Appendix J — CLEAN AIR DELIVERY — 2025 California Mechanical Code (Title 24, Part 4)

(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 Agency	BSC	BSC- CG	SFM	HCD			DSA			OSHPD							BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
Adopting Agency	BSC	BSC- CG	SFM	1	2	1-AC	AC	SS	SS/CC	1	1R	2	3	4	5	6	6	6	6	6	6	6	6	6
Adopt Entire Chapter
Adopt Entire Chapter as amended (amended sections listed below)
Adopt only those sections that are listed below
Chapter/Section

This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

560 2025 CALIFORNIA MECHANICAL CODE

APPENDIX J

CLEAN AIR DELIVERY

The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency, or referenced in the adopting ordinance.

J 101.0 General.

J 101.1 Applicability. This appendix provides criteria for an increased protection level for occupant health by delivering and monitoring clean air in occupied areas of certain buildings. The provisions contained in this appendix are not mandatory unless specifically referenced in the adopting ordi nance.

J 201.0 Clean Air Delivery Capability. J 201.1 General. In groups A, B, E, and I occupancies, each mechanical system shall meet the requirements in Section J 201.1.1.

Exception: Occupiable spaces where 100 percent of the supply air meets High-Efficiency Particulate Air (HEPA) filtration.

J 201.1.1 Airflow for Increased Filtration. Mechanical systems shall be sized to accommodate a design airflow at a total static pressure drop which assumes the utilization of a supply air filter with a Minimum Efficiency Reporting Value (MERV) of no less than 13.

J 301.0 Demand Control Ventilation (DCV). J 301.1 General. Group A, B, E and I occupancies shall be equipped with a minimum of one carbon dioxide sensor for every 500 square feet (46.45 m [2] ) of occupiable space. Carbon dioxide sensors installed in accordance with this section shall meet the requirements in Sections J 301.1.1 and Section J 301.1.3 Mechanical equipment serving each zone(s) shall be equipped with controls which meet the requirements in Section J 301.1.2.

d I occupancies shall be equipped with a minimum of one carbon dioxide sensor for every 500 square feet (46.45 m [2] ) of occupiable space. Carbon dioxide sensors installed in accordance with this section shall meet the requirements in Sections J 301.1.1 and Section J 301.1.3 Mechanical equipment serving each zone(s) shall be equipped with controls which meet the requirements in Section J 301.1.2.

J 301.1.1 Carbon Dioxide Sensor Performance Specifications. Carbon dioxide sensors installed in accordance with Section J 301.0 shall comply with the following carbon dioxide measurement specifications as certified by the equipment manufacturer:

(1) Range lower bound less than or equal to 400 ppm.

(2) Range upper bound greater than or equal to 2000

ppm.

(3) Accuracy within ±75 ppm at a reading of 1000 ppm.

(4) Output resolution of 20 ppm or less. J 301.1.2 Mechanical System Controls. Controls installed in accordance with Section J 301.0 shall comply with the following:

(1) Receive data from the carbon dioxide sensor in the occupiable zone(s) at least once per 15 minutes.

(2) Be calibrated to provide pre-established outdoor airflow rates, or be equipped with the necessary instrumentation to measure outdoor airflow rate.

(3) Be capable of adjusting the outdoor airflow in response to an adjustable outdoor airflow setpoint.

(4) Increase the amount of outdoor air provided to each occupiable zone until the carbon dioxide level in each occupiable zone falls below a maximum threshold as defined by the user.

J 301.1.3 Carbon Dioxide Detection Threshold

Level. The default detection threshold level for carbon dioxide measurement above which triggers an alert in accordance with Section J 301.1.4 shall be set to 1100 parts per million (ppm). The end user can modify the detection threshold level based on specific operations and needs.

J 301.1.4 Carbon Dioxide Detection Threshold

Level Exceeded. When carbon dioxide levels exceed

the detection threshold level established in Section J 301.1.3, the mechanical equipment shall modify the outdoor airflow rate as required in Section J 301.1.2. When the carbon dioxide concentration remains above the detection threshold level for a period of 30 minutes or more, the occupants in the zone shall be alerted by approved audible and visual notification devices or through a building monitoring system.

562 2025 CALIFORNIA MECHANICAL CODE

USEFUL TABLES

CONVERSION TABLES

Note: The information contained in these tables are not part of this American National Standard (ANS) and have not been processed in accordance with ANSI’s requirements for an ANS. As such, these tables may contain material that has not been subjected to public review or a consensus process. In addition, they do not contain requirements necessary for conformance to the standard.

