rate, properly designed relief openings, or an interlocked powered exhaust system, or a combination of these methods. [NFPA 54:10.8.7] 914.7.1 Infiltration Rate. The structure’s designed infiltration rate and the size of relief opening(s) shall be determined by engineering methods.…
914.8 Purging. Inlet ducting, when used, shall be purged ¶
914.8 Purging. Inlet ducting, when used, shall be purged with at least four air changes prior to an ignition attempt. [NFPA 54:10.8.8]
915.0 Room Heaters. ¶
915.1 Application. ¶
915.1 Application. Room heaters shall be listed in accordance with Section 915.1.1 or Section 915.1.2. [NFPA 54:10.21.1] 915.1.1 Vented Room Heaters. Vented room heaters shall be listed in accordance with ANSI Z21.86/CSA 2.32 or CSA/ANSI Z21.88/CSA 2.33. [NFPA 54:10.21.1.1] 915.1.2 Unvented Room Heaters. Unvented room heaters shall be listed in accordance with CSA/ANSI Z21.11.2. [NFPA 54:10.21.1.2]
915.2 Electric Room Heaters. Electric room heaters shall ¶
915.2 Electric Room Heaters. Electric room heaters shall comply with UL 2021.
915.3 Gas-Fired Room Heaters. Gas-fired room heaters ¶
915.3 Gas-Fired Room Heaters. Gas-fired room heaters shall comply with Section 915.3.1 through Section 915.3.4. 915.3.1 Prohibited Installations. Unless specifically permitted by the Authority Having Jurisdiction, unvented room heaters shall not be installed as primary heat sources. Unvented room heaters shall not be permitted in spaces that do not have the required volume of indoor air as defined in Section 701.4. [HCD 1 & HCD 2] Unvented fuel-burning room heaters shall not be installed, used, maintained, or permitted to exist in a Group R Occupancy. 915.3.1.1 Unvented Room Heaters. Unvented…
916.4 Combustion and Circulating Air. Combustion and ¶
916.4 Combustion and Circulating Air. Combustion and circulating air shall be provided in accordance with Section 701.0. [NFPA 54:10.24.4]
916.5 Ductwork. A unit heater shall not be attached to a ¶
916.5 Ductwork. A unit heater shall not be attached to a warm air duct system unless listed and marked for such installation. [NFPA 54:10.24.5]
916.6 Installation in Commercial Garages and Air- ¶
916.6 Installation in Commercial Garages and Air- craft Hangars. Unit heaters installed in garages for more than three motor vehicles or in aircraft hangars shall be installed in accordance with Section 303.11 and Section 303.12. [NFPA 54:10.24.6]
916.7 Oil-Fired Unit Heaters. Oil-fired unit heaters shall ¶
916.7 Oil-Fired Unit Heaters. Oil-fired unit heaters shall comply with UL 731 and installed in accordance with the manufacturer’s installation instructions.
917.0 Food Service Appliance, Floor-Mounted. ¶
917.0 Food Service Appliance, Floor-Mounted.
917.1 Application. Floor-mounted food service appliances ¶
917.1 Application. Floor-mounted food service appliances shall be listed in accordance with ANSI Z83.11/CSA 1.8. [NFPA 54:10.11.1]
917.2 Clearance for Listed Appliances. Floor-mounted ¶
917.2 Clearance for Listed Appliances. Floor-mounted food service appliances, such as ranges for hotels and restaurants, deep fat fryers, unit broilers, kettles, steam cookers, steam generators, and baking and roasting ovens, shall be installed not less than 6 inches (152 mm) from combustible material except that at least a 2 inch (51 mm) clearance shall be maintained between a draft hood and combustible material. Floor-mounted food service appliances listed for installation at lesser clearances shall be installed in accordance with its listing and the manufacturer’s installation…
917.3 Mounting on Combustible Floors. Floor-mounted ¶
917.3 Mounting on Combustible Floors. Floor-mounted food service appliances that are listed specifically for installation on floors constructed of combustible material shall be permitted to be installed on combustible floors in accordance with its listing and the manufacturer’s installation instructions. [NFPA 54:10.11.3.1] 917.3.1 Not Listed for Mounting on Combustible Floors. Floor-mounted food service appliances that are not listed for installation on a combustible floor shall be » » » » » » such as to interfere with combustion air and accessibility. Unlisted room heaters shall be…
915.4 Solid-Fuel Type Room Heaters. Solid-fuel type ¶
915.4 Solid-Fuel Type Room Heaters. Solid-fuel type room heaters shall comply with UL 1482.
916.0 Unit Heaters. ¶
916.1 Application. ¶
916.1 Application. Unit heaters shall be listed in accordance with ANSI Z83.8/CSA 2.6 and installed in accordance with the manufacturer’s installation instructions. [NFPA 54:10.24.1]
916.2 Support. Suspended-type unit heaters shall be safely ¶
916.2 Support. Suspended-type unit heaters shall be safely and adequately supported, with due consideration given to their weight and vibration characteristics. Hangers and brackets shall be of noncombustible material. [NFPA 54:10.24.2]
916.3 Clearance for Suspended-Type Unit Heaters. ¶
916.3 Clearance for Suspended-Type Unit Heaters. Suspended-type unit heaters shall comply with the following requirements: (1) Unit heaters shall be installed with clearances from combustible material of not less than 18 inches (457 mm) at the sides, 12 inches (305 mm) at the bottom, and 6 inches (152 mm) above the top where the unit heater has an internal draft hood, or 1 inch (25.4 mm) above the top of the sloping side of a vertical draft hood. A unit heater listed for reduced clearances shall be installed in accordance with its listing and the manufacturer’s installation instructions. (2)…
917.6 Use with Casters. Floor-mounted appliances with ¶
917.6 Use with Casters. Floor-mounted appliances with casters shall be listed for such construction and shall be installed in accordance with the manufacturer’s installation instructions for limiting the movement of the appliance to prevent strain on the connection. [NFPA 54:10.11.6]
917.7 Level Installation. Floor-mounted food service ¶
917.7 Level Installation. Floor-mounted food service appliances shall be installed level on a firm foundation. [NFPA 54:10.11.7]
917.8 Ventilation. ¶
917.8 Ventilation. Means shall be provided to properly ventilate the space in which a food service appliance is installed to permit proper combustion of the gas. [NFPA 54:10.11.8]
918.0 Food Service Appliances, Counter Appliances. ¶
918.0 Food Service Appliances, Counter Appliances.
918.1 Application. Food service counter appliances shall ¶
918.1 Application. Food service counter appliances shall be listed in accordance with ANSI Z83.11/CSA 1.8. [NFPA 54:10.12.1]
918.2 Vertical Clearance. A vertical distance of not less ¶
918.2 Vertical Clearance. A vertical distance of not less than 48 inches (1219 mm) shall be provided between the top of all food service hot plates and griddles and combustible material. [NFPA 54:10.12.2]
918.3 Clearance for Listed Appliances. Listed food ¶
918.3 Clearance for Listed Appliances. Listed food service counter appliances such as hot plates and griddles, food and dish warmers, and coffee brewers and urns, where installed on combustible surfaces, shall be set on their own bases or legs and shall be installed with a horizontal clearance of not less than 6 inches (152 mm) from combustible material, except that not less than a 2 inches (51 mm) clearance shall be maintained between a draft hood and combustible material. Food service counter appliances listed for installation at lesser clearances shall be installed in accordance with their…
918.4 Clearance for Unlisted Appliances. ¶
918.4 Clearance for Unlisted Appliances. Food service counter appliances, where installed on combustible surfaces, shall be installed with a minimum horizontal clearance of 6 inches (152 mm) from combustible material, except that at least a 2 inch (51 mm) clearance shall be maintained between a draft hood and combustible material. Food service counter appliances listed for installation at lesser clearances shall be installed in accordance with the manufacturer’s installation instructions. [NFPA 54:10.12.3]
919.0 Household Cooking Appliances. ¶
919.1 Application. Household cooking appliances shall be ¶
919.1 Application. Household cooking appliances shall be listed in accordance with CSA/ANSI Z21.1/CSA 1.1. [NFPA 54:10.13.1]
919.2 Electric Household Cooking Appliances. ¶
919.2 Electric Household Cooking Appliances. Electric household cooking appliances designed for permanent installations shall be installed in accordance with the manufacturer’s installation instructions. Household electric ranges shall comply with UL 858.
919.3 Gas-Fired Household Cooking Appliances. ¶
919.3 Gas-Fired Household Cooking Appliances. Gas-fired household cooking appliances shall comply with Section 919.4 though Section 919.6. » » installed in accordance with Section 917.4 or be installed in accordance with one of the following: (1) Where the appliance is set on legs that provide not less than 18 inches (457 mm) open space under the base of the appliance or where it has no burners and no portion of any oven or broiler within 18 inches (457 mm) of the floor, it shall be permitted to be installed on a combustible floor without special floor protection, provided at least one sheet…
917.4 Installation on Noncombustible Floors. ¶
917.4 Installation on Noncombustible Floors. Floorinstalled food service appliances that are designed and marked “For use only in noncombustible locations” shall be installed on floors of noncombustible construction with noncombustible flooring and surface finish and with no combustible material against the underside thereof, or on noncombustible slabs or arches having no combustible material against the underside thereof. Such construction shall in all cases extend not less than 12 inches (305 mm) beyond the appliance on all sides. [NFPA 54:10.11.4.1, 10.11.4.2]
917.5 Combustible Material Adjacent to Cooking Top. ¶
917.5 Combustible Material Adjacent to Cooking Top. Food service ranges shall be installed to provide clearance to combustible material of not less than 18 inches (457 mm) horizontally for a distance up to 2 feet (610 mm) above the surface of the cooking top where the combustible material is not completely shielded by high shelving, a warming closet, or other system. Reduced combustible material clearances are « « « « « « « « « « ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. INSTALLATION OF SPECIFIC APPLIANCES » » ~~»~~ »…
919.4 Floor-Mounted Units. Floor mounted units shall be ¶
919.4 Floor-Mounted Units. Floor mounted units shall be installed in accordance with Section 919.4.1 and Section 919.4.2. 919.4.1 Clearances. Floor-mounted household cooking appliances, where installed on combustible floors, shall be set on their own bases or legs and shall not interfere with combustion air, accessibility for operation, and servicing. [NFPA 54:10.13.3] 919.4.2 Vertical Clearance Above Cooking Top. Household cooking appliances shall have a vertical clearance above the cooking top of not less than 30 inches (762 mm) to combustible material or metal cabinets. A minimum clearance…
919.5 Built-In Units. Built-in units shall be installed in accor ¶
919.5 Built-In Units. Built-in units shall be installed in accor dance with Section 919.5.1 and Section 919.5.2. 919.5.1 Installation. Listed built-in household cooking appliances shall be installed in accordance with their listing and the manufacturer’s installation instructions. The installation shall not interfere with combustion air, accessibility for operation, and servicing. Unlisted builtin household cooking appliances shall not be installed in or adjacent to combustible material. 919.5.2 Vertical Clearance Above Cooking Top. Built-in top (or surface) cooking appliances shall have a…
919.6 Level Installation. Cooking appliances shall be ¶
919.6 Level Installation. Cooking appliances shall be installed so that the cooking top, broiler pan, or oven racks are level. [NFPA 54-2018:10.14.3]
920.0 Cooking Appliance Listings. ¶
920.1 Commercial Electric Ranges. ¶
920.1 Commercial Electric Ranges. Commercial electric ranges shall comply with UL 197 and installed in accordance with the manufacturer’s installation instructions.
920.2 Commercial Wood-Fired Baking Ovens. ¶
920.2 Commercial Wood-Fired Baking Ovens. Commercial wood-fired baking ovens (refractory type) shall comply with UL 2162 and installed in accordance with the manufacturer’s installation instructions.
920.3 Oil-Burning Ranges. ¶
920.3 Oil-Burning Ranges. Oil-burning ranges shall comply with UL 896 and installed in accordance with the manufacturer’s installation instructions.
921.0 Open-Top Broiler Units. ¶
921.1 Application. Open-top broiler units shall be listed in ¶
921.1 Application. Open-top broiler units shall be listed in accordance with ANSI Z83.11/CSA 1.8 or ANSI/CSA Z21.1/CSA 1.1 and installed in accordance with the manu facturer’s installation instructions. [NFPA 54:10.17.1]
921.2 Protection Above Domestic Units. ¶
921.2 Protection Above Domestic Units. Domestic opentop broiler units shall be provided with a metal ventilating hood not less than 0.0122 of an inch (0.3099 mm) thick with a clearance of not less than [1] ⁄ 4 of an inch (6.4 mm) between the hood and the underside of combustible material or metal cabinets. A clearance of at least 24 inches (610 mm) shall be maintained between the cooking top and the combustible material or metal cabinet, and the hood shall be at least as wide as the open-top broiler unit and centered over the unit. Domestic open-top broiler units incorporating an integral…
921.3 Commercial Units. Commercial open-top broiler ¶
921.3 Commercial Units. Commercial open-top broiler units shall be provided with ventilation in accordance with Chapter 5, Part II. {NFPA 54:10.17.3}
922.0 Outdoor Cooking Appliances. ¶
922.1 Application. Outdoor cooking appliances shall be ¶
922.1 Application. Outdoor cooking appliances shall be listed in accordance with ANSI Z83.11/CSA 1.8, ANSI Z21.58/CSA 1.6, or ANSI Z21.89/CSA 1.18, and installed in accordance with the manufacturer’s installation instructions. [NFPA 54:10.18] 210 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. INSTALLATION OF SPECIFIC APPLIANCES »» » » »
923.0 Illuminating Appliances. ¶
923.1 Clearances for Listed Appliances. ¶
923.1 Clearances for Listed Appliances. Listed illuminating appliances shall be installed in accordance with their listing and the manufacturer’s installation instructions. {NFPA 54:10.14.1}
923.2 Clearances for Unlisted Appliances. Clearances ¶
923.2 Clearances for Unlisted Appliances. Clearances for unlisted illuminating appliances shall comply with the following: (1) Unlisted enclosed illuminating appliances installed outdoors shall be installed with clearances in any direction from combustible material of not less than 12 inches (305 mm). [NFPA 54:10.14.2.1(1)] (2) Unlisted enclosed illuminating appliances installed indoors shall be installed with clearances in any direction from combustible material of not less than 18 inches (457 mm). [NFPA 54:10.14.2.1(2)] 923.2.1 Open-Flame Type. Clearance shall comply with the following: (1)…
923.3 Mounting on Buildings. Illuminating appliances ¶
923.3 Mounting on Buildings. Illuminating appliances designed for installation on a wall or ceiling shall be securely attached to substantial structures in such a manner that they are not dependent on the gas piping for support. [NFPA 54:10.14.3]
923.4 Mounting on Posts. Illuminating appliances ¶
923.4 Mounting on Posts. Illuminating appliances designed for installation on a post shall be securely and rigidly attached to a post. Posts shall be rigidly installed. The strength and rigidity of posts greater than 3 feet (914 mm) in height shall be at least equivalent to that of a 2 [1] ⁄ 2 inch (64 mm) diameter post constructed of 0.064 of an inch (1.626 mm) thick steel or a 1 inch (25.4 mm) Schedule 40 steel pipe. Posts 3 feet (914 mm) or less in height shall not be smaller than a 3 ⁄ 4 of an inch (19.1 mm) Schedule 40 steel pipe. Drain openings shall be provided near the base of posts…
923.5 Appliance Pressure Regulators. ¶
923.5 Appliance Pressure Regulators. Where an appliance pressure regulator is not supplied with an illuminating appliance and the service line is not equipped with a service pressure regulator, an appliance pressure regulator shall be installed in the line serving one or more illuminating appliances. [NFPA 54:10.14.5]
924.0 Incinerators and Crematories. ¶
924.1 Field Constructed Commercial-Industrial ¶
924.1 Field Constructed Commercial-Industrial Incinerators. Field constructed commercial-industrial incin erators shall be constructed and installed in accordance with NFPA 82.
924.2 Factory-Built Commercial Crematories. ¶
924.2 Factory-Built Commercial Crematories. Factorybuilt commercial incinerators and crematories shall comply with UL 2790 and installed in accordance with the manufac turer’s installation instructions.
924.3 Residential Incinerators. Residential incinerators ¶
924.3 Residential Incinerators. Residential incinerators shall comply with UL 791 and installed in accordance with the manufacturer’s installation instructions.
925.0 Infrared Heaters. ¶
925.1 Application. Infrared heaters having an input rating ¶
925.1 Application. Infrared heaters having an input rating of 400 000 Btu/hr (117 kW) or less shall be listed in accordance with ANSI Z83.19/CSA 2.35 or ANSI Z83.20/CSA 2.34. [NFPA 54:10.16.1]
925.2 Support. Suspended-type infrared heaters shall be ¶
925.2 Support. Suspended-type infrared heaters shall be fixed in position independent of gas and electric supply lines. Hangers and brackets shall be of noncombustible material. Heaters subject to vibration shall be provided with vibrationisolating hangers. [NFPA 54:10.16.2]
925.3 Clearance. The installation of infrared heaters shall ¶
925.3 Clearance. The installation of infrared heaters shall comply with the following clearance requirements: (1) Listed heaters shall be installed with clearances from combustible material in accordance with their listing and the manufacturer’s installation instructions. (2) Unlisted heaters shall be installed in accordance with clearances from combustible material acceptable to the Authority Having Jurisdiction. (3) In locations used for the storage of combustible materials, signs shall be posted to specify the maximum per « « « «« « « « « « FLAME HEIGHT ABOVE<brBURNER…
927.2 Clearance. ¶
927.2 Clearance. Refrigerators shall be provided with clearances for ventilation at the top and back in accordance with the manufacturer’s instructions. Where such instructions are not available, at least 2 inches (51 mm) shall be provided between the back of the refrigerator and the wall at least 12 inches (305 mm) above the top. [NFPA 54:10.20.2]
927.3 Venting or Ventilating Kits Approved for Use ¶
927.3 Venting or Ventilating Kits Approved for Use with a Refrigerator. Where an accessory kit is used for conveying air for burner combustion or unit cooling to the refrigerator from areas outside the room in which it is located, or for conveying combustion products diluted with air containing waste heat from the refrigerator to areas outside the room in which it is located, the kit shall be installed in accordance with the refrigerator manufacturer’s instructions. [NFPA 54:10.20.3]
928.0 Gas-Fired Toilets. ¶
928.1 Clearance. A listed gas-fired toilet shall be installed ¶
928.1 Clearance. A listed gas-fired toilet shall be installed in accordance with its listing and the manufacturer’s installation instructions, provided that the clearance shall be such to afford ready accessibility for use, cleanout, and necessary servicing. {NFPA 54:10.23.1}
928.2 Installation on Combustible Floors. ¶
928.2 Installation on Combustible Floors. Listed gasfired toilets installed on combustible floors shall be listed for such installation. [NFPA 54:10.23.2]
928.3 Vents. Vents or vent connectors that are capable of ¶
928.3 Vents. Vents or vent connectors that are capable of being contacted during casual use of the room in which the toilet is installed shall be protected or shielded to prevent such contact. [NFPA 54:10.23.3]
929.0 Appliances for Installation in Manufactured ¶
929.0 Appliances for Installation in Manufactured Housing. [Not adopted by HCD]
929.1 General. [Not adopted by HCD] Appliances ¶
929.1 General. [Not adopted by HCD] Appliances installed in manufactured housing after the initial sale shall be listed for installation in manufactured housing, or approved, and shall be installed in accordance with the requirements of this code and the manufacturer’s installation instructions. Appliances installed in the living space of manufactured housing shall be in accordance with the requirements of Section 701.0. [NFPA 54:10.28]
930.0 Small Ceramic Kilns. ¶
930.1 General. The provisions of this section apply to kilns ¶
930.1 General. The provisions of this section apply to kilns used for ceramics that have a maximum interior volume of 20 cubic feet (0.57 m [3] ) and are used for hobby or noncommercial purposes.
930.2 Installation. Kilns shall be installed in accordance ¶
930.2 Installation. Kilns shall be installed in accordance with the manufacturer’s installation instructions and the provisions of this code.
930.3 Fuel-Gas Controls. Fuel-gas controls shall comply ¶
930.3 Fuel-Gas Controls. Fuel-gas controls shall comply with Section 306.0 and Section 902.4. Standing pilots shall not be used with gas-fired kilns.
930.4 Electrical Equipment. All electrical equipment ¶
930.4 Electrical Equipment. All electrical equipment used as part of, or in connection with, the installation of a kiln » » » » » » ~~»~~ ~~»~~ » » missible stacking height to maintain required clearances from the heater to the combustibles. {NFPA 54:10.16.3}
925.4 Combustion and Ventilation Air. Where unvented ¶
925.4 Combustion and Ventilation Air. Where unvented infrared heaters are used, natural or mechanical means shall be provided to supply and exhaust at least 4 ft [3] /min/1000 Btu/h (0.38 m [3] /min/kW) input of installed heaters. [NFPA 54:10.16.4.1] 925.4.1 Exhaust Openings. Exhaust openings for removing flue products shall be above the level of the heaters. [NFPA 54:10.16.4.2]
925.5 Installation in Commercial Garages and Air- ¶
925.5 Installation in Commercial Garages and Air- craft Hangars. Overhead heaters installed in garages for more than three motor vehicles or in aircraft hangars shall be listed and shall be installed in accordance with Section 303.11 and Section 303.12. [NFPA 54:10.16.5]
925.6 Electric Radiant Heaters. Electric radiant heaters ¶
925.6 Electric Radiant Heaters. Electric radiant heaters shall comply with UL 2021 and installed in accordance with the manufacturer’s installation instructions.
926.0 Pool Heaters. ¶
926.1 Application. ¶
926.1 Application. Pool heaters shall be listed in accordance with CSA/ANSI Z21.56/CSA 4.7. [NFPA 54:10.19.1]
926.2 Location. A pool heater shall be located or protected ¶
926.2 Location. A pool heater shall be located or protected so as to minimize accidental contact of hot surfaces by persons. [NFPA 54:10.19.2]
926.3 Clearance. The installation of pool heaters shall ¶
926.3 Clearance. The installation of pool heaters shall comply with the following requirements: (1) The clearances shall not interfere with combustion air, draft hood or vent terminal clearance and relief, and accessibility for servicing. (2) A pool heater shall be installed in accordance with its listing and the manufacturer’s installation instructions. [NFPA 54:10.19.3]
926.4 Temperature or Pressure-Limiting Devices. ¶
926.4 Temperature or Pressure-Limiting Devices. Where a pool heater is provided with over-temperature protection only and is installed with any device in the discharge line of the heater that can restrict the flow of water from the heater to the pool (such as a check valve, shutoff valve, therapeutic pool valving, or flow nozzles), a pressure relief valve shall be installed either in the heater or between the heater and the restrictive device. [NFPA 54:10.19.4]
926.5 Bypass Valves. Where an integral bypass system is ¶
926.5 Bypass Valves. Where an integral bypass system is not provided as a part of the pool heater, a bypass line and valve shall be installed between the inlet and outlet piping for use in adjusting the flow of water through the heater. [NFPA 54:10.19.5]
926.6 Venting. A pool heater listed for outdoor installation ¶
926.6 Venting. A pool heater listed for outdoor installation shall be installed with the venting means supplied by the manufacturer and in accordance with the manufacturer’s installation instructions. [NFPA 54:10.19.6]
927.0 Refrigerators. ¶
927.1 Application. ¶
927.1 Application. Refrigerators shall be listed in accordance with CSA/ANSI Z21.19/CSA 1.4. [NFPA 54:10.20.1] « « «« « « « « « « « « 212 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. INSTALLATION OF SPECIFIC APPLIANCES enclosed by more than two vertical wall surfaces, a hood and gravity ventilation duct shall be installed in accordance with Section 930.5.2, Section 930.5.3, and Section 603.13.6.
931.0 Outdoor Open Flame Decorative Appliances. ¶
931.0 Outdoor Open Flame Decorative Appliances.
931.1 General. Permanently fixed in place outdoor open ¶
931.1 General. Permanently fixed in place outdoor open flame decorative appliances shall be installed in accordance with Section 931.1.1 and Section 931.1.2. [NFPA 54:10.30] 931.1.1 Application. Outdoor open flame decorative appliances shall be listed in accordance with ANSI Z21.97/CSA 2.41 and shall be installed in accordance with the manufacturer’s installation instructions. [NFPA 54:10.30.1] 931.1.2 Connection to the Piping System. The connection to the gas piping system shall be in accordance with Section 1312.1(1), Section 1312.1(2), Section 1312.1(4), or Section 1312.1(5). [NFPA…
932.0 Evaporative Cooling Systems. ¶
932.1 General. Evaporative cooling systems, including air ¶
932.1 General. Evaporative cooling systems, including air ducts and fire dampers that are a portion of an evaporative cooling system, shall be in accordance with Section 932.2 through Section 932.4.3. Evaporative cooling systems shall be provided with outside air as specified for cooling systems in Section 403.0.
932.2 Location. Evaporative cooling systems shall be ¶
932.2 Location. Evaporative cooling systems shall be installed so as to minimize the probability of damage from an external source.
932.3 Access, Inspection, and Repair. Evaporative ¶
932.3 Access, Inspection, and Repair. Evaporative coolers shall be accessible for inspection, service, and replacement without removing permanent construction.
932.4 Installation. An evaporative cooler supported by the ¶
932.4 Installation. An evaporative cooler supported by the building structure shall be installed on a level base and shall be secured directly or indirectly to the building structure, to prevent displacement of the cooler. 932.4.1 Modifications to the Supporting Struc- ture. Modifications made to the supporting framework of buildings as a result of the installation shall be in accordance with the requirements of the building code. Openings in exterior walls shall be flashed in an approved manner in accordance with the requirements of the building code. 932.4.2 On the Ground. An evaporative…
933.0 Refrigeration Appliances. ¶
933.1 Self-Contained Refrigerators and Freezers. ¶
933.1 Self-Contained Refrigerators and Freezers. Factory-built commercial refrigerators and freezers shall comply with UL 471 or UL 60335-2-89 and shall be installed in accor dance with the manufacturer’s installation instructions. » » » » » » shall be in accordance with the requirements in NFPA 70. Electric kilns shall be listed and labeled in accordance with UL 499.
930.5 Installations Inside Buildings. In addition to other ¶
930.5 Installations Inside Buildings. In addition to other requirements specified in this section, interior installations shall comply with the requirements of Section 603.13.6 and Section 930.5.1 through Section 930.5.4. 930.5.1 Kiln Clearances. The sides and tops of kilns shall be located not less than 18 inches (457 mm) from a noncombustible wall surface and 3 feet (914 mm) from a combustible wall surface. Kilns shall be installed on noncombustible flooring consisting of not less than 2 inches (51 mm) of solid masonry or concrete extending not less than 12 inches (305 mm) beyond the base…
930.6 Exterior Installations. Kilns shall be installed with ¶
930.6 Exterior Installations. Kilns shall be installed with minimum clearances as specified in Section 930.5.1. Wherever a kiln is located under a roofed area and is partially «« « ~~«~~ « [«] « « « « « « « [«] » » »» » [»] » » [»] » » ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. INSTALLATION OF SPECIFIC APPLIANCES
933.2 Unit Coolers. Factory-built unit coolers for use in ¶
933.2 Unit Coolers. Factory-built unit coolers for use in refrigerators, freezers, refrigerated warehouses, and walk-in coolers shall comply with UL 412 or UL 60335-2-89 and shall be installed in accordance with the manufacturer’s installation instructions.
933.3 Self-Contained Mechanical Refrigeration Sys- ¶
933.3 Self-Contained Mechanical Refrigeration Sys- tems. Self-contained mechanical refrigeration systems for use in walk-in coolers shall comply with UL 427 or UL 60335-2-89 and shall be installed in accordance with the man ufacturer’s installation instructions.
934.0 Ductless Mini-Split Systems Installation. ¶
934.0 Ductless Mini-Split Systems Installation.
934.1 General. A ductless mini-split system installation ¶
934.1 General. A ductless mini-split system installation shall be installed in accordance with the manufacturer’s installation instructions and Section 310.2 for condensate control.
935.0 Air Filter Appliances. ¶
935.1 Electrostatic Air Cleaners. ¶
935.1 Electrostatic Air Cleaners. Electrostatic air cleaners shall comply with UL 867 and installed in accordance with the manufacturer’s installation instructions.
