CRC · California Residential Code

Commercial/residential exhaust hoods: Type I/II, termination and makeup-air requirements

Q: What is the difference between a Type I and a Type II hood?

A Type I hood is for appliances that produce grease or smoke (e.g., fryers, grills); a Type II hood is for steam, heat, or odors where grease/smoke is not present. See § 508.1 and § 519.1 . file

Q: How much makeup air do I need for a Type II hood?

Makeup air must prevent negative pressure greater than 0.02 in. w.c. in the cooking area (see § 511.3 ). If internal makeup is used, it must be ≤ 10% of the hood exhaust; use E_NET = E_HOOD − MA_ID to compute net exhaust.

Q: Can a dishwasher exhaust terminate over a sidewalk or street?

No. Moisture‑conveying exhaust ducts (e.g., dishwasher) shall not terminate over a public way or where condensate/vapor could create a nuisance or hazard (see § 519.5 ). Also observe the Class 3 separation requirements in § 502.2.2 . file

Q: Are Type II systems allowed to share ducts with other exhaust systems?

No. Single or combined Type II exhaust systems shall be independent of all other exhaust systems per § 519.7 .

If your kitchen produces grease or smoke you need a **Type I hood**; for steam/heat/odors use a **Type II hood**. Size hoods per the code (dishwashers: **200 cfm/ft**), terminate exhaust ducts with the separation distances in **§ 502.2.2** (Type I has its own detailed rooftop rules in **§ 510.9**), and supply makeup air so room negative pressure never exceeds **0.02 in. w.c.**; internal makeup into the hood must not exceed **10%** of exhaust. filefile

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

Type II hoods are required over equipment that generates steam, heat, or products of combustion (but not grease or smoke) per § 519.1. Makeup air must be provided so the cooking area does not develop negative pressure exceeding 0.02 inch water column and compensating/internal makeup limits are specified in § 511.3. Exhaust terminations for Type II systems must meet the general termination rules for Class 3 air in § 502.2.2 (and Type I termination rules are in § 510.9).

The single most important plain-English rule: provide the correct hood type for the source (Type I for grease/smoke; Type II for steam/heat/odors), size and terminate the duct per the termination rules, and provide makeup air that keeps room negative pressure ≤ 0.02 in. w.c..

Requirements in detail

Which hood is required

Type I hood — for appliances that generate grease or smoke (deep fryers, grills, broilers, etc.). See § 508.1 for where Type I is required.
Type II hood — for equipment and dishwashers that generate steam, heat, or products of combustion where grease or smoke is not present, per § 519.1.

Construction and duct requirements

Type II hoods constructed of steel must be at least No. 24 gauge (0.024 in.); ducts serving Type II hoods must be rigid metallic and comply with Chapter 6; Type II exhaust systems must be independent of other exhaust systems (§ 519.2, § 519.4, § 519.7).

Makeup air (key performance requirements)

Makeup air must prevent negative pressures in the commercial cooking area from exceeding 0.02 inch water column (0.005 kPa) (§ 511.3).
For compensating hoods (internal-discharge makeup into the hood): internal makeup flow shall not exceed 10% of the exhaust airflow; net exhaust is determined by E_NET = E_HOOD − MA_ID (Equation 511.3) (§ 511.3).

Termination (where the duct discharges)

Type II exhaust systems: terminate per the Class 3 air termination rules in § 502.2.2; rooftop terminations shall be directed away from roof surfaces within 40 inches (1016 mm) and moisture-carrying ducts (e.g., dishwasher) must not terminate over a public way or where condensate/vapor creates a nuisance or hazard (§ 519.5).
Type I exhaust systems: termination and rooftop/clearance rules are in § 510.9 (minimum horizontal/vertical clearances, grease drainage, upblast fan clearances, etc.) — see § 510.9.1 for specific rooftop clearance numeric requirements.

Decision-relevant dimensions / values

Decision item	Value or threshold	Code Reference
When a Type II hood is required	Above equipment/dishwashers that generate steam/heat/combustion products and no grease or smoke	§ 519.1
Type II hood material (steel)	Minimum 0.024 in. (No. 24 gauge)	§ 519.2
Net airflow for dishwashing Type II hoods	Not less than 200 cfm per linear foot of hood length	§ 519.3.1
Makeup air negative-pressure limit	≤ 0.02 in. water column (0.005 kPa)	§ 511.3
Compensating/internal makeup limit	≤ 10% of exhaust airflow (internal discharge)	§ 511.3
Type II rooftop discharge distance from roof surface	40 in. (1016 mm) direction away from roof surfaces	§ 519.5
Class 3 termination minimum separations (summary)	10 ft from property line; 3 ft from exterior walls/roofs in the direction of discharge; 10 ft from openings into building; 10 ft above adjoining grade	§ 502.2.2
Type I rooftop horizontal/vertical clearances (selected)	10 ft horizontal clearance to adjacent buildings/air intakes; 5 ft clearance to combustible structures; 3 ft vertical separation above air intakes within 10 ft	§ 510.9.1(1–3)

(Use the full section text for precise measuring and additional conditions — the table summarizes common, decision-driving numbers.)

Exceptions & special cases

Dishwashing machines that are exhausted directly outdoors are excepted from the Type II hood requirement in § 519.1. Also, a dishwasher with a self‑contained UL 921 condensing system may be used where the HVAC system is engineered for the heat load and the appliance is interlocked to prevent opening mid‑cycle (§ 519.1 exceptions).
Moisture‑conveying exhaust (dishwashers) must not terminate over a public way or where condensate/vapor creates a nuisance or hazard (§ 519.5).
For combined (manifolded) systems and special installations, Chapter 5 cross-references (Type I vs Type II; listed devices; grease duct requirements) and NFPA/ASHRAE requirements may apply — check the specific cross-referenced sections (e.g., § 510.9, § 508, § 511) for additional constraints.

If a provision you expect to see is not explicitly stated in the retrieved sections, I will not invent it — consult the full chapter or your Authority Having Jurisdiction for interpretations or additional local amendments.

Common mistakes

Misclassifying the hood: installing a Type II hood where a Type I is required (and vice versa). Confirm whether grease/smoke are generated — § 508.1 / § 519.1. file
Omitting makeup air or undersizing it so negative pressure exceeds 0.02 in. w.c., which can cause back‑drafting and poor capture/containment (see § 511.3).
Using internal makeup discharge that exceeds 10% of exhaust without accounting for net exhaust (E_NET = E_HOOD − MA_ID) — leads to incorrect fan sizing/capture calculations.
Terminating ducts too close to openings, property lines, intakes, or over public ways — check § 502.2.2 and § 510.9 (Type I) and the § 519.5 Type II rooftop/40‑inch note. filefile
Failure to provide grease drainage/collection and correct upblast fan clearances for Type I terminations under § 510.9.1.

