Exhaust systems, combustion air, chimneys and refrigeration

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

• CRC § 101.2 High relevance — show source text

  Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101.2

  COMBUSTIBLE CONSTRUCTION, CLOSED

  Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205.0

  COMBUSTIBLE CONSTRUCTION, OPEN

  Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217.0

  COMBUSTIBLE MATERIAL

  Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205.0

  COMBUSTIBLE MATERIAL, LIMITED

  Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214.0

  COMBUSTION AIR

  Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205.0

  Duct . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 701.11, 701.12

  General requirements . . . . . . . . . . . . . . . . . . Chapter 7

  COMBUSTION AIR FOR

  Boilers, low pressure,

  installed in closets . . . . . . . . . . . . . . . . . . . . . . . 904.2

  Engineered installations. . . . . . . . . . . . . . . . . . . . . 701.8

  Fireplaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 912.4

  Fossil fuel heating equipment. . . . . . . . . . . . . E 502.6.1

  Furnaces, central heating . . . . . . . . . . . . . . 904.2, 907.4

  COMBUSTION AIR FROM

  Bedroom or bathroom. . . . . . . . . . . . . . . . . . . . . . 902.2

  Chimneys and vents . . . . . . . . . . . . . . . . . . . 802.5.11.1

  Combination, indoor and outdoor. . . . . . . 701.7, F 103.0

  Indoors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 701.4

  Louvers, grilles and screens . . . . . . . . . . . . . . . . 701.10

  Mechanical supply . . . . . . . . . . . . . . . . . . . . . . . . . 701.9

  Outdoors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 701.6

  Refrigeration machinery rooms . . . . . . . . . . . . . . 1106.5

  COMMERCIAL FOOD

  HEAT-PROCESSING EQUIPMENT

• CRC § 1108.0 High relevance — show source text

  Equipment and controls in. . . . . . . . . . . . . . . . . . 1108.0

  Ventilation of . . . . . . . . . . . . . . . . . . . 1106.2.7, 1106.2.8

  Where required . . . . . . . . . . . . . . . . . . . . . . . . . . 1106.0

  MAKEUP AIR . . . . . . . . . . . . . . . . . . . . . . (see Air, Makeup)

  MARKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.1.1

  MASONRY, CHIMNEYS . . . . . . . . . (see Chimney, masonry)

  MATERIALS

  Alternate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.2

  For construction of

  hoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.3

  For piping, containers, and valves of

  refrigeration systems . . . . . . . . . . . . . . . . . . . . 1109.1

  For ducts . . . . . . . . . . . . . . . . . . . 506.1, 510.5.1, 602.0

  For fuel piping. . . . . . . . . . . . . . . . . . . . 1308.0, D 109.0

  For piping, tubing

  and fittings hydronics . . . . . . . . . 1210.0, Table 1210.1

  For vent connectors. . . . . . . . . . . 802.10.1.1–802.10.1.4

  MECHANICAL

  Combustion air supply. . . . . . . . . . . . . . . 701.9, E 502.6

  Equipment Schedules [OSHPD] . . . . . . . . . . . . . 323.0

  Exhaust system. . . . . . . . . . . . . . . . . . . . . . . . . . . 505.1

  Ventilating system . . . . . . . . . . . 402.3, 1106.7, E 502.6,

  E 605.1.2, Table E 502.6

  MECHANICAL EXHAUSTING FOR

  Bathrooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E 605.2

  Low-rise residential dwelling . . . . . . . . . . . . . . E 605.1.3

  Product conveying. . . . . . . . . . . . . . . . . . . . . . . . . 505.0

  Refrigeration . . . . . . . . . . . . . . . . . . . . 1105.5.2, 1106.0,

  MECHANICAL JOINTS . . . . . . . . . . . . . . . . . . . . (see Joints

  and connections)

• CRC § 1210.0 High relevance — show source text

  For piping, tubing

  and fittings hydronics . . . . . . . . . 1210.0, Table 1210.1

  For vent connectors. . . . . . . . . . . 802.10.1.1–802.10.1.4

  MECHANICAL

  Combustion air supply. . . . . . . . . . . . . . . 701.9, E 502.6

  Equipment Schedules [OSHPD] . . . . . . . . . . . . . 323.0

  Exhaust system. . . . . . . . . . . . . . . . . . . . . . . . . . . 505.1

  Ventilating system . . . . . . . . . . . 402.3, 1106.7, E 502.6,

  E 605.1.2, Table E 502.6

  MECHANICAL EXHAUSTING FOR

  Bathrooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E 605.2

  Low-rise residential dwelling . . . . . . . . . . . . . . E 605.1.3

  Product conveying. . . . . . . . . . . . . . . . . . . . . . . . . 505.0

  Refrigeration . . . . . . . . . . . . . . . . . . . . 1105.5.2, 1106.0,

  MECHANICAL JOINTS . . . . . . . . . . . . . . . . . . . . (see Joints

  and connections)