935.2 High-Efficiency Particulate Air Filter Units. ¶
935.2 High-Efficiency Particulate Air Filter Units. High-efficiency particulate air filter units for use in industrial and laboratory exhaust and ventilation systems shall be installed in accordance with the manufacturer’s installation instructions.
936.0 Gaseous Hydrogen Systems. ¶
936.1 General. Gaseous hydrogen systems shall be installed ¶
936.1 General. Gaseous hydrogen systems shall be installed in accordance with NFPA 2.
937.0 Compressed Natural Gas (CNG) Vehicular Fuel ¶
937.0 Compressed Natural Gas (CNG) Vehicular Fuel Systems.
937.1 General. The installation of compressed natural gas ¶
937.1 General. The installation of compressed natural gas (CNG) fueling (dispensing) systems shall be in accordance with NFPA 52. Residential CNG fueling appliances shall be listed in accordance with ANSI/CSA NGV 5.1 and installed in accordance to the appliance manufacturer’s installation instructions. Non-residential CNG fueling appliances shall be listed in accordance with ANSI/CSA NGV 5.2 and installed in accordance with the appliance manufacturer’s installation instructions. [NFPA 54:10.27]
938.0 Dehumidifiers. ¶
938.1 General. ¶
938.1 General. Dehumidifiers shall comply with UL 603352-40, and be installed in accordance with the manufacturer’s installation instructions.
939.0 Sauna Heaters. ¶
939.1 Electric Sauna Heaters. ¶
939.1 Electric Sauna Heaters. Sauna heaters shall comply with UL 875 and shall be installed in accordance with the manufacturer’s installation instructions. 214 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE CHAPTER 10 – BOILERS AND PRESSURE VESSELS (Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.) Adopting…
1001.0 General. ¶
1001.1 Applicability. The requirements of this chapter ¶
1001.1 Applicability. The requirements of this chapter shall apply to the construction, installation, operation, repair, and alteration of boilers and pressure vessels. Low-pressure boilers shall comply with this chapter and Section 904.0. Exceptions: (1) Listed and approved potable water heaters with a nominal capacity not exceeding 120 gallons (454 L) and having a heat input not exceeding 200 000 British thermal units per hour (Btu/h) (58.6 kW) used for hot water supply at a pressure not exceeding 160 pounds-force per square inch (psi) (1103 kPa) and at temperatures not exceeding 210°F…
1001.2 Boiler Rooms and Enclosures. Boiler rooms and ¶
1001.2 Boiler Rooms and Enclosures. Boiler rooms and enclosures shall comply with the California Building Code . 1001.2.1 [OSHPD 1, 1R, 2, 3, 4 & 5] In no case shall boiler room volume or clearances be reduced below those required by the conditions of the boiler listing. The boiler and the boiler room ventilation system, including fans, con- trols, and damper motors shall be on essential power when required by Section 321.0. The ventilation system shall either operate continuously, or, if interlocked with the boiler(s) it shall not interfere with the proper boiler oper- ation. Listed boilers…
1001.3 Air for Combustion and Ventilation. Air for ¶
1001.3 Air for Combustion and Ventilation. Air for combustion and ventilation shall be provided in accordance with Chapter 7.
1001.4 Drainage. For heating or hot-water-supply boiler ¶
1001.4 Drainage. For heating or hot-water-supply boiler applications, the boiler room shall be equipped with a floor drain or other approved means for disposing of the accumulation of liquid wastes incident to cleaning, recharging, and routine maintenance. No steam pipe shall be directly connected to a part of a plumbing or drainage system, nor shall a water having a temperature above 140°F (60°C) be discharged under pressure directly into a part of a drainage system. Pipes from boilers shall discharge by means of indirect waste piping as determined by the Authority Having Jurisdiction or the…
1001.5 Mounting. Equipment shall be set or mounted on a ¶
1001.5 Mounting. Equipment shall be set or mounted on a level base capable of supporting and distributing the weight contained thereon. Boilers, tanks, and equipment shall be securely anchored to the structure. Equipment requiring vibration isolation shall be installed as designed by a registered design professional and approved by the Authority Having Jurisdiction. 1001.5.1 Floors. Boilers shall be mounted on floors of noncombustible construction unless listed for mounting on combustible flooring.
1001.6 Chimneys or Vents. Boilers shall be connected to ¶
1001.6 Chimneys or Vents. Boilers shall be connected to a chimney or vent, as provided for other fuel-burning equipment in Chapter 8 of this code.
1002.0 Standards. ¶
1002.1 General. Pressure vessels shall be constructed and ¶
1002.1 General. Pressure vessels shall be constructed and designed in accordance with the ASME Boiler & Pressure Vessel Code (BPVC) Section VIII.1. Boilers shall be constructed, designed, and installed in accordance with one of the following: (1) ASME BPVC Section I (2) ASME BPVC Section IV (3) NFPA 85
1002.2 Oil-Burning Boilers. Oil-burning boilers shall ¶
1002.2 Oil-Burning Boilers. Oil-burning boilers shall comply with Section 1002.2.1 and Section 1002.2.2. 1002.2.1 Listing & Labeling. Oil-burning boilers shall be listed and labeled in accordance with UL 726. 1002.2.2 Installation. Tanks, piping, and valves for oil-burning boilers shall be installed in accordance with NFPA 31.
1002.3 Electric Boilers. Electric boilers shall be listed and ¶
1002.3 Electric Boilers. Electric boilers shall be listed and labeled in accordance with UL 834.
1002.4 Solid-Fuel-Fired Boilers. ¶
1002.4 Solid-Fuel-Fired Boilers. Solid-fuel-fired boilers shall comply with UL 2523 and shall be installed in accordance with the manufacturer’s installation instruc tions.
1002.5 Dual Purpose Water Heaters. ¶
1002.5 Dual Purpose Water Heaters. Water heaters utilized for combined space- and water-heating applications shall comply with the standards referenced in Table 1203.2, and shall be installed in accordance with the manufacturer’s installation instructions. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. BOILERS AND PRESSURE VESSELS
1003.0 Detailed Requirements. ¶
1003.1 Safety Requirements. ¶
1003.1 Safety Requirements. The construction of boilers and pressure vessels and the installation thereof shall be in accordance with minimum requirements for safety from structural and mechanical failure and excessive pressures as established by the Authority Having Jurisdiction in accordance with nationally recognized standards.
1003.2 Controls. Required electrical, mechanical, safety, ¶
1003.2 Controls. Required electrical, mechanical, safety, and operating controls shall carry the approval of an approved testing agency or be accepted by the Authority Having Jurisdiction. Electrical controls shall be of such design and construction as to be suitable for installation in the environment in which they are located. 1003.2.1 Automatic Boilers. Automatic boilers shall be equipped with controls and limit devices in accordance with ASME CSD-1 or Table 1003.2.1. The Authority Having Jurisdiction shall have the authority to approve solid-fuel-fired boilers that comply with the safety…
1003.3 Gauges. Steam boilers shall be provided with a ¶
1003.3 Gauges. Steam boilers shall be provided with a pressure gauge and a water level glass. Water boilers shall be provided with a pressure gauge and a temperature gauge. Automatic boilers shall be equipped with the following gauges, as applicable : (1) Oil temperature (2) Oil suction pressure (3) High and low gas pressure (4) Stack temperature (5) Windbox pressure
1003.4 Stack Dampers. Stack dampers on boilers fired ¶
1003.4 Stack Dampers. Stack dampers on boilers fired with oil or solid fuel shall not close off more than 80 percent of the stack area. Operative dampers shall not be placed within a stack, flue, or vent of a gas-fired boiler. Exception: Automatic boilers with prepurge, automatic draft control, and interlock.
1003.5 Welding. Welding on pressure vessels shall be done ¶
1003.5 Welding. Welding on pressure vessels shall be done by certified welders in accordance with nationally recognized standards.
1004.0 Expansion Tanks. ¶
1004.1 General. An expansion tank shall be installed in a ¶
1004.1 General. An expansion tank shall be installed in a hot-water-heating system as a means for controlling increased pressure caused by thermal expansion. Expansion tanks shall be of the closed or open type and securely fastened to or supported by the structure. Tanks shall be rated for the pressure of the system. Supports shall be capable of carrying twice the weight of the tank filled with water without placing a strain on connecting piping. Hot-water-heating systems incorporating hot water tanks or fluid relief columns shall be installed to prevent freezing under normal operating…
1004.2 Open-Type Expansion Tanks. ¶
1004.2 Open-Type Expansion Tanks. Open type expansion tanks shall be located not less than 3 feet (914 mm) above the highest point of the system. Such tanks shall be sized based on the capacity of the system. An overflow with a diameter of not less than one-half the size of the supply or not less than 1 inch (25 mm) in diameter shall be installed at the top of the tank. The overflow shall discharge through an air gap into the drainage system.
1004.3 Closed-Type Systems. Closed-type systems shall ¶
1004.3 Closed-Type Systems. Closed-type systems shall have an airtight tank or other approved air cushion that will be consistent with the volume and capacity of the system, and shall be designed for a hydrostatic test pressure of two and one-half times the allowable working pressure of the system. Expansion tanks for systems designed to operate at more than 30 pounds-force per square inch (psi) (207 kPa) shall comply with ASME BPVC Section VIII.1. Provisions shall be made for draining the tank without emptying the system.
1004.4 Minimum Capacity of Closed-Type Tank. The ¶
1004.4 Minimum Capacity of Closed-Type Tank. The minimum capacity for a gravity-type hot water system expansion tank shall be in accordance with Table 1004.4(1). The minimum capacity for a forced-type hot water system expansion tank shall be in accordance with Table 1004.4(2) or Equation 1004.4(1). The minimum capacity for a diaphragmtype hot water system expansion tank shall be in accordance with Table 1004.4(2) or Equation 1004.4(2). [Equation 1004.4(1)] Vt (forced-type) = [(0.00041] [t] [ - 0.0466) ] [V][s] ~~(~~ P P a a Pf Po ) [Equation 1004.4(2)] Vt (diaphragm-type) = [(0.00041] [t] [ -…
1005.0 Safety or Relief Valve Discharge. ¶
1005.0 Safety or Relief Valve Discharge.
1005.1 General. ¶
1005.1 General. Pressurized vessels or boilers shall be provided with overpressure protection by means of a listed pressure relief valve installed in accordance with the manufacturer’s installation instructions.
1005.2 Discharge Piping. The discharge piping serving a ¶
1005.2 Discharge Piping. The discharge piping serving a temperature relief valve, pressure relief valve, or combination of both shall have no valves, obstructions, or means of isolation and provided with the following: (1) Not less than the size of the valve outlet and shall discharge full size to the flood level of the area receiving the discharge and pointing down. (2) Materials shall be rated at not less than the operating temperature of the system and approved for such use or shall comply with ASME A112.4.1. (3) Discharge pipe shall discharge independently by gravity through an air gap…
1005.3 Splash Shield. Where the operating temperature ¶
1005.3 Splash Shield. Where the operating temperature exceeds 212°F (100°C), the discharge pipe shall be installed with a splash shield or centrifugal separator.
1005.4 Hazardous Discharge. Where the discharge from ¶
1005.4 Hazardous Discharge. Where the discharge from safety valves is capable of being hazardous, discharge of steam inside the boiler room, such discharge shall be discharged to the outside of the boiler room. Discharges from relief valves on industrial boilers shall be discharged to an approved location.
1005.5 Vacuum Relief Valve. Hot-water heating systems ¶
1005.5 Vacuum Relief Valve. Hot-water heating systems that are subjected to a vacuum while in operation or during shutdown shall be protected with a vacuum relief valve that complies with ANSI Z21.22/CSA 4.4. Where the piping configuration, equipment location, and valve outlets are located below the boiler elevation, the system shall be equipped with a vacuum relief valve at the highest point.
1006.0 Shutoff Valves. ¶
1006.1 General. An approved manual shutoff valve shall ¶
1006.1 General. An approved manual shutoff valve shall be installed upstream of all control devices on the main burner of a gas-fired boiler. The takeoff point for the gas supply to the pilot shall be upstream of the gas shutoff valve of the main burner and shall be valved separately. A union or other approved means of disconnect shall be provided immediately downstream of these shutoff valves.
1007.0 Gas-Pressure Regulators. ¶
1007.1 General. An approved gas-pressure regulator shall ¶
1007.1 General. An approved gas-pressure regulator shall be installed on gas-fired boilers where the gas supply pressure is exceeding that at which the main burner is designed to operate. A separate approved gas-pressure regulator shall be installed to regulate the gas pressure to the pilot or pilots. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. BOILERS AND PRESSURE VESSELS
1008.0 Low-Water Cutoff. ¶
1008.1 General. Hot water boilers and steam boilers shall ¶
1008.1 General. Hot water boilers and steam boilers shall be installed with a low-water cutoff. A coil-type boiler or a water-tube boiler that requires forced circulation to prevent overheating of the coils or tubes shall be installed with a flowsensing device in the outlet piping in lieu of the low-water cutoff. The low-water cutoff or the flow sensing device shall be installed so as to prevent damage to the boiler and to permit testing of the fuel-supply cutoff without draining the heating system. The low-water cutoff shall shut off the energy source at a water level setpoint that is in…
1009.0 Combustion Regulators – Safety Valves. ¶
1009.0 Combustion Regulators – Safety Valves.
1009.1 General. The following requirements shall be ¶
1009.1 General. The following requirements shall be retroactive: (1) Hot-water-heating boilers, other than manually fired, shall be equipped with two temperature combustion regulators in series. Steam-heating boilers, other than manually fired, shall be equipped with a pressure combustion regulator and a low-water cutoff. (See Section 1008.0) (2) Boilers and pressure vessels shall be provided with the required number, size, and capacity of safety or relief valves to ensure positive relief of overpressure in accordance with nationally recognized standards, as applicable. Valves so employed…
1010.0 Clearance for Access. ¶
1010.1 General. Where boilers are installed or replaced, ¶
1010.1 General. Where boilers are installed or replaced, clearance shall be provided to allow access for inspection, maintenance, and repair. Passageways around all sides of boilers shall have an unobstructed width of not less than 18 inches (457 mm). Clearance for repair and cleaning shall be permitted to be provided through a door or access panel into another area, provided the opening is of sufficient size. Exception: Subject to the approval of the Authority Having Jurisdiction, boilers shall be permitted to be installed with a side clearance of less than 18 inches (457 mm), provided that…
1010.2 Power Boilers. ¶
1010.2 Power Boilers. Power boilers having a steam-generating capacity in excess of 5000 pounds per hour (lb/h) (0.6299 kg/s) or having a heating surface in excess of 1000 square feet (92.9 m [2] ) or input in excess of 5 000 000 Btu/h (1464 kW) shall have a clearance of not less than 7 feet (2134 mm) from the top of the boiler to the ceiling.
1010.3 Steam-Heating Boilers, Hot Water Boilers, and ¶
1010.3 Steam-Heating Boilers, Hot Water Boilers, and Power Boilers. Steam-heating boilers and hot-water-heating boilers that exceed one of the following limits: (1) 5 000 000 Btu/h input (1464 kW) (2) 5000 pounds steam per hour (0.6299 kg/s) capacity (3) 1000 square foot (92.9 m [2] ) heating surface Power boilers that do not exceed one of the following limits: (1) 5 000 000 Btu/h input (1464 kW) (2) 5000 pounds steam per hour (0.6299 kg/s) capacity (3) 1000 square foot (92.9 m [2] ) heating surface Boilers with manholes on top of the boiler, except those described in Section 1010.2 and…
1010.4 Package Boilers, Steam-Heating Boilers, and ¶
1010.4 Package Boilers, Steam-Heating Boilers, and Hot-Water-Heating Boilers. Package boilers, steam-heating boilers, and hot-water-heating boilers with no manhole on top of the shell and not exceeding one of the above limits shall have a clearance of not less than 2 feet (610 mm) from the ceiling.
1011.0 Boilers, Stokers, and Steam Generators. ¶
1011.0 Boilers, Stokers, and Steam Generators.
1011.1 General. The design, installation, and operation of ¶
1011.1 General. The design, installation, and operation of single burner boilers, multiple burner boilers, stokers, and atmospheric fluidized-bed boilers with not less than a fuel input rating of 12.5 E+06 Btu/h (3.663 MW) to pulverized fuel systems, fired or unfired steam generators used to recover heat from combustion turbines and to other combustion turbine exhaust systems shall be in accordance with NFPA 85. That portion of the oil-burning system supplied on boilers and covered within the scope of NFPA 85 shall be installed in accordance with NFPA 85.
1012.0 Operating Adjustments and Instructions. ¶
1012.0 Operating Adjustments and Instructions.
1012.1 General. ¶
1012.1 General. Hot water boiler installations, upon completion, shall have controls set, adjusted, and tested by the installing contractor. A complete control diagram of a permanent legible type, together with complete boiler operating instructions, shall be furnished by the installer for each installation.
1013.0 Inspections and Tests. ¶
1013.1 General. An installation for which a permit is ¶
1013.1 General. An installation for which a permit is required shall not be put into service until it has been inspected and approved by the Authority Having Jurisdiction. It shall be the duty of the owner or his authorized representative to notify the Authority Having Jurisdiction that the installation is ready for inspection and test. It also shall be the duty of the owner or his authorized representative to post in a conspicuous position on the installation a notice in substantially the following form: “WARNING! THIS INSTALLATION HAS NOT BEEN INSPECTED AND APPROVED BY THE AUTHORITY HAVING…
1013.2 Operating Permit. It shall be unlawful to operate a ¶
1013.2 Operating Permit. It shall be unlawful to operate a boiler or pressure vessel without first obtaining a valid operating permit to do so from the Authority Having Jurisdiction. Such permit shall be displayed in a conspicuous place adjacent to the boiler or vessel. The operating permit shall not be issued until the equipment has been inspected and approved by the Authority Having Jurisdiction. Exception: The operation of steam-heating boilers, low-pressure hot-water-heating boilers, hot water supply boilers, and pressure vessels in residential occupancies of less than six dwelling units…
1013.3 Maintenance Inspection. The Authority Having ¶
1013.3 Maintenance Inspection. The Authority Having Jurisdiction shall inspect boilers and pressure vessels operated under a permit in accordance with ASHRAE/ACCA 180 at such intervals as deemed necessary, but not less frequently than in accordance with Section 1013.4 through Section 1013.7.
1013.4 Power and Miniature Boilers. Power boilers and ¶
1013.4 Power and Miniature Boilers. Power boilers and miniature boilers shall be inspected externally annually. Where construction and operating conditions permit, they shall be subject to inspection internally annually.
1013.5 Steam-Heating and Water-Heating Boilers. ¶
1013.5 Steam-Heating and Water-Heating Boilers. Steam-heating boilers and hot-water-heating boilers shall be inspected externally annually. Where construction and operating conditions permit, they shall also be subject to inspection internally annually.
1013.6 Automatic Steam-Heating Boilers. Automatic ¶
1013.6 Automatic Steam-Heating Boilers. Automatic steam-heating boilers shall be inspected externally biennially. Where construction and operating conditions permit, they shall be subject to inspection internally biennially.
1013.7 Unfired Pressure Vessels. Unfired pressure vessels ¶
1013.7 Unfired Pressure Vessels. Unfired pressure vessels shall be inspected externally biennially. Where subject to corrosion and construction permits, they shall be subject to inspection internally biennially. Inspection of boilers and pressure vessels covered by insurance shall be permitted to be made by employees of the insuring company holding commissions from the National Board of Boiler and Pressure Vessel Inspectors, subject to approval of the Authority Having Jurisdiction. Approved insuring company inspectors shall make reports on prescribed forms on inspections authorized by the…
1014.0 Operation and Maintenance of Boilers and ¶
1014.0 Operation and Maintenance of Boilers and Pressure Vessels.
1014.1 General. ¶
1014.1 General. Boilers and pressure vessels shall be operated and maintained in accordance with requirements for pro tection of the public established by the Authority Having Jurisdiction in accordance with nationally recognized standards. The Authority Having Jurisdiction shall notify the owner or authorized representative of defects or deficiencies and properly corrected. Where such corrections are not made, or where the operation of the boiler or pressure vessel is deemed unsafe by the Authority Having Jurisdiction, they shall have the authority to revoke the permit to operate the boiler…
1101.0 General. ¶
1101.1 Applicability. Part I governs the design, installation, ¶
1101.1 Applicability. Part I governs the design, installation, and construction of refrigeration systems, equipment, refrigerant piping, pressure vessels, safety devices, replacement of parts, alterations, and substitution of different refrigerants. Part II governs the installation and construction of cooling towers.
1101.2 Equipment. Equipment for refrigerant recovery, ¶
1101.2 Equipment. Equipment for refrigerant recovery, recycling, or both shall comply with UL 1963. Part I – Refrigeration Systems.
1102.0 Refrigeration Systems. ¶
1102.1 General. Refrigeration systems using a refrigerant ¶
1102.1 General. Refrigeration systems using a refrigerant other than ammonia shall comply with this chapter and ASHRAE 15. Refrigeration systems containing carbon dioxide as the refrigerant shall also comply with IIAR CO2.
1102.2 Ammonia Refrigeration Systems. Refrigeration ¶
1102.2 Ammonia Refrigeration Systems. Refrigeration systems using ammonia as the refrigerant shall comply with IIAR 2, IIAR 3, IIAR/ANSI 4, IIAR 5, and IIAR 6 and shall not be required to comply with this chapter.
1102.3 Refrigerants. The refrigerant used shall be of a type ¶
1102.3 Refrigerants. The refrigerant used shall be of a type listed in Table 1102.3 or in accordance with ASHRAE 34 where approved by the Authority Having Jurisdiction. Exception: Lithium bromide absorption systems using water as the refrigerant.
1103.0 Classification. ¶
1103.1 Classification of Refrigerants. Refrigerants shall ¶
1103.1 Classification of Refrigerants. Refrigerants shall be classified in accordance with Table 1102.3 or in accor dance with ASHRAE 34 where approved by the Authority Having Jurisdiction. 1103.1.1 Safety Group. Table 1102.3 classifies refrigerants by toxicity and flammability, and assigns safety groups using combinations of toxicity class and flammability class. For the purposes of this chapter, the refrigerant Groups A1, A2L, A2, A3, B1, B2L, B2, and B3 shall be considered to be individual and distinct safety groups, as shown in Table 1103.1.1. Each refrigerant is assigned into not more…
1103.2 Classification of Refrigeration Systems. ¶
1103.2 Classification of Refrigeration Systems. Refrigeration systems shall be classified according to the degree of probability that a leakage of refrigerant will enter an occupancy-classified area in accordance with Section 1103.2.1 and Section 1103.2.2. [ASHRAE 15:5.2] 1103.2.1 High-Probability System. Systems in which the basic design, or the location of components, is such that a leakage of refrigerant from a failed connection, seal, or component will enter the occupied space shall be classified as high-probability systems. A typical high-probability system shall be one of the following:…
1103.3 Higher Flammability Refrigerants. Group A3 ¶
1103.3 Higher Flammability Refrigerants. Group A3 and B3 refrigerants shall not be used except where approved by the Authority Having Jurisdiction. Exceptions: (1) Laboratories with more than 100 square feet (9.29 m [2] ) of space per person. (2) Industrial occupancies. (3) Listed self-contained systems containing not more than 0.331 pounds (0.150 kg) of Group A3 refrigerant, provided that the equipment is installed in accordance with the listing and the manufacturer’s installation instructions. [ASHRAE 15:7.5.3]
1104.0 Requirements for Refrigerant and Refrigera- ¶
1104.0 Requirements for Refrigerant and Refrigera- tion System Use.
1104.1 System Selection. Refrigeration systems shall be ¶
1104.1 System Selection. Refrigeration systems shall be limited in application in accordance with Table 1104.1, and the requirements of Section 1104.0.
1104.2 Refrigerant Concentration Limit (RCL). The ¶
1104.2 Refrigerant Concentration Limit (RCL). The concentration of refrigerant in a complete discharge of an Higher FlammabilityA3B3 --------- FlammableA2B2 Lower FlammabilityA2LB2L No Flame Propagation<brA1B1 Lower ToxicityHigher Toxicity ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. REFRIGERATION TABLE 1104.1 PERMISSIBLE REFRIGERATION SYSTEMS [1 ] OCCUPANCY GROUP3HIGH-PROBABILITY SYSTEMLOW PROBABILITY SYSTEMMACHINERY ROOM ------------ A-1Group A1 or A2L4 onlyAnyAny A-2Group A1 or A2L4 onlyAnyAny A-3Group A1 or A2L4…
1104.3 Institutional Occupancies. The RCL value ¶
1104.3 Institutional Occupancies. The RCL value required in Section 1104.2 shall be reduced by 50 percent for the areas of institutional occupancies. The total of Group A2, B2, A3, and B3 refrigerants shall not exceed 550 pounds (249.5 kg) in the occupied areas and machinery rooms of institutional occupancies. [ASHRAE 15:7.2.1] Exception: The total of all Group A2L refrigerants shall not be limited in machinery rooms of institutional occupancies. [OSHPD 1 & 4] Exception: For technology equipment cen- ters not attached to a patient care area the amounts shown in Table 1102.3 may be calculated…
1104.4 Industrial Occupancies and Refrigerated ¶
1104.4 Industrial Occupancies and Refrigerated Rooms. Section 1104.2 shall not apply in industrial occupancies and refrigerated rooms where in accordance with the following: (1) The space(s) containing the machinery is (are) separated from other occupancies by tight construction with tightfitting doors. (2) Access is restricted to authorized personnel. (3) Refrigerant detectors are installed with the sensing location and alarm level as required in refrigeration machinery rooms in accordance with Section 1106.2.6. (4) Open flames and surfaces exceeding 800°F (427°C) shall not be permitted…
1104.5 Flammable Refrigerants. The total of Group A2, ¶
1104.5 Flammable Refrigerants. The total of Group A2, B2, A3, and B3 refrigerants, other than Group A2L and B2L refrigerants shall not exceed 1100 pounds (498.9 kg) without approval by the Authority Having Jurisdiction. Institutional Occupancies shall comply with Section 1104.3. Machinery rooms required in accordance with Section 1106.0 based on flammability shall be constructed and maintained in accordance with Section 1106.2.1 through Section 1106.2.6 and Section 1106.11 for Group A2L and B2L refrigerants.
1104.6 Group A2L Refrigerants for Human Comfort. ¶
1104.6 Group A2L Refrigerants for Human Comfort. High-probability systems using Group A2L refrigerants for human comfort applications shall comply with this section. [ASHRAE 15:7.6] 1104.6.1 Refrigerant Concentration Limits. Occupied spaces shall comply with the releasable charge limitations of the equipment listing and ASHRAE 15. Unoccupied spaces with refrigerant containing equipment, not including continuous piping or tubing, shall comply with the releasable charge limitations of the equipment listing or Section 1104.6.4. {ASHRAE 15:7.6.1-7.6.1.2} 1104.6.2 Listing and Installation…
1104.7 Applications for Human Comfort and for Non- ¶
1104.7 Applications for Human Comfort and for Non- industrial Occupancies. In nonindustrial occupancies, Group A2, A3, B1, B2L, B2, and B3 refrigerants shall not be used in high-probability systems for human comfort. Use of Group A2L refrigerants used in high-probability systems for human comfort shall be in accordance with Section 1104.6.