Worked example — concrete scenario

Scenario: A small commercial dishwashing bay uses a 6‑ft long hood over the dishwasher and will discharge outdoors as a Type II hood.

Hood sizing (dishwashing): minimum net airflow = 200 cfm per linear foot × 6 ft = 1,200 cfm (use § 519.3.1).
Makeup air: provide makeup so negative pressure ≤ 0.02 in. w.c. per § 511.3. If you supply makeup via an internal discharge into the hood (compensating hood), do not exceed 10% of exhaust: 10% of 1,200 cfm = 120 cfm maximum internal makeup; net exhaust E_NET = 1,200 − 120 = 1,080 cfm (Equation 511.3). If the rest of makeup comes from conditioned/transfer air, ensure total replacement equals total exhaust and the cooking area stays within the pressure limit.
Termination: design the termination to comply with § 502.2.2 (Class 3) distances and note that § 519.5 requires rooftop discharge to be directed away from roof surfaces within 40 in.; avoid terminating over a public way or where condensate/vapor creates a nuisance. Confirm local AHJ on roof‑top layout. file

Related provisions (quick list)

§ 519.1 — Where Type II hoods are required (steam/heat/combustion, no grease/smoke).
§ 519.3 / § 519.3.1 — Net airflow for Type II hoods; dishwashing minimum 200 cfm/ft.
§ 519.4 — Type II exhaust duct construction (rigid metallic / Chapter 6).
§ 519.5 — Termination notes for Type II (references § 502.2.2 and 40 in. roof direction).
§ 519.6 — Makeup air cross‑reference (see § 511.3).
§ 511.3 — Makeup air performance, limits, and Equation 511.3.
§ 510.9 — Termination of Type I hood exhaust systems (detailed rooftop clearances, grease drainage, upblast fan requirements).
§ 502.2.2 — Termination requirements for Class 3 air ducts (minimum separations).
§ 508.1 — Where Type I hoods are required (grease‑producing appliances).

Code references

Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:

CRC § 511.2.3 High relevance — show source text
511.2.3 Exhaust Fan Operation. A hood exhaust fan(s) shall continue to operate after the extinguishing system has been activated unless fan shutdown is required by a listed component of the ventilation system or by the design of the extinguishing system. The hood exhaust fan shall start upon actuation of the extinguishing system if the exhaust fan and all cooking equipment served by the fan have been shut down, unless fan shutdown is required by a listed component of the ventilation system or by the listing of the extinguishing system. The exhaust fan shall be provided with a means so that the fan is activated when any heat-producing cooking appliance under the hood is turned on. [NFPA 96:8.2.3.1 – 8.2.3.3]

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 determined in accordance with Equation 511.3.

E NET = E HOOD – MA ID (Equation 511.3)

Where:

E NET = net hood exhaust, CFM (L/s)

E HOOD = total hood exhaust, CFM (L/s)

MA ID = makeup air, internal discharge, CFM (L/s)

For SI units: 1 cubic foot per minute = 0.0283 m [3] /min, 1 cubic foot per

minute = 0.4719 L/s

511.3.1 Air Balance. Design plans for a facility with a commercial kitchen ventilation system shall include a schedule or diagram indicating the design outdoor air balance. The design outdoor air balance shall indicate the exhaust and replacement air for the facility and the net exfiltration where applicable. The total replacement airflow rate shall equal the total exhaust airflow rate and the net exfiltration.

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. The bleed-air
CRC § 519.0 High relevance — show source text
519.0 Type II Hood Exhaust System Requirements . . . . . . . . . . . . . . . . 132

519.1 Where Required . . . . . . . . . . . . . . 132

519.2 Construction of Type II Hoods . . . 132

519.3 Type II Hood Exhaust System Net Airflow . . . . . . . . . . . . . . . . . . 132

519.4 Type II Exhaust Duct Systems . . . 132

519.5 Termination of Type II Hood Exhaust System . . . . . . . . . . . . . . 132

519.6 Makeup Air . . . . . . . . . . . . . . . . . . 133

519.7 Independent Exhaust Duct System . . . . . . . . . . . . . . . . . 133

CHAPTER 6 DUCT SYSTEMS . . . . . . . . . . . . . 135

601.0 General. . . . . . . . . . . . . . . . . . . . . 137

601.1 Applicability. . . . . . . . . . . . . . . . . . 137

601.2 Sizing Requirements . . . . . . . . . . 137

602.0 Material. . . . . . . . . . . . . . . . . . . . . 137

602.1 General. . . . . . . . . . . . . . . . . . . . . 137

602.2 Combustibles Within Ducts or

Plenums . . . . . . . . . . . . . . . . . . . . 137

2025 CALIFORNIA MECHANICAL CODE

602.3 Tall Wood (Mass Timber) Buildings . . . . . . . . . . . . . . . . . . . . 137

602.4 Metallic . . . . . . . . . . . . . . . . . . . . . 138

602.5 Nonmetallic Ducts. . . . . . . . . . . . . 138

602.6 Vibration Isolators. . . . . . . . . . . . . 138

602.7 Corridors. . . . . . . . . . . . . . . . . . . . 138

603.0 Installation of Ducts . . . . . . . . . . . 138

603.1 General. . . . . . . . . . . . . . . . . . . . . 138

603.2 Under-Floor or Crawl Space. . . . . 138

603.3 Metal Ducts. . . . . . . . . . . . . . . . . . 138

603.4 Flexible Air Ducts . . . . . . . . . . . . . 138

603.5 Plastic Ducts. . . . . . . . . . . . . . . . . 139

603.6 Protection of Ducts . . . . . . . . . . . . 139

603.7 Support of Ducts. . . . . . . . . . . . . . 139

603.8 Protection Against Flood Damage . 139

603.9 Joints and Seams of Ducts. . . . . . 139

Table 603.9.1 Closure Markings . . . . . . . . . . . . . 140
CRC § 8.1.3.2 High relevance — show source text
CONNECTION–SEALANT METHOD

[NFPA 96: FIGURE 8.1.3.2(c)]

FIGURE 511.1.2(4) TYPICAL SECTION OF DUCT-TO-FAN CONNECTION-DIRECT

TO FAN INLET CONE METHOD

[NFPA 96: FIGURE 8.1.3.2(d)]

2025 CALIFORNIA MECHANICAL CODE 121

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

EXHAUST SYSTEMS

511.2.2.1 Performance Test. A performance test shall be conducted upon completion and before final approval of the installation of a ventilation system serving commercial cooking appliances. The test shall verify the rate of exhaust airflow in accordance with Section 508.5.1.2 through Section 508.5.1.5. The permit holder shall furnish the necessary test equipment and devices required to perform the tests.