UNIT CONVERSIONS

MULTIPLY BY TO OBTAIN

Acres.........................................................................43 560 ............................Square feet (ft [2] ) Acre-feet...................................................................43 560 ............................Cubic feet (ft [3] )

Acre-feet.................................................................325 851 ............................Gallons (U. S. liquid)

Atmosphere (atm).........................................................76.0 ............................Centimeters of mercury (0°C)

Atmosphere (standard) (atm)........................................76.0 ............................Centimeters of mercury (0°C)

Atmosphere (standard) (atm)......................................33.90 ............................Feet of water (4°C)

Atmosphere (standard) (atm)......................................29.92 ............................Inches of mercury

Atmosphere (standard) (atm)..............................101.32501 ............................Kilopascals (kPa) Atmosphere (standard) (atm)......................................14.70 ............................Pounds-force/square inch (lbf/in [2] )

Barrels..............................................................................42 ............................Gallons (gal)

Barrels...................................................................158.9873 ............................Liters (L)

British thermal units (Btu)....................................1055.055 ............................Joules (J)

British thermal units/hour (Btu/h) ........................0.000293 ............................Kilowatts (kW)

British thermal units/hour (Btu/h) ..............................0.293 ............................Watts (W)

British thermal unit hour (Btu/h)..........................1.055056 ............................Kilojoules (kJ)

British thermal unit hour (Btu/h)..........................1055.056 ............................Joule (J)

British thermal units/minute (Btu/min) ......................12.97 ............................Foot pounds-force/second (ft•lbf/s)

British thermal units/minute (Btu/min) ..................0.02358 ............................Horsepower (hp) (international)

British thermal unit per hour square foot degree Fahrenheit [Btu/(h•ft [2] - °F)] .............5.678263 ............................Watt per square meter kelvin [W/(m [2] - K)]

British thermal unit inch per hour foot degree Fahrenheit [Btu•in/(h•ft•°F)] ......0.14442279 ............................Watt per meter kelvin [W/(m•K)] Candelas per square inch (cd/in [2] )................1.550003 x 10 [3] ............................Candela per square meters (cd/m [2] )

Celsius (°C)......................................................°C + 273.15 ............................Kelvin (k)

Celsius (°C)....................................................1.8 x °C + 32 ............................Fahrenheit (°F)

Centimeters (cm) ......................................................0.3937 ............................Inches (in)

Centimeters of mercury (0°C) ................................0.01316 ............................Atmosphere (standard)

Centimeters of mercury (0°C) ....................................0.446 ............................Feet of water (4°C) Centimeters of mercury (0°C) ....................................27.84 ............................Pounds-force/square feet (lbf/ft [2] ) Centimeters of mercury (0°C) ..................................0.1934 ............................Pounds-force/square inch (lbf/in [2] )

Circumference ............................................................6.283 ............................Radians (rad) Cubic feet (ft [3] ) .............................................................1728 ............................Cubic inches (in [3] ) Cubic feet (ft [3] ) ..........................................................0.0283 ............................Cubic meters (m [3] ) Cubic feet (ft [3] ) ........................................................0.03704 ............................Cubic yards (yd [3] ) Cubic feet (ft [3] ) ........................................................7.48052 ............................Gallons (U.S. liquid) (gal) Cubic feet (ft [3] ) ............................................................28.32 ............................Liters (L) Cubic feet (ft [3] ) ............................................................29.92 ............................Quarts (U.S. liquid) Cubic feet/hour (ft [3] /h)...............................................0.0283 ............................Cubic meters/hour (m [3] /h)

USEFUL TABLES

UNIT CONVERSIONS (continued)

MULTIPLY BY TO OBTAIN

Cubic feet/minute (ft [3] /min )..................................0.000472 ............................Cubic meters/second (m [3] /s) Cubic feet/minute (ft [3] /min )......................................0.1247 ............................Gallons/second Cubic feet/minute (ft [3] /min )....................................0.47194 ............................Liters/second (L/s) Cubic feet/second (ft [3] /s) ....................................646 316.89 ............................Gallons/day Cubic feet/second (ft [3] /s) .........................................448.831 ............................Gallons/minute (gpm) Cubic inches (in [3] )...............................................1.64 x 10 [-5] ............................Cubic meters (m [3] ) Cubic inches (in [3] ) ...................................................0.01639 ............................Liters (L) Cubic meters (m [3] ).....................................................264.17 ............................Gallons (U.S. liquid) Cubic yards (yd [3] ).............................................................27 ............................Cubic feet (ft [3] ) Cubic yards (yd [3] )....................................................0.76455 ............................Cubic meters (m [3] ) Cubic yards (yd [3] )......................................................201.97 ............................Gallons (U.S. liquid)

id) Cubic yards (yd [3] ).............................................................27 ............................Cubic feet (ft [3] ) Cubic yards (yd [3] )....................................................0.76455 ............................Cubic meters (m [3] ) Cubic yards (yd [3] )......................................................201.97 ............................Gallons (U.S. liquid)