1104.8 Refrigerant Type and Purity. Refrigerants shall ¶
1104.8 Refrigerant Type and Purity. Refrigerants shall be of a type specified by the equipment manufacturer. Unless otherwise specified by the equipment manufacturer, refrigerants used in new equipment shall be of purity in accordance with AHRI 700. 1104.8.1 Recovered Refrigerants. Recovered refrigerants shall not be reused except in the system from which they were removed, or as provided in Section 1104.8.2 or Section 1104.8.3. When contamination is evident by discoloration, odor, acid test results, or system history, recovered refrigerants shall be reclaimed in accordance with Section…
1105.3 Access. ¶
1105.3 Access. An unobstructed readily accessible opening and passageway not less than 36 inches (914 mm) in width and 80 inches (2032 mm) in height shall be provided and maintained to the compressor, valves required by this chapter, or other portions of the system requiring routine maintenance. Exceptions: (1) Refrigerant evaporators, suspended overhead, shall be permitted to use portable means of access. (2) Air filters, brine control or stop valves, fan motors or drives, and remotely de-energized electrical connections shall be permitted to be provided access to an unobstructed space not…
1105.4 Illumination and Service Receptacles. ¶
1105.4 Illumination and Service Receptacles. In addition to the requirements of Section 301.4, permanent luminaires shall be installed for equipment required by this code to be accessible or readily accessible. Such luminaires shall provide illumination to perform the required tasks for which access is provided. Control of the illumination source shall be provided at the access entrance. Exceptions: (1) Luminaires shall be permitted to be omitted where the fixed lighting of the building will provide the required illumination. (2) Equipment located on the roof or on the exterior walls of a…
1105.5 Ventilation of Rooms Containing Condensing ¶
1105.5 Ventilation of Rooms Containing Condensing Units. Where not in a refrigerant machinery room, rooms or spaces in which a refrigerant-containing portion of a condensing unit is installed shall be provided with ventilation in accordance with Section 1105.5.1 or Section 1105.5.2. Ventilation for machinery rooms shall comply with Section 1106.0. 1105.5.1 Permanent Gravity Ventilation Open- ings. Permanent gravity ventilation openings of not less » (2) The resulting mixture does not change the refrigerant safety group. [ASHRAE 15:7.5.1.7]
1104.9 Changing Refrigerants. Changes of refrigerant in ¶
1104.9 Changing Refrigerants. Changes of refrigerant in an existing system to a refrigerant with a different refrigerant designation shall only be allowed where in accordance with Section 1104.9.1 through Section 1104.9.4. [ASHRAE 15:5.3] 1104.9.1 Approval. The change of refrigerant shall be approved by the owner. [ASHRAE 15:5.3.1] 1104.9.2 Procedures. The change of refrigerant shall be in accordance with one of the following: (1) Written instructions of the original equipment manufacturer. (2) An evaluation of the system by a registered design professional or by an approved nationally…
1105.0 General Requirements. ¶
1105.1 Human Comfort. Cooling systems used for human ¶
1105.1 Human Comfort. Cooling systems used for human comfort shall be in accordance with the return-air and outside-air provisions for furnaces in Section 604.1 and Section 904.8. Cooling equipment used for human comfort in residential buildings shall be selected in accordance with ACCA Manual S to satisfy the calculated loads determined in accordance with ACCA Manual J or other approved methods. Refrigerants used for human comfort shall be in accordance with Section 1104.7.
1105.2 Supports and Anchorage. ¶
1105.2 Supports and Anchorage. Supports and anchorage for refrigeration equipment and piping shall be designed in accordance with the building code as Occupancy Category H (hazardous facilities). Supports shall be made of noncombustible materials. Exceptions: (1) Equipment containing Group A1 refrigerants shall be permitted to be supported by the same materials permitted for the building type. (2) The use of approved vibration isolators specifically designed for the normal, wind, and seismic loads encountered, shall be permitted. ), Copyright © 2025 IAPMO, and may not be used for any other…
1105.6 Prohibited Locations. Refrigeration systems or ¶
1105.6 Prohibited Locations. Refrigeration systems or portions thereof shall not be located within a required exit enclosure. Refrigeration compressors exceeding 5 horsepowers (3.7 kW) rating shall be located not less than 10 feet (3048 mm) from an exit opening in a Group A; Group B; Group E; Group F; Group I; Group R, Division 1; or Group S Occupancy, unless separated by a one-hour fire-resistive occupancy separation.
1105.7 Condensate. Condensate from air-cooling coils ¶
1105.7 Condensate. Condensate from air-cooling coils shall be collected and drained to an approved location. Drain pans and coils shall be arranged to allow thorough drainage and access for cleaning. Where temperatures drop below freezing, heat tracing and insulation of condensate drains shall be installed.
1105.8 Defrost. ¶
1105.8 Defrost. Where defrost cycles are required for portions of the system, provisions shall be made for collection and disposal of the defrost liquid in a safe and sanitary man ner.
1105.9 Overflows. Where condensate or defrost liquids are ¶
1105.9 Overflows. Where condensate or defrost liquids are generated in an attic or furred space, and structural damage will result from overflow, provisions for overflow shall be provided.
1105.10 Condensate, Defrost, and Overflow Dis- ¶
1105.10 Condensate, Defrost, and Overflow Dis- posal. Disposal of condensate, defrost, or overflow discharges shall comply with Section 310.0.
1105.11 Refrigerant Port Protection. Air conditioning ¶
1105.11 Refrigerant Port Protection. Air conditioning refrigerant circuit access ports located outdoors shall be protected from unauthorized access with locking-type tamperresistant caps or in a manner approved by the Authority Having Jurisdiction. Exception: Refrigerant ports in secure locations protected by walls or fencing and requiring key access.
1105.12 Storage. Refrigerants and refrigerant oils not ¶
1105.12 Storage. Refrigerants and refrigerant oils not charged within the refrigeration system shall be stored in accordance with Section 1105.12.1 and the fire code. Storage of materials in a refrigeration machinery room shall comply with the fire code. 1105.12.1 Storing Refrigerant. The total amount of refrigerant stored in a machinery room in all containers not provided with relief valves and piping in accordance with Section 1113.0 shall not exceed 330 pounds (149.7 kg). Refrigerant shall be stored in approved storage containers. Additional quantities of refrigerant shall be stored in an…
1106.0 Refrigeration Machinery Rooms. ¶
1106.0 Refrigeration Machinery Rooms.
1106.1 Where Required. Refrigeration systems shall be ¶
1106.1 Where Required. Refrigeration systems shall be provided with a refrigeration machinery room where the conditions as outlined in Section 1106.1.1 through Section 1106.1.4 exist. Exception: Refrigeration equipment shall be permitted to be located outdoors in accordance with ASHRAE 15. 1106.1.1 Quantity. The quantity of refrigerant in a single, independent refrigerant circuit of a system exceeds the amounts of Table 1102.3. 1106.1.2 Equipment. Direct- and indirect-fired absorption equipment is used. Exception: Direct and indirect-fired lithium bromide absorption systems using water as the…
1106.2 Refrigeration Machinery Room, General ¶
1106.2 Refrigeration Machinery Room, General Requirements. Where a refrigeration system is located indoors and a machinery room is required in accordance with Section 1106.1, the machinery room shall be in accordance with Section 1106.2.1 through Section 1106.2.9.1. 1106.2.1 Access. Machinery rooms shall not be prohibited from housing other mechanical equipment unless specifically prohibited elsewhere in this chapter. A machinery room shall be so dimensioned that parts are accessible with space for service, maintenance, and operations. There shall be clear head room of not less than 7.25 feet…
1106.3 Normal Operation. A part of the refrigeration ¶
1106.3 Normal Operation. A part of the refrigeration machinery room mechanical ventilation shall be in accordance with the following: « « « « ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. REFRIGERATION « « « «
1106.7 Maximum Temperature. ¶
1106.7 Maximum Temperature. Ventilation or mechanical cooling systems shall be provided to maintain a temperature of not more than 104°F (40°C) in the refrigerant machinery room under design load and weather conditions.
1106.8 Refrigerant Parts in Air Duct. ¶
1106.8 Refrigerant Parts in Air Duct. Joints and refrigerant-containing parts of a refrigerating system located in an air duct carrying conditioned air to and from an occupied space shall be constructed to withstand a temperature of 700°F (371°C) without leakage into the airstream. [ASHRAE 15:8.8]
1106.9 Dimensions. Refrigeration machinery rooms shall ¶
1106.9 Dimensions. Refrigeration machinery rooms shall be of such dimensions that system parts are readily accessible with approved space for maintenance and operations. An unobstructed walking space not less than 36 inches (914 mm) in width and 80 inches (2032 mm) in height shall be maintained throughout, allowing free access to not less than two sides of moving machinery and approaching each stop valve. Access to refrigeration machinery rooms shall be restricted to authorized personnel and posted with a permanent sign.
1106.10 Exits. Exits shall comply with the building code for ¶
1106.10 Exits. Exits shall comply with the building code for special hazards.
1106.11 Machinery Room, A2L and B2L. When required ¶
1106.11 Machinery Room, A2L and B2L. When required by Section 1106.1, machinery rooms shall comply with Section 1106.11.1 through Section 1106.11.6. [ASHRAE 15:8.13] 1106.11.1 Flame-Producing Device. There shall be no flame-producing device or hot surface over 1290°F (700°C) in the room, other than that used for maintenance or repair, unless installed in accordance with Section 1106.5. [ASHRAE 15:8.13.1] 1106.11.2 Communicating Spaces. Doors communicating with the building shall be approved, self-closing, tight-fitting fire doors. [ASHRAE 15:8.13.2] 1106.11.3 Noncombustible Construction.…
1106.4 Natural Ventilation. When a refrigerating system ¶
1106.4 Natural Ventilation. When a refrigerating system is located outdoors more than 20 feet (6096 mm) from building openings and is enclosed by a penthouse, lean-to, or other open structure, natural or mechanical ventilation shall be provided. The requirements for such natural ventilation shall be in accordance with the following: (1) The free-aperture cross section for the ventilation of a machinery room shall be not less than as determined in accordance with Equation 1106.4. F = √ G (Equation 1106.4) Where: F = The free opening area, ft [2] (m [2] ). G = The mass of refrigerant in the…
1106.5 Combustion Air. ¶
1106.5 Combustion Air. No open flames that use combustion air from the machinery room shall be installed where refrigerant is used. Combustion equipment shall not be installed in the same machinery room with refrigerant-containing equipment except under one of the following conditions: (1) Combustion air shall be ducted from outside the machinery room and sealed in such a manner as to prevent refrigerant leakage from entering the combustion chamber. (2) A refrigerant detector, that is in accordance with Section 1106.2.5, shall be installed to automatically shut down the combustion process in…
1106.6 Ventilation Intake. Makeup air intakes to replace ¶
1106.6 Ventilation Intake. Makeup air intakes to replace the exhaust air shall be provided to the refrigeration machinery room directly from outside the building. Intakes shall be located as required by other sections of the code and fitted with backdraft dampers or other approved flow-control means to prevent reverse flow. Distribution of makeup air shall be arranged to provide thorough mixing within the refrigeration machinery room to prevent short circuiting of the makeup air directly to the exhaust. 234 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any…
1107.0 Machinery Room, Special Requirements. ¶
1107.0 Machinery Room, Special Requirements.
1107.1 General. In cases specified in the rules of Section ¶
1107.1 General. In cases specified in the rules of Section 1106.1, a refrigeration machinery room shall comply with the special requirements in accordance with Section 1107.1.1 through Section 1107.1.10, in addition to Section 1106.2. 236 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. REFRIGERATION 1107.1.1 Flame-Producing Devices. There shall be no flame-producing device or continuously operating hot surface over 800°F (427°C) permanently installed in the room. 1107.1.2 Doors. Doors…
1108.0 Refrigeration Machinery Room Equipment ¶
1108.0 Refrigeration Machinery Room Equipment and Controls.
1108.1 General. Equipment, piping, ducts, vents, or similar ¶
1108.1 General. Equipment, piping, ducts, vents, or similar devices that are not essential for the refrigeration process, maintenance of the equipment, or for the illumination, ventilation, or fire protection of the room shall not be placed in or pass through a refrigeration machinery room.
1108.2 Electrical. Electrical equipment and installations shall ¶
1108.2 Electrical. Electrical equipment and installations shall comply with California Electrical Code . The refrigeration machinery room shall not be classified as a hazardous location except as provided in Section 1107.1.7 or Section 1107.1.8.
1108.3 Emergency Shutoff. ¶
1108.3 Emergency Shutoff. A clearly identified emergency shutoff switch of the break-glass type or with an approved tamper-resistant cover shall be provided immediately adjacent to and outside of the principal refrigeration machinery room entrance. The switch shall provide off-only control of refrigerant compressors, refrigerant pumps, and normally-closed automatic refrigerant valves located in the machinery room. For other than A1 and B1 refrigerants, emergency shutoff shall be automatically activated by refrigerant Alarm 2 in accordance with Section 1106.2.5.
1108.4 Installation, Maintenance, and Testing. ¶
1108.4 Installation, Maintenance, and Testing. Detection and alarm systems in accordance with Section 1106.2.5 shall be installed, maintained, and tested in accordance with the California Fire Code and with the equipment manufac- turer’s specification .
1108.5 Emergency Pressure Control System. Where ¶
1108.5 Emergency Pressure Control System. Where required by the fire code, an emergency pressure control system shall be installed in accordance with applicable fire code requirements.
1109.0 Refrigeration Piping, Containers, and Valves. ¶
1109.0 Refrigeration Piping, Containers, and Valves.
1109.1 Materials. Materials used in the construction and ¶
1109.1 Materials. Materials used in the construction and installation of refrigerating systems shall be suitable for conveying the refrigerant used. Materials shall not be used that will deteriorate because of the refrigerant, the lubricant, or their combination in the presence of air or moisture to a degree that poses a safety hazard. [ASHRAE 15:9.1.1] Refrigerant piping shall be metallic. Materials for refrigerant piping, tubing, and fittings shall comply with the applicable standards in Table 1109.1. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any…
1109.2 Joints. Iron or steel pipe joints shall be of approved ¶
1109.2 Joints. Iron or steel pipe joints shall be of approved threaded, flanged, or welded types. Exposed threads shall be tinned or coated with an approved corrosion inhibitor. Copper or copper alloy pipe joints of iron pipe size shall be of approved threaded, flanged, press-connect or brazed types. Copper tubing joints and connections shall be connected by approved flared, lapped, swaged, or brazed joints, soldered joints, or mechanical joints that comply with UL 207 either individually or as part of an assembly or a system by an approved nationally recognized laboratory. Piping and tubing…
1109.3 Penetration of Piping. Refrigerant piping shall not ¶
1109.3 Penetration of Piping. Refrigerant piping shall not penetrate floors, ceilings, or roofs. Exceptions: (1) Penetrations connecting the basement and the first floor. (2) Penetrations connecting the top floor and a machinery penthouse or roof installation. (3) Penetrations connecting adjacent floors served by the refrigeration system. (4) Penetrations of a direct system where the refrigerant concentration does not exceed that listed in Table 1102.3 for the smallest occupied space through which the refrigerant piping passes. (5) In other than industrial occupancies and where the…
1109.4 Location of Refrigeration Piping. Refrigerant ¶
1109.4 Location of Refrigeration Piping. Refrigerant piping crossing an open space that affords passageway in any building shall be not less than 7.25 feet (2210 mm) above the floor unless the piping is located against the ceiling of such space and is permitted by the Authority Having Jurisdiction. [ASHRAE 15:8.10.1] 1109.4.1 Protection from Mechanical Damage. Passages shall not be obstructed by refrigerant piping. Refrigerant piping shall not be placed in any elevator, dumbwaiter, or other shaft containing a moving object or in any shaft that has openings to living quarters or to means of…
1109.5 Underground Piping. Refrigerant piping placed ¶
1109.5 Underground Piping. Refrigerant piping placed underground shall be protected against corrosion. 1109.5.1 Piping in Concrete Floors. Refrigerant piping installed in concrete floors shall be encased in pipe duct. Refrigerant piping shall be isolated and supported to prevent damaging vibration, stress, or corrosion. [ASHRAE 15:8.10.4]
1109.6 Support. In addition to the requirements of Section ¶
1109.6 Support. In addition to the requirements of Section 1105.2, piping and tubing shall be securely fastened to a permanent support within 6 feet (1829 mm) following the first bend in such tubing from the compressor and within 2 feet (610 mm) of each subsequent bend or angle. Piping and tubing shall be supported at points not more than 15 feet (4572 mm) apart.
1109.7 Pipe Enclosure. Refrigerant piping and tubing ¶
1109.7 Pipe Enclosure. Refrigerant piping and tubing shall be installed so that it is not subject to damage from an external source. Soft annealed copper tubing shall not exceed 1 [3] ⁄ 8 inches (35 mm) nominal size. Mechanical joints, other than approved press-connect joints, shall not be made on tubing exceeding [3] ⁄ 4 of an inch (20 mm) nominal size. Soft annealed copper tubing conveying refrigerant shall be enclosed in iron or steel piping and fittings, or in conduit, molding, or raceway that will protect the tubing against mechanical injury from an exterior source. ), Copyright © 2025…
1109.8 Visual Inspection. Refrigerant piping and joints ¶
1109.8 Visual Inspection. Refrigerant piping and joints erected on the premises shall be exposed to view for visual inspection prior to being covered or enclosed. Exception: Copper tubing enclosed in iron or steel piping conduit, molding, or raceway, provided there are no fittings or joints concealed therein.
1109.9 Condensation. Piping and fittings that convey ¶
1109.9 Condensation. Piping and fittings that convey brine, refrigerant, or coolants that during normal operation are capable of reaching a surface temperature below the dew point of the surrounding air and that are located in spaces or areas where condensation will cause a hazard to the building occupants or damage to the structure, electrical or other equipment shall be protected to prevent such damage.
1109.10 Identification. Piping shall be in accordance with ¶
1109.10 Identification. Piping shall be in accordance with the reference standard for identification. The type of refrigerant, function and pressure shall be indicated.
1110.0 Valves. ¶
1110.1 More than 6.6 Pounds of Refrigerant. Systems ¶
1110.1 More than 6.6 Pounds of Refrigerant. Systems containing more than 6.6 pounds (2.99 kg) of refrigerant shall have stop valves installed at the following locations: (1) The suction inlet of each compressor, compressor unit, or condensing unit. (2) The discharge of each compressor, compressor unit, or condensing unit. (3) The outlet of each liquid receiver. Exceptions: (1) Systems that have a refrigerant pumpout function capable of storing the entire refrigerant charge. (2) Systems that are equipped with the provisions for pumpout of the refrigerant. (3) Self-contained systems. [ASHRAE…
1110.2 More than 110 Pounds of Refrigerant. Systems ¶
1110.2 More than 110 Pounds of Refrigerant. Systems containing more than 110 pounds (49.9 kg) of refrigerant shall have stop valves installed at the following locations: (1) The suction inlet of each compressor, compressor unit, or condensing unit. (2) The discharge outlet of each compressor, compressor unit, or condensing unit. (3) The inlet of each liquid receiver, except for self-contained systems or where the receiver is an integral part of the condenser or condensing unit. (4) The outlet of each liquid receiver. (5) The inlets and outlets of condensers when more than one condenser is…
1110.3 Support. Stop valves installed in copper refrigerant ¶
1110.3 Support. Stop valves installed in copper refrigerant lines of [3] ⁄ 4 of an inch (20 mm) or less outside diameter shall be supported independently of the tubing or piping.
1110.4 Access. Stop valves required by Section 1110.0 shall ¶
1110.4 Access. Stop valves required by Section 1110.0 shall be readily accessible from the refrigeration machinery room floor or a level platform.
1110.5 Identification. ¶
1110.5 Identification. Stop valves shall be identified by tagging in accordance with the reference standard for identification. A valve chart shall be mounted under glass at an approved location near the principal entrance to a refrigeration machinery room.
1111.0 Pressure-Limiting Devices. ¶
1111.1 Where Required. ¶
1111.1 Where Required. Pressure-limiting devices complying with Section 1111.2 through Section 1111.4 shall be provided for compressors on all systems operating above atmospheric pressure. Exception: Pressure limiting devices are not required for listed factory-sealed systems containing less than 22 pounds (9.9 kg) of Group A1 refrigerant. [ASHRAE 15:9.9.1]
1111.2 Setting. Pressure limiting devices shall be set in ¶
1111.2 Setting. Pressure limiting devices shall be set in accordance with one the following: (1) For positive displacement compressors: (a) When systems are protected by a highside pressure relief device, the compressor’s pressure limiting device shall be set not more than 90 percent of the operating pressure for the highside pressure relief device. (b) When systems are not protected by a highside pressure relief device, the compressor’s pressure limiting device shall be set not more than the system’s highside design pressure. (2) For nonpositive displacement compressors: (a) When systems are…
1111.3 Location. Stop valves shall not be installed between ¶
1111.3 Location. Stop valves shall not be installed between the pressure imposing element and pressure limiting devices serving compressors. [ASHRAE 15:9.9.3]
1111.4 Emergency Stop. Activation of a pressure-limiting ¶
1111.4 Emergency Stop. Activation of a pressure-limiting device shall stop the action of the pressure-imposing element. [ASHRAE 15:9.9.4] 240 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. REFRIGERATION
1112.0 Pressure-Relief Devices. ¶
1112.1 General. Refrigeration systems shall be protected by ¶
1112.1 General. Refrigeration systems shall be protected by a pressure-relief device or other approved means to safely relieve pressure due to fire or abnormal conditions. [ASHRAE 15:9.4.1]
1112.2 Positive Displacement Compressor. A positive ¶
1112.2 Positive Displacement Compressor. A positive displacement compressor with a stop valve in the discharge connection shall be equipped with a pressure-relief device that is sized, and with a pressure setting, in accordance with the compressor manufacturer to prevent rupture of the compressor or to prevent the pressure from increasing to more than 10 percent above the maximum allowable working pressure of any other component located in the discharge line between the compressor and the stop valve or in accordance with Section 1113.5, whichever is larger. The pressure-relief device shall…
1112.3 Liquid-Containing Portions of Systems. ¶
1112.3 Liquid-Containing Portions of Systems. Liquid-containing portions of systems, including piping, that is isolated from pressure-relief devices required elsewhere, and that develops pressures exceeding their working design pressures due to temperature rise, shall be protected by the installation of pressure-relief devices.
1112.4 Evaporators. ¶
1112.4 Evaporators. Heat exchanger coils located downstream, or upstream within 18 inches (457 mm), of a heating source and capable of being isolated shall be fitted with a pressure-relief device that discharges to another part of the system in accordance with Section 1112.5 through Section 1112.5.2 or outside any enclosed space in accordance with Section 1112.11. The pressure relief device shall be connected at the highest possible location of the heat exchanger or piping between the heat exchanger and its manual isolation valves. Exceptions: (1) Relief valves shall not be required on heat…
1112.5 Hydrostatic Expansion. Pressure rise resulting ¶
1112.5 Hydrostatic Expansion. Pressure rise resulting from hydrostatic expansion due to temperature rise of liquid refrigerant trapped in or between closed valves shall be addressed in accordance with Section 1112.5.1 and Section 1112.5.2. [ASHRAE 15:9.4.3] 1112.5.1 Hydrostatic Expansion During Normal Operation. Where trapping of liquid with subsequent hydrostatic expansion is capable of occurring automatically during normal operation or during standby, shipping, or power failure, engineering controls shall be used that are capable of preventing the pressure from exceeding the design…
1112.6 Actuation. Pressure-relief devices shall be direct ¶
1112.6 Actuation. Pressure-relief devices shall be direct pressure actuated or pilot operated. Pilot-operated pressurerelief valves shall be self-actuated, and the main valve shall open automatically at the set pressure and, where an essential part of the pilot fails, shall discharge its full rated capacity. [ASHRAE 15:9.4.5]
1112.7 Stop Valves Prohibited. Stop valves shall not be ¶
1112.7 Stop Valves Prohibited. Stop valves shall not be located between a pressure-relief device and parts of the system protected thereby. A three-way valve, used in conjunction with the dual relief valve in accordance with Section 1113.6, shall not be considered a stop valve. [ASHRAE 15:9.4.6]
1112.8 Location. Pressure-relief devices shall be connected ¶
1112.8 Location. Pressure-relief devices shall be connected directly to the pressure vessel or other parts of the system protected thereby. These devices shall be connected above the liquid refrigerant level and installed so that they are accessible for inspection and repair, and so that they are not capable of being readily rendered inoperative. Exception: Where fusible plugs are used on the highside, they shall be located above or below the liquid refrigerant level. [ASHRAE 15:9.4.8]
1112.9 Materials. The seats and discs of pressure-relief ¶
1112.9 Materials. The seats and discs of pressure-relief devices shall be constructed of compatible material to resist refrigerant corrosion or other chemical action caused by the refrigerant. Seats or discs of cast iron shall not be used. Seats and discs shall be limited in distortion, by pressure or other cause, to a set pressure change of not more than 5 percent in a span of five years. [ASHRAE 15:9.4.9]
1112.10 Pressure-Relief Valve Setting. Pressure-relief ¶
1112.10 Pressure-Relief Valve Setting. Pressure-relief valves shall start to function at a pressure not exceeding the design pressure of the parts of the system protected. Exception: Relief valves that discharge into other parts of the system shall comply with Section 1112.11.3. [ASHRAE 15:9.5.1] 1112.10.1 Rupture Member Setting. Rupture members used in lieu of, or in series with, a relief valve shall have a nominal rated rupture pressure not exceeding the design pressure of the parts of the system protected. The conditions of application shall comply with ASME BPVC Section VIII.1. The size…
1112.11 Discharge from Pressure-Relief Devices. ¶
1112.11 Discharge from Pressure-Relief Devices. Pressure-relief systems designed for vapor shall comply with Section 1112.11.1 through Section 1112.11.4.1. 1112.11.1 Discharging Location Interior to Build- ing. Pressure-relief devices, including fusible plugs, serving refrigeration systems shall be permitted to discharge to the interior of a building where in accordance with all of the following: (1) The system contains less than 110 pounds (49.9 kg) of a Group A1 or A2L refrigerant. (2) The system contains less than 6.6 pounds (2.99 kg) of a Group A2, B1, B2 or B2L refrigerant. (3) The…
1112.12 Discharge Piping. ¶
1112.12 Discharge Piping. The piping used for pressure-relief device discharge shall be in accordance with Section 1112.12.1 through Section 1112.12.5. [ASHRAE 15:9.7.9] 1112.12.1 Piping Connection. Piping connected to the discharge side of a fusible plug or rupture member shall have provisions to prevent plugging of the pipe upon operation of a fusible plug or rupture member. [ASHRAE 15:9.7.9.1] 1112.12.2 Pipe Size. The size of the discharge pipe from the pressure-relief device or fusible plug shall be not less than the outlet size of the pressure-relief device or fusible plug. [ASHRAE…
1112.13 Rating of Pressure-Relief Device. The rated ¶
1112.13 Rating of Pressure-Relief Device. The rated discharge capacity of a pressure-relief device expressed in pounds of air per minute (kg/s), shall be determined in accordance with ASME BPVC Section VIII.1. Pipe and fittings between the pressure-relief valve and the parts of the system it protects shall have not less than the area of the pressurerelief valve inlet area. [ASHRAE 15:9.7.6]
1112.14 Rating of Rupture Members and Fusible ¶
1112.14 Rating of Rupture Members and Fusible Plugs. The rated discharge capacity of a rupture member or fusible plug discharging to the atmosphere under critical flow conditions, in pounds of air per minute (kg/s), shall be determined in accordance with the following formulas: C = 0.64 P l d [2] [Equation 1112.14(1)] d = 1.25 ~~√~~ C / P l [Equation 1112.14(2)] Where: C = Rated discharge capacity expressed as mass flow of air, pounds per minute. d = Smallest of the internal diameter of the inlet pipe, retaining flanges, fusible plug, and rupture member , inches. For rupture members:…
1113.0 Overpressure Protection. ¶
1113.1 General. Pressure vessels shall be provided with ¶
1113.1 General. Pressure vessels shall be provided with overpressure protection in accordance with ASME BPVC Section VIII.1. Pressure vessels containing liquid refrigerant that are capable of being isolated by stop valves from other parts of a refrigerating system shall be provided with overpressure protection. Pressure relief devices or fusible plugs shall be sized in accordance with Section 1113.5. [ASHRAE 15:9.7.1, 9.7.2] » Unless the maximum allowable back pressure ( P0 ) is specified by the relief valve manufacturer, the following maximum allowable back pressure values shall be used for…
1113.2 Type of Protection. ¶
1113.2 Type of Protection. Pressure vessels with an internal gross volume of 3 cubic feet (0.1 m [3] ) or less shall use one or more pressure relief devices or a fusible plug. Pressure vessels of more than 3 cubic feet (0.1 m [3] ) but less than 10 cubic feet (0.28 m [3] ) internal gross volume shall use one or more pressure relief devices. Fusible plugs shall not be used. [ASHRAE 15:9.7.2.1, 9.7.2.2]
1113.3 Discharging into Lowside of System. ¶
1113.3 Discharging into Lowside of System. For pressure-relief valves discharging into the lowside of the system, a single relief valve (not rupture member) of the required relieving capacity shall not be used on vessels of 10 cubic feet (0.28 m [3] ) or more internal gross volume except under the conditions permitted in Section 1112.11.3. [ASHRAE 15:9.7.3]
1113.4 Parallel Pressure-Relief Devices. Two or more ¶
1113.4 Parallel Pressure-Relief Devices. Two or more pressure-relief devices in parallel to obtain the required capacity shall be considered as one pressure-relief device. The discharge capacity shall be the sum of the capacities required for each pressure vessel being protected.
1113.5 Discharge Capacity. ¶
1113.5 Discharge Capacity. The minimum required discharge capacity of the pressure-relief device or fusible plug for a pressure vessel shall be determined in accordance with ASHRAE 15.
1113.6 Three-Way Valve. Pressure vessels of 10 cubic feet ¶
1113.6 Three-Way Valve. Pressure vessels of 10 cubic feet (0.28 m [3] ) or more internal gross volume shall use one or more rupture member(s) or dual pressure-relief valves where discharging to the atmosphere. Dual pressure-relief valves shall be installed with a three-way valve to allow testing or repair. Where dual relief valves are used, the valve shall comply with Section 1113.5. Exception: A single relief valve shall be permitted on pressure vessels of 10 cubic feet (0.28 m [3] ) or more internal gross volume where in accordance with the following conditions: (1) The relief valves are…
1114.0 Special Discharge Requirements. ¶
1114.0 Special Discharge Requirements.
1114.1 General. Systems containing other than Group A1 or ¶
1114.1 General. Systems containing other than Group A1 or B1 refrigerants shall discharge to atmosphere through an approved flaring device. Exceptions: (1) Where the Authority Having Jurisdiction determines upon review of a rational engineering analysis that fire, health, or environmental hazards will not result from the proposed atmospheric release. (2) Lithium bromide absorption system using water as the refrigerant.
1114.2 Design Requirements. Flaring devices shall be ¶
1114.2 Design Requirements. Flaring devices shall be designed to incinerate the entire discharge. The products of refrigerant incineration shall not pose health or environmental hazards. Incineration shall be automatic upon initiation of discharge, shall be designed to prevent blow-back, and shall not expose structures or materials to the threat of fire. Standby fuel, such as LP-Gas, and standby power shall have the capacity to operate for one and a half times the required time for complete incineration of the charge.
1114.3 Testing. ¶
1114.3 Testing. Flaring systems shall be tested to demonstrate their safety and effectiveness. A report from an approved agency shall be submitted detailing the emission products from the system as installed.
1115.0 Labeling and Identification. ¶
1115.1 General. In addition to labels required elsewhere in ¶
1115.1 General. In addition to labels required elsewhere in this chapter, a refrigeration system shall be provided with identification labels in accordance with Section 1115.2 through Section 1115.5.
1115.2 Volume and Type. A condenser, receiver, absorber, ¶
1115.2 Volume and Type. A condenser, receiver, absorber, accumulator and similar equipment having an internal volume of more than 3 cubic feet (0.1 m [3] ) and containing refrigerant shall be equipped with a permanent label setting forth the type of refrigerant in such vessel.
1115.3 Permanent Sign. In a refrigeration machinery ¶
1115.3 Permanent Sign. In a refrigeration machinery room and for a direct refrigerating system of more than 10 horsepower (7.5 kW), there shall be a permanent sign at an approved location giving the following information: (1) Name of contractor installing the equipment. (2) Name and number designation of refrigerant in system. (3) Pounds of refrigerant in system.
1115.4 Marking of Pressure-Relief Devices. ¶
1115.4 Marking of Pressure-Relief Devices. Pressurerelief valves for refrigerant containing components shall be set and sealed by the manufacturer or an assembler as defined in ASME BPVC Section VIII.1. Each pressure relief valve shall be marked by the manufacturer or assembler with the data required in ASME BPVC Section VIII.1. Exception: Relief valves for systems with design pressures of 15 pounds-force per square inch gauge (psig) (103 kPa gauge) or less shall be marked by the manufacturer with the pressure setting capacity. [ASHRAE 15:9.6.1] 1115.4.1 Rupture Members. Rupture members for…
1115.5 Nameplate. Each self-contained system and each ¶
1115.5 Nameplate. Each self-contained system and each separate condensing unit, compressor, or compressor unit sold for field assembly in a refrigerating system shall carry a nameplate marked with the manufacturer’s name, nationally registered trademark or trade name, identification num ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. REFRIGERATION ber, design pressures, and refrigerant for which it is designed. The refrigerant shall be designated by the refrigerant number (“R-” number) as shown in Table 1102.3. {ASHRAE…
1116.0 Testing of Refrigeration Equipment. ¶
1116.0 Testing of Refrigeration Equipment.
1116.1 Factory Tests. Refrigerant-containing parts of unit ¶
1116.1 Factory Tests. Refrigerant-containing parts of unit systems shall be tested and proved tight by the manufacturer at not less than the design pressure for which they are rated. Pressure vessels shall be tested in accordance with Section 1117.0. [ASHRAE 15:9.14.1] 1116.1.1 Testing Procedure. Tests shall be performed with dry nitrogen or another nonflammable, nonreactive, dried gas. Oxygen, air, or mixtures containing them shall not be used. The means used to build up the test pressure shall have either a pressure limiting device or a pressure reducing device and a gauge on the outlet…
1116.2 Field Tests. ¶
1116.2 Field Tests. Refrigerant-containing parts of a system that is field-erected shall be tested and proved tight after complete installation and before the operation. The high and low sides of each system shall be tested and proved tight at not less than the lower of the design pressure or the setting of the pressure-relief device. Exceptions: (1) Compressors, condensers, evaporators, coded pressure vessels, safety devices, pressure gauges, control mechanisms, and systems that are factory tested. (2) Refrigeration systems containing Group R-22, not exceeding 5 tons of refrigeration…
1116.3 Test Gases. ¶
1116.3 Test Gases. Tests shall be performed with dry nitrogen or another nonflammable, nonreactive, dried gas. Oxygen, air, or mixtures containing them shall not be used. The means used to build up the test pressure shall have either a pressure limiting device or a pressure reducing device and a gauge on the outlet side. The pressure relief device shall be set above the test pressure but low enough to prevent permanent deformation of the system’s components. Exceptions: (1) Mixtures of dry nitrogen, inert gases, or a combination thereof such with Class 1 refrigerants in concentrations of a…
1116.4 Declaration. A dated declaration of test shall be ¶
1116.4 Declaration. A dated declaration of test shall be provided for systems containing more than 55 pounds (24.9 kg) of refrigerant. The declaration shall give the name of the refrigerant and the field test pressure applied to the highside and the lowside of the system. The declaration of test shall be signed by the installer and, where an inspector is present at the tests, the inspector shall also sign the declaration. Where requested, copies of this declaration shall be furnished to the Authority Having Jurisdiction. [ASHRAE 15:10.2] 246 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025…
1116.5 Brine Systems. ¶
1116.5 Brine Systems. Brine-containing portions of a system shall be tested at one and a half times the design pressure of the system using brine as the test fluid.
1117.0 Refrigerant-Containing Pressure Vessels. ¶
1117.0 Refrigerant-Containing Pressure Vessels.
1117.1 Inside Dimensions 6 Inches or Less. Pressure ¶
1117.1 Inside Dimensions 6 Inches or Less. Pressure vessels having inside dimensions of 6 inches (152 mm) or less shall be: (1) Listed either individually or as part of an assembly by an approved, nationally recognized testing laboratory, or (2) Marked directly on the vessel or on a nameplate attached to the vessel with a “U” or “UM” symbol signifying compliance with ASME BPVC Section VIII.1, or (3) When requested by the Authority Having Jurisdiction, the manufacturer shall provide documentation to confirm that the vessel meets the design, fabrication, and testing requirements of ASME BPVC…
1117.2 Inside Dimensions More than 6 Inches. ¶
1117.2 Inside Dimensions More than 6 Inches. Pressure vessels having an inside diameter exceeding 6 inches (152 mm) and having an internal or external design pressure greater than 15 psig (103 kPag) shall be directly marked, or marked on a nameplate, with a “U” or “UM” symbol signifying compliance with the rules of ASME BPVC Section VIII.1. [ASHRAE 15:9.3.2]
1117.3 Pressure Vessels for 15 psig or Less. Pressure ¶
1117.3 Pressure Vessels for 15 psig or Less. Pressure vessels having an internal or external design pressure of 15 psig (103 kPag) or less shall have an ultimate strength to withstand not less than 3.0 times the design pressure and shall be tested with a pneumatic test pressure of not less than 1.25 times the design pressure or a hydrostatic test pressure of not less than 1.5 times the design pressure. [ASHRAE 15:9.3.3]
1118.0 Maintenance and Operation. ¶
1118.1 General. Refrigeration systems shall be operated and ¶
1118.1 General. Refrigeration systems shall be operated and maintained as required by the fire code. Part II – Cooling Towers.
1119.0 General. ¶
1119.1 Applicability. ¶
1119.1 Applicability. Cooling towers, evaporative condensers, fluid coolers, and associated remote sump tanks shall be readily accessible. Where located on roofs, such equipment having combustible exterior surfaces shall be protected with an approved automatic fire-extinguishing system.
1120.0 Support and Anchorage. ¶
1120.1 General. Cooling towers, evaporative condensers, ¶
1120.1 General. Cooling towers, evaporative condensers, and fluid coolers shall be supported on noncombustible grillage designed in accordance with the building code. Seismic restraints shall be as required by the building code.
1121.0 Drainage. ¶
1121.1 General. ¶
1121.1 General. Drains, overflows, and blow-down provisions shall have an indirect connection to an approved disposal location. Discharge of chemical waste shall be as approved by the Authority Having Jurisdiction.
1122.0 Chemical Treatment Systems. ¶
1122.1 General. Chemical treatment systems shall comply ¶
1122.1 General. Chemical treatment systems shall comply with the fire code. Where chemicals used present a contact hazard to personnel, approved emergency eye-wash and shower facilities shall be installed.
1122.2 Automated Control of Cycles of Concentra- ¶
1122.2 Automated Control of Cycles of Concentra- tion. Cooling towers, evaporative condensers, and fluid coolers shall include controls that automate system bleed based on conductivity, fraction of metered makeup volume, metered bleed volume, recirculating pump run time, or bleed time.
1123.0 Location. ¶
1123.1 General. Cooling towers, evaporative condensers, ¶
1123.1 General. Cooling towers, evaporative condensers, and fluid coolers shall be located such that their plumes cannot enter occupied spaces as required by Section 402.4.1. Location on the property shall be as required for buildings by Section 502.2.3.
1124.0 Electrical. ¶
1124.1 General. Electrical systems shall be in accordance ¶
1124.1 General. Electrical systems shall be in accordance with NFPA 70. Equipment shall be provided with a vibration switch to shut off fans operating with excessive vibration. In climates commonly subject to electrical storms, lightning protection shall be provided on roof-mounted equipment.
1125.0 Refrigerants and Hazardous Fluids. ¶
1125.0 Refrigerants and Hazardous Fluids.
1125.1 General. Equipment containing refrigerants as a part ¶
1125.1 General. Equipment containing refrigerants as a part of a closed-cycle refrigeration system shall comply with Part I of this chapter. Equipment containing other fluids that are flammable, combustible, or hazardous shall be in accordance with this code and the fire code. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. REFRIGERATION
1126.0 Drift Eliminators. ¶
1126.1 General. Cooling towers, evaporative condensers, ¶
1126.1 General. Cooling towers, evaporative condensers, and fluid coolers shall be equipped with drift eliminators that have a drift rate of not more than 0.005 percent of the circulated water flow rate in accordance with the equipment manufacturer’s instructions.
1127.0 Water Supply. ¶
1127.1 General. Cooling towers, evaporative coolers and ¶
1127.1 General. Cooling towers, evaporative coolers and fluid coolers shall be provided with an approved water supply, sized for peak demand. The quality of water shall be provided in accordance with the equipment manufacturer’s recommendations. The piping system and protection of the potable water supply system shall be installed in accordance with the plumbing code. 248 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. REFRIGERATION TABLE 1102.3 REFRIGERANT GROUPS, PROPERTIES, AND ALLOWABLE…
1201.0 General. ¶
1201.1 Applicability. This chapter shall apply to hydronic ¶
1201.1 Applicability. This chapter shall apply to hydronic piping systems that are part of heating, cooling, ventilation, refrigeration, and air conditioning systems. Such piping systems include steam, hot water, radiant heating and cooling, chilled water, steam condensate, condenser water, ground source heat pump systems, snow and ice melting systems, ambient temperature loops (ATL), and district ambient temperature loops. The regulations of this chapter shall govern the construction, location, and installation of hydronic piping systems.
1201.2 Insulation. ¶
1201.2 Insulation. Surfaces within reach of building occupants shall not exceed 140°F (60°C). Where sleeves are installed, the insulation shall continue full size through them. Coverings and insulation used for piping shall be of material approved for the operating temperature of the system and the installation environment. Where installed in a plenum, the insulation, jackets, and lap-seal adhesives, including pipe coverings and linings, shall have a flamespread index not to exceed 25 and a smoke-developed index not to exceed 50 where tested in accordance with ASTM E84 or UL 723.
1201.3 Water Hammer Protection. The piping system ¶
1201.3 Water Hammer Protection. The piping system shall be designed to prevent water hammer.
1201.4 Terminal Units. Terminal units, valves, and flow ¶
1201.4 Terminal Units. Terminal units, valves, and flow control devices shall be installed in accordance with the man ufacturer’s installation instructions.
1201.5 Return-Water Low-Temperature Protection. ¶
1201.5 Return-Water Low-Temperature Protection. Where a minimum return-water temperature to the heat source is specified by the manufacturer, the heating system shall be designed and installed to meet or exceed the minimum return-water temperature during the normal operation of the heat source.
1201.6 Heat Transfer Fluid Quality. Heat transfer fluid ¶
1201.6 Heat Transfer Fluid Quality. Heat transfer fluid used in closed loop hydronic systems shall be in accordance with IAPMO/ANSI H1001.1. 1201.6.1 Ethylene Glycol. Ethylene glycol shall not be used in one- and two-unit residential systems. In existing systems, where ethylene glycol is used, there shall be no direct or permanent potable water connections. Where a temporary potable water connection is required, a backflow preventer shall be installed.
1201.7 Heat Emitters. Heat emitters shall be installed in ¶
1201.7 Heat Emitters. Heat emitters shall be installed in accordance with the manufacturer’s installation instructions.
1201.8 Mechanical Devices. Where listed mechanical ¶
1201.8 Mechanical Devices. Where listed mechanical devices are used, the manufacturer’s installation instructions as to the location and method of installation shall be followed.
1201.9 Flexible Connectors. Listed flexible connectors ¶
1201.9 Flexible Connectors. Listed flexible connectors shall be installed in readily accessible locations.
1201.10 Freeze Protection. ¶
1201.10 Freeze Protection. Hydronic systems and components shall be designed, installed, and protected from freez ing. The percent of glycol by volume shall be determined based on the freezing point of the solution and type of mixture in accordance with Table 1201.10 or the manufacturer’s specifications. For SI units: °C = (°F-32)/1.8 Note: - Ethylene glycol shall not be used in one- and two-unit residential systems. In existing systems, where ethylene glycol is used, there shall be no direct or permanent potable water connections. Where a temporary potable water connection is required, a…
1202.0 Protection of Potable Water Supply. ¶
1202.0 Protection of Potable Water Supply.
1202.1 Prohibited Sources. Hydronic systems or parts ¶
1202.1 Prohibited Sources. Hydronic systems or parts thereof shall be constructed in such a manner that polluted, contaminated water or substances shall not enter a portion of the potable water system either during normal use or where the system is subject to pressure that exceeds the operating pressure in the potable water system. Piping, components and devices in contact with the potable water shall be approved for such use and where an additive is used it shall not affect the performance of the system.
1202.2 Chemical Injection. Additives or chemicals shall ¶
1202.2 Chemical Injection. Additives or chemicals shall be compatible with system components. Where systems include an additive, chemical injection or provisions for such ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. HYDRONICS injection, the potable water supply shall be protected by an air gap in accordance with ASME A112.1.2, an air gap fitting that complies with ASME A112.1.3, or a reduced-pressure principle backflow prevention assembly that complies with ASSE 1013.
1202.3 Compatibility. Fluids used in hydronic systems ¶
1202.3 Compatibility. Fluids used in hydronic systems shall be compatible with all components that will contact the fluid. Where a heat exchanger is installed with a dual purpose water heater, such application shall comply with the requirements for a single wall heat exchanger in Section 1218.1.
1203.0 Capacity of Heat Source. ¶
1203.1 Heat Source. The heat source shall be sized to the ¶
1203.1 Heat Source. The heat source shall be sized to the design load.
1203.2 Dual Purpose Water Heaters. ¶
1203.2 Dual Purpose Water Heaters. Water heaters utilized for combined space-heating and water-heating applications shall comply with the standards referenced in Table 1203.2, and shall be installed in accordance with the manufacturer’s installation instructions. The total heating capacity of a dual purpose water heater shall be based on the sum of the potable hot water requirements and the space heating design requirements corrected for hot water first-hour draw recovery. TABLE 1203.2 WATER HEATERS TYPESTANDARDS ------ <br <brGas-Fired, 75 000 Btu/h or less,<brStorageCSA/ANSI Z21.10.1/CSA…
1203.3 Tankless Water Heaters. Tankless water heaters ¶
1203.3 Tankless Water Heaters. Tankless water heaters used in space-heating applications shall be rated by the manufacturer for space-heating applications, and the output performance shall be determined by the temperature rise and flow rate of water through the unit. The ratings shall be expressed by the water temperature rise at a given flow rate. Manufacturer’s flow rates shall not be exceeded.
1204.0 Identification of Potable and Nonpotable ¶
1204.0 Identification of Potable and Nonpotable Water Systems.
1204.1 General. ¶
1204.1 General. In buildings where potable water and nonpotable water systems are installed, each system shall be clearly identified in accordance with Section 1204.2 through Section 1204.7.
1204.2 Color and Information. ¶
1204.2 Color and Information. Each system shall be identified with a colored pipe or band and coded with paint, wraps, and materials compatible with the piping.
1204.3 Potable Water. ¶
1204.3 Potable Water. Potable water systems shall be identified with a green background with white lettering. The minimum size of letters and length of the color field shall be in accordance with Table 1204.3. TABLE 1204.3 MINIMUM LENGTH OF COLOR FIELD AND SIZE OF LETTERS OUTSIDE DIAMETER OF<brPIPE OR COVERING<br(inches)MINIMUM LENGTH<brOF COLOR FIELD<br(inches)MINIMUM SIZE OF<brLETTERS<br(inches) --------- 1/2 to 11/481/2 <br<br11/2 to 283/4 <br<br21/2 to 61211/4 <br8 to 102421/2 <br<brover 103231/2 For SI units: 1 inch = 25.4 mm TABLE 1203.2 WATER HEATERS
1204.4 Nonpotable Water. Nonpotable water systems ¶
1204.4 Nonpotable Water. Nonpotable water systems shall have a yellow background with black uppercase lettering, with the words: “CAUTION: NONPOTABLE WATER, DO NOT DRINK.” Each nonpotable system shall be identified to designate the liquid being conveyed, and the direction of normal flow shall be clearly shown. The minimum size of the letters and length of the color field shall comply with Table 1204.3. TABLE 1204.3 MINIMUM LENGTH OF COLOR FIELD AND SIZE OF LETTERS For SI units: 1 inch = 25.4 mm
1204.5 Location of Piping Identification. The background ¶
1204.5 Location of Piping Identification. The background color and required information shall be indicated every 20 feet (6096 mm) but not less than once per room, and shall be visible from the floor level.
1204.6 Flow Directions. Flow directions shall be indicated ¶
1204.6 Flow Directions. Flow directions shall be indicated on the system.
1204.7 Heat Transfer Fluid. ¶
1204.7 Heat Transfer Fluid. Hydronic piping shall be identified with an orange background with black uppercase lettering, with the words “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.” Each hydronic system shall be identified to designate the fluid being conveyed. The minimum size of the letters and length of the color field shall comply with Table 1204.3. Each outlet on the hydronic piping system shall be posted with black uppercase lettering as follows: “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.”
1204.8 Identification of Chemical Additives. In systems ¶
1204.8 Identification of Chemical Additives. In systems where chemical additives are used, documentation including the following information shall be readily accessible and maintained onsite: (1) Concentrations (2) Maintenance requirements (3) Maintenance log (4) Material Safety Data Sheet (SDS) For SI units: 1000 British thermal units per hour = 0.293 kW
1205.0 Installation, Testing, and Inspection. ¶
1205.0 Installation, Testing, and Inspection.
1205.1 Operating Instructions. Operating and maintenance ¶
1205.1 Operating Instructions. Operating and maintenance information shall be provided to the building owner.
1205.2 Pressure Testing. System piping and components ¶
1205.2 Pressure Testing. System piping and components shall be tested with a pressure of not less than one and one-half times the operating pressure but not less than 100 psi (689 kPa). Piping shall be tested with water or air except that plastic pipe 258 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. HYDRONICS shall not be tested with air. Test pressures shall be held for a period of not less than 30 minutes with no perceptible drop in pressure. These tests shall be made in the presence of…
1205.3 Flushing. ¶
1205.3 Flushing. Heating and cooling sources, system piping and tubing shall be flushed after installation with water or a cleaning solution. Cleaning and flushing of the heating and cooling sources shall comply with the manufacturer’s instructions. The cleaning solution shall be compatible with all system components and shall be used in accordance with the manufacturer’s instructions.
1206.0 Pressure and Safety Devices. ¶
1206.1 General. ¶
1206.1 General. Each closed hydronic system shall be protected against pressures exceeding design limitations with not less than one pressure relief valve. Each closed section of the system containing a heat source shall have a relief valve located so that the heat source is not capable of being isolated from a relief device. Pressure relief valves shall be installed in accordance with their listing and the manufacturer’s installation instructions.
1206.2 Discharge Piping. The discharge piping serving a ¶
1206.2 Discharge Piping. The discharge piping serving a temperature relief valve, pressure relief valve, or combination of both shall have no valves, obstructions, or means of isolation and be provided with the following: (1) Not less than the size of the valve outlet and shall discharge full size to the flood level of the area receiving the discharge and pointing down. (2) Materials shall be rated at not less than the operating temperature of the system and approved for such use or shall comply with ASME A112.4.1. (3) Discharge pipe shall discharge independently by gravity through an air gap…
1207.0 Heating Appliances and Equipment. ¶
1207.0 Heating Appliances and Equipment.
1207.1 General. Heating appliances, equipment, safety and ¶
1207.1 General. Heating appliances, equipment, safety and operational controls shall be listed for its intended use in a hydronic heating system and installed in accordance with the manufacturer’s installation instructions.
1207.2 Boilers. Boilers and their control systems shall comply with Section 1002.0. ¶
1207.2 Boilers. Boilers and their control systems shall comply with Section 1002.0. 1207.2.1 Condensing Boilers. A condensing boiler, in which the heat exchanger and venting system are designed to operate with condensing flue gases, shall be permitted to be connected directly to the panel heating system without a protective mixing device. 1207.2.2 Noncondensing Boilers. Where the heat exchanger and venting system are not designed to operate with condensed flue gases, the boiler shall be permitted to connect directly to the panel heating system where protected from flue gas condensation. The…
1207.3 Dual Purpose Water Heaters. Water heaters used ¶
1207.3 Dual Purpose Water Heaters. Water heaters used for combined space- and water-heating applications shall be in accordance with the standards referenced in Table 1203.2, and shall be installed in accordance with the manufacturer’s instal lation instructions. Water used as the heat transfer fluid in the hydronic heating system shall be isolated from the potable water supply and distribution in accordance with Section 312.1, Section 1202.0, and Section 1218.0. 1207.3.1 Temperature Limitations. Where a combined space- and water-heating application requires water for space heating at…
1207.4 Solar Heat Collector Systems. ¶
1207.4 Solar Heat Collector Systems. Solar water heating systems used in hydronic panel radiant heating systems shall be installed in accordance with the Uniform Solar, Hydronics and Geothermal Code (USHGC).
1207.5 Heat Pumps. Heat pumps shall comply with UL ¶
1207.5 Heat Pumps. Heat pumps shall comply with UL 1995 or UL 60335-2-40. Air source heat pumps shall also comply with AHRI 210/240. In addition, ground-source heat pumps shall comply with AHRI/ASHRAE/ISO 13256-1 for water-to-air heat pumps and AHRI/ASHRAE/ISO 13256-2 for water-to-water heat pumps. Heat pumps shall be fitted with a means to indicate that the compressor is locked out.
1208.0 Circulators and Pumps. ¶
1208.1 General. Circulators and pumps shall be selected for ¶
1208.1 General. Circulators and pumps shall be selected for their intended use based on the heat transfer fluid, intended operating temperature range and pressure. Circulators and pumps shall be installed to allow for service and maintenance. The manufacturer’s installation instructions shall be followed for correct orientation and installation. Motor operated pumps rated 600V or less shall comply with CSA C22.2 No. 108 or UL 778. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. HYDRONICS temperature and pressure of the…
1210.2 Expansion and Contraction. Pipe and tubing shall ¶
1210.2 Expansion and Contraction. Pipe and tubing shall be so installed that it will not be subject to undue strains or stresses, and provisions shall be made for expansion, contraction, and structural settlement. [OSHPD 1, 1R, 2, 4 & 5] Pipe connections less than 2½ inches (64 mm) to heating coils, cool- ing coils, humidifiers, and similar equipment shall have flexible connectors or three (3) 90-degree offsets in close proximity of the connection.
1210.3 Hangers and Supports. Pipe and tubing shall be ¶
1210.3 Hangers and Supports. Pipe and tubing shall be supported in accordance with Section 313.0. Equipment that is part of the piping system shall be provided with additional support in accordance with this code and manufacturer’s installation instructions. Radiant systems utilizing heat emission or transfer plates shall have a gap of at least ¼ inch (6.4 mm) between adjacent plates.
1210.4 Oxygen Diffusion Corrosion. ¶
1210.4 Oxygen Diffusion Corrosion. PEX and PE-RT tubing in closed hydronic systems shall contain an oxygen barrier. 1210.4.1 Vented Closed-Loop Systems. All components installed in a vented closed-loop system shall be constructed of non-ferrous or other corrosion resistant materials. 1210.4.2 Non-Oxygen Barrier Closed-Loop Sys- tems. All components installed in a non-oxygen barrier system shall be constructed of non-ferrous or other corrosion resistant materials.
1211.0 Joints and Connections. ¶
1211.1 General. Joints and connections shall be of an ¶
1211.1 General. Joints and connections shall be of an approved type. Joints shall be gas and watertight and designed for the pressure of the hydronic system. Changes in direction shall be made by the use of fittings or with pipe bends. Joints between pipe and fittings shall be installed in accordance with the manufacturer’s installation instructions. Joints used underground shall be of an approved type for buried applications in accordance with Section 1221.2.3.
1211.2 Pipe Bends. ¶
1211.2 Pipe Bends. Pipe bends shall be formed in accordance with Section 1211.2.1 for PEX or Section 1211.2.2 for PE. 1211.2.1 Crosslinked Polyethylene (PEX) Tubing. Crosslinked polyethylene (PEX) tubing bends shall have a bend radius of not less than eight times the outside diameter of the tubing or shall be in accordance with the manufacturer’s installation instructions. 1211.2.2 Polyethylene (PE) Plastic Pipe/Tubing. Polyethylene pipe and tubing bends shall have a bend radius in accordance with Table 1211.2.2. When a fitting or flange connection is present in the pipe bend, the minimum…
1208.2 Mounting. The circulator or pump shall be installed ¶
1208.2 Mounting. The circulator or pump shall be installed in such a way that strain from the piping is not transferred to the circulator or pump housing. The circulator or pump shall be permitted to be directly connected to the piping, provided the piping is supported on each side of the circulator or pump. Where the installation of a circulator or pump will cause strain on the piping, the circulator or pump shall be installed on a mounting bracket or base plate or securely fastened to or supported by the structure with approved fastening devices. Where means for controlling vibration of a…
1208.3 Sizing. The selection and sizing of a circulator or ¶
1208.3 Sizing. The selection and sizing of a circulator or pump shall be based on all of the following: (1) Loop or system head pressure, feet of head (m) (2) Capacity, gallons per minute (L/s) (3) Maximum and minimum temperature, °F (°C) (4) Maximum working pressure, pounds per square inch (kPa) (5) Fluid type
1209.0 Expansion Tanks. ¶
1209.1 General. An expansion tank shall be installed in each ¶
1209.1 General. An expansion tank shall be installed in each closed hydronic system to control system pressure due to thermal expansion and contraction. Expansion tanks shall be of the closed type. Expansion tanks shall be rated for the pressure of the system.