[ASHRAE 154:4.7.1]

511.2.2.2 Capture and Containment Test. The permit holder shall verify the capture and containment performance of Type I hoods. A field test shall be conducted with all appliances under the hood at operating temperatures, all the hoods operating at design airflows, and with all sources of replacement air operating at design airflows for the restaurant. Capture and containment shall be verified visually by observing smoke or steam produced by actual cooking operation or by simulating cooking using devices such as smoke candles or smoke puffers. Smoke bombs shall not be used. [ASHRAE 154:4.7.2]

511.2.3 Exhaust Fan Operation. A hood exhaust fan(s) shall continue to operate after the extinguishing system has been activated unless fan shutdown is required by a listed component of the ventilation system or by the design of the extinguishing system. The hood exhaust fan shall start upon actuation of the extinguishing system if the exhaust fan and all cooking equipment served by the fan have been shut down, unless fan shutdown is required by a listed component of the ventilation system or by the listing of the extinguishing system. The exhaust fan shall be provided with a means so that the fan is activated when any heat-producing cooking appliance under the hood is turned on. [NFPA 96:8.2.3.1 – 8.2.3.3]

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 determined in accordance with Equation 511.3.

E NET = E HOOD – MA ID (Equation 511.3)

Where:

E NET = net hood exhaust, CFM (L/s)

E HOOD = total hood exhaust, CFM (L/s)
CRC § 516.4 High relevance — show source text
516.4 Location and Application Restrictions. . . . . . . . . . . . . . . . . . 129

516.5 Additional Fire Safety Requirements . . . . . . . . . . . . . . . . 129

516.6 Use and Maintenance. . . . . . . . . . 129

517.0 Solid-Fuel Cooking Operations. . . 129

517.1 Venting Application. . . . . . . . . . . . 129

517.2 Location of Appliances . . . . . . . . . 130

517.3 Hoods for Solid-Fuel Cooking. . . . 130

517.4 Exhaust Systems for Solid-Fuel Cooking . . . . . . . . . . . . 130

517.5 Grease Removal Devices

for Solid-Fuel Cooking . . . . . . . . . 130

517.6 Air Movement for Solid-Fuel

Cooking . . . . . . . . . . . . . . . . . . . . 130

517.7 Fire-Extinguishing Equipment for Solid-Fuel Cooking . . . . . . . . . 131

517.8 Other Safety Requirements . . . . . 131

518.0 Downdraft Appliances. . . . . . . . . . 131

518.1 General. . . . . . . . . . . . . . . . . . . . . 131

518.2 Ventilation System . . . . . . . . . . . . 132

518.3 Fire-Extinguishing Equipment. . . . 132

518.4 Airflow Switch or Transducer . . . . 132

518.5 Surface Materials . . . . . . . . . . . . . 132

519.0 Type II Hood Exhaust System Requirements . . . . . . . . . . . . . . . . 132

519.1 Where Required . . . . . . . . . . . . . . 132

519.2 Construction of Type II Hoods . . . 132

519.3 Type II Hood Exhaust System Net Airflow . . . . . . . . . . . . . . . . . . 132

519.4 Type II Exhaust Duct Systems . . . 132

519.5 Termination of Type II Hood Exhaust System . . . . . . . . . . . . . . 132

519.6 Makeup Air . . . . . . . . . . . . . . . . . . 133

519.7 Independent Exhaust Duct System . . . . . . . . . . . . . . . . . 133

CHAPTER 6 DUCT SYSTEMS . . . . . . . . . . . . . 135

601.0 General. . . . . . . . . . . . . . . . . . . . . 137

601.1 Applicability. . . . . . . . . . . . . . . . . . 137

601.2 Sizing Requirements . . . . . . . . . . 137

602.0 Material. . . . . . . . . . . . . . . . . . . . . 137

602.1 General. . . . . . . . . . . . . . . . . . . . . 137

602.2 Combustibles Within Ducts or

Plenums . . . . . . . . . . . . . . . . . . . . 137
CMC § 2025 High relevance — show source text
The building’s structural stability is protected by the regulations for cutting and notching of structural members.

Chapter 4 Ventilation Air. Chapter 4 regulates the minimum requirements for ventilation air supply, exhaust, and makeup air for occupiable spaces within a building. Building ventilation is one important factor affecting the relationship between airborne transmission of respiratory infections and the health and productivity of workers. Ventilation air may be composed of mechanical or natural ventilation, infiltration, recirculated air, transfer air, or a suitable combination of these. Providing a comfortable and healthy indoor environment for building occupants is of primary concern. When determining ventilation rates, typical and unusual significant sources of indoor pollution need to be controlled. Areas such as kitchens, bathrooms, and laundries are all built to allow specific functions. These spaces produce pollutants such as moisture, odors, volatile organic compounds, particles, or combustion byproducts. The purpose of local exhaust is to control concentrates of these pollutants in the room into which they were emitted and to reduce the spread of pollutants into other parts of the occupancy. Local exhaust ventilation is the source control for pollution that is expected in certain rooms. Using local exhaust to extract contaminants before they mix with the indoor environment is essential.

Chapter 5 Exhaust Systems. Chapter 5 regulates the minimum requirements for exhaust systems. Chapter 5 contains two parts: Part I provides exhaust requirements for environmental air ducts and product conveying systems; Part II provides exhaust requirements for commercial hoods and kitchen ventilation. Environmental air ducts include exhaust ducts used for transporting the air from domestic kitchens, bathrooms, shower rooms, locker rooms, janitor’s closets, and clothes dryers. Systems that carry nonabrasive exhaust, such as smoke, moderate abrasives such as sawdust, and high abrasives such as manganese or acid vapors use product-conveying ducts. Part II provides the minimum fire safety requirements related to the design, installation, inspection, and maintenance of grease-type operations, such as cooking, for both fuel-gas and solid fuel. Cooking produces a significant amount of smoke, fumes, vapors, heat, and other pollutants. Therefore, acceptable kitchen ventilation is necessary to prevent fires from the build-up of grease and to provide the occupants protection from smoke, unpleasant odors, pollutants, and dangerous gases. There are two types of exhaust hoods (Type I and Type II) used in commercial kitchen applications.

xiv 2025 CALIFORNIA MECHANICAL CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

FORMAT OF THE UNIFORM MECHANICAL CODE

Type I hoods are intended to be installed above equipment or appliances that generate grease or smoke. Type II hoods are intended to be installed above equipment or appliances that generate steam, vapor, heat, or odors and do not generate grease or smoke.