  MECHANICAL PERMIT FEE . . . . . . . . . 104.5, Table 104.5

  MECHANICAL SYSTEMS

  Application to existing . . . . . . . . . . . . . . . . . . . . . . 102.2

  In elevator shaft. . . . . . . . . . . . . . . . . . . . . . . . . . . 305.4

  METAL

  Chimneys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 802.5.2

  Ducts. . . . . . . . . . . . . . . . . . . . . . . . 506.1, 602.5, 603.3

  METER, GAS . . . . . . . . . . . . . . . . . . . . . . . . 1308.5, D 104.0

  METHODS OF CONSTRUCTION,

  ALTERNATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.2

  MINIMUM REQUIREMENTS

  Purpose of Code . . . . . . . . . . . . . . . . . . . . . . . . . . 101.3

  MINIMUM STANDARDS . . . . . . . . . . . . . . . . . . . . . . . 302.1

  MOBILE HOME PARKS

  FUEL GAS EQUIPMENT

  AND INSTALLATION . . . . . . . . . . . . . . . . . . . . . D 101.1

• CMC § 2025 Medium relevance — show source text

  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.

  Chapter 9 Installation of Specific Appliances. Chapter 9 regulates the minimum requirements for the design, construction and installation of specific appliances. The provisions address the minimum requirements for gas-fired appliances, oil-fired appliances, wood-fired appliances, and electric-type appliances. In addition to the requirements of this chapter, appliances are also required to comply with the general requirements of Chapter 3.

  Chapter 10 Boilers and Pressure Vessels. Chapter 10 regulates the construction, installation, operation, repair, and alteration of boilers and pressure vessels. The safety provisions within this chapter address controls and limit devices for automatic boilers, methods of determining expansion tank capacities, discharge piping, relief valves, shutoff valves, gas-pressure and combustion regulators, and inspections and tests. Potable water heaters are free from the requirements of Chapter 10 as they are within the scope of the Uniform Plumbing Code (UPC).

  Pressure vessels store large amounts of energy and must comply with ASME Boiler and Pressure Vessel Code (BPVC) Section VIII.1. The stored energy must be contained to prevent disastrous failures. Boilers must comply with ASME BPVC Section I, ASME BPVC Section IV, or NFPA 85. Installing a safety relief valve and expansion tank prevents pressures in the tank from exceeding the design threshold.

  Chapter 11 Refrigeration. Chapter 11 regulates the design, installation, and construction requirements of refrigeration systems and the installation and construction of cooling towers. Refrigeration is a method used for achieving heat transfer to cool spaces. Refrigerants are the most common medium used to transfer the heat energy from the low-temperature level to the high-temperature level. Table

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  FORMAT OF THE UNIFORM MECHANICAL CODE

• CRC § 8-902.5 Medium relevance — show source text

  8-902.5 Combustion air.

  8-902.5.1 All fuel-burning appliances and equipment shall be provided a sufficient supply of air for proper fuel combustion, ventilation and draft hood dilution.

  8-902.5.2 The enforcing agency may require operational tests for combustion air systems which do not comply with applicable requirements of the regular code.

  8-902.6 Venting of appliances.

  8-902.6.1 Every appliance required to be vented shall be connected to an approved venting system. Venting systems shall develop a positive flow adequate to convey all combustion products to the outside atmosphere.

  8-902.6.2 Masonry chimneys in structurally sound condition may remain in use for all fuel-burning appliances, provided the flue is evaluated and documentation provided that the masonry and grout are in good condition. Terra cotta chimneys and Type C metallic vents installed in concealed spaces shall not remain in use unless otherwise mitigated and approved on a case-by-case basis.

  8-902.6.3 The enforcing agency may require operational tests for venting systems which do not comply with applicable requirements of the regular code.

  8-902.7 Ducts.

  8-902.7.1 New ducts shall be constructed and installed in accordance with applicable requirements of the regular code.

  8-902.7.2 Existing duct systems which do not comply with applicable requirements of the regular code and do not, in the opinion of the enforcing agency, constitute a safety or health hazard may remain in use.

  8-902.8 Ventilating systems.