1209.2 Installation. Expansion tanks shall be accessible for ¶
1209.2 Installation. Expansion tanks shall be accessible for maintenance and shall be installed in accordance with the manufacturer’s installation instructions. Each expansion tank shall be equipped with a shutoff device that will remain open during operation of the hydronic system. Valve handles shall be locked open or removed to prevent from being inadvertently shut off. Provisions shall be made for draining the tank without emptying the system. Expansion tanks shall be securely fastened to or supported by the structure. Supports shall be capable of carrying twice the weight of the tank…
1209.3 Closed-Type Tanks. Closed-type expansion tanks ¶
1209.3 Closed-Type Tanks. Closed-type expansion tanks shall be designed for a hydrostatic test pressure of two and one-half times the allowable working pressure of the system. Expansion tanks for systems designed to operate at more than 30 pounds-force per square inch (psi) (207 kPa) shall comply with ASME BPVC Section VIII.1.
1209.4 Sizing. Expansion tanks shall be sized to accept the ¶
1209.4 Sizing. Expansion tanks shall be sized to accept the full expansion volume of the fluid in the system. The minimum capacity of a closed-type expansion tank shall be sized in accordance with Section 1004.4.
1210.0 Materials. ¶
1210.1 Piping, Tubing, and Fittings. Hydronic pipe and ¶
1210.1 Piping, Tubing, and Fittings. Hydronic pipe and tubing shall comply with the applicable standards referenced in Table 1210.1 and shall be approved for use based on the intended purpose. Materials shall be rated for the operating 260 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. HYDRONICS TABLE 1210.1 MATERIALS FOR HYDRONIC SYSTEM PIPING, TUBING, AND FITTINGS MATERIALSTANDARDSCol3 --------- MATERIALPIPING/TUBINGFITTINGS Copper/Copper AlloyASTM B42, ASTM B43, ASTM B75,<brASTM B88, ASTM…
1211.4 CPVC/AL/CPVC Plastic Pipe and Joints. Joints ¶
1211.4 CPVC/AL/CPVC Plastic Pipe and Joints. Joints between chlorinated polyvinyl chloride/aluminum/ chlorinated polyvinyl chloride (CPVC/AL/CPVC) pipe and fittings shall be installed in accordance with one of the following methods: (1) Mechanical joints shall include flanged, grooved, and push-fit fittings. (2) Solvent cement joints for CPVC/AL/CPVC pipe and fittings shall be clean from dirt and moisture. Solvent cements in accordance with ASTM F493, requiring the use of a primer shall be orange in color. The primer shall be colored and be in accordance with ASTM F656. Listed solvent cement…
1211.5 Copper or Copper Alloy Pipe and Tubing. ¶
1211.5 Copper or Copper Alloy Pipe and Tubing. Joints between copper or copper alloy pipe or tubing and fittings shall be installed in accordance with one of the following methods: (1) Brazed joints between copper or copper alloy pipe or tubing and fittings shall be made with brazing alloys having a liquid temperature above 1000°F (538°C). The joint surfaces to be brazed shall be cleaned bright by either manual or mechanical means. Tubing shall be cut square and reamed to full inside diameter. Brazing flux shall be applied to the joint surfaces where required by manufacturer’s recommendation.…
1211.3 Chlorinated Polyvinyl Chloride (CPVC) Pipe. ¶
1211.3 Chlorinated Polyvinyl Chloride (CPVC) Pipe. Joints between chlorinated polyvinyl chloride (CPVC) pipe and fittings shall be installed in accordance with one of the following methods: (1) Mechanical joints shall include flanged, grooved, and push fit fittings. Removable and non-removable push fit fittings with an elastomeric O-ring that employ quick assembly push fit connectors shall be in accordance with ASSE 1061. (2) Solvent cement joints for CPVC pipe and fittings shall be clean from dirt and moisture. Solvent cements in accor dance with ASTM F493, requiring the use of a primer…
1211.6 Cross-Linked Polyethylene (PEX) Pipe. Joints ¶
1211.6 Cross-Linked Polyethylene (PEX) Pipe. Joints between cross-linked polyethylene (PEX) pipe and fittings shall be installed with fittings for PEX tubing that comply with the applicable standards referenced in Table 1210.1. PEX tubing labeled in accordance with ASTM F876 or ASTM F3253 shall be marked with the applicable standard designation for the fittings specified for use with the tubing. Mechanical joints shall be installed in accordance with the manufacturer’s installation instructions.
1211.7 Cross-Linked Polyethylene/Aluminum/Cross- ¶
1211.7 Cross-Linked Polyethylene/Aluminum/Cross- Linked Polyethylene (PEX-AL-PEX) Pipe. Joints between cross-linked polyethylene/aluminum/cross-linked polyethylene (PEX-AL-PEX) pipe and fittings shall be installed in accordance with one of the following methods: (1) Mechanical joints between PEX-AL-PEX pipe and fittings shall include mechanical and compression type fittings and insert fittings with a crimping ring. Insert fittings utilizing a crimping ring shall be in accordance with ASTM F1974 or ASTM F2434. Crimp joints for crimp insert fittings shall be joined to PEX-AL-PEX pipe by the…
1211.8 Ductile Iron Pipe. Joints between ductile iron pipe ¶
1211.8 Ductile Iron Pipe. Joints between ductile iron pipe and fittings shall be installed in accordance with one of the following methods: (1) Mechanical joints for ductile iron pipe and fittings shall consist of a bell that is cast integrally with the pipe or fitting and provided with an exterior flange having bolt holes and a socket with annular recesses for the sealing gasket and the plain end of the pipe or fitting. The elastomeric gasket shall comply with AWWA C111/A21.11. Lubricant recommended for the application by the pipe manufacturer shall be applied to the gasket and plain end of…
1211.9 Polyethylene (PE) Plastic Pipe/Tubing. Joints ¶
1211.9 Polyethylene (PE) Plastic Pipe/Tubing. Joints between polyethylene (PE) plastic pipe or tubing and fittings shall be installed in accordance with one of the following methods: ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. HYDRONICS the pipe. The compression nut and split ring shall be placed around the pipe. The ribbed end of the fitting shall be inserted onto the pipe until the pipe contacts the shoulder of the fitting. Position and compress the split ring by tightening the compression nut onto the insert fitting.
1211.11 Polyethylene of Raised Temperature (PE-RT). ¶
1211.11 Polyethylene of Raised Temperature (PE-RT). Joints between polyethylene of raised temperature (PE-RT) tubing and fittings shall be installed with fittings for PE-RT tubing that comply with the applicable standards referenced in Table 1210.1. Metal insert fittings, metal compression fittings, and plastic fittings shall be manufactured to and marked in accordance with the standards for fittings in Table 1210.1.
1211.12 Polypropylene (PP) Pipe. Joints between ¶
1211.12 Polypropylene (PP) Pipe. Joints between polypropylene pipe and fittings shall be installed in accordance with one of the following methods: (1) Heat fusion joints for polypropylene (PP) pipe shall be installed with socket-type heat-fused polypropylene fittings, butt-fusion polypropylene fittings or pipe, or electro-fusion polypropylene fittings. Joint surfaces shall be clean and free from moisture. The joint shall be undisturbed until cool. Joints shall be made in accordance with ASTM F2389 or CSA B137.11. (2) Mechanical and compression sleeve joints shall be installed in accordance…
1211.13 Polyvinyl Chloride (PVC) Pipe. Joints between ¶
1211.13 Polyvinyl Chloride (PVC) Pipe. Joints between polyvinyl chloride pipe and fittings shall be installed in accordance with one of the following methods: (1) Mechanical joints shall be designed to provide a permanent seal and shall be of the mechanical or push-on joint. The mechanical joint shall include a pipe spigot that has a wall thickness to withstand without deformation or collapse; the compressive force exerted where the fitting is tightened. The push-on joint shall have a minimum wall thickness of the bell at any point between the ring and the pipe barrel. The elastomeric gasket…
1211.10 Polyethylene/Aluminum/Polyethylene (PE- ¶
1211.10 Polyethylene/Aluminum/Polyethylene (PE- AL-PE). Joints between polyethylene/aluminum/polyethylene (PE-AL-PE) pipe and fittings shall be installed in accordance with one of the following methods: (1) Mechanical joints for PE-AL-PE pipe or tubing and fittings shall be either of the metal insert fittings with a split ring and compression nut or metal insert fittings with copper crimp rings. Metal insert fittings shall comply with ASTM F1974. Crimp insert fittings shall be joined to the pipe by placing the copper crimp ring around the outer circumference of the pipe, forcing the pipe…
1212.0 Valves. ¶
1212.1 General. ¶
1212.1 General. Valves shall be rated for the operating temperature and pressure of the system. Valves shall be compatible with the type of heat transfer medium and piping material.
1212.2 Where Required. Valves shall be installed in ¶
1212.2 Where Required. Valves shall be installed in hydronic piping systems in accordance with Section 1212.3 through Section 1212.12. Valves shall be accessible.
1212.3 Heat Exchanger. Isolation valves shall be installed ¶
1212.3 Heat Exchanger. Isolation valves shall be installed on the supply and return side of the heat exchanger.
1212.4 Pressure Vessels. Isolation valves shall be installed ¶
1212.4 Pressure Vessels. Isolation valves shall be installed on connections to pressure vessels.
1212.5 Pressure Reducing Valves. Isolation valves shall ¶
1212.5 Pressure Reducing Valves. Isolation valves shall be installed on both sides of a pressure reducing valve.
1212.6 Equipment, Components, and Appliances. ¶
1212.6 Equipment, Components, and Appliances. Serviceable equipment, components, and appliances within the system shall have isolation valves installed upstream and downstream of such devices.
1212.7 Expansion Tank. Isolation valves shall be installed ¶
1212.7 Expansion Tank. Isolation valves shall be installed at connections to non-diaphragm-type expansion tanks.
1212.8 Flow Balancing Valves. Where flow balancing ¶
1212.8 Flow Balancing Valves. Where flow balancing valves are installed, such valves shall be capable of increasing or decreasing the amount of flow by means of adjustment.
1212.9 Mixing or Temperature Control Valves. Where ¶
1212.9 Mixing or Temperature Control Valves. Where mixing or temperature control valves are installed, such valves shall be capable of obtaining the design water temperature and design flow requirements.
1212.10 Thermosiphoning. An approved type check valve ¶
1212.10 Thermosiphoning. An approved type check valve shall be installed on liquid heat transfer piping to control thermosiphoning of heated liquids.
1212.11 Air Removal Device or Air Vents. Isolation valves ¶
1212.11 Air Removal Device or Air Vents. Isolation valves shall be installed where air removal devices or automatic air vents are utilized to permit cleaning, inspection, or repair without shutting the system down.
1212.12 District Energy and Central Utility Systems. ¶
1212.12 District Energy and Central Utility Systems. Isolation valves shall be installed on the building supply and return of a district energy or central utility system.
1213.0 System Controls. ¶
1213.1 Water Temperature Controls. ¶
1213.1 Water Temperature Controls. A heat source or system of commonly connected heat sources shall be protected by a water-temperature-activated operating control to stop heat out « » » » cent reduction in the pressure rating of the pipe provided that the molded fittings shall be fabricated so that the wall thickness of the material is maintained at the threads. Thread sealant compound that is compatible with the pipe and fitting, insoluble in water, and nontoxic shall be applied to male threads. Caution shall be used during assembly to prevent over tightening of the PVC components once the…
1211.14 Steel Pipe and Tubing. Joints between steel pipe ¶
1211.14 Steel Pipe and Tubing. Joints between steel pipe or tubing and fittings shall be installed in accordance with one of the following methods: (1) Mechanical joints shall be made with an approved and listed elastomeric gasket. (2) Threaded joints shall be made with pipe threads that are in accordance with ASME B1.20.1. Thread sealant tape or compound shall be applied only on male threads, and such material shall be of approved types, insoluble in water, and nontoxic. (3) Welded joints shall be made by electrical arc or oxygen/acetylene method. Joint surfaces shall be cleaned by an…
1211.15 Stainless Steel Pipe and Joints. ¶
1211.15 Stainless Steel Pipe and Joints. Joining methods for stainless steel pipe and fittings shall be installed in accordance with the manufacturer’s installation instructions and shall comply with Section 1211.15.1 or Section 1211.15.2. 1211.15.1 Mechanical Joints. Mechanical joints shall be designed for their intended use. Such joints shall include compression, flanged, grooved, press-connect, and threaded. 1211.15.2 Welded Joints. Welded joints shall be either fusion or resistance welded based on the selection of the base metal. The chemical composition of the filler metal shall comply…
1211.16 Joints Between Various Materials. Joints ¶
1211.16 Joints Between Various Materials. Joints between various materials shall be installed in accordance with the manufacturer’s installation instructions and shall comply with Section 1211.16.1 and Section 1211.16.2. 1211.16.1 Copper or Copper Alloy Pipe or Tubing to Threaded Pipe Joints. Joints from copper or copper alloy pipe or tubing to threaded pipe of a material other than copper or copper alloy shall be made by the use of copper alloy adapter, copper alloy nipple [minimum 6 inches (152 mm)], dielectric fitting, or dielectric union in accordance with ASSE 1079. The joint between the…
1213.2 Operating Steam Controls. A steam heat source or ¶
1213.2 Operating Steam Controls. A steam heat source or system of commonly connected steam heat sources shall be protected by a pressure-actuated control to shut off the fuel supply where the system pressure reaches a pre-set operating pressure. 1213.2.1 Water-Level Controls. A primary water-level control shall be installed on a steam heat source to control the water level in the heat source. The control shall be installed in accordance with the manufacturer’s installation instructions.
1213.3 Occupied Spaces. A temperature-sensing device ¶
1213.3 Occupied Spaces. A temperature-sensing device shall be installed in the occupied space to regulate the operation of the hydronic system.
1213.4 Simultaneous Operation. ¶
1213.4 Simultaneous Operation. Radiant heating and cooling systems sharing a common space temperature control shall be configured to prevent simultaneous heating and cooling.
1213.5 Temperature Reading. A temperature gauge or ¶
1213.5 Temperature Reading. A temperature gauge or transmitter shall be installed for reading the fluid temperatures in the panel system supply and heat source outlet. One temperature gauge or transmitter shall be permitted where the temperature between the heat source outlet and panel system supply are the same.
1214.0 Pressure and Flow Controls. ¶
1214.1 Balancing. A means for balancing distribution ¶
1214.1 Balancing. A means for balancing distribution loops, heat emitting devices, and multiple boiler installations shall be provided in accordance with the manufacturer’s instructions. A means for balancing and flow control shall include the piping design, pumping equipment, or balancing devices.
1214.2 Low-Water Control. Direct-fired heat sources ¶
1214.2 Low-Water Control. Direct-fired heat sources within a closed heating system shall have a low-water fuel cut-off device, except as specified in Section 1214.3. Where a low-water control is integral with the heat source as part of the appliance’s integrated control and is listed for such use, a separate low-water control shall not be required. An external cut-off device shall be installed in accordance with the heat source manufacturer’s installation instructions. No valve shall be located between the external low-water fuel cut-off and the heat-source unit. Where a pumped condensate…
1214.3 Flow-Sensing Devices. A direct-fired heat source, ¶
1214.3 Flow-Sensing Devices. A direct-fired heat source, requiring forced circulation to prevent overheating, shall have a flow-sensing device installed with the appliance, or such device shall be integral with the appliance. A low-water fuel cut-off device shall not be required.
1214.4 Automatic Makeup Fluid. Automatic makeup ¶
1214.4 Automatic Makeup Fluid. Automatic makeup fluid shall be in accordance with Section 1214.4.1 for potable water makeup fluid or Section 1214.4.2 for nonpotable makeup fluid. 1214.4.1 Potable Makeup Fluid. Where a potable water automatic makeup fluid supply fill device is used to maintain the fluid content of the heat-source unit, or any closed-loop in the system, the potable water makeup supply shall be located at the expansion tank connection or other approved location. A potable water makeup sup ply shall be decoupled and provided with a monitoring system. A potable water makeup supply…
1214.5 Differential Pressure Regulation. Provisions ¶
1214.5 Differential Pressure Regulation. Provisions shall be made to bypass zone flows in excess of design velocity in a multi-zone hydronic system where the closing of some or all of the two-way zone valves causes excess flow through the open zones or deadheading of a fixed-speed circulator or pump. 1214.5.1 Differential Pressure Bypass Valve. Where a differential pressure bypass valve is used for the purpose specified in Section 1214.5, it shall be installed and adjusted to provide bypass of the distribution system when most or all of the zones are closed.
1214.6 Air-Removal Device. Provision shall be made for ¶
1214.6 Air-Removal Device. Provision shall be made for the removal of air from fluid in hydronic systems. Airremoval devices shall be located in the areas of the hydronic piping system where air is likely to accumulate. Air-removal devices shall be installed to facilitate their removal for examination, repair, or replacement.
1214.7 Air-Separation Device. To assist with the removal ¶
1214.7 Air-Separation Device. To assist with the removal of entrained air, an air-separation device shall be installed in hydronic systems. The device shall be located in accordance with the manufacturer’s installation instructions or at the point of no mechanically-induced pressure change within the hydronic system.
1214.8 Secondary Loops. ¶
1214.8 Secondary Loops. Secondary loops that are isolated from the primary heat-distribution loop by a heat exchanger are closed-loop hydronic systems and shall have an expansion tank in accordance with Section 1209.0, an airremoval device in accordance with Section 1214.6, and an air-separation device in accordance with Section 1214.7.
1215.0 Hydronic Space Heating. ¶
1215.1 General. ¶
1215.1 General. Based on the system design, the heat-distribution units shall be selected in accordance with the manufacturer’s specifications.
1215.2 Installation. Heat-distribution units shall be ¶
1215.2 Installation. Heat-distribution units shall be installed in accordance with the manufacturer’s installation instructions and this code. 266 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. HYDRONICS » »
1215.3 Balancing. System loops shall be installed so that ¶
1215.3 Balancing. System loops shall be installed so that the design flow rates are achieved within the system.
1215.4 Heat Transfer Fluid. The ignitable flash point of ¶
1215.4 Heat Transfer Fluid. The ignitable flash point of heat transfer fluid in a hydronic piping system shall be a minimum of 50°F (28°C) above the maximum system operating temperature. The heat transfer fluid shall be compatible with the makeup fluid supplied to the system.
1216.0 Steam Systems. ¶
1216.1 Steam Traps. ¶
1216.1 Steam Traps. For other than one-pipe steam systems, each heat-distribution unit shall be supplied with a steam trap that is listed for the application.
1216.2 Sloping for Two-Pipe System. Two-pipe steam ¶
1216.2 Sloping for Two-Pipe System. Two-pipe steam system piping and heat-distribution units shall be sloped down at not less than [ 1] / 8 inch per foot (10.4 mm/m) in the direction of the steam flow.
1216.3 Sloping for One-Pipe System. One-pipe steam ¶
1216.3 Sloping for One-Pipe System. One-pipe steam system piping and heat-distribution units shall be sloped down at not less than [ 1] / 8 inch per foot (10.4 mm/m) towards the steam boiler, without trapping.
1216.4 Automatic Air Vents. Steam automatic air vents ¶
1216.4 Automatic Air Vents. Steam automatic air vents shall be installed to eliminate air pressure in heat-distribution units on gravity steam piping systems. Air vents shall not be used on a vacuum system.
1216.5 Condensate Flow. System piping shall be installed ¶
1216.5 Condensate Flow. System piping shall be installed to allow condensate to flow to the condensate receiver or steam boiler either by gravity or pump-assisted.
1216.6 Steam-Distribution Piping. ¶
1216.6 Steam-Distribution Piping. Where multi-row elements are installed in an enclosure, they shall be top fed and piped in parallel down to the steam trap. A single steam trap for each row of heating elements shall be installed. Where the size of the return header is increased by a minimum of one pipe size, a single steam trap shall be permitted to be installed for multiple rows. Where multiple steam unit heaters are installed, an individual steam trap for each unit shall be installed.
1217.0 Radiant Heating and Cooling. ¶
1217.1 Installation. Radiant heating and cooling systems ¶
1217.1 Installation. Radiant heating and cooling systems shall be installed in accordance with the system design. 1217.1.1 Manifolds. Manifolds shall be equipped with isolation valves on the supply and return lines. Manifolds shall be capable of withstanding the pressure and temperature of the system. The material of the manifold shall be compatible with the system fluid and shall be installed in accordance with the manufacturer’s installation instructions.
1217.2 Radiant Under-Floor Heating. ¶
1217.2 Radiant Under-Floor Heating. Floor finished surface temperatures shall not exceed the following temperatures for space heating applications: (1) 85°F (29°C) in general occupied applications. (2) 90°F (32°C) in bathrooms, foyers, distribution areas such as hallways and indoor swimming pools. (3) 88°F (31°C) in industrial spaces. (4) 95°F (35°C) in radiant panel perimeter areas, i.e., up to 2.5 feet (762 mm) from outside walls. The radiant heating system temperature shall not exceed the maximum temperature rating of the materials used in its construction.
1217.3 Radiant Cooling Systems. ¶
1217.3 Radiant Cooling Systems. Radiant cooling systems shall be designed to minimize the potential for condensation. To prevent condensation on any cooled radiant surface, the supply water temperature for a radiant cooling system shall be above the space dewpoint temperature, or in accordance with the manufacturer’s recommendation. 1217.3.1 Minimum Floor Temperatures. The minimum floor surface temperature shall not be less than 66°F (19°C) in general occupied applications.
1217.4 Chilled Water Supply/Distribution Piping. ¶
1217.4 Chilled Water Supply/Distribution Piping. Chilled water piping, valves, fittings, and manifolds shall be insulated and vapor sealed to prevent surface condensation. Exception: Piping, valves, fittings, and manifolds used to supply radiant cooling systems and where the water temperature is above the space dewpoint temperature shall not require insulation.
1217.5 Tube Placement. Hydronic radiant system tubing ¶
1217.5 Tube Placement. Hydronic radiant system tubing shall be installed in accordance with the manufacturer’s installation instructions and with the tube layout and spacing in accordance with the system design. Except for distribution mains, the individual loop lengths shall be installed with a variance of not more than ±10 percent from the design.
1217.6 Tube Length. ¶
1217.6 Tube Length. The maximum loop length of continuous tubing from a supply-and-return manifold shall not exceed the lengths specified by the manufacturer or, in the absence of manufacturer’s specifications, the lengths specified in Table 1217.6. Actual loop lengths shall be determined by spacing, flow rate, and pressure drop requirements as specified in the system design. TABLE 1217.6 MAXIMUM LENGTH OF CONTINUOUS TUBING FROM A SUPPLY-AND-RETURN MANIFOLD ARRANGEMENT NOMINAL TUBE SIZE<br(inches)MAXIMUM LOOP LENGTH<br(feet) ------ <br1/4125 <br5/16200 <br3/8250 <br1/2300 5/8400 <br<br3/4500…
1217.7 Tube Identification. ¶
1217.7 Tube Identification. For the purpose of system balancing, each individual loop shall have a tag or label securely affixed to the manifold to indicate the length of the loop and the room(s) and area(s) served. TABLE 1217.6 MAXIMUM LENGTH OF CONTINUOUS TUBING FROM A SUPPLY-AND-RETURN MANIFOLD ARRANGEMENT « « For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. HYDRONICS » » » » » »
1217.8 Poured Floor Structural Concrete Slab Sys- ¶
1217.8 Poured Floor Structural Concrete Slab Sys- tems (Thermal Mass). Where tubing is embedded in a structural concrete slab such tubes shall not be larger in outside dimension than one-third of the overall thickness of the slab and shall be spaced not less than three diameters on center except within 10 feet (3048 mm) of the distribution manifold. The top of the tubing shall be embedded in the slab not less than 2 inches (51 mm) below the surface. 1217.8.1 Slab Penetration Tube and Joint Protec- tion. Where embedded in or installed under a concrete slab, tubing shall be protected from…
1217.9 Joist Systems and Subfloors. Where tubing is ¶
1217.9 Joist Systems and Subfloors. Where tubing is installed below a subfloor, the tube spacing shall be in accordance with the system design and joist space limitations. Where tubing is installed above or in the subfloor, the tube spacing shall not exceed 12 inches (305 mm) center-tocenter for living areas. Where tubing is installed in the joist cavity, the cavity shall be insulated with not less than R-12 material below the heated space. An air space of not less than 1 inch (25.4 mm) and not more than 3 inches (76 mm) shall be maintained between the top of the insulation and the underside…
1217.10 Wall and Ceiling Panels. Where radiant tubing is ¶
1217.10 Wall and Ceiling Panels. Where radiant tubing is installed in the stud wall cavity or the ceiling joist cavity, the cavity shall be insulated with not less than R-12 material. The insulation shall be installed in such a manner as to prevent heating or cooling loss from the space intended to be controlled. An air space of not less than 1 inch (25.4 mm) and not more than 3 inches (76 mm) shall be maintained between the insulation and the interior surface of the panel unless a conductive plate is installed. 1217.10.1 California Energy Code Pipe Insulation Requirements. See California…
1217.11 Radiant Heating and Cooling Panels. Radiant ¶
1217.11 Radiant Heating and Cooling Panels. Radiant heating and cooling panels shall be installed in accordance with the manufacturer’s installation instructions. 1217.11.1 Electric Heating Panel Systems. Clearances for electric heating panels or between outlets, junction boxes, mounting luminaries, ventilating, or other openings shall comply with the California Electrical Code . « « « « 268 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. HYDRONICS » 1217.11.2 Radiant Wall and Ceiling Panels.…
1218.0 Heat Exchangers. ¶
1218.1 General. Systems utilizing heat exchangers shall ¶
1218.1 General. Systems utilizing heat exchangers shall protect the potable water system from being contaminated by the heat transfer medium. Systems that incorporate a singlewall heat exchanger to separate potable water from the heattransfer fluid shall meet the following requirements: (1) Heat transfer medium is either potable water or contains fluids recognized as safe by the Food and Drug Administration (FDA) as food grade. (2) A tag or label shall be securely affixed to the heat source with the word, “CAUTION” and the following statements: (a) The heat transfer medium shall be water or…
1219.0 Indirect-Fired Domestic Hot-Water Storage ¶
1219.0 Indirect-Fired Domestic Hot-Water Storage Tanks.
1219.1 General. Domestic hot-water heat exchangers, ¶
1219.1 General. Domestic hot-water heat exchangers, whether internal or external to the heating appliance, shall be permitted to be used to heat water in domestic hot-water storage tanks. Tanks used to store hot water shall be listed for the intended use and constructed in accordance with nationally recognized standards. A pressure- and temperature-relief valve with a set pressure not exceeding 150 percent of the maximum operating pressure of the system, and at a temperature of 210°F (99°C), shall be installed on the storage tank. Where the normal operating temperature of the boiler or…
1220.0 Snow and Ice Melt Systems. ¶
1220.1 Use of Chemical Additives and Corrosive Flu- ¶
1220.1 Use of Chemical Additives and Corrosive Flu- ids. Where auxiliary systems contain chemical additives, corrosive fluids, or both not intended or designed for use in the primary system, a double wall heat exchanger shall be used in accordance with Section 1218.1. The chemical additives in the auxiliary systems shall be compatible with auxiliary system components and accepted for use by the heat exchanger manufacturer.
1220.2 Types of Tube Fasteners. ¶
1220.2 Types of Tube Fasteners. Tubing that is embedded within concrete shall be fastened according to manufacturer’s instructions. Unless prohibited by the manufacturer, tube fasteners include the following: (1) Ties made of wire, typically fastened to anchors such as rebar or wire mesh. (2) Plastic tube/cable ties, typically nylon, fastened to anchors such as rebar or wire mesh. (3) Staples made of metal or plastic or combination thereof, without sharp edges that would harm tube, fastened to insulation or subfloor. (4) Plastic rails with integrated tube holders intended for the specific…
1220.3 Spacing of Tube Fasteners. ¶
1220.3 Spacing of Tube Fasteners. The maximum spacing between tube fasteners within a concrete area shall not exceed the spacing specified by the manufacturer or, in the absence of manufacturer’s specifications, 2.5 feet (762 mm).
1220.4 Snow and Ice Melt Controls. ¶
1220.4 Snow and Ice Melt Controls. An automatic operating control device that controls the supply hydronic fluid temperature to the snow and ice melt area shall be installed in the system. Snow and ice melt systems shall be protected from freezing with a mixture of propylene glycol or ethylene glycol, and water or other approved fluid. Automotive antifreeze shall not be used. 1220.4.1 Tube Placement. Snow and ice melt tubing shall be installed in accordance with the manufacturer’s installation instructions and with the tube layout and spacing in accordance with the system design. Except for…
1220.5 Hydronic Makeup Air Units. Hydronic makeup ¶
1220.5 Hydronic Makeup Air Units. Hydronic makeup air units that are affected by freezing shall be protected against freezing by a hydronic solution.
1221.0 Piping Installation. ¶
1221.1 General. Piping, fittings, and connections shall be ¶
1221.1 General. Piping, fittings, and connections shall be installed in accordance with the conditions of their approval and manufacturer’s installation instructions.
1221.2 Embedded Piping Materials and Joints. ¶
1221.2 Embedded Piping Materials and Joints. Piping embedded in concrete shall be steel pipe, Type L copper tubing or plastic pipe or tubing rated at not less than 80 psi at 180°F (552 kPa at 82°C). Joints of pipe or tubing that are embedded in a portion of the building, such as concrete or plaster shall be installed in accordance with Section 1221.2.1 through Section 1221.2.3. 1221.2.1 Steel Pipe. Steel pipe shall be welded by electrical arc or oxygen/acetylene method. 1221.2.2 Copper Tubing. Copper tubing shall be joined by brazing with filler metals having a melting point not less than…
1221.3 Pressure Testing. ¶
1221.3 Pressure Testing. Piping to be embedded in concrete shall be pressure-tested in accordance with Section 1205.2 prior to pouring concrete. During the pour, the pipe system shall maintain the test pressure of not less than one and one-half times the hydronic system operating pressure and not less than 100 psi (689 kPa). During freezing or the possibility of freezing conditions, testing shall be done with air where permitted by the manufacturer.
1221.4 System Drainage. Hydronic piping systems shall ¶
1221.4 System Drainage. Hydronic piping systems shall be installed to permit the system to be drained. The system » » » » 1220.4.2 Tube Length. The maximum loop length of continuous tubing from a supply-and-return manifold arrangement shall not exceed the lengths specified by the manufacturer or, in the absence of manufacturer’s specifications, the lengths specified in Table 1220.4.2. Actual loop lengths shall be determined by spacing, flow rate, and pressure drop in accordance with the system design. 1220.4.3 Multizone Systems. In multizone systems, each zone shall have a tag or label…
1221.5 Condensate Drainage. Condensate drains from ¶
1221.5 Condensate Drainage. Condensate drains from dehumidifying coils shall be constructed and sloped for condensate removal. Such drains shall be installed in accordance with Section 310.0.
1221.6 Hydronic Fluid Disposal. Hydronic system fluids ¶
1221.6 Hydronic Fluid Disposal. Hydronic system fluids that contain additives such as antifreeze, corrosion inhibitors, and cleaning solutions shall be recycled or disposed of in an approved manner in accordance with Environmental Protection Agency (EPA), the Department of Health, and as required by the Authority Having Jurisdiction.
1221.7 Clearance to Combustibles. Hydronic piping ¶
1221.7 Clearance to Combustibles. Hydronic piping where the exterior temperature exceeds 250°F (121°C) shall have a clearance of not less 1 inch (25.4 mm) to combustible materials. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. 272 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE CHAPTER 13 – FUEL GAS PIPING (Matrix Adoption Tables are non-regulatory, intended only as an aid…
1301.0 Scope of Gas Piping. ¶
1301.1 Applicability. The regulations of this chapter shall ¶
1301.1 Applicability. The regulations of this chapter shall govern the installation of fuel gas piping in or in connection with a building, structure or within the property lines of premises up to 5 pounds-force per square inch (psi) (34 kPa) for natural gas and 10 psi (69 kPa) for undiluted propane, other than service pipe.
1302.0 Coverage of Piping System. ¶
1302.1 General. Coverage of piping systems shall extend ¶
1302.1 General. Coverage of piping systems shall extend from the point of delivery to the appliance connections. For other than undiluted liquefied petroleum gas (LP-Gas) systems, the point of delivery shall be the outlet of the service meter assembly or the outlet of the service regulator or service shutoff valve where no meter is provided. For undiluted LP-Gas systems, the point of delivery shall be considered to be the outlet of the final pressure regulator, exclusive of line gas regulators where no meter is installed. Where a meter is installed, the point of delivery shall be the outlet…
1302.2 Piping System Requirements. Requirements for ¶
1302.2 Piping System Requirements. Requirements for piping systems shall include design, materials, components, fabrication, assembly, installation, testing, inspection, operation, and maintenance. [NFPA 54:1.1.1.1(E)]
1302.3 Applications. This chapter shall not apply to the ¶
1302.3 Applications. This chapter shall not apply to the following items: (1) Portable LP-Gas appliances and equipment of all types that are not connected to a fixed fuel piping system. (2) Installation of appliances such as brooders, dehydrators, dryers, and irrigation equipment used for agricultural purposes. (3) Raw material (feedstock) applications except for piping to special atmosphere generators. (4) Oxygen-fuel gas cutting and welding systems. (5) Industrial gas applications using such gases as acetylene and acetylenic compounds, hydrogen, ammonia, carbon monoxide, oxygen, and…
1303.0 Inspection. ¶
1303.1 Inspection Notification. Upon completion of the ¶
1303.1 Inspection Notification. Upon completion of the installation, alteration, or repair of gas piping, and prior to the use thereof, the Authority Having Jurisdiction shall be notified that such gas piping is ready for inspection.
1303.2 Excavation. ¶
1303.2 Excavation. Excavations required for the installation of underground piping shall be kept open until such time as the piping has been inspected and approved. Where such piping is covered or concealed before such approval, it shall be exposed upon the direction of the Authority Having Jurisdiction.
1303.3 Type of Inspections. ¶
1303.3 Type of Inspections. The Authority Having Jurisdiction shall make the following inspections and either shall approve that portion of the work as completed or shall notify the permit holder wherein the same fails to be in accordance with this code. 1303.3.1 Rough Piping Inspection. This inspection shall be made after gas piping authorized by the permit has been installed before such piping has been covered or concealed, or before fixture or appliance has been attached thereto. This inspection shall include a determination that the gas piping size, material, and installation meet the…
1303.4 Inspection Waived. ¶
1303.4 Inspection Waived. In cases where the work authorized by the permit consists of a minor installation of additional piping to piping already connected to a gas meter, the foregoing inspections shall be permitted to be waived at the discretion of the Authority Having Jurisdiction. In this event, the Authority Having Jurisdiction shall make such inspection as deemed advisable in order to be assured that the work has been performed in accordance with the intent of this code.
1304.0 Certificate of Inspection. ¶
1304.1 Issuance. Whereupon final piping inspection, the ¶
1304.1 Issuance. Whereupon final piping inspection, the installation is found to be in accordance with the provisions of this code, a certificate of inspection shall be permitted to be issued by the Authority Having Jurisdiction.
1304.2 Gas Supplier. A copy of the certificate of such final ¶
1304.2 Gas Supplier. A copy of the certificate of such final piping inspection shall be issued to the serving gas supplier supplying gas to the premises.
1304.3 Unlawful. ¶
1304.3 Unlawful. It shall be unlawful for a serving gas supplier or person furnishing gas, to turn on or cause to be turned on, fuel gas or a gas meter or meters until such certificate of final inspection, as herein provided, has been issued.
1305.0 Authority to Render Gas Service. ¶
1305.0 Authority to Render Gas Service.
1305.1 Authorized Personnel. It shall be unlawful for a ¶
1305.1 Authorized Personnel. It shall be unlawful for a person, firm, or corporation, excepting an authorized agent or employee of a person, firm, or corporation engaged in the business of furnishing or supplying gas and whose service pipes supply or connect with the particular premises, to turn on or reconnect gas service in or on a premises where gas service is, at the time, not being rendered.
1305.2 Outlets. It shall be unlawful to turn on or connect gas ¶
1305.2 Outlets. It shall be unlawful to turn on or connect gas in or on the premises unless outlets are securely connected to gas appliances or capped or plugged with screw joint fittings.
1306.0 Authority to Disconnect. ¶
1306.1 Disconnection. The Authority Having Jurisdiction ¶
1306.1 Disconnection. The Authority Having Jurisdiction or the serving gas supplier is hereby authorized to disconnect gas piping or appliance or both that shall be found not to be in accordance with the requirements of this code or that are found defective and in such condition as to endanger life or property.
1306.2 Notice. Where such disconnection has been made, a ¶
1306.2 Notice. Where such disconnection has been made, a notice shall be attached to such gas piping or appliance or both that shall state the same has been disconnected, together with the reasons thereof.
1306.3 Capped Outlets. It shall be unlawful to remove or ¶
1306.3 Capped Outlets. It shall be unlawful to remove or disconnect gas piping or gas appliance without capping or plugging with a screw joint fitting, the outlet from which said pipe or appliance was removed. Outlets to which gas appliances are not connected shall be left capped and gastight on a piping system that has been installed, altered, or repaired. Exception: Where an approved listed quick-disconnect device is used.
1307.0 Temporary Use of Gas. ¶
1307.1 General. Where temporary use of gas is desired, and ¶
1307.1 General. Where temporary use of gas is desired, and the Authority Having Jurisdiction deems the use necessary, a permit shall be permitted to be issued for such use for a period of time not to exceed that designated by the Authority Having Jurisdiction, provided that such gas piping system otherwise is in accordance with to the requirements of this code regarding material, sizing, and safety.
1308.0 Gas Piping System Design, Materials, and ¶
1308.0 Gas Piping System Design, Materials, and Components.
1308.1 Installation of Piping System. Where required ¶
1308.1 Installation of Piping System. Where required by the Authority Having Jurisdiction, a piping sketch or plan shall be prepared before proceeding with the installation. The plan shall show the proposed location of piping, the size of different branches, the various load demands, and the location of the point of delivery. [NFPA 54:5.1.1] 1308.1.1 Addition to Existing System. When additional appliances are being connected to a gas piping system, the existing piping shall be checked to determine whether it has adequate capacity. If the capacity of the system is determined to be inadequate…
1308.2 Interconnections Supplying Separate Users. ¶
1308.2 Interconnections Supplying Separate Users. Where two or more meters, or two or more service regulators where meters are not provided, are located on the same premises and supply separate users, the gas piping systems shall not be interconnected on the outlet side of the meters or service regulators. [NFPA 54:5.2.1] 1308.2.1 Interconnections for Standby Fuels. Where a supplementary gas for standby use is connected downstream from a meter or a service regulator where a meter is not provided, equipment to prevent backflow shall be installed. A three-way valve installed to admit the…
1308.3 Sizing of Gas Piping Systems. ¶
1308.3 Sizing of Gas Piping Systems. Gas piping systems shall be of such size and so installed as to provide a supply of gas sufficient to meet the maximum demand and supply gas to each appliance inlet at not less than the minimum supply pressure required by the appliance. [NFPA 54:5.3.1] 1308.3.1 Maximum Gas Demand. The volumetric flow rate of gas to be provided shall be the sum of the maximum input of the appliances served. The volumetric flow rate of gas to be provided shall be adjusted for altitude where the installation is above 2 000 feet (610 m). [NFPA 54:5.3.2.1 – 5.3.2.2] Where the…
1308.4 Acceptable Piping Materials and Joining ¶
1308.4 Acceptable Piping Materials and Joining Methods. Materials used for piping systems shall comply with the requirements of Section 1308.4.1 through Section 1308.4.4.2.3. {NFPA 54:5.5.1.1} 1308.4.1 Used Materials. Pipe, fittings, valves, or other materials shall not be used again unless they are free of foreign materials and have been ascertained to be adequate for the service intended. [NFPA 54:5.5.1.2] 1308.4.2 Metallic Pipe. Metallic pipe shall be in accordance with Section 1308.4.2.1 through Section 1308.4.2.4. 1308.4.2.1 Cast Iron. Cast-iron pipe shall not be used. [NFPA 54:5.5.2.1]…
1308.5 Gas Meters. Gas meters shall be selected for the ¶
1308.5 Gas Meters. Gas meters shall be selected for the maximum expected pressure and permissible pressure drop. [NFPA 54:5.6.1] 1308.5.1 Location. Gas meters shall be located in ven tilated spaces readily accessible for examination, reading, replacement, or necessary maintenance. [NFPA 54:5.6.2.1] 1308.5.1.1 Protection from Damage. Gas meters shall not be placed where they will be subjected to damage, such as adjacent to a driveway, under a fire escape, in public passages, halls, or where they will be subject to excessive corrosion or vibration. [NFPA 54:5.6.2.2] 1308.5.1.2 Extreme…
1308.6 Gas Pressure Regulators. ¶
1308.6 Gas Pressure Regulators. A line pressure regulator shall be installed where the gas supply pressure exceeds the maximum allowable inlet pressure of the appliance served. [NFPA 54:5.7.1] « « « « « « « « « « « « 280 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. FUEL GAS PIPING » » » ~~»~~ » » » » » » 1308.6.1 Listing. Line pressure regulators shall be listed in accordance with CSA/ANSI Z21.80/CSA 6.22 where the outlet pressure is set to 2 psi (14 kPa) or less. [NFPA 54:5.7.2] 1308.6.2…
1308.7 Overpressure Protection. Where the serving gas ¶
1308.7 Overpressure Protection. Where the serving gas supplier delivers gas at a pressure greater than 2 psi for piping systems serving appliances designed to operate at a gas pressure of 14 inches water column or less, overpressure protection devices shall be installed. Piping systems serving equipment designed to operate at inlet pressures greater than 14 inches water column (3.5 kPa) shall be equipped with overpressure protection devices as required by the appliance manufacturer’s installation instructions. [NFPA 54:5.8.1]
1308.8 Pressure Limitation Requirements. ¶
1308.8 Pressure Limitation Requirements. Where piping systems serving appliances designed to operate with a gas supply pressure of 14 inches water column (3.5 kPa) or less are required to be equipped with overpressure protection by Section 1308.7, each overpressure protection device shall be adjusted to limit the gas pressure to each connected appliance to 2 psi (14 kPa) or less upon a failure of the line pressure regulator. [NFPA 54:5.8.2.1] 1308.8.1 Overpressure Protection Required. Where piping systems serving appliances designed to operate with a gas supply pressure greater than 14 inches…
1308.9 Overpressure Protection Devices. ¶
1308.9 Overpressure Protection Devices. Overpressure protection devices shall be one of the following: (1) Pressure relief valve. (2) Monitor regulator. (3) Series regulator installed upstream from the line regulator and set to continuously limit the pressure on the inlet of the line regulator to the maximum values specified by Section 1308.8 or less. (4) Automatic shutoff device installed in series with the line pressure regulator and set to shut off when the pressure on the downstream piping system reaches the maximum values specified by Section 1308.8 or less. This device shall be designed…
1308.13 Expansion and Flexibility. Piping systems shall ¶
1308.13 Expansion and Flexibility. Piping systems shall be designed to prevent failure from thermal expansion or contraction. [NFPA 54:5.13.1] 1308.13.1 Special Local Conditions. Where local conditions include earthquake, tornado, unstable ground, or flood hazards, special consideration shall be given to increased strength and flexibility of piping supports and connections. [NFPA 54:5.13.2]
1308.14 Pressure Regulator and Pressure Control ¶
1308.14 Pressure Regulator and Pressure Control Venting. The venting of the atmospheric side of diaphragms in line pressure regulators, gas appliance regulators, and gas pressure limit controls shall be in accordance with all of the following: (1) An independent vent pipe to the outdoors, sized in accordance with the device manufacturer’s instructions, shall be provided where the location of a device is such that a discharge of fuel gas will cause a hazard. For devices other than appliance regulators, vents are not required to be independent where the vents are connected to a common manifold…
1308.10 Backpressure Protection. Protective devices ¶
1308.10 Backpressure Protection. Protective devices shall be installed as close to the equipment as practical where the design of equipment connected is such that air, oxygen, or standby gases could be forced into the gas supply system. Gas and air combustion mixers incorporating double diaphragm “zero” or “atmosphere” governors or regulators shall require no further protection unless connected directly to compressed air or oxygen at pressures of 5 psi (34 kPa) or more. [NFPA 54:5.9.1.1, 5.9.1.2] 1308.10.1 Protective Devices. Protective devices shall include but not be limited to the…
1308.11 Low-Pressure Protection. A protective device ¶
1308.11 Low-Pressure Protection. A protective device shall be installed between the meter and the appliance or equipment if the operation of the appliance or equipment is such that it could produce a vacuum or a dangerous reduction in gas pressure at the meter. Such protective devices include, but are not limited to, mechanical, diaphragm-operated, or electrically operated low-pressure shutoff valves. [NFPA 54:5.10]
1308.12 Shutoff Valves. Shutoff valves shall be selected in ¶
1308.12 Shutoff Valves. Shutoff valves shall be selected in accordance with Table 1308.12. Shutoff valves of size 1 inch (25 mm) National Pipe Thread and smaller shall be listed and labeled. Where used outdoors, such use shall be in accordance with the manufacturer’s recommendation. [NFPA 54:5.11] « « 282 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. FUEL GAS PIPING Exceptions: (1) A regulator and vent limiting means combination listed as complying with CSA/ANSI Z21.80/CSA 6.22, shall not be…
1309.0 Excess Flow Valve. ¶
1309.1 General. Where automatic excess flow valves are ¶
1309.1 General. Where automatic excess flow valves are installed, they shall be listed in accordance with ANSI Z21.93/CSA 6.30 and shall be sized and installed in accordance with the manufacturers’ instructions. [NFPA 54:5.12]
1310.0 Gas Piping Installation. ¶
1310.1 Piping Underground. Underground gas piping shall ¶
1310.1 Piping Underground. Underground gas piping shall be installed with sufficient clearance from any other underground structure to avoid contact therewith, to allow maintenance, and to protect against damage from proximity to other structures. Underground plastic piping shall be installed with sufficient clearance or shall be insulated from any source of heat so as to prevent the heat from impairing the serviceability of the pipe. [NFPA 54:7.1.1.1, 7.1.1.2] 1310.1.1 Cover Requirements. Underground piping systems shall be installed with a minimum of 12 inches (305 mm) of cover. The minimum…
1310.2 CSST Piping Systems. CSST piping systems shall ¶
1310.2 CSST Piping Systems. CSST piping systems shall be installed in accordance with this code and the manufac turer’s installation instructions. [NFPA 54:7.1.8]
1310.3 Installation of Aboveground Piping. Piping ¶
1310.3 Installation of Aboveground Piping. Piping installed aboveground shall comply with all of the following: (1) Piping shall be securely supported and located where it will be protected from physical damage. (2) Where passing through an exterior wall, the piping shall also be protected from corrosion by coating or wrapping with an inert material approved for such applications. (3) The piping shall be sealed around its circumference at the point of the exterior penetration to prevent the entry of water, insects, and rodents. 284 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO,…
1310.4 Concealed Piping in Buildings. Gas piping in ¶
1310.4 Concealed Piping in Buildings. Gas piping in concealed locations shall be installed in accordance with this section. [NFPA 54:7.3.1] 1310.4.1 Connections. Where gas piping is to be concealed, connections shall be of the following type: (1) Pipe fittings, such as elbows, tees, couplings, and right/left nipple/couplings. (2) Joining tubing by brazing (see Section 1308.4.7.1). (3) Press-connect fittings listed to CSA/ANSI LC 4/CSA 6.32. (4) CSST fittings listed to CSA/ANSI LC 1/CSA 6.26. (5) Where necessary to insert fittings in gas pipe that has been installed in a concealed location,…
1310.5 Piping in Vertical Chases. Where gas piping ¶
1310.5 Piping in Vertical Chases. Where gas piping exceeding 5 psi (34 kPa) is located within vertical chases in accordance with Section 1310.6, the requirements of Section 1310.5.1 through Section 1310.5.3 shall apply. [NFPA 54:7.4] 1310.5.1 Pressure Reduction. Where pressure reduction is required in branch connections for compliance with Section 1310.6, such reduction shall take place either inside the chase or immediately adjacent to the outside wall of the chase. Regulator venting and downstream overpressure protection shall comply with Section 1308.6.4 and Section 1308.7. The regulator…
1310.6 Maximum Operating Pressure in Buildings. ¶
1310.6 Maximum Operating Pressure in Buildings. The maximum operating pressure for any piping systems located inside buildings shall not exceed 5 psi (34 kPa) unless one or more of the following conditions are met: (1) The piping joints are welded or brazed. (2) The piping is joined by fittings listed to CSA/ANSI LC 4/CSA 6.32 and installed according to the manufacturer’s installation instructions. (3) The piping joints are flanged and all pipe-to-flange connections are made by welding or brazing. (4) The piping is located in a ventilated chase or otherwise enclosed for protection against…
1310.7 Appliance Overpressure Protection. ¶
1310.7 Appliance Overpressure Protection. The maximum operating pressure for piping systems serving appliances designed to operate at 14 inches water column (3.5 kPa) inlet pressure or less shall be 2 pounds-force per square inch gauge (psig) (14 kPa) unless an over pressure protection device designed to limit pressure at the appliance to 2 psig (14 kPa) upon failure of the line gas pressure regulator is installed.
1310.8 Gas Pipe Turns. Changes in direction of gas pipe ¶
1310.8 Gas Pipe Turns. Changes in direction of gas pipe shall be made by the use of fittings, factory bends, or field bends. [NFPA 54:7.5] 1310.8.1 Metallic Pipe. Metallic pipe bends shall comply with the following: (1) Bends shall be made only with bending tools and procedures intended for that purpose. 286 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. FUEL GAS PIPING (2) All bends shall be smooth and free from buckling, cracks, or other evidence of mechanical damage. (3) The longitudinal…
1310.9 Drips and Sediment Traps. For other than dry gas ¶
1310.9 Drips and Sediment Traps. For other than dry gas conditions, a drip shall be provided at any point in the line of pipe where condensate could collect. Where required by the Authority Having Jurisdiction or the serving gas supplier, a drip shall also be provided at the outlet of the meter. This drip shall be installed so as to constitute a trap wherein an accumulation of condensate shuts off the flow of gas before it runs back into the meter. [NFPA 54:7.6.1] 1310.9.1 Location of Drips. All drips shall be installed only in such locations that they are readily accessible to permit…
1310.10 Outlets. Outlets shall be located and installed in ¶
1310.10 Outlets. Outlets shall be located and installed in accordance with the following requirements: (1) The outlet fittings or piping shall be securely fastened in place. (2) Outlets shall not be located behind doors. (3) Outlets shall be located far enough from floors, walls, patios, slabs, and ceilings to permit the use of wrenches without straining, bending, or damaging the piping. (4) The unthreaded portion of gas piping outlets shall extend not less than 1 inch (25.4 mm) through finished ceilings or indoor or outdoor walls. (5) The unthreaded portion of gas piping outlets shall extend…
1310.11 Manual Gas Shutoff Valves. An accessible gas ¶
1310.11 Manual Gas Shutoff Valves. An accessible gas shutoff valve shall be provided upstream of each gas pressure regulator. Where two gas pressure regulators are installed in series in a single gas line, a manual valve shall not be required at the second regulator. [NFPA 54:7.8.2] 1310.11.1 Accessibility of Gas Valves. System shutoff valves shall be readily accessible for operation and installed so as to be protected from physical damage. System shutoff valves shall be marked with a metal tag or other permanent means attached by the installing agency so that the gas piping systems supplied…
1310.12 Prohibited Devices. Devices shall not be placed ¶
1310.12 Prohibited Devices. Devices shall not be placed within the interior of gas piping or fittings where such devices reduce the cross-sectional area or otherwise obstruct the free flow of gas, except where allowance in the piping system design has been made for such devices. [NFPA 54:7.9]
1310.13 Systems Containing Gas-Air Mixtures Out- ¶
1310.13 Systems Containing Gas-Air Mixtures Out- side the Flammable Range. Where gas-air mixing machines are employed to produce mixtures above or below the flammable range, they shall be provided with stops to prevent adjustment of the mixture to within or approaching the flammable range. [NFPA 54:7.10]
1310.14 Systems Containing Flammable Gas-Air ¶
1310.14 Systems Containing Flammable Gas-Air Mixtures. Systems containing flammable gas-air mixtures shall be in accordance with Section 1310.14.1 through Section 1310.14.6. 1310.14.1 Required Components. A central premix system with a flammable mixture in the blower or compressor shall consist of the following components: (1) Gas-mixing machine in the form of an automatic gas-air proportioning device combined with a downstream blower or compressor. (2) Flammable mixture piping, minimum Schedule 40. (3) Automatic firecheck(s). (4) Safety blowout(s) or backfire preventers for systems utilizing…
1311.0 Electrical Bonding and Grounding. ¶
1311.0 Electrical Bonding and Grounding.
1311.1 Pipe and Tubing Other than CSST. ¶
1311.1 Pipe and Tubing Other than CSST. Each aboveground portion of a gas piping system, other than CSST, that is likely to become energized shall be electrically continuous and bonded to an effective ground-fault current path. Gas piping, other than CSST, shall be considered to be bonded when it is connected to appliances that are connected to the appliance grounding conductor of the circuit supplying that appliance. [NFPA 54:7.12.1]
1311.2 Bonding of CSST Gas Piping. CSST gas piping ¶
1311.2 Bonding of CSST Gas Piping. CSST gas piping systems, and gas piping systems containing one or more segments of CSST, shall be electrically continuous and bonded to the electrical service grounding electrode system or, where provided, lightning protection grounding electrode system. [NFPA 54:7.12.2] 1311.2.1 Bonding Jumper Connection. The bonding jumper shall connect to a metallic pipe, pipe fitting, or CSST fitting. [NFPA 54:7.12.2.1] 1311.2.2 Bonding Jumper Size. The bonding jumper shall not be smaller than 6 AWG copper wire or equivalent. [NFPA 54:7.12.2.2] 1311.2.3 Bonding Jumper…
1311.3 Arc-Resistant Jacketed CSST. CSST listed with ¶
1311.3 Arc-Resistant Jacketed CSST. CSST listed with an arc-resistant jacket or coating system in accordance with CSA/ANSI LC 1/CSA 6.26 shall be electrically continuous and bonded to an effective ground fault current path. Where any CSST component of a piping system does not have an arc-resistant jacket or coating system, the bonding requirements of Section 1311.2 shall apply. Arc-resistant jacketed CSST shall be considered to be bonded when it is connected to appliances that are connected to the appliance grounding conductor of the circuit supplying that appliance. [NFPA 54:7.12.3]
1311.4 Prohibited Use. Gas piping shall not be used as a ¶
1311.4 Prohibited Use. Gas piping shall not be used as a grounding conductor or electrode. [NFPA 54:7.12.4.1]
1311.5 Lightning Protection System. Where a lightning ¶
1311.5 Lightning Protection System. Where a lightning protection system is installed, the bonding of the gas piping shall be in accordance with NFPA 780. [NFPA 54:7.12.5]
1311.6 Electrical Circuits. ¶
1311.6 Electrical Circuits. Electrical circuits shall not utilize gas piping or components as conductors. Exception: Low-voltage (50V or less) control circuits, ignition circuits, and electronic flame detection device circuits shall be permitted to make use of piping or components as a part of an electric circuit. [NFPA 54:7.13]
1311.7 Electrical Connections. All electrical connections ¶
1311.7 Electrical Connections. All electrical connections between wiring and electrically operated control devices in a piping system shall conform to the requirements of NFPA 70. [NFPA 54:7.14.1] 1311.7.1 Safety Control. Any essential safety control depending on electric current as the operating medium shall be of a type that shuts off (fail safe) the flow of gas in the event of current failure. [NFPA 54:7.14.2]
1312.0 Appliance and Equipment Connections to ¶
1312.0 Appliance and Equipment Connections to Building Piping.
1312.1 Connecting Appliances and Equipment. ¶
1312.1 Connecting Appliances and Equipment. Appliances and equipment shall be connected to the building piping in compliance with Section 1312.6 through Section 1312.8 by one of the following: (1) Rigid metallic pipe and fittings. (2) Semirigid metallic tubing and metallic fittings. Aluminum alloy tubing shall not be used in exterior locations. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. FUEL GAS PIPING
1312.3 Use of Nonmetallic Gas Hose Connectors. ¶
1312.3 Use of Nonmetallic Gas Hose Connectors. Listed gas hose connectors shall be used in accordance with the manufacturer’s installation instructions and in accor dance with Section 1312.3.1 or Section 1312.3.2. [NFPA 54:9.6.2] 1312.3.1 Indoor. Indoor gas hose connectors shall be used only to connect laboratory, shop, and ironing appliances requiring mobility during operation and installed in accordance with the following: (1) An appliance shutoff valve shall be installed where the connector is attached to the building piping. (2) The connector shall be of minimum length and shall not…
1312.4 Injection (Bunsen) Burners. Injection (Bunsen) ¶
1312.4 Injection (Bunsen) Burners. Injection (Bunsen) burners used in laboratories and educational facilities shall be permitted to be connected to the gas supply by an unlisted hose. [NFPA 54:9.6.3]
1312.5 Connection of Portable and Mobile Industrial ¶
1312.5 Connection of Portable and Mobile Industrial Appliances. Where portable industrial appliances or appliances requiring mobility or subject to vibration are connected to the building gas piping system by the use of a flexible hose, the hose shall be suitable and safe for the conditions under which it can be used. [NFPA 54:9.6.4.1] 1312.5.1 Swivel Joints or Couplings. Where industrial appliances requiring mobility are connected to the rigid piping by the use of swivel joints or couplings, the swivel joints or couplings shall be suitable for the service required and only the minimum number…
1312.2 Suspended Low-Intensity Infrared Tube ¶
1312.2 Suspended Low-Intensity Infrared Tube Heaters. Suspended low-intensity infrared tube heaters shall be connected to the building piping system with a connector listed for the application in accordance with ANSI Z21.24/CSA 6.10 as follows: (1) The connector shall be installed in accordance with the tube heater installation instructions, and shall be in the same room as the appliance. (2) Only one connector shall be used per appliance. [NFPA 54:9.6.1.5] 290 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other…
1312.6 Appliance Shutoff Valves and Connections. ¶
1312.6 Appliance Shutoff Valves and Connections. Each appliance connected to a piping system shall have an accessible, approved manual shutoff valve with a nondisplaceable valve member, or a listed gas convenience outlet. Appliance shutoff valves and convenience outlets shall serve a single appliance only. [NFPA 54:9.6.5] The shutoff valve shall be located within 6 feet (1829 mm) of the appliance it serves. [NFPA 54:9.6.5.1] Where a connector is used, the valve shall be installed upstream of the connector. A union or flanged connection shall be provided downstream from the valve to permit…
1312.7 Quick-Disconnect Devices. Quick-disconnect ¶
1312.7 Quick-Disconnect Devices. Quick-disconnect devices used to connect appliances to the building piping shall be listed in accordance with ANSI Z21.41/CSA 6.9. Where installed indoors, an approved manual shutoff valve with a nondisplaceable valve member shall be installed upstream of the quick-disconnect device. [NFPA 54:9.6.6 – 9.6.6.2]
1312.8 Gas Convenience Outlets. Appliances shall be ¶
1312.8 Gas Convenience Outlets. Appliances shall be permitted to be connected to the building piping by means of a listed gas convenience outlet, in conjunction with a listed appliance connector, installed in accordance with the manufacturer’s installation instructions. Gas convenience outlets shall be listed in accordance with CSA/ANSI Z21.90/CSA 6.24 and installed in accor dance with the manufacturer’s installation instructions. [NFPA 54:9.6.7]
1312.9 Sediment Trap. ¶
1312.9 Sediment Trap. Where a sediment trap is not incorporated as a part of the appliance, a sediment trap shall be installed downstream of the appliance shutoff valve as close to the inlet of the appliance as practical at the time of appliance installation. The sediment trap shall be either a tee fitting with a capped nipple in the bottom outlet, as illustrated in Figure 1312.9, or another device recognized as an effective sediment trap. Illuminating appliances, gas ranges, clothes dryers, decorative appliances for installation in vented fireplaces, gas fireplaces, and outdoor cooking…
1312.10 Installation of Piping. Piping shall be installed in ¶
1312.10 Installation of Piping. Piping shall be installed in a manner not to interfere with inspection, maintenance, or servicing of the appliances. [NFPA 54:9.6.9]
1312.11 Liquefied Petroleum Gas (LP-Gas) Facilities ¶
1312.11 Liquefied Petroleum Gas (LP-Gas) Facilities and Piping. Liquefied petroleum gas (LP-Gas) facilities shall comply with NFPA 58.
1313.0 Pressure Testing, Inspection, and Purging. ¶
1313.0 Pressure Testing, Inspection, and Purging.
1313.1 Piping Installations. ¶
1313.1 Piping Installations. Prior to acceptance and initial operation, all piping installations shall be visually inspected and pressure tested to determine that the materials, design, fabrication, and installation practices comply with the requirements of this code. [NFPA 54:8.1.1.1] 1313.1.1 Inspection Requirements. Inspection shall consist of visual examination, during or after manufacture, fabrication, assembly, or pressure tests. [NFPA 54:8.1.1.2] 1313.1.2 Repairs and Additions. Where repairs or additions are made following the pressure test, the affected piping shall be tested. Minor…
1313.2 Test Preparation. Test preparation shall comply ¶
1313.2 Test Preparation. Test preparation shall comply with Section 1313.2.1 through Section 1313.2.6. 1313.2.1 Pipe Joints. Pipe joints, including welds, shall be left exposed for examination during the test. Exception: Covered or concealed pipe end joints that have been previously tested in accordance with this code. [NFPA 54:8.1.3.1] 1313.2.2 Expansion Joints. Expansion joints shall be provided with temporary restraints, if required, for the additional thrust load under test. [NFPA 54:8.1.3.2] 1313.2.3 Appliances and Equipment. Appliances and equipment that are not to be included in the…
1313.3 Test Pressure. This inspection shall include an air, ¶
1313.3 Test Pressure. This inspection shall include an air, CO2, or nitrogen pressure test, at which time the gas piping shall stand a pressure of not less than 10 psi (69 kPa) gauge pressure. Test pressures shall be held for a length of time satisfactory to the Authority Having Jurisdiction but in no case less than 15 minutes with no perceptible drop in pressure. For welded piping, and for piping carrying gas at pressures in excess of 14 inches water column (3.5 kPa) pressure, the test pressure shall be not less than 60 psi (414 kPa) and shall be continued for a length of time satisfactory…
1313.4 Detection of Leaks and Defects. ¶
1313.4 Detection of Leaks and Defects. The piping system shall withstand the test pressure specified without showing any evidence of leakage or other defects. Any reduction of test pressures as indicated by pressure gauges shall be deemed to indicate the presence of a leak unless such reduction can be readily attributed to some other cause. [NFPA 54:8.1.5.1] 1313.4.1 Detecting Leaks. The leakage shall be located by means of an approved gas detector, a noncorrosive leak detection fluid, or other approved leak detection methods. [NFPA 54:8.1.5.2] 1313.4.2 Repair or Replace. Where leakage or…
1313.5 Piping System Leak Test. Leak checks using fuel ¶
1313.5 Piping System Leak Test. Leak checks using fuel gas shall be permitted in piping systems that have been pressure-tested in accordance with Section 1313.0 through Section 1313.4.2. [NFPA 54:8.2.1] 1313.5.1 Turning Gas On. During the process of turning gas on into a system of new gas piping, the entire system shall be inspected to determine that there are no open fittings or ends and that all valves at unused outlets are closed and plugged or capped. [NFPA 54:8.2.2] 1313.5.2 Leak Check. Immediately after the gas is turned on into a new system or into a system that has been initially…
1313.6 Purging Requirements. The purging of piping ¶
1313.6 Purging Requirements. The purging of piping shall be in accordance with Section 1313.6.1 through Section 1313.6.3. [NFPA 54:8.3] 1313.6.1 Piping Systems Required to be Purged Outdoors. The purging of piping systems shall be in accordance with Section 1313.6.1.1 through Section 1313.6.1.4 where the piping system meets either of the following: (1) The design operating gas pressure is greater than 2 psig (14 kPag). (2) The piping being purged contains one or more sections of pipe or tubing meeting the size and length criteria of Table 1313.6.1. [NFPA 54:8.3.1] 292 2025 CALIFORNIA…
1314.0 Required Gas Supply. ¶
1314.1 General. The following regulations, shall comply ¶
1314.1 General. The following regulations, shall comply with this section and Section 1315.0, shall be the standard for the installation of gas piping. Natural gas regulations and tables are based on the use of gas having a specific gravity of 0.60 and for undiluted liquefied petroleum gas having a specific gravity of 1.50. Where gas of a different specific gravity is to be delivered, the serving gas supplier shall be permitted to be contacted for specific gravity conversion factors to use in sizing piping systems from the pipe sizing tables in this chapter.
1314.2 Volume. The hourly volume of gas required at each ¶
1314.2 Volume. The hourly volume of gas required at each piping outlet shall be taken as not less than the maximum hourly rating as specified by the manufacturer of the appliance or appliances to be connected to each such outlet. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. FUEL GAS PIPING
1314.3 Gas Appliances. Where the gas appliances to be ¶
1314.3 Gas Appliances. Where the gas appliances to be installed have not been definitely specified, Table 1308.3.1 shall be permitted to be used as a reference to estimate requirements of typical appliances. To obtain the cubic feet per hour (m [3] /h) of gas required, divide the input of the appliances by the average Btu (kW•h) heating value per cubic foot (m [3] ) of the gas. The average Btu (kW•h) per cubic foot (m [3] ) of the gas in the area of the installation shall be permitted to be obtained from the serving gas supplier.
1314.4 Size of Piping Outlets. ¶
1314.4 Size of Piping Outlets. The size of the supply piping outlet for a gas appliance shall be not less than [1] ⁄ 2 of an inch (15 mm). The size of a piping outlet for a mobile home shall be not less than [3] ⁄ 4 of an inch (20 mm).
1315.0 Required Gas Piping Size. ¶
1315.1 Pipe Sizing Methods. Where the pipe size is to be ¶
1315.1 Pipe Sizing Methods. Where the pipe size is to be determined using any of the methods in Section 1315.1.1 through Section 1315.1.3, the diameter of each pipe segment shall be obtained from the pipe sizing tables in Section 1315.2 or from the sizing equations in Section 1315.3. [NFPA 54:6.1] 1315.1.1 Longest Length Method. The pipe size of each section of gas piping shall be determined using the longest length of piping from the point of delivery to the most remote outlet and the load of the section. [NFPA 54:6.1.1] 1315.1.2 Branch Length Method. Pipe shall be sized as follows: (1) Pipe…
1315.2 Sizing of Gas Piping Systems. Sizing of piping ¶
1315.2 Sizing of Gas Piping Systems. Sizing of piping systems shall be in accordance with Section 1315.2.1 for natural gas piping systems and Section 1315.2.2 for propane piping systems. 1315.2.1 Natural Gas Piping Systems. Table 1315.2(1) through Table 1315.2(23) shall be used in conjunction with one of the methods described in Section 1315.1.1 through Section 1315.1.3 for piping materials other than non-corrugated stainless steel tubing. Section 1315.3 shall be used in conjunction with one of the methods described in Section 1315.1.1 through Section 1315.1.3 for non-corrugated stainless…
1315.3 Sizing Equations. The inside diameter of smooth ¶
1315.3 Sizing Equations. The inside diameter of smooth wall pipe or tubing shall be determined by Equation 1315.3(1), Equation 1315.3(2) and Table 1315.3 using the equivalent pipe length determined by the methods in Section 1315.1.1 through Section 1315.1.3. [NFPA 54:6.4] LOW-PRESSURE GAS FORMULA [LESS THAN 1.5 psi (10.3 kPa)] [NFPA 54:6.4.1] [Equation 1315.3(1)] Q [0.381] D = Δ H 0.206 19.17 ~~(~~ Cr x L ~~)~~ Where: D = inside diameter of pipe, inches Q = input rate appliance(s), cubic feet per hour at 60°F and 30 inch mercury column L = equivalent length of pipe, feet Δ H = pressure drop,…
1315.4 Sizing of Piping Sections. To determine the size ¶
1315.4 Sizing of Piping Sections. To determine the size of each section of pipe in a system within the range of Table 1315.2(1) through Table 1315.2(36), proceed as follows: (1) Measure the length of the pipe from the gas meter location to the most remote outlet on the system. (2) Select the length in feet column and row showing the distance, or the next longer distance where the table does not give the exact length. (3) Starting at the most remote outlet, find in the just selected the gas demand for that outlet. Where the exact figure of demand is not shown, choose the next larger figure in…
1315.5 Engineering Methods. For conditions other than ¶
1315.5 Engineering Methods. For conditions other than those covered by Section 1315.1, such as longer runs or greater gas demands, the size of each gas piping system shall be determined by standard engineering methods acceptable to the Authority Having Jurisdiction, and each such system shall be so designed that the total pressure drop between the meter or other point of supply and an outlet where full demand is being supplied to outlets, shall be in accordance with the requirements of Section 1308.3.
1315.6 Variable Gas Pressures. Where the supply gas ¶
1315.6 Variable Gas Pressures. Where the supply gas pressure exceeds 5 psi (34 kPa) for natural gas and 10 psi (69 kPa) for undiluted propane or is less than 6 inches (1.5 kPa) of water column, or where diversity demand factors are used, the design, pipe, sizing, materials, location, and use of such systems first shall be approved by the Authority Having Jurisdiction. Piping systems designed for pressures exceeding the serving gas supplier’s standard delivery pressure shall have prior verification from the gas supplier of the availability of the design pressure. ), Copyright © 2025 IAPMO, and…
1401.0 General. ¶
1401.1 Applicability. Except as otherwise addressed in this ¶
1401.1 Applicability. Except as otherwise addressed in this code, this chapter shall govern the installation of process piping in or in conjunction with a building or structure located upon the premises.
1402.0 Permit. ¶
1402.1 General. It shall be unlawful to install, alter, or ¶
1402.1 General. It shall be unlawful to install, alter, or repair or cause to be installed, altered, or repaired process material piping without first obtaining a permit. Permits for process piping shall show the total number of outlets to be provided for on each system and such other information as required by the Authority Having Jurisdiction. Fees for process piping permits are included in Table 104.5.
1403.0 Plans Required. ¶
1403.1 General. Plans, engineering calculations, diagrams, ¶
1403.1 General. Plans, engineering calculations, diagrams, and other data shall be submitted in one or more sets with each application for a permit. The Authority Having Jurisdiction shall be permitted to require plans, computations, and specifications to be prepared and designed by a registered design professional. Where plans or other data are submitted for review, a plan review fee shall be paid, as provided in Section 104.3.2.
1404.0 Workmanship. ¶
1404.1 General. Process piping shall not be strained or bent, ¶
1404.1 General. Process piping shall not be strained or bent, nor shall tanks, vessels, vats, appliances, or cabinets be supported by or develop strain or stress on the piping.
1405.0 Inspections. ¶
1405.1 General. ¶
1405.1 General. Upon completion of the installation, alteration, or repair of process piping, and prior to the use thereof, the Authority Having Jurisdiction shall be notified that such piping is ready for inspection. Excavations required for the installation of underground piping shall be kept open until such time as the piping has been inspected and approved. Where such piping is covered or concealed before such approval, it shall be exposed upon the direction of the Authority Having Jurisdiction.
1405.2 Required Inspections. The Authority Having ¶
1405.2 Required Inspections. The Authority Having Jurisdiction shall make the following inspections and shall either approve that portion of the work as completed or shall notify the permit holder wherein the same fails to be in accordance with this code. 1405.2.1 Rough Piping Inspection. This inspection shall be made after process piping authorized by the permit has been installed and before piping has been cov ered or concealed. This inspection shall include a determination that the piping size, material, and installation are in accordance with the requirements of this code. 1405.2.2 Final…
1405.3 Other Inspections. In addition to the inspections ¶
1405.3 Other Inspections. In addition to the inspections required by this section, the Authority Having Jurisdiction shall be permitted to require a special inspector, as specified in the building code, during installation of piping systems. In cases where the work authorized was installed in accordance with plans and specifications prepared by a registered design professional, the Authority Having Jurisdiction shall be permitted to require a final signed report stating that the work was installed in accordance with approved plans and specifications and the applicable provisions of this…
1406.0 Pipe, Tubing, and Fittings. ¶
1406.1 General. Process pipe, tubing, and fittings shall ¶
1406.1 General. Process pipe, tubing, and fittings shall comply with ASME B31.3 and shall be installed in accordance with the manufacturer’s installation instructions. Materials shall be rated for the operating temperatures and pressures of the system, and shall be compatible with the type of liquid.
1406.2 Hazardous Process Piping (HPP). HPP supply ¶
1406.2 Hazardous Process Piping (HPP). HPP supply piping or tubing in service corridors shall be exposed to view. HPP piping shall be identified in accordance with nationally recognized standards to indicate the material being transported. Liquid HPP piping shall have an approved means for directing spilled materials to an approved containment or drainage system. Liquid HPP waste or drainage systems shall be installed in accordance with the plumbing code. 1406.2.1 Installation in Exit Corridors and Above Other Occupancies. Hazardous process supply pipe shall not be located within exit…
1406.3 Special Requirements for HPP Gases. ¶
1406.3 Special Requirements for HPP Gases. In addition to other requirements of this section, HPP gases shall comply with this subsection and the fire code. 1406.3.1 Special Provisions. Where HPP supply gas is carried in pressurized piping, a fail-safe system shall shut off flow due to a rupture in the piping. Where the piping originates from outside the building, the valve shall be located outside the building as close to the bulk source as practical. 1406.3.2 Piping and Tubing Installation. Piping and tubing shall be installed in accordance with approved standards. Supply piping for…
1501.0 General. ¶
1501.1 Applicability. See Section 1203.0 and the Uniform ¶
1501.1 Applicability. See Section 1203.0 and the Uniform Solar, Hydronics and Geothermal Code (USHGC), published by the International Association of Plumbing and Mechanical Officials. The Uniform Solar, Hydronics and Geothermal Code (USHGC) provides requirements that shall be permitted to be adopted as part of the code by the Authority Having Jurisdiction.
1502.0 General. [HCD 1 & HCD 2] For applications listed ¶
1502.0 General. [HCD 1 & HCD 2] For applications listed in Section 1.8.2 regulated by the Department of Housing and Community Development, see Health and Safety Code Sec- tion 17959.1, Civil Code Sections 714 and 801.5, and Gov- ernment Code Section 65850.5. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. 340 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE CHAPTER 16 –…
1601.0 Stationary Fuel Cell Power Plants. ¶
1601.0 Stationary Fuel Cell Power Plants.
1601.1 General. ¶
1601.1 General. Fuel cell power plants with a power output of less than 50 kW shall be listed in accordance with CSA/ANSI FC 1/CSA C22.2 No. 62282-3-100 and installed in accordance with the manufacturer’s instructions. Fuel cell power plants with a power output of greater than 50 kW shall be installed in accordance with NFPA 853. [NFPA 54:10.29]
1602.0 Stationary Gas Engines and Generators and ¶
1602.0 Stationary Gas Engines and Generators and Gas Turbines .
1602.1 Gas Engines . The installation of stationary gas ¶
1602.1 Gas Engines . The installation of stationary gas engines shall conform to NFPA 37. [NFPA 54:10.22] 1602.1.1 Connection to the Gas Supply Piping. Stationary gas engines shall not be rigidly connected to the gas supply piping. [NFPA 54:10.22.1]
1602.2 Liquid-Fueled Engines and Gas Turbines. In ¶
1602.2 Liquid-Fueled Engines and Gas Turbines. In accordance with California Building Code Section 442.1, the installation of liquid-fueled stationary internal combustion engines and gas turbines shall conform to NFPA 37.
1602.3 Stationary Engine Generators. Stationary ¶
1602.3 Stationary Engine Generators. Stationary engine generators shall be tested in accordance with UL 2200, and shall be installed in accordance with NFPA 37 and the manufacturer’s installation instructions. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. 344 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE CHAPTER 17 – GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS…
1701.0 General. ¶
1701.1 Applicability. Part I of this chapter shall apply to ¶
1701.1 Applicability. Part I of this chapter shall apply to geothermal energy systems such as, but not limited to, building systems coupled with a ground-heat exchanger, submerged heat exchanger using water-based fluid as a heat transfer medium, or groundwater (well). The regulations of this chapter shall govern the construction, location and installation of geothermal energy systems. Part I through Part V of this chapter shall apply to geothermal energy systems and district ambient temperature loop systems that circulate ground-ambient-temperature water to be used in end-use buildings as a…
1701.2 Construction Documents. The construction doc ¶
1701.2 Construction Documents. The construction doc uments for the building system portion of the geothermal energy system shall be submitted to the Authority Having Jurisdiction.
1701.3 Site Survey. A site survey shall be conducted prior ¶
1701.3 Site Survey. A site survey shall be conducted prior to designing the geothermal system. The requirements for construction documents shall be defined by the Authority Having Jurisdiction. Where no guidance is provided, the following information shall be provided: CHAPTER 17 GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS (1) Ground-heat exchanger dimensions. (2) Grout or sealing specifications, as applicable. (3) Dimensions from building to water well, ground-heat exchanger, or submerged heat exchanger. (4) Operating temperatures and pressures.
1701.4 Used Materials. ¶
1701.4 Used Materials. The installation of used pipe, fittings, valves, and other materials shall not be permitted.
1701.5 Contact with Building Material. A ground source ¶
1701.5 Contact with Building Material. A ground source heat pump ground-loop piping system shall not be in direct contact with building materials that cause the piping or fitting material to degrade or corrode, or that interferes with the operation of the system.
1701.6 Strains and Stresses. Piping shall be installed so ¶
1701.6 Strains and Stresses. Piping shall be installed so as to prevent detrimental strains and stresses in the pipe. Provisions shall be made to protect piping from damage resulting from expansion, contraction, and structural settlement. Piping shall be installed so as to avoid structural stresses or strains within building components.
1701.7 Flood Hazard. Piping located in a flood hazard area ¶
1701.7 Flood Hazard. Piping located in a flood hazard area shall be capable of resisting hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy, during the occurrence of flooding to the design flood elevation.
1701.8 Pipe Support. Pipe shall be supported in accordance with Section 313.1. ¶
1701.8 Pipe Support. Pipe shall be supported in accordance with Section 313.1.
1701.9 Velocities. Ground source heat pump ground-loop ¶
1701.9 Velocities. Ground source heat pump ground-loop systems shall be designed so that the flow velocities do not exceed the maximum flow velocity recommended by the pipe and fittings manufacturer. Flow velocities shall be controlled to reduce the possibility of water hammer.
1701.10 Chemical Compatibility. Antifreeze and other ¶
1701.10 Chemical Compatibility. Antifreeze and other materials used in the system shall be chemically compatible with the pipe, tubing, fittings, and mechanical systems.
1701.11 Heat Transfer Fluid. The heat transfer fluid shall ¶
1701.11 Heat Transfer Fluid. The heat transfer fluid shall be compatible with the makeup fluid supplied to the system. 1701.11.1 Water Quality. The makeup water quality within the closed loop ground source heat pump system shall be in accordance with IAPMO/ANSI H1001.1, ANSI/CSA/IGSHPA C448, or Table 1701.11.1. The quality of potable water shall be in accordance with the Authority Having Jurisdiction. 1701.11.2 Compatibility. System components shall be compatible with system fluids including, but not limited to, antifreeze. For systems utilizing chemical additives, system components and…
1702.0 Groundwater Systems. ¶
1702.1 General. The potable water supply connected to a ¶
1702.1 General. The potable water supply connected to a groundwater system shall be protected with an approved « « « « « « « « «« ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS
1703.3 Fittings. For water-based systems, fittings for ¶
1703.3 Fittings. For water-based systems, fittings for ground source heat pump systems shall be approved for installation with the piping materials to be installed, and shall comply with the standards listed in Table 1703.3. Fittings for use in DX systems shall comply with Section 1715.3. TABLE 1703.3 GROUND SOURCE LOOP PIPE FITTINGS MATERIALSTANDARD ------ <br <br <br <br <br <brCross-linked Polyethylene<br(PEX)ASTM F877, ASTM F1055,<brASTM F1807, ASTM F1960,<brASTM F2080, ASTM F2159,<brASTM F2434, ASTM F3347,<brASTM F3348, CSA B137.5,<brANSI/CSA/IGSHPA C448,<brNSF/ANSI 358-3 <br <br <brHigh…
1703.4 Underground Piping and Submerged Materi- ¶
1703.4 Underground Piping and Submerged Materi- als. Underground and submerged piping for a ground-heat exchanger shall be polyethylene (PE) pipe or tubing in accordance with Section 1703.4.1 and Section 1703.4.1.1, or crosslinked polyethylene (PEX) pipe or tubing in accordance with Section 1703.4.2 and Section 1703.4.2.1. 1703.4.1 Polyethylene (PE). Polyethylene pipe or tubing shall be manufactured in accordance with the standards listed in Table 1703.2. Pipe or tubing shall have a minimum wall thickness equal to SDR-11 and shall have a minimum pressure rating of not less than 160 psi (1103…
1703.0 Design of Systems. ¶
1703.1 Ground-Heat Exchanger Design. ¶
1703.1 Ground-Heat Exchanger Design. The groundheat exchanger design shall be provided by a licensed professional or a designer with the appropriate certifications or credentials as defined by the Authority Having Jurisdiction.
1703.2 Piping and Tubing Materials Standards. For ¶
1703.2 Piping and Tubing Materials Standards. For water-based systems, ground source heat pump ground-loop pipe and tubing shall comply with the standards listed in Table 1703.2. Piping and tubing used for DX systems shall be of copper in accordance with Section 1715.3. TABLE 1703.2 PLASTIC GROUND SOURCE LOOP PIPING MATERIALSTANDARD ------ <br <br<brCross-linked Polyethylene (PEX)ASTM F876, CSA B137.5,<brANSI/CSA/IGSHPA C448,<brNSF/ANSI 358-3 <br <br <br <brHigh Density Polyethylene <br(HDPE)ASTM D2737, ASTM D3035, <brASTM F714, AWWA C901, <brCSA B137.1,<brANSI/CSA/IGSHPA C448,<brNSF/ANSI…
1703.5 Indoor Piping. ¶
1703.5 Indoor Piping. Indoor piping, fittings, and accessories that are part of the groundwater system shall be in accordance with Chapter 12. Such materials shall be rated for the operating temperature and pressures of the system and shall be compatible with the type of transfer medium.
1704.0 Heat Pumps. ¶
1704.1 Heat Pump Distribution System. The heat pump ¶
1704.1 Heat Pump Distribution System. The heat pump distribution system shall be designed as follows: (1) Individual heat pumps shall have the capacity to handle the peak load for each zone at its peak hour. (2) Distribution piping and fittings shall be insulated to prevent condensation inside the building. (3) An isolation valve shall be installed on both supply and return of each unit. (4) Condensate drains on heat pumps shall be installed in accordance with the manufacturer’s installation instruc tions. (5) Air filters shall be installed for heat pump units. (6) Drain valves shall be…
1704.2 Circulating Pumps. The circulating pump shall be ¶
1704.2 Circulating Pumps. The circulating pump shall be sized for the operating conditions and the heat transfer fluid properties.
1705.0 Valves. ¶
1705.1 Where Required. Shutoff valves shall be installed ¶
1705.1 Where Required. Shutoff valves shall be installed in ground source-loop piping systems in the locations indicated in Section 1705.2 through Section 1705.8.
1705.2 Heat Exchangers. Shutoff valves shall be installed ¶
1705.2 Heat Exchangers. Shutoff valves shall be installed on the supply and return side of a heat exchanger. Exception: Where the heat exchanger is integral with a boiler or is a component of a manufacturer’s boiler and heat exchanger packaged unit, and is capable of being isolated from the hydronic system by the supply and return valves.
1705.3 Central Systems. Shutoff valves shall be installed ¶
1705.3 Central Systems. Shutoff valves shall be installed on the building supply and return of a central utility system.
1705.4 Pressure Vessels. Shutoff valves shall be installed ¶
1705.4 Pressure Vessels. Shutoff valves shall be installed on the connection to a pressure vessel.
1705.5 Pressure-Reducing Valves. Shutoff valves shall ¶
1705.5 Pressure-Reducing Valves. Shutoff valves shall be installed on both sides of a pressure-reducing valve.
1705.6 Equipment and Appliances. Shutoff valves shall ¶
1705.6 Equipment and Appliances. Shutoff valves shall be installed on connections to mechanical equipment and appliances. This requirement does not apply to components of a ground source loop system such as pumps, air separators, metering devices, and similar equipment.
1705.7 Expansion Tanks. Shutoff valves shall be installed ¶
1705.7 Expansion Tanks. Shutoff valves shall be installed at connections to nondiaphragm-type expansion tanks. « «« « « « « « « ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS » »» » » » »» »
1705.8 Reduced Pressure. A pressure relief valve shall ¶
1705.8 Reduced Pressure. A pressure relief valve shall be installed on the low-pressure side of a hydronic piping system that has been reduced in pressure. The relief valve shall be set at the maximum pressure of the system design.
1706.0 Specific System Components Design. ¶
1706.0 Specific System Components Design.
1706.1 General. Heat pumps shall be in compliance with ¶
1706.1 General. Heat pumps shall be in compliance with Table 1706.1, as applicable. Heat pumps shall also be listed and labeled in accordance with UL 1995 or UL 60335-2-40. Ground coupled and water source heat pumps shall be listed in accordance with AHRI/ASHRAE/ISO 13256-1 for water-to air heat pumps and AHRI/ASHRAE/ISO 13256-2 for water-towater heat pumps. DX heat pumps shall be listed in accordance with ASHRAE 194. All heat pump equipment used in DX systems shall comply with AHRI 870. Heat pumps shall be fitted with a means to indicate that the compressor is locked out. TABLE 1706.1 HEAT…
1706.2 Heat Exchangers. Heat exchangers used for heat ¶
1706.2 Heat Exchangers. Heat exchangers used for heat transfer or heat recovery shall protect the potable water system from being contaminated by the heat transfer medium. Singlewall heat exchangers shall comply with Section 1218.1. Double-wall heat exchangers shall separate the potable water from the heat transfer medium by providing a space between the two walls that are vented to the atmosphere.
1706.3 Heat-Transfer Medium. The heat-transfer medium ¶
1706.3 Heat-Transfer Medium. The heat-transfer medium shall be compatible with components with which it comes into contact. Where antifreeze or corrosion inhibitors are used, such solutions shall be approved by the Authority Having Jurisdiction. The heat-transfer fluid flash point shall be not less than 50°F (27.8°C) above the maximum system operating temperature. For DX systems, the heat transfer medium shall be a refrigerant listed in ASHRAE 34 or this code.
1706.4 Insulation. The temperature of surfaces within ¶
1706.4 Insulation. The temperature of surfaces within reach of building occupants shall not exceed 140°F (60°C) unless they are protected by insulation. Where sleeves are installed, the sleeve insulation shall retain its full size over the length of the material being protected.
1707.0 Installation Practices. ¶
1707.1 Prior to Construction. Documents for permits ¶
1707.1 Prior to Construction. Documents for permits shall be submitted prior to the construction of a building system, or water well. Permits shall be issued by the Authority Having Jurisdiction.
1707.2 Equipment, Accessories, Components, and ¶
1707.2 Equipment, Accessories, Components, and Materials. The mechanical equipment, accessories, components, and materials used shall be of the type and rating approved for the specific use. « « « « «
1707.3 Construction Documents. ¶
1707.3 Construction Documents. The construction documents for the building system portion of the geothermal energy system shall be submitted to the Authority Having Jurisdiction.
1707.4 Site Survey Requirements. The site survey shall ¶
1707.4 Site Survey Requirements. The site survey shall identify the physical limitations of the land area, including its extent, structures, existing wells of all types, proximity of other existing ground source heat pump systems, pavements, trees, grading, ponds, waterways, easements, overhead and underground services, septic systems, any identified septic repair areas, utility of rights-of-way, and any other elements that could affect an open-loop configuration. Permission shall be obtained from any adjoining property owner(s), as evidenced by the registration and approval of a formal…
1707.5 Subsurface Investigation. ¶
1707.5 Subsurface Investigation. A subsurface investigation shall be performed in accordance with Section 1707.6 as determined by the registered design professional conducting the site survey.
1707.6 Subsurface Conditions. The water well logs and ¶
1707.6 Subsurface Conditions. The water well logs and other geological records shall be used to anticipate the subsurface conditions of the aquifer and its potential supply of fresh water, multiple aquifers, saltwater intrusions, contaminated soils and groundwater, hazardous gases, and any interference with neighboring water wells and ground source heat exchangers. Geological issues such as permafrost conditions and building stability shall be considered when reviewing available records.
1707.7 Ground-Heat Exchanger Installation Prac- ¶
1707.7 Ground-Heat Exchanger Installation Prac- tices. A ground-heat exchanger system shall be installed as follows: (1) Outside piping or tubing located within 5 feet (1524 mm) of any wall or structure shall be continuously insulated with insulation that has a minimum R-5 value. Such pipe or tubing installed under the slab or basement floors shall be insulated within 5 feet (1524 mm) from the structure to the exterior point of exit from the slab. (2) Freeze protection shall be provided where the design of the ground-heat exchanger system would permit the heattransfer medium to freeze. (3)…
1707.13 Steel Nail Plates. Steel nail plates shall be ¶
1707.13 Steel Nail Plates. Steel nail plates shall be installed for plastic and copper piping penetrating framing members to within 1 inch (25.4 mm) of the exposed framing in accordance with Section 316.6.
1707.14 Exterior Piping Protection. Exterior piping shall ¶
1707.14 Exterior Piping Protection. Exterior piping shall be fitted with end caps and protected from freezing, UV radiation, corrosion, and degradation.
1707.15 Heat Pump and Distribution System Instal- ¶
1707.15 Heat Pump and Distribution System Instal- lation. The heat pump and distribution system shall be installed in accordance with the system’s design, with this code, and the manufacturer’s installation instructions.
1707.16 Pressurizing During Installation. Ground ¶
1707.16 Pressurizing During Installation. Ground source heat pump ground loop piping to be embedded in concrete shall be pressure tested prior to pouring concrete. During pouring, the pipe shall be maintained at the proposed operating pressure.
1707.17 Horizontal Geothermal Piping - Materials ¶
1707.17 Horizontal Geothermal Piping - Materials and Methods. Horizontal geothermal piping shall be in accordance with Section 1707.17.1 through Section 1707.18.8. 1707.17.1 Piping Material. Piping materials and joining methods for horizontal piping from the ground-heat exchanger shall be in accordance with Section 1703.2, Section 1703.3, Section 1703.4, Section 1703.5 and Section 1715.3. 1707.17.2 Dissimilar Materials. Transition fittings between dissimilar materials shall be inside or accessible. 1707.17.3 Protection of Piping. Pipes passing through walls shall be sleeved and sealed in…
1707.18 Trenches, Excavation, and Backfill. Excavation ¶
1707.18 Trenches, Excavation, and Backfill. Excavation for horizontal piping shall comply with Section 1707.18.1 through Section 1707.18.8, Section 1707.8 through Section 1707.11, and in accordance with the requirements of the Authority Having Jurisdiction. Prior to any excavation, trenching, or drilling, all buried utilities including drainage, and irrigation systems shall be located and flagged by the appropriate utility and ground source heat pump system contractor representative. 1707.18.1 Trenches. Trenches for underground piping or tubing shall be excavated in accordance with the…
1707.8 Trenching, Excavation, and Backfill. Prior to ¶
1707.8 Trenching, Excavation, and Backfill. Prior to excavation, trenching, or drilling, buried utilities, drainage, water, and irrigation systems shall be located. Prior to excavation, trenching, or drilling, the contractor, and owner shall agree in writing to site restoration requirements and submit to the Authority Having Jurisdiction for approval. Prior to any excavation, trenching, or drilling, all buried utilities including drainage and irrigation systems shall be located and flagged by the appropriate utility and ground source heat pump system contractor representative.
1707.9 Trenches, Tunneling, and Driving. Trenches shall ¶
1707.9 Trenches, Tunneling, and Driving. Trenches shall comply with Section 317.1. Tunneling and driving shall comply with Section 317.2.
1707.10 Excavations and Open Trenches. Excavations ¶
1707.10 Excavations and Open Trenches. Excavations required to be made for the installation of piping or tubing shall be in accordance with Section 317.3. Piping or tubing shall be supported to maintain its alignment and prevent sagging. Piping in the ground shall be laid on a firm bed for its entire length; where other support is otherwise provided, it shall be approved in accordance with Section 302.0. Piping or tubing shall be backfilled after an inspection in accordance with Section 317.4.
1707.11 Protection of Piping, Materials, and Struc- ¶
1707.11 Protection of Piping, Materials, and Struc- tures. Piping and tubing passing under or through walls shall be protected from breakage in accordance with Section 316.1. Piping and tubing shall be installed in accordance with Section 316.2 to provide for expansion, contraction, and structural settlement. An electrically continuous corrosion-resistant tracer wire (not less than AWG 14) or tape shall be buried with the plastic pipe to facilitate locating. One end shall be brought aboveground at a building wall or riser.
1707.12 Sleeves. In exterior walls, annular space between ¶
1707.12 Sleeves. In exterior walls, annular space between sleeves and pipes shall be sealed and made watertight and shall not be subject to a load from building construction in accordance with Section 316.7 through Section 316.7.2. ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS » » » » »» 1707.18.5 Insulation. Insulation shall be provided on the piping where there is close proximity of all site services to prevent thermal interference between fluid-based onsite service…
1708.0 System Start-Up. ¶
1708.1 General. The following requirements shall be verified prior to system start-up: ¶
1708.1 General. The following requirements shall be verified prior to system start-up: (1) Piping shall be cleaned, flushed, and purged. (2) The ground-heat exchanger and building piping shall be cleaned, flushed, and, where required, shall be filled with the heat transfer fluid medium. The ground loop system shall be tested at the design flow rate(s) and differential pressure(s) recorded. Where the actual pressure change at design flow is more than +/- 10 percent of the design flow pressure drop, the cause shall be identified and corrective action taken. (3) A method for the removal of air…
1708.2 Operation and Maintenance Manual. ¶
1708.2 Operation and Maintenance Manual. An operation and maintenance manual for the geothermal system shall be provided to the owner. The manual shall include information on required testing and maintenance of the system. Training shall be provided on the system’s operation, maintenance requirements, and on the content of the operation and maintenance manual. The operation and maintenance manual shall contain a layout of the ground-heat exchanger and building loop.
1708.3 Labeling and Marking. Ground source heat pump ¶
1708.3 Labeling and Marking. Ground source heat pump ground-loop system piping shall be marked with tape, metal tags, or other methods where it enters a building. The marking shall indicate the following words: “GROUND SOURCE HEAT PUMP-LOOP SYSTEM.” The marking shall indicate antifreeze used in the system by name and concentration.
1708.4 Documentation. ¶
1708.4 Documentation. The ground source heat pump system as-built installation drawings and instructions shall be provided to the building owner or designated agent.
1708.5 Maintenance. The periodic maintenance required, ¶
1708.5 Maintenance. The periodic maintenance required, in accordance with the design requirements, shall be provided and be made available to the owner or designated agent.
1708.6 Records. ¶
1708.6 Records. The ground source heat pump system construction documents shall be provided to the owner.
1708.7 System Start-Up. ¶
1708.7 System Start-Up. System start-up shall be in accordance with ANSI/ CSA/IGSHPA C448 and Section 1708.0.
1708.8 Contaminants. Particulate contaminants shall be ¶
1708.8 Contaminants. Particulate contaminants shall be removed from the indoor piping system prior to initial start up.
1709.0 Decommissioning and Abandonment. ¶
1709.0 Decommissioning and Abandonment.
1709.1 General. Decommissioning of geothermal systems ¶
1709.1 General. Decommissioning of geothermal systems shall comply with ANSI/ CSA/IGSHPA C448. Prior to the abandonment or decommissioning of geothermal systems, the owner shall obtain the necessary permits from the Authority Having Jurisdiction. Part II – Closed-Loop Systems.
1710.0 General. ¶
1710.1 Applicability. Part II of this chapter shall apply to ¶
1710.1 Applicability. Part II of this chapter shall apply to geothermal closed-loop systems such as, but not limited to, building systems coupled with a closed-loop system using water-based fluid as a heat transfer medium.
1710.2 Piping and Tubing. ¶
1710.2 Piping and Tubing. Piping and tubing for closedloop systems shall be in accordance Section 1703.2 and Table 1703.2.
1710.3 Borehole Piping and Tubing. Borehole piping or ¶
1710.3 Borehole Piping and Tubing. Borehole piping or tubing for vertical and horizontally drilled closed-loop systems shall have a minimum wall thickness equal to SDR-11 and shall have a minimum pressure rating of not less than 160 psi (1103 kPa) at 73°F (23°C).
1710.4 Underground Fittings. Underground fittings for ¶
1710.4 Underground Fittings. Underground fittings for closed-loop systems shall be in accordance with Section 1703.3 and Table 1703.3. 352 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS » » » » » »
1710.5 Verification. For closed-loop systems, the system ¶
1710.5 Verification. For closed-loop systems, the system shall be flushed of debris and purged of air after completion of the entire ground-heat exchanger. Flow rates and pressure drops shall be compared to calculated values to assure no blockage or kinking of the pipe. A report shall be submitted to the owner to confirm that the loop flow is in accordance with the construction documents.
1710.6 Vertical Bores. Vertical bores shall be drilled to a ¶
1710.6 Vertical Bores. Vertical bores shall be drilled to a depth to provide complete insertion of the u-bend pipe to its specified depth. The borehole diameter shall be sized for the installation and placement of the heat exchange u-bend and the tremie used to place the grouting material. ANSI/ CSA/IGSHPA C448 shall be used for vertical loop depth and borehole diameter sizing guidance. The u-bend joint and pipe shall be visually inspected for integrity in accordance with the manufacturer’s installation instructions. The u-bend joint and pipe shall be pressurized to not less than 100 psi (689…
1711.0 Ground-Heat Exchanger Testing. ¶
1711.0 Ground-Heat Exchanger Testing.
1711.1 Testing. Pressure-testing of the ground-heat ¶
1711.1 Testing. Pressure-testing of the ground-heat exchanger shall be performed in accordance with the testing method in Section 1710.6.
1711.2 Individual Loop Pressure Testing. Individual ¶
1711.2 Individual Loop Pressure Testing. Individual loop testing shall be performed as required by the Authority Having Jurisdiction.
1711.3 Field Pressure Testing – Final. The ground-heat ¶
1711.3 Field Pressure Testing – Final. The ground-heat exchanger and building piping shall be cleaned, flushed, and, where required, shall be filled with the heat transfer fluid medium. The ground loop system shall be tested at the design flow rate(s) and differential pressure(s) recorded. Where the actual pressure change at design flow is more than +/- 10 percent of the design flow pressure drop, the cause shall be identified, and corrective action taken.
1711.4 Field Flow Testing – Final. Final field flow testing ¶
1711.4 Field Flow Testing – Final. Final field flow testing shall be performed as required by the Authority Having Jurisdiction. Part III – Open-Loop Systems.
1712.0 General. ¶
1712.1 Applicability. Part III of this chapter shall apply to ¶
1712.1 Applicability. Part III of this chapter shall apply to geothermal open-loop systems such as, but not limited to, building systems coupled with a groundwater (well) or surface water open-loop system using water-based fluid as a heat transfer medium. The regulations of this chapter shall govern the construction, location and installation of geothermal energy systems. Indoor piping, fittings, and accessories that are part of the groundwater system shall be in accordance with Section 1703.5 and Chapter 12. Components installed in a geothermal open-loop system shall be constructed of…
1712.2 Test Wells. ¶
1712.2 Test Wells. Test wells drilled to investigate subsurface conditions shall provide details of the groundwater location, chemical and physical characteristics, rock strata, and temperature profiles. The number of test wells shall be determined in accordance with the Authority Having Jurisdiction. Each test well shall be tested for flow rate for a period of not less than 24 hours. Water samples shall be collected in accor « « «« « « « «« « ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GEOTHERMAL ENERGY SYSTEMS AND…
1712.3 Installation of Water Wells. Water supply, ¶
1712.3 Installation of Water Wells. Water supply, recharge wells, and pumping equipment shall be hydraulically tested, sealed, and grouted in accordance with approved well construction practices and submitted to the Authority Having Jurisdiction for approval. Wells shall be tested for water production and recovery, water quality before final system design. Wells shall be disinfected upon completion in accordance with NGWA-01 or in accordance with the Authority Having Jurisdiction. A copy of the water quality test results and the log of well construction in accordance with NGWA-01 shall be…
1712.4 Setbacks. Open-loop ground-heat exchangers shall ¶
1712.4 Setbacks. Open-loop ground-heat exchangers shall maintain the following minimum setbacks or at distances specified by the Authority Having Jurisdiction: (1) Ten feet (3048 mm) horizontally from a pressure-tested sewer lateral into a building. (2) Twenty feet (6096 mm) horizontally from a non-pressure tested sewer lateral into a building. (3) Three feet (914 mm) horizontally from buried utilities such as electrical, gas, or water. (4) Fifty feet (15 240 mm) from a water well. (5) Fifty feet (15 240 mm) from a septic tank and 100 feet (30 480 mm) from a subsurface sewage leaching field.…
1713.0 Open Ground Water Systems. ¶
1713.1 General. The installation and use of water wells ¶
1713.1 General. The installation and use of water wells shall be in accordance with the Authority Having Jurisdiction. The water well records shall include well logs, pumping tests, and aquifer information.
1713.2 Open-Loop Water Well Drilling Logs. The water ¶
1713.2 Open-Loop Water Well Drilling Logs. The water well drilling logs shall include the following: (1) The subsurface stratigraphy. (2) The aquifer type and conditions such as, but not limited to, confined, unconfined, flowing and depth. (3) The drilling method used and the penetration speed. (4) The presence of substances known to have a potential risk to health and safety shall be documented in the drill logs and the property owner shall be advised of the potential risk to health and safety.
1713.3 Design Considerations. A groundwater heat ¶
1713.3 Design Considerations. A groundwater heat pump system shall be designed by a registered design professional. Due design consideration shall be given to the following: (1) Where multiple heat pumps or fan coils are connected to a common water loop, a diversified building design load shall be used to design a ground water heat pump. (2) The water supply well(s) and injection wells, or water discharge system, shall be capable of being operated at sustainable pumping rates that exceed the maximum daily requirements without causing an adverse impact to existing or future offsite uses of…
1713.4 Water Wells and Injection Wells. Water wells ¶
1713.4 Water Wells and Injection Wells. Water wells and injection wells for groundwater heat pump systems shall be installed and tested by a registered design professional who is qualified to drill wells that comply with the requirements of the Authority Having Jurisdiction. Water supply wells and injection wells shall be developed in accordance with NGWA-01.
1713.5 Testing and Sampling. Pumping tests and water ¶
1713.5 Testing and Sampling. Pumping tests and water sampling shall be done as required by the registered design professional.
1713.6 Disinfection. Water wells shall be disinfected upon ¶
1713.6 Disinfection. Water wells shall be disinfected upon completion in accordance with the requirements of the Authority Having Jurisdiction and NGWA-01.
1714.0 Testing and Verification. ¶
1714.1 Pumping Test. Water supply wells and injection ¶
1714.1 Pumping Test. Water supply wells and injection wells shall undergo a stop and start pumping test to demonstrate the sand-free yield.
1714.2 Retesting. Where sediment is present, the problem ¶
1714.2 Retesting. Where sediment is present, the problem shall be corrected and the test shall be repeated until acceptable results are obtained. « « « «« « 354 2025 CALIFORNIA MECHANICAL CODE ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties. GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS » » » » » »» » » »
1714.3 Variable Rate Pump Test. ¶
1714.3 Variable Rate Pump Test. The operating conditions of the water supply wells and injection wells shall be evaluated and verified with a variable rate pumping.
1714.4 Constant Rate Pump Test. The sustainable well ¶
1714.4 Constant Rate Pump Test. The sustainable well yield, aquifer coefficients, and zones of influences on the groundwater flow requirements shall be confirmed with a constant rate-pumping test. The constant rate-pumping test shall be done on the water supply and injection wells at rates and durations as specified by the registered design professional.
1714.5 Water Level Monitoring. Water levels shall be ¶
1714.5 Water Level Monitoring. Water levels shall be monitored in the pumping well and observation wells during pumping and recovery periods. The monitoring time intervals shall be as specified by the registered design professional.
1714.6 Injection Wells. Injection testing shall be performed ¶
1714.6 Injection Wells. Injection testing shall be performed on water wells that are designated to be used as injection wells at rates specified by the registered design professional. The results of the drilling and pumping tests shall be provided to the owner or the owner’s representative and provided in accordance with requirements of the Authority Having Jurisdiction.
1714.7 Re-Injected Water. The water quality of re-injected ¶
1714.7 Re-Injected Water. The water quality of re-injected water into the earth shall comply with the requirements of the Authority Having Jurisdiction. Part IV – Direct Exchange (DX) Systems.
1715.0 Direct Exchange (DX) Systems. ¶
1715.0 Direct Exchange (DX) Systems.
1715.1 General. The installation and use of Direct ¶
1715.1 General. The installation and use of Direct Exchange (DX) wells shall be in accordance with the Authority Having Jurisdiction. The DX well records shall include well logs, pressure tests, and aquifer information.
1715.2 Applicability. Part IV of this chapter shall apply to ¶
1715.2 Applicability. Part IV of this chapter shall apply to geothermal energy systems such as, but not limited to, building systems coupled with a DX closed-loop using refrigerant as a heat transfer medium. The regulations of this Chapter shall govern the construction, location and installation of geothermal energy systems. Indoor piping, fittings, and accessories that are part of the ground source system shall be in accordance with Section 1703.5 and Chapter 12.
1715.3 DX Systems. Copper pipe and tubing installed for ¶
1715.3 DX Systems. Copper pipe and tubing installed for DX systems shall be manufactured in accordance with ASTM B280 and copper fittings in accordance with ASME B16.22. Joints shall be purged with an inert gas and brazed with a brazing alloy having 15 percent silver content in accordance with AWS A5.8. Underground piping and tubing shall have a cathodic protection system installed.
1715.4 DX System Testing. ¶
1715.4 DX System Testing. For direct exchange (DX) systems, each refrigerant u-bend shall be tested and proved tight with an inert gas at not less than 315 psi (2172 kPa) and maintained for 15 minutes without pressure drop. The pressure reading after tremie grouting of the boreholes shall be maintained in the ground-heat exchanger for not less than 2 hours, in accordance with ANSI/ CSA/IGSHPA C448.
1715.5 Indoor Piping. For DX systems, joints shall be ¶
1715.5 Indoor Piping. For DX systems, joints shall be purged with an inert gas and brazed with a brazing alloy having 15 percent silver content in accordance with AWS A5.8.
1715.6 On Site Storage. For DX systems, copper piping ¶
1715.6 On Site Storage. For DX systems, copper piping and fittings shall be stored to prevent physical damage, contamination, and each pipe or tubing shall be pressurized with an inert gas and sealed with a cap.
1715.7 System Start-Up. DX system start-up shall be in ¶
1715.7 System Start-Up. DX system start-up shall be in accordance with Section 1708.1 and the following: (1) DX systems shall be pressurized using nitrogen for not less than 1 hour. There shall be no allowable variance to the test pressure after being corrected for ambient temperature changes during the test. The test pressure shall not exceed 150 psig (1034 kPa) when pressure testing the compressor unit and indoor system components. (2) DX systems shall have permanent type labels installed and affixed on the compressor unit with the refrigerant type and quantity. (3) For DX systems,…
1715.8 DX Piping. ¶
1715.8 DX Piping. DX Piping should be installed in accordance with approved plans and specifications, including provisions for cathodic protection. Part V – Geothermal Ambient Temperature Loops (ATL).
1716.0 Ambient Temperature Loop (ATL) Distributed ¶
1716.0 Ambient Temperature Loop (ATL) Distributed Energy Systems.
1716.1 General. ¶
1716.1 General. An Ambient Temperature Loop (ATL) distributed energy system shall be installed in accordance with Section 1716.1.1 through Section 1716.6.3 and Section 1717.0. ATL systems shall comply with Part I through Part IV of this chapter, as applicable. 1716.1.1 Fourth Generation (4G) System Config- uration. A fourth-generation system configuration shall be a district geothermal energy system distributing hot water, cold water, or both to the conditioned space or building for a specific use. Where a geothermal energy source is used, such system shall comply with Part I through Part IV…
1716.2 Permitting. Permits required for the installation and ¶
1716.2 Permitting. Permits required for the installation and application of an ATL distributed energy system shall be obtained as required by the Authority Having Jurisdiction.
1716.3 Ambient Loop Temperature Range. ¶
1716.3 Ambient Loop Temperature Range. The operating loop temperature range of an ambient temperature loop (ATL) system shall be not less than the freeze point of the circulating fluid and not more than the maximum temperature as required by the manufacturer’s installation instructions for the attached heat pump equipment in accordance with Section 1716.3.1 and Section 1716.3.2. The ATL system shall use treated water as the heat transfer medium. 1716.3.1 ATL Operating Temperature. For equipment listed to AHRI/ASHRAE/ISO 13256-1 and AHRI/ASHRAE/ISO 13256-2, the controlled temperature range of…
1716.4 Shutoff Valve. An automatic shutoff valve shall be ¶
1716.4 Shutoff Valve. An automatic shutoff valve shall be provided for each individual building or facility transferring energy to or from an ATL distribution system. The automatic shutoff valve shall automatically shutoff upon operating command. 1716.4.1 Shutoff Valve Operation. The operation of the automatic shutoff valve shall be in accordance with the system operating procedures. Where the operation of a shutoff valve was due to an emergency response, an auxiliary heating or cooling methodology shall be provided in accordance with Section 1717.1.2.
1716.5 Bypass. The ATL distributed energy system shall ¶
1716.5 Bypass. The ATL distributed energy system shall be provided with bypass path(s) to reroute the circulating fluid when necessary.
1716.6 Metering. Where meters are required by the system ¶
1716.6 Metering. Where meters are required by the system design, meter(s) shall be located as specified by the manufacturer on each consumptive or supply source and the range of the metering shall be appropriate to the thermal properties and flow rate(s) of the transport fluid. 1716.6.1 Sub-Metering System Specification. The entire energy measurement system shall be provided with a sub-metering system. The metering system shall be calibrated and shall consist of a flow meter, temperature sensors, temperature thermowells, or other required mechanical installation metering. The sub-meter…
1717.0 ATL Distributed Energy Systems Design ¶
1717.0 ATL Distributed Energy Systems Design Requirements.
1717.1 Thermal Resources. The ambient temperature loop ¶
1717.1 Thermal Resources. The ambient temperature loop shall be permitted to connect to a thermal resource(s). Such resources may be an alternative energy source and sink, such as but not limited to solar photovoltaic (PV), solar thermal, combined heat power (CHP), and phase change thermal storage. These systems shall be installed and comply with the respective system requirements. ATL distributed energy systems coupled with solar thermal systems shall comply with the Uniform, Solar, Hydronics and Geothermal Code (USHGC) or equivalent. ATL systems coupled with a solar PV system shall comply…
1717.2 District Load Profiles. The district load profile of ¶
1717.2 District Load Profiles. The district load profile of an ambient temperature loop (ATL) distributed energy system shall be identified and shall be included in the basis-of-design (BOD). 1717.2.1 System Asset Identification. System assets shall be listed and included in the system design. The system asset shall include, but not be limited to, the following: (1) Building type and quantity. (2) Natural or constructed sources and sinks such as ground water, boreholes, etc. (3) Other renewable assets. (4) Wasted heat recovery. (5) Potable and non-potable water or fluid sources. (6)…
1801.0 General. ¶
1801.1 Standards. The standards listed in Table 1801.1 are ¶
1801.1 Standards. The standards listed in Table 1801.1 are referenced in various sections of this code and shall be con sidered part of the requirements of this document. The standards are listed herein by the standard number and effective date, the title, application and the section(s) of this code that CHAPTER 18 REFERENCED STANDARDS reference the standard. The application of the referenced standard(s) shall be as specified in Section 302.1.2. The promulgating agency acronym referred to in Table 1801.1 are defined in a list found at the end of the table. TABLE 1801.1 REFERENCED STANDARDS «…