Chapter 6 Duct Systems. Chapter 6 regulates requirements for ducts and plenums that are portions of a heating, cooling, ventilation, or exhaust system. This chapter contains material and installation requirements for metal, gypsum, factory-made, flexible, and plastic ducts. It also contains provisions for duct insulation, dampers, fire protection, and automatic shutoff for the building’s air distribution system. It is worth noting that exhaust ducts are regulated by Chapter 5, and combustion air ducts are regulated by Chapter 7.
CRC § 140.9 High relevance — show source text
1. Kitchen ventilation.
A. Mechanically cooled or heated makeup air delivered to any space with a kitchen hood shall not exceed the greater of: i. The supply flow required to meet the space heating and cooling load; or ii. The hood exhaust flow minus the available transfer air from adjacent spaces. Available transfer air is that portion of outdoor ventilation air serving adjacent spaces not required to satisfy other exhaust needs, such as restrooms, not required to maintain pressurization of adjacent spaces, and that would otherwise be relieved from the building. Exception to Section 140.9(b)2A: Existing kitchen makeup air units not being replaced as part of an addition or alteration.

142 2025 CALIFORNIA ENERGY CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

NONRESIDENTIAL AND HOTEL/MOTEL OCCUPANCIES—PERFORMANCE AND PRESCRIPTIVE

COMPLIANCE APPROACHES FOR ACHIEVING ENERGY EFFICIENCY

B. A kitchen/dining facility having a total Type I and Type II kitchen hood exhaust airflow rate greater than 5,000 cfm shall have one of the following: i. At least 50 percent of all replacement air is transfer air that would otherwise be exhausted; or ii. Demand ventilation system(s) on at least 75 percent of the exhaust air. Such systems shall: a. Include controls necessary to modulate airflow in response to appliance operation and to maintain full capture and containment of smoke, effluent and combustion products during cooking and idle; and b. Include failsafe controls that result in full flow upon cooking sensor failure; and c. Include an adjustable timed override to allow occupants the ability to temporarily override the system to full flow; and d. Be capable of reducing exhaust and replacement air system airflow rates to the larger of: (i) 50 percent of the total design exhaust and replacement air system airflow rates; or (ii) The ventilation rate required as specified by Section 120.1(c)3. iii. Listed energy recovery devices with a sensible heat recovery effectiveness of not less than 40 percent on at least 50 percent of the total exhaust airflow; or iv. A minimum of 75 percent of makeup air volume that is:

a. Unheated or heated to no more than 60°F; and

b. Uncooled or cooled without the use of mechanical cooling.

Exception to Section 140.9(b)2B: Existing hoods not being replaced as part of an addition or alteration. 3. Kitchen exhaust system acceptance. Before an occupancy permit is granted for a commercial kitchen subject to Section 140.9(b), the following equipment and systems shall be certified as meeting the acceptance requirements for code compliance, as specified by the Reference Nonresidential Appendix NA7. A certificate of acceptance shall be submitted to the enforcement agency that certifies that the equipment and systems meet the acceptance requirements specified in NA7.11.

Exception to Section 140.9(b): Healthcare facilities.

(c) Prescriptive requirements for laboratory and factory exhaust systems.
1. Airflow reduction requirements. Building laboratory exhaust systems shall be able to reduce zone exhaust and makeup airflow rates to the occupied and unoccupied minimum exhaust airflow rates based on demand and sensed occupancy as follows:
A. Occupied minimum exhaust airflow. When occupant sensing controls sense occupants in the space, the minimum exhaust and makeup airflow rates shall be the greater of: i. User-defined airflow not to exceed 1.0 cfm/ft [2] (equivalent to 6 air changes per hour for a 10-foot high ceiling); or ii.
CRC § 509.1 High relevance — show source text
Hoods . . . . . . . . . . . . . . . . . . . . . . 114

509.1 Grease Removal Devices. . . . . . . 114

509.2 Installation . . . . . . . . . . . . . . . . . . 114

509.3 Solid-Fuel Grease Removal

Devices. . . . . . . . . . . . . . . . . . . . . 115

510.0 Exhaust Duct Systems . . . . . . . . . 115

510.1 General. . . . . . . . . . . . . . . . . . . . . 115

510.2 Clearance . . . . . . . . . . . . . . . . . . . 115

510.3 Openings . . . . . . . . . . . . . . . . . . . 115

510.4 Listed Grease Ducts . . . . . . . . . . . 116

510.5 Other Grease Ducts . . . . . . . . . . . 116

510.6 Exterior Installations . . . . . . . . . . . 117

xxxii

510.7 Interior Installations . . . . . . . . . . . 118

510.8 Underground Installations. . . . . . . 118

510.9 Termination of Type I Hood Exhaust System . . . . . . . . . . . . . . 119

510.10 Solid-Fuel Duct Systems . . . . . . . 120

511.0 Air Movement . . . . . . . . . . . . . . . . 120

511.1 Exhaust Fans for Commercial

Cooking Operations . . . . . . . . . . . 120

511.2 Airflow. . . . . . . . . . . . . . . . . . . . . . 121

511.3 Makeup Air . . . . . . . . . . . . . . . . . . 122

511.4 Common Duct (Manifold) Systems . . . . . . . . . . . . . . . . . . . . 122

511.5 Solid-Fuel Air Movement

Requirements . . . . . . . . . . . . . . . . 122

512.0 Auxiliary Equipment . . . . . . . . . . . 122

512.1 Dampers . . . . . . . . . . . . . . . . . . . . 122

512.2 Electrical Equipment. . . . . . . . . . . 122

512.3 Other Equipment . . . . . . . . . . . . . 123

512.4 Solid-Fuel Auxiliary Equipment. . . 123

513.0 Fire-Extinguishing Equipment. . . . 123

513.1 General. . . . . . . . . . . . . . . . . . . . . 123

513.2 Types of Equipment . . . . . . . . . . . 123

513.3 Simultaneous Operation . . . . . . . . 124

513.4 Fuel and Electric Power Shutoff . . 125

513.5 Manual Actuation . . . . . . . . . . . . . 125

513.6 System Annunciation . . . . . . . . . . 125

513.7 Special Design and Application . . 125

513.8 Review and Certification. . . . . . . . 125
CRC § 505.8 High relevance — show source text
505.8 Product-Conveying Duct Classifications. . . . . . . . . . . . . . . . 102

505.9 Minimum Velocities and

Circulation. . . . . . . . . . . . . . . . . . . 102

505.10 Makeup Air . . . . . . . . . . . . . . . . . . 102

505.11 Hoods and Enclosures . . . . . . . . . 103

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 . . . . . . . . . . . . . . . . . 107