Degrees (deg)............................................................0.0174 ............................Radians (rad)

Fahrenheit (°F)...................................................(°F-32)/1.8 ............................Celsius (°C)

Feet (ft) .....................................................................0.3048 ............................Meters (m)

Feet (ft) .......................................................................304.8 ............................Millimeters (mm)

Feet of water (4°C)...................................................0.0295 ............................Atmosphere (standard) (atm)

Feet of water (4°C)...................................................0.8827 ............................Inches of mercury (0°C)

Feet of water (4°C).....................................................62.43 ............................Pounds-force/square feet

Feet of water (4°C)...................................................0.4335 ............................Pounds-force/square inch

Feet/minute (ft/min)................................................0.01667 ............................Feet/second (ft/s)

Feet/minute (ft/min)................................................0.01136 ............................Miles/hour (mi/h)

Feet/second (ft/s) ......................................................0.3048 ............................Meters/second (m/s)

Feet/second (ft/s) ......................................................0.6818 ............................Miles/hour (mi/h)

Feet/second (ft/s) ....................................................0.01136 ............................Miles/minute (mi/min) Foot lambert (fL) ..................................................3.426259 ............................Candela per square meter (cd/m [2] )

Foot pounds-force (ft•lbf)...........................................1.355 ............................Joules (J) Foot pounds-force/minute (ft•lbf/min).............2.260 x 10 [-5] ............................Kilowatts (kW) Foot pounds-force/second (ft•lbf/s)..................1.356 x 10 [-3] ............................Kilowatts (kW) Gallons (U.S. liquid) (gal).............................................231 ............................Cubic inches (in [3] ) Gallons (U.S. liquid) (gal)....................................0.003785 ............................Cubic meters (m [3] ) Gallons (U.S. liquid) (gal)........................................0.1337 ............................Cubic feet (ft [3] )

Gallons (U.S. liquid) (gal)..........................................3.785 ............................Liters (L)

Gallons (U.S. liquid) (gal).................................................4 ............................Quarts (U.S. liquid) Gallons/day...........................................................4.3 x 10 [-5] ............................Liters/second Gallons/minute (gal/min) (gpm)...............................8.0208 ............................Cubic feet/hour (ft [3] /h) Gallons/minute (gal/min) (gpm).....................0.003785412 ............................Cubic meters/minute (m [3] /min) Gallons/minute (gal/min) (gpm).............................0.00223 ............................Cubic feet/second (ft [3] /s) Gallons/minute (gal/min) (gpm).................6.309020 x 10 [-5] ............................Cubic meters/second (m [3] /s)

Gallons/minute (gal/min) (gpm).............................0.06309 ............................Liters/second (L/s)

Grains (gr) ........................................................0.00006479 ............................Kilograms (kg)

Horsepower (hp).......................................................0.7457 ............................Kilowatts (kW) Horsepower-hours............................................2.684 x 10 [+6] ............................Joules (J)

Horsepower-hours ....................................................0.7457 ............................Kilowatt-hours (kW•h)

Inch (water column at 60°F)...................................0.24884 ............................Kilopascals (kPa)

Inches (in).....................................................................2.54 ............................Centimeters (cm)

564 2025 CALIFORNIA MECHANICAL CODE

USEFUL TABLES

UNIT CONVERSIONS (continued)

MULTIPLY BY TO OBTAIN

Inches (in).....................................................................25.4 ............................Millimeters (mm)

Inches/hour ...................................................................25.4 ............................Millimeters/hour (mm/h)

Inches of mercury (0°C).........................................0.03342 ............................Atmosphere (standard) (atm)

Inches of mercury (0°C).............................................1.133 ............................Feet of water (4°C)

Inches mercury (0°C) ...............................................3.3863 ............................Kilopascals (kPa)

Inches of mercury (0°C)...........................................0.4912 ............................Pounds-force/square inch

Inches of water (4°C)............................................0.002458 ............................Atmosphere (standard) (atm)

Inches of water (4°C)..............................................0.07356 ............................Inches of mercury (0°C)