  2025 CALIFORNIA HISTORICAL BUILDING CODE 19

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  MECHANICAL, PLUMBING AND ELECTRICAL REQUIREMENTS

  8-902.8.1 Ventilating systems shall be installed so that no safety hazard is created.

  8-902.8.2 Grease hoods and grease hood exhaust systems shall be furnished and installed in accordance with applicable requirements of the regular code. Existing systems which are altered shall comply with the regular code.

  8-902.9 Miscellaneous equipment requirements.

  8-902.9.1 The following appliances and equipment shall be installed so that no safety hazard is created: warm air furnaces, space heating equipment, vented decorative appliances, floor furnaces, vented wall furnaces, unit heaters, room heaters, absorption units, refrigeration equipment, duct furnaces, infrared radiant heaters, domestic incinerators, miscellaneous heat-producing appliances and water heaters.

  8-902.9.2 Storage-type water heaters shall be equipped with a temperature- and pressure-relief valve in accordance with applicable requirements of the regular code.

  SECTION 8-903 — PLUMBING

  8-903.1 General. Plumbing systems shall comply with the regular code unless otherwise noted.

  8-903.1.1 The provisions of the CHBC shall apply to the acceptance, location, installation, alteration, repair, relocation, replacement or addition of any plumbing system or equipment within or attached to a historical building.

  8-903.1.2 Existing systems which do not, in the opinion of the enforcing agency, constitute a safety hazard may remain in use.

  8-903.1.3 The enforcing agency may approve any alternative to these regulations which achieves reasonably equivalent life safety.

  8-903.2 Residential occupancies.

• CRC § 9.3.4 Medium relevance — show source text

  [NFPA 54:9.3.4(3)] 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 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 operation where the mechanical air supply system is not in operation. [NFPA 54:9.3.6.2] 701.9.3 Specified Combustion Air. Where combustion air is provided by the building’s mechanical ventilation system, the system shall provide the specified combustion air rate in addition to the required ventilation air. [NFPA 54:9.3.6.3] 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 54:9.3.7.1]

  701.10.1 Minimum Screen Mesh Size. Screens shall not be smaller than [1] ⁄ 4 of an inch (6.4 mm) mesh. [NFPA 54:9.3.7.2]

  701.10.2 Motorized Louvers. Motorized louvers shall be interlocked with the appliance so they are proven in the full open position prior to main burner ignition and during main burner operation. Means shall be provided to prevent the main burner from igniting should the louver fail to open during burner startup and to shut down the main burner if the louvers close during burner operation.

  [NFPA 54:9.3.7.3]

  2025 CALIFORNIA MECHANICAL CODE 149

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  COMBUSTION AIR

  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.

• 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.

  xiv 2025 CALIFORNIA MECHANICAL CODE

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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 § 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|

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• CRC § 8.13.6 Medium relevance — show source text

  [ASHRAE 15:8.13.6]

  »

  (1) Operated, where occupied, to supply not less than 0.5 CFM/ft [2] [2.54 L/(s•m [2] )] of machinery room area or 20 cubic feet per minute (9.44 L/s) per person.

  (2) Operable, where occupied at a volume required to not exceed the higher of a temperature rise of 18°F (10°C) above inlet air temperature or a maximum temperature of 122°F (50°C).

  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 largest system, any part of which is located in the machinery room, pounds.

  For SI units: 1 square foot = 0.0929 m [2], 1 pound = 0.453 kg

  (2) Locations of the gravity ventilation openings shall be based on the relative density of the refrigerant to air.

  [ASHRAE 15:8.14]

  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 the event of refrigerant leak age.

  Exception: Machinery rooms where carbon dioxide (R-744) or water (R-718) is the refrigerant.

  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.

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  REFRIGERATION

  1106.11.6.1 Mechanical Ventilation. The machinery room shall have a mechanical ventilation system in accordance with Section 1106.11.11. The mechanical ventilation system shall:

  (1) Run continuously, and failure of the mechanical ventilation system actuates an alarm, or

• CRC § 150.0 Medium relevance — show source text

  For this scenario, 4 in. (100 mm) oval duct shall be permitted, provided the minor axis of the oval is greater than or equal to 3 in. (75 mm)
  f. When a vented range hood utilizes a capture efficiency rating to demonstrate compliance with 150.0(o)1Giiib, a static pressure greater than or equal to 0.25 in. of water at the
  rating point shall not be required, and the airflow listed in the approved directory corresponding to the compliant capture efficiency rating point shall be applied to Table
  150.0-H for determining compliance.|