506.5 Fittings . . . . . . . . . . . . . . . . . . . . . 107

506.6 Explosion Venting. . . . . . . . . . . . . 107

506.7 Supports . . . . . . . . . . . . . . . . . . . . 107

506.8 Fire Protection . . . . . . . . . . . . . . . 107

506.9 Protection from Physical Damage . . . . . . . . . . . . . . . . . . . . 107

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TABLE OF CONTENTS

506.10 Duct Clearances . . . . . . . . . . . . . . 107

Table 506.10.4 Basic Minimum Clearances to

Unprotected Surfaces. . . . . . . . . . 107

506.11 Clearance Reduction Methods . . . 108

Table 506.11 Reduction of Duct Clearance with

Specified Forms of Protection . . . 108

Part II Commercial Hoods and

Kitchen Ventilation . . . . . . . . . . . 109

507.0 General Requirements . . . . . . . . . 109

507.1 Exhaust Systems . . . . . . . . . . . . . 109

507.2 Type I Hood Exhaust System Requirements . . . . . . . . . . . . . . . . 109

507.3 Listed Devices . . . . . . . . . . . . . . . 109

507.4 Clearance . . . . . . . . . . . . . . . . . . . 109

507.5 Drawings. . . . . . . . . . . . . . . . . . . . 110
CRC § 519.1 Medium relevance — show source text
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 equipment shall be provided with an interlocking device to prevent opening of the appliance prior to completion of its cycle. 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 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 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. The exhaust system shall terminate in accordance with Section 502.2.2. Rooftop terminations shall be directed away

«

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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.

519.7 Independent Exhaust Duct System. Single or combined Type II exhaust systems shall be independent of all other exhaust systems.

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CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE

CHAPTER 6 – DUCT SYSTEMS
CMC § 2025 Medium relevance — show source text
Systems that carry nonabrasive exhaust, such as smoke, moderate abrasives such as sawdust, and high abrasives such as manganese or acid vapors use product-conveying ducts. Part II provides the minimum fire safety requirements related to the design, installation, inspection, and maintenance of grease-type operations, such as cooking, for both fuel-gas and solid fuel. Cooking produces a significant amount of smoke, fumes, vapors, heat, and other pollutants. Therefore, acceptable kitchen ventilation is necessary to prevent fires from the build-up of grease and to provide the occupants protection from smoke, unpleasant odors, pollutants, and dangerous gases. There are two types of exhaust hoods (Type I and Type II) used in commercial kitchen applications.

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FORMAT OF THE UNIFORM MECHANICAL CODE

Type I hoods are intended to be installed above equipment or appliances that generate grease or smoke. Type II hoods are intended to be installed above equipment or appliances that generate steam, vapor, heat, or odors and do not generate grease or smoke.

Chapter 6 Duct Systems. Chapter 6 regulates requirements for ducts and plenums that are portions of a heating, cooling, ventilation, or exhaust system. This chapter contains material and installation requirements for metal, gypsum, factory-made, flexible, and plastic ducts. It also contains provisions for duct insulation, dampers, fire protection, and automatic shutoff for the building’s air distribution system. It is worth noting that exhaust ducts are regulated by Chapter 5, and combustion air ducts are regulated by Chapter 7.

Chapter 7 Combustion Air. Chapter 7 regulates combustion air requirements for ventilation and dilution of flue gases for appliances installed in buildings. Fuel-gas appliances not regulated by chapter include direct vent appliances and Type I clothes dryers. Makeup air requirements for Type I clothes dryers are located in Chapter 5. Chapter 7 provides acceptable methods for supplying satisfactory combustion air to ensure proper combustion. Combustion air can be supplied by using indoor combustion air or by introducing the air from the outdoors.

Combustion is the rapid oxidation of fuel to release energy. The oxygen required to release the energy from the fuel normally comes from the air. Incomplete combustion of fuel occurs when inadequate oxygen is provided to the appliance. Combustion is needed to provide ventilation cooling for the casing and internal controls. When a lack of oxygen occurs, some of the carbon is not oxidized, and carbon monoxide forms.

Chapter 8 Chimneys and Vents. Chapter 8 regulates the installation, design, and construction of venting systems for fuel-burning appliances. The provisions addressed within this chapter follow procedures an installer would use to design or evaluate a venting system. Many requirements apply to the design and construction of venting systems, chimneys, installation of gas vents, and the sizing of venting system for a Category I appliance. Sizing venting systems require rigorous engineering calculations. However, the venting sizing requirements and sizing tables in this chapter already perform the calculations for the benefit of the end user.

Combustion appliances produce products of incomplete combustion, including potentially harmful carbon monoxide (CO). It is desirable to vent these products to the outdoors. Although the gas is clean-burning fuel, the products of combustion must not be allowed to collect within a building.
CRC § 140.9 Medium relevance — show source text
Listed energy recovery devices with a sensible heat recovery effectiveness of not less than 40 percent on at least 50 percent of the total exhaust airflow; or iv. A minimum of 75 percent of makeup air volume that is:

a. Unheated or heated to no more than 60°F; and

b. Uncooled or cooled without the use of mechanical cooling.

Exception to Section 140.9(b)2B: Existing hoods not being replaced as part of an addition or alteration. 3. Kitchen exhaust system acceptance. Before an occupancy permit is granted for a commercial kitchen subject to Section 140.9(b), the following equipment and systems shall be certified as meeting the acceptance requirements for code compliance, as specified by the Reference Nonresidential Appendix NA7. A certificate of acceptance shall be submitted to the enforcement agency that certifies that the equipment and systems meet the acceptance requirements specified in NA7.11.

Exception to Section 140.9(b): Healthcare facilities.

(c) Prescriptive requirements for laboratory and factory exhaust systems.
1. Airflow reduction requirements. Building laboratory exhaust systems shall be able to reduce zone exhaust and makeup airflow rates to the occupied and unoccupied minimum exhaust airflow rates based on demand and sensed occupancy as follows:
A. Occupied minimum exhaust airflow. When occupant sensing controls sense occupants in the space, the minimum exhaust and makeup airflow rates shall be the greater of: i. User-defined airflow not to exceed 1.0 cfm/ft [2] (equivalent to 6 air changes per hour for a 10-foot high ceiling); or ii. The regulated minimum occupied circulation rate documented to comply with code, accreditation, or facility environmental health and safety department requirements; or iii. The minimum needed to maintain occupied pressurization. B. Unoccupied minimum exhaust airflow. Within 20 minutes of no occupancy being detected by any occupant sensors covering the space, the minimum exhaust and makeup airflow rates shall be the greater of: i. User-defined airflow not to exceed 0.67 cfm/ft [2] (equivalent to 4 air changes per hours for a 10-foot high ceiling);

or

ii. The regulated minimum unoccupied circulation rate documented to comply with code, accreditation, or facility environmental health and safety department requirements; or iii. The minimum needed to maintain unoccupied pressurization. C. Applicable equipment and systems shall be certified as meeting the acceptance requirements for code compliance, as specified by the reference Nonresidential Appendix NA7.16. A certificate of acceptance shall be submitted to the enforcement agency that certifies that the equipment and systems meet the acceptance requirements specified in Nonresidential Appendix NA7.16.

Exception to Section 140.9(c)1: New zones on an existing constant volume exhaust system. 2. Exhaust System Transfer Air. Conditioned supply air delivered to any space with mechanical exhaust shall comply with the requirements of Section 140.4(o). 3. Fan System Power Consumption. All newly installed fan exhaust systems serving a laboratory or factory with a design exhaust fan system airflow rate greater than 10,000 cfm shall meet Subsection A and either B, C, or D. Exhaust air in laboratories or factories includes all indoor air and gases removed by the exhaust system, including exhaust air from fume hoods, hazardous exhaust flows, or other manifolded exhaust streams. Exhaust fan system airflow rate is the total of the airflow rates entering the exhaust fans, which includes exhaust air and bypass air but does not include entrained or induced airflow downstream of the exhaust fans.
CRC § 6.1507 Medium relevance — show source text
LIFT = Entering Condenser Water Temperature (°F) – Leaving Chilled Water Temperature (°F)
2. Condenser DT = Leaving Condenser Water Temperature (°F) – Entering Condenser Water Temperature (°F)
Kadj = 6.1507 – 0.30244(×) + 0.0062692(×)2 – 0.000045595(×)3
where× = Condenser DT + LIFT
COPadj = Kadj * COPstd|1. LIFT = Entering Condenser Water Temperature (°F) – Leaving Chilled Water Temperature (°F)
2. Condenser DT = Leaving Condenser Water Temperature (°F) – Entering Condenser Water Temperature (°F)
Kadj = 6.1507 – 0.30244(×) + 0.0062692(×)2 – 0.000045595(×)3
where× = Condenser DT + LIFT
COPadj = Kadj * COPstd|1. LIFT = Entering Condenser Water Temperature (°F) – Leaving Chilled Water Temperature (°F)
2. Condenser DT = Leaving Condenser Water Temperature (°F) – Entering Condenser Water Temperature (°F)
Kadj = 6.1507 – 0.30244(×) + 0.0062692(×)2 – 0.000045595(×)3
where× = Condenser DT + LIFT
COPadj = Kadj * COPstd|1. LIFT = Entering Condenser Water Temperature (°F) – Leaving Chilled Water Temperature (°F)
2. Condenser DT = Leaving Condenser Water Temperature (°F) – Entering Condenser Water Temperature (°F)
Kadj = 6.1507 – 0.30244(×) + 0.0062692(×)2 – 0.000045595(×)3
where× = Condenser DT + LIFT
COPadj = Kadj * COPstd|1. LIFT = Entering Condenser Water Temperature (°F) – Leaving Chilled Water Temperature (°F)
2. Condenser DT = Leaving Condenser Water Temperature (°F) – Entering Condenser Water Temperature (°F)
Kadj = 6.1507 – 0.30244(×) + 0.0062692(×)2 – 0.000045595(×)3
where× = Condenser DT + LIFT
COPadj = Kadj * COPstd|1. LIFT = Entering Condenser Water Temperature (°F) – Leaving Chilled Water Temperature (°F)
2. Condenser DT = Leaving Condenser Water Temperature (°F) – Entering Condenser Water Temperature (°F)
Kadj = 6.1507 – 0.30244(×) + 0.0062692(×)2 – 0.000045595(×)3
where× = Condenser DT + LIFT
COPadj = Kadj * COPstd|

A6.207.1.2 Controls for heat pumps with supplementary electric resistance heaters. Heat pumps with supplementary electric resistance heaters shall have controls:

A6.207.1.2.1 That prevent supplementary heater operation when the heating load can be met by the heat pump alone; and
CRC § 510.3 Medium relevance — show source text
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EXHAUST SYSTEMS

on the top portion of the grease duct in accordance with Section 510.3 and shall be labeled at the interior portion of the duct.

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 any combustible structure.

(3) A vertical separation of 3 feet (914 mm) above any air intakes within 10 feet (3048 mm) of the exhaust outlet.

(4) The ability to drain grease out of any traps or low points formed in the fan or duct near the termination of the system into a collection container that is noncombustible, closed, rainproof, and structurally sound for the service to which it is applied and that will not sustain combustion.

(5) A grease collection device that is applied to exhaust systems that does not inhibit the performance of any fan.

(6) Grease collection systems that meet the requirements of Section 510.9.1(4) and Section 510.9.1(5).

(7) A listed grease duct complying with Section 507.4.7 or ductwork complying with Section 507.4.8.

(8) A hinged upblast fan supplied with flexible weatherproof electrical cable and service hold-open retainer to permit inspection and cleaning that is listed for commercial cooking equipment with the following conditions:

(a) Where the fan attaches to the ductwork, the ductwork is a minimum of 18 inches (457 mm) away from any roof surface, as shown in Figure 510.9.1.

(b) The fan discharges a minimum of 40 inches (1016 mm) away from any roof surface, as shown in Figure 510.9.1.

(9) Other approved fan, provided it meets all of the following criteria:

(a) The fan meets the requirements of Section 510.9.1(3) and Section 511.1.3.

(b) Its discharge or its extended duct discharge meets the requirements of Section 510.9.1(2). (See Section 511.1.3)

(c) Exhaust fan discharge is directed up and away from the roof surface. {NFPA 96:7.8.2.1}

For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm

FIGURE 510.9.1

UPBLAST FAN CLEARANCES

[NFPA 96: FIGURE 7.8.2.1]

510.9.1.1 Listed Vibration Isolation Connec-
CRC § 507.6 Medium relevance — show source text
507.6 Notification of Change . . . . . . . . . 111

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 Medium-Duty Cooking Appliance

Airflow. . . . . . . . . . . . . . . . . . . . . . 113

Table 508.5.1.5 Light-Duty Cooking Appliance

Airflow. . . . . . . . . . . . . . . . . . . . . . 113

508.6 Solid-Fuel Hood Assemblies . . . . 114

508.7 Exhaust Outlets . . . . . . . . . . . . . . 114

509.0 Grease Removal Devices in

Hoods . . . . . . . . . . . . . . . . . . . . . . 114

509.1 Grease Removal Devices. . . . . . . 114

509.2 Installation . . . . . . . . . . . . . . . . . . 114

509.3 Solid-Fuel Grease Removal

Devices. . . . . . . . . . . . . . . . . . . . . 115

510.0 Exhaust Duct Systems . . . . . . . . . 115

510.1 General. . . . . . . . . . . . . . . . . . . . . 115

510.2 Clearance . . . . . . . . . . . . . . . . . . . 115

510.3 Openings . . . . . . . . . . . . . . . . . . . 115

510.4 Listed Grease Ducts . . . . . . . . . . . 116

510.5 Other Grease Ducts . . . . . . . . . . . 116

510.6 Exterior Installations . . . . . . . . . . . 117

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510.7 Interior Installations . . . . . . . . . . . 118

510.8 Underground Installations. . . . . . . 118

510.9 Termination of Type I Hood Exhaust System . . . . . . . . . . . . . . 119

510.10 Solid-Fuel Duct Systems . . . . . . . 120

511.0 Air Movement . . . . . . . . . . . . . . . . 120

511.1 Exhaust Fans for Commercial

CRC § 140.9 Medium relevance — show source text

B. For kitchen/dining facilities having total Type I and Type II kitchen hood exhaust airflow rates greater than 5,000 cfm, each Type I hood shall have an exhaust rate that complies with Table 140.9-C. If a single hood or hood section is installed over appliances with different duty ratings, then the maximum allowable flow rate for the hood or hood section shall not exceed the Table 140.9-C values for the highest appliance duty rating under the hood or hood section. Refer to ASHRAE Standard 154-2011 for definitions of hood type, appliance duty and next exhaust flow rate.

Exception 1 to Section 140.9(b)1B: 75 percent of the total Type I and Type II exhaust replacement air is transfer air that would otherwise be exhausted.

Exception 2 to Section 140.9(b)1B: Existing hoods not being replaced as part of an addition or alteration.

TABLE 140.9-C—MAXIMUM NET EXHAUST FLOW RATE, CFM PER LINEAR FOOT OF HOOD LENGTH	Col2	Col3	Col4	Col5
TYPE OF HOOD	LIGHT DUTY EQUIPMENT	MEDIUM DUTY EQUIPMENT	HEAVY DUTY EQUIPMENT	EXTRA HEAVY DUTY EQUIPMENT
Wall-mounted canopy	140	210	280	385
Single island	280	350	420	490
Double island	175	210	280	385
Eyebrow	175	175	Not allowed	Not allowed
Backshelf/passover	210	210	280	Not allowed

Kitchen ventilation.

A. Mechanically cooled or heated makeup air delivered to any space with a kitchen hood shall not exceed the greater of: i. The supply flow required to meet the space heating and cooling load; or ii. The hood exhaust flow minus the available transfer air from adjacent spaces. Available transfer air is that portion of outdoor ventilation air serving adjacent spaces not required to satisfy other exhaust needs, such as restrooms, not required to maintain pressurization of adjacent spaces, and that would otherwise be relieved from the building. Exception to Section 140.9(b)2A: Existing kitchen makeup air units not being replaced as part of an addition or alteration.

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COMPLIANCE APPROACHES FOR ACHIEVING ENERGY EFFICIENCY

B. A kitchen/dining facility having a total Type I and Type II kitchen hood exhaust airflow rate greater than 5,000 cfm shall have one of the following: i. At least 50 percent of all replacement air is transfer air that would otherwise be exhausted; or ii. Demand ventilation system(s) on at least 75 percent of the exhaust air.

CRC § 513.2.2 Medium relevance — show source text
Fire-extinguishing systems. . . . . . . . . . . . . . . . . 513.2.2

Fuel gas piping. . . . . . . . . . . . . . . . . . . . . . . . . . D 115.1

Hydronics . . . . . . . . . . . . . 1203.2, 1207.3, Table 1210.1

Oil-or liquid-fuel

burning equipment. . . . . . . . . . . . . . . . . . . . . C 103.0 Referenced. . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 18

Steam and hot water boilers . . . . . . . . . . . . . . . . 1002.0

STATIONARY

Engine generators. . . . . . . . . . . . . . . . . . . . . . . . 1602.0

Fuel Cell Power Plant . . . . . . . . . . . . . . . . 221.0, 1601.0

Gas Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . .1602.0

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INDEX

STEAM AND HOT-WATER SYSTEMS (Hospitals) . . . .319.0

SUPPORT AND HANGERS . . . . . . . . . .313.0, Table 313.3

SUSTAINABLE PRACTICES . . . . . . . . . . . . . . .Appendix E SWITCHES, ELECTRICAL SUPPLY LINE . . . . . . .903.2.7

– T –

TANKLESS WATER HEATERS . . . . . . . . . . . . . . . . .1203.3

TERMINATION

Chimneys . . . . . . . . . . . . . . . . . . . . .802.5.4, 802.5.4.2

Environmental air ducts . . . . . . . . . . . . . . . . . . .502.2.1

Exhaust duct systems,

commercial kitchen . . . . . . . . . . . . . . . . .510.9, 519.5

Exhaust

ducts, clothes dryer . . . . . . . . . . . . . . . . . . . . . .504.4 Gas vents . . . . . . . . . . . . . . . . . . . . . . . .802.6, 802.6.1,

802.7.2, 802.8, 802.8.1

Product conveying ducts . . . . . . . . . . . . . . . . . .502.2.3 Type I hood exhaust system . . . . . . . . . . . . . . . . .510.9 Type II hood exhaust system . . . . . . . . . . . . . . . . .519.5

TESTING
CRC § 503.5.11.3 Medium relevance — show source text
A + B - ( E/M ) ≥ 50% (Equation E 503.5.11.3)

Where:

A = Percentage that the exhaust and makeup airflow rates are capable of being reduced from design conditions.

B = Sensible energy recovery ratio.

E = Exhaust airflow rate through the heat recovery device at design conditions.

M = Makeup airflow rate of the system at design conditions.

(2) VAV laboratory exhaust and room supply systems that are required to have minimum circulation rates to be in accordance with the codes or

accreditation standards shall be capable of and configured to reduce zone exhaust and makeup airflow rates to the regulated minimum circulation values, or the minimum required to maintain pressurization relationship requirements. Systems serving nonregulated zones shall be capable of and configured to reduce exhaust and makeup airflow rates to 50 percent of the zone design values, or the minimum required to maintain pressurization relationship requirements.

(3) Direct makeup (auxiliary) air supply of 75 percent or more of the exhaust airflow rate, heated not more than 2°F (1°C) below room setpoint, cooled to not less than 3°F (2°C) above room setpoint, no humidification added, and no simultaneous heating and cooling are used for dehumidification control. [ASHRAE 90.1:6.5.7.3]

E 503.5.12 Radiant Heating Systems. Radiant heating systems shall be in accordance with Section E 503.5.12.1 through Section E 503.5.12.2.

E 503.5.12.1 Heating Unenclosed Spaces. Radiant heating shall be used when heating is required for unenclosed spaces.

Exception: Loading docks equipped with air curtains. [ASHRAE 90.1:6.5.8.1]

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APPENDIX E

to permit a determination of compliance by the building official and to indicate compliance with the requirements of this appendix. [ASHRAE 90.1:4.2.2.1] E 503.6.2 Supplemental Information. Supplemental information necessary to verify compliance with this appendix, such as calculations, worksheets, compliance forms, vendor literature, or other data, shall be made available where required by the Authority Having Jurisdiction. [ASHRAE 90.1:4.2.2.2]

E 503.6.3 Manuals. Operating and maintenance information shall be provided to the building owner. This information shall include, but not be limited to, the information specified in Section E 503.6.3.1, Section E 503.6.3.2, and Section E 503.6.5.2. [ASHRAE 90.1:4.2.2.3]

E 503.6.3.1 Required Information. Construction documents shall require that an operating manual and maintenance manual be provided to the building owner. The manuals shall include, at a minimum, the following:

(1) Submittal data stating equipment rating and selected options for each piece of equipment requiring maintenance.

(2) Operation manuals and maintenance manuals for each piece of equipment requiring maintenance. Required routine maintenance actions shall be clearly identified.

(3) Names and addresses of not less than one qualified service agency.
CRC § 903.2.7 Medium relevance — show source text
SUSTAINABLE PRACTICES . . . . . . . . . . . . . . .Appendix E SWITCHES, ELECTRICAL SUPPLY LINE . . . . . . .903.2.7

– T –

TANKLESS WATER HEATERS . . . . . . . . . . . . . . . . .1203.3

TERMINATION

Chimneys . . . . . . . . . . . . . . . . . . . . .802.5.4, 802.5.4.2

Environmental air ducts . . . . . . . . . . . . . . . . . . .502.2.1

Exhaust duct systems,

commercial kitchen . . . . . . . . . . . . . . . . .510.9, 519.5

Exhaust

ducts, clothes dryer . . . . . . . . . . . . . . . . . . . . . .504.4 Gas vents . . . . . . . . . . . . . . . . . . . . . . . .802.6, 802.6.1,

802.7.2, 802.8, 802.8.1

Product conveying ducts . . . . . . . . . . . . . . . . . .502.2.3 Type I hood exhaust system . . . . . . . . . . . . . . . . .510.9 Type II hood exhaust system . . . . . . . . . . . . . . . . .519.5

TESTING

Of boilers . . . . . . . . . . . . . . . . . . . . . . . . .1012.1, 1013.0

Of ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .602.2

Of exhaust systems . . . . . . . . . . . . . . . . . . . . . . . .514.0 Of fuel-gas piping . . . . . . . . . . . . . . . . . . .105.3, 1313.0

Of hood assemblies . . . . . . . . . . . . . . . . . . . . . . .508.2

Of insulating materials . . . . . . . . . . . . . .508.3.4, 602.2

Of louvers . . . . . . . . . . . . . . . . . . . . . . .315.1.1, 315.1.2

Of recirculating systems . . . . . . . . . . .516.2.2, 516.2.5,

516.6.4

Of refrigerating equipment . . . . . . . . . . . .105.3, 1114.3,

1116.0

Of safety interlocks . . . . . . . . . . . . . . . . . . . . . . .516.6.4

Required by the Authority

Having Jurisdiction . . . . . . . . . . . . . . . . . . . . .302.2.1

TESTING AGENCY

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .222.0
CRC § 1220.4.2 Medium relevance — show source text
8|1220.4.2 – 1220.4.6| |1221.7|1221.6| |1308.2 – 1308.4.1|1308.3 – 1308.5.1| |Table 1308.3.1|Table 1308.4.1| |1308.4.2|1308.5.2| |1308.4.2.2 – 1308.6.4|1308.5.2.1 – 1308.7.3| |Table 1308.4.6.2|Table 1308.5.6.2| |1308.6.5 – 1308.13.1|1308.7.7 – 1308.14.1| |1312.1.2 – 1312.1.3|1312.1.1 – 1312.1.2| |Chapter 17|Appendix F| |Chapter 18|Chapter 17| |D 103.2|D 103.1| |E 503.5.6.7|E 503.5.6.6| |E 503.5.7.2 – E 503.5.7.6|E 503.5.7.1 – E 503.5.7.5| |Table E 503.5.7.2|Table E 503.5.7.1| |Table E 503.5.7.6|Table E 503.5.7.5| |Table E 503.5.10.1.2(1)|Table E 503.5.10(1)| |Table E 503.5.10.1.2(2)|Table E 503.5.10(2)| |E 503.5.10.1.2|E 503.5.10| |E 503.5.10.2 – E 503.5.10.2.2|E 503.5.10.1 – E 503.5.10.1.2| |E 503.5.12.1|E 503.5.12| |E 503.5.12.2|E 503.5.12.1| |E 503.6.5.4|E 503.6.5.4.1|

xxii 2025 CALIFORNIA MECHANICAL CODE

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Uniform Mechanical Code – 2024 Edition:

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Frequently asked questions

What is the difference between a Type I and a Type II hood?

A Type I hood is for appliances that produce grease or smoke (e.g., fryers, grills); a Type II hood is for steam, heat, or odors where grease/smoke is not present. See § 508.1 and § 519.1. file

How much makeup air do I need for a Type II hood?

Makeup air must prevent negative pressure greater than 0.02 in. w.c. in the cooking area (see § 511.3). If internal makeup is used, it must be ≤ 10% of the hood exhaust; use E_NET = E_HOOD − MA_ID to compute net exhaust.

Can a dishwasher exhaust terminate over a sidewalk or street?

No. Moisture‑conveying exhaust ducts (e.g., dishwasher) shall not terminate over a public way or where condensate/vapor could create a nuisance or hazard (see § 519.5). Also observe the Class 3 separation requirements in § 502.2.2. file

Where do I find rooftop clearances for a Type I hood fan?

Rooftop and clearance requirements for Type I terminations — horizontal clearance to buildings/intakes, vertical separation above air intakes, grease drainage, and upblast fan clearances — are in § 510.9.1 (see § 510.9).

Are Type II systems allowed to share ducts with other exhaust systems?

No. Single or combined Type II exhaust systems shall be independent of all other exhaust systems per § 519.7.

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Related in the CRC

Combustion air, chimneys and vents — CRC guidance and CMC chapters to consult

Refrigerant piping, valves, detection and machinery room controls

Exhaust systems, combustion air, chimneys and refrigeration

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