Inches of water (4°C)..................................................5.202 ............................Pounds-force/square feet

Inches of water (4°C)..............................................0.03613 ............................Pounds-force/square inch Joules (J)...........................................................9.480 x 10 [-4] ............................British thermal units (Btus)

Joules (J)...................................................................0.7376 ............................Foot-pounds Joules (J)...........................................................2.778 x 10 [-4] ............................Watt-hours

Kelvin (K).........................................................°K - 273.15 ............................Celsius (°C)

Kilograms (kg)..........................................................2.2046 ............................Pounds (lbs) Kilograms (kg) .................................................1.102 x 10 [-3] ............................Tons (short)

Kilopascals (kPa)..................................................0.145038 ............................Pounds-force/square inch

Kilometers (km)........................................................0.6214 ............................Miles (statute)

Kilometers/hour (km/h)............................................0.6214 ............................Miles/hour (mi/h)

Kilowatts (kW) .......................................................3412.14 ............................British thermal units/hour (Btus/hour)

Kilowatts (kW) ...........................................................1.341 ............................Horsepower (hp)

Kilowatt-hours.............................................................3413 ............................British thermal units (Btus) Kilowatt-hours.................................................2.655 x 10 [+6] ............................Foot-pounds (ft•lbs) Kilowatt-hours.....................................................3.6 x 10 [+6] ............................Joules (J)

Kip (1000 lbf).......................................................4.448222 ............................Kilonewtons (kN)

Kip-foot ..................................................................1.35671 ............................Kilonewton meters (kN•m) Kips per square inch (kip/in [2] )...................................6.8947 ............................Megapascals (MPa) Lambert (la).................................................3.183099 x 10 [3] ............................Candela per square meter (cd/m [2] ) Liters (L).................................................................0.03531 ............................Cubic feet (ft [3] ) Liters (L).....................................................................61.02 ............................Cubic inches (in [3] ) Liters (L).....................................................................0.001 ............................Cubic meters (m [3] )

Liters (L)...................................................................0.2642 ............................Gallons (U.S. liquid) Lumens per square foot (lm/ft [2] ) (footcandle).......10.76391 ............................Lux (lx)

Meters (m) ..................................................................3.281 ............................Feet (ft)

Meters (m) ..................................................................39.37 ............................Inches (in)

Meters (m) ..................................................................1.094 ............................Yards

Meters/second (m/s) ...................................................3.281 ............................Feet/second (ft/s)

Meters/second (m/s) ...................................................2.237 ............................Miles/hour (mi/h)

Miles (mi) ....................................................................5280 ............................Feet (ft)

Miles (statute).............................................................1.609 ............................Kilometers (km)

Miles/hour (mi/h).............................................................88 ............................Feet/minute (ft/min)

Miles/hour (mi/h)........................................................1.467 ............................Feet/second (ft/s)

Miles/hour (mi/h)..................................................1.609344 ............................Kilometers/hour (km/h)

Miles/hour (mi/h)........................................................26.82 ............................Meters/minute (m/min)

Miles/hour (mi/h)....................................................0.44704 ............................Meters/second (m/s)

USEFUL TABLES

UNIT CONVERSIONS (continued)

MULTIPLY BY TO OBTAIN

Millimeters (mm)............................................................0.1 ............................Centimeters (cm)

Millimeters (mm)....................................................0.03937 ............................Inches (in)

Millimeters (mm)........................................................0.001 ............................Meters (m) Minutes (min).............................................2.908882 x 10 [-4] ............................Radians (rads) Ounces/square inch (oz/in [2] )..................................43.94185 ............................Kilograms/square meter (kg/m [2] )

Ounces/square feet (oz/ft [2] ) ...............................0.03051517 ............................Kilograms/square meter (kg/m [2] )

Ounces (oz).............................................................0.02834 ............................Kilograms (kg)

Ounces (oz)...........................................................29.57353 ............................Millimeters (mL)

Pints....................................................................0.4731765 ............................Liters (L)

Pound-force feet (lbf•ft) .......................................1.355818 ............................Newton meters (N•m)

Pound-force inch (lbf•in)....................................0.1129848 ............................Newton meters (N•m)

Pound-force per foot (lbf/ft) ...................................14.5939 ............................Newton meters (N•m) Pound-force per square foot (lbf/ft [2] ) ....................47.88026 ............................Pascals (Pa) Pound-force per square inch (lbf/in [2] ) .....................6.89476 ............................Kilopascals (kPa)

Pound-force per inch (lbf/in)................................175.1268 ............................Newton meters (N•m) Pounds/cubic inch (lb/in [3] )...........................2.767990 x 10 [4] ............................Kilograms/cubic meter (kg/m [3] ) Pounds/cubic yard (lb/yd [3] ) .................................0.5932764 ............................Kilograms/cubic meter (kg/m [3] )

Pounds (lb)..............................................................0.45359 ............................Kilograms (kg) Pounds/cubic foot (lb/ft [3] ) .......................................16.0184 ............................Kilograms/cubic meters (kg/m [3] )

Pounds/foot (lb/ft) ....................................................1.4881 ............................Kilograms/meters (kg/m) Pounds/square inch (lb/in [2] ).........................................703.1 ............................Kilograms-force/square meter (kg/m [2] ) Pounds/square foot (lb/ft [2] )....................................4.882427 ............................Kilograms-force/square meter (kg/m [2] )

Pounds-force (lbf).....................................................4.4482 ............................Newtons (N)

Pounds-force/square inch (psi)...............................0.06805 ............................Atmosphere (standard) (atm)

Pounds-force/square inch (psi)...................................2.307 ............................Feet of water (4°C)

Pounds-force/square inch (psi)...................................2.036 ............................Inches of mercury (0°C)

Pounds-force/square inch (psi)...............................6.89476 ............................Kilopascals (kPa) Quarts (U.S. dry) (dry qt) ...........................................67.20 ............................Cubic inches (in [3] ) Quarts (U.S. liquid) (liq qt) ........................................57.75 ............................Cubic inches (in [3] )

Quarts (liquid) ....................................................0.9463529 ............................Liters (L)

Radians (rads).............................................................57.30 ............................Degrees (deg) Seconds (s) ..................................................4.848137 x10 [-6] ............................Radians (rads) Square acre ...........................................................0.404687 ............................Square kilometers (km [2] ) Square feet (ft [2] )..............................................................144 ............................Square inches (in [2] ) Square feet (ft [2] ).........................................................0.0929 ............................Square meters (m [2] ) Square inches (in [2] )....................................................645.16 ............................Square millimeters (mm [2] ) Square inches (in [2] )................................................0.000645 ............................Square meters (m [2] ) Square meters (m [2] ) ......................................................1550 ............................Square inches (in [2] ) Square miles (mi [2] ) .........................................................640 ............................Acres Square miles (mi [2] ) ................................................2.589988 ............................Square kilometers (km [2] ) Square millimeters (mm [2] ) ................................1.550 x 10 [-3] ............................Square inches (in [2] ) Square yards (yd [2] ) .............................................................9 ............................Square feet (ft [2] ) Square yards (yd [2] ) ..............................................0.8361274 ............................Square meters (m [3] )

Temperature (°C) + 17.28 ..............................................1.8 ............................Temperature (°F) Temperature (°F) – 32 .................................................... 5 ⁄ 9 ............................Temperature (°C)

566 2025 CALIFORNIA MECHANICAL CODE

USEFUL TABLES

UNIT CONVERSIONS (continued)

MULTIPLY BY TO OBTAIN

Ton-force (tonf) (2000 lbf)...................................8.896443 ............................Kilonewtons (kN)

Ton-force foot (tonf•f/ft) ........................................2.71342 ............................Kilonewton meters (kN•m) Ton-force per square foot (tonf/ft [2] ) ........................95.7605 ............................Kilopascals (kPa) Ton-force per square inch (tonf/in [2] ).......................13.7895 ............................Megapascals (MPa)

Tons (metric) ...............................................................1000 ............................Kilograms (kg)

Tons (long) (2240 lbs)..........................................1016.047 ............................Kilograms (kg)

Tons (short) .................................................................2000 ............................Pounds (lbs)

Watts.........................................................................3.4121 ............................British thermal units per hour (Btus/hour) Watts.................................................................1.341 x 10 [-3] ............................Horsepower (hp)

Yards (y)...................................................................0.9144 ............................Meters (m)

Sl SYMBOLS AND PREFIXES

SI PREFIXES

MULTIPLICATION FACTOR	PREFIX	SYMBOL
1 000 000 000 000 000 000 = E+18	exa	E
1 000 000 000 000 000 = E+15	peta	P
1 000 000 000 000 = E+12	tera	T
1 000 000 000 = E+09	giga	G
1 000 000 = E+06	mega	M
1 000 = E+03	kilo	k
100 = E+02	hecto	h
10 = E+01	deka	da
0.1 = E-01	deci	d
0.01 = E-02	centi	c