  vi. Sound ratings for local mechanical exhaust. Local mechanical exhaust systems shall be rated for sound in accordance with Section 7.2 of ASHRAE 62.2 at no less than the minimum airflow rate required by Section 150.0(o)1G. Exception to Section 150.0(o)1Gvi: Kitchen range hoods may be rated for sound at no less than 100 cfm at a static pressure determined at working speed as specified in HVI 916 section 7.2. H. Airflow measurement of whole-dwelling unit ventilation. The airflow required by Section 150.0(o)1C is the quantity of outdoor ventilation air supplied or indoor air exhausted by the mechanical ventilation system as installed and shall be measured by using a flow hood, flow grid or other airflow measuring device at the mechanical ventilation fan’s inlet terminals/grilles or outlet terminals/grilles in accordance with the procedures in Reference Residential Appendix RA3.7. Balanced mechanical ventilation system airflow shall be the average of the supply fan and exhaust fan flows.

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  SINGLE-FAMILY RESIDENTIAL BUILDINGS— MANDATORY FEATURES AND DEVICES

  I. Sound ratings for whole-dwelling unit ventilation systems. Whole-dwelling unit ventilation systems shall be rated for sound in accordance with Section 7.3 of ASHRAE 62.2 at no less than the minimum airflow rate required by Section 150.0(o)1C.

  J. Label for whole-dwelling unit ventilation system on-off control. Compliance with ASHRAE 62.2 Section 4.4 (Control and Operation) shall require manual ON-OFF control switches associated with whole-dwelling unit ventilation systems to have a label clearly displaying the following text, or equivalent text: “This switch controls the indoor air quality ventilation for the home. Leave switch in the ‘on’ position at all times unless the outdoor air quality is very poor.” K. Combustion air and compensating outdoor air or makeup air. i. All dwelling units shall conform to the applicable requirements specified in California Mechanical Code Chapter 7, Combustion Air. ii. All dwelling units shall conform to the requirements in ASHRAE 62.2 Section 6.4, Combustion and Solid-FuelBurning Appliances. 2. Field verification and diagnostic testing. A. Whole-dwelling unit ventilation airflow performance. The whole-dwelling unit ventilation airflow required by Section 150.0(o)1C shall be confirmed through field verification and diagnostic testing in accordance with the applicable procedures specified in Reference Residential Appendix RA3.7. Balanced mechanical ventilation system airflow shall be the average of the supply fan and exhaust fan flows. Ventilation airflow of systems with multiple operating modes shall be tested in all modes designed to comply with the required ventilation airflows. B.

• CRC § 1106.2.5 Medium relevance — show source text

  (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 the event of refrigerant leak age.

  Exception: Machinery rooms where carbon dioxide (R-744) or water (R-718) is the refrigerant.

  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.

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  REFRIGERATION

  1106.11.6.1 Mechanical Ventilation. The machinery room shall have a mechanical ventilation system in accordance with Section 1106.11.11. The mechanical ventilation system shall:

  (1) Run continuously, and failure of the mechanical ventilation system actuates an alarm, or

  (2) Be activated by one or more refrigerant detectors, conforming to requirements of Section 1106.11.8. [ASHRAE 15:8.13.6.1] 1106.11.6.2 Detection System. Detection of refrigerant concentration that exceeds 25 percent of the LFL or the upper detection limit of the refrigerant detector, whichever is lower, shall automatically de-energize the following equipment in the machin ery room:

  (1) Refrigerant compressors

  (2) Refrigerant pumps

  (3) Normally closed automatic refrigerant valves

  (4) Other unclassified electrical sources of ignition with apparent power rating greater than 1 kVA, where the apparent power is the product of the circuit voltage and current rating. [ASHRAE 15:8.13.6.2] 1106.11.7 Mechanical Equipment Control. Remote control of the mechanical equipment in the refrigerating machinery room shall be provided immediately outside the machinery room door solely for the purpose of shutting down the equipment in an emergency. Ventilation fans shall be on a separate electrical circuit and have a control switch located immediately outside the machinery room door. [ASHRAE 15:8.13.7] 1106.11.8 Refrigerant Detectors. Each refrigerating machinery room in accordance with Section 1106.11 shall contain one or more refrigerant detectors in accordance with Section 1106.11.9. The detector(s) sensing element shall be located in areas where refrigerant from a leak will concentrate, with one or more set points that activate responses in accordance with Section 1106.11.10 for alarms and Section 1106.11.11 for mechanical ventilation. Multiport-type devices shall be prohibited. {ASHRAE 15:8.13.8} 1106.11.9 Refrigerant Detectors Requirements. Refrigerant detectors required by Section 1106.11 shall meet all of the following conditions:

• CMC § 2025 Medium 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.

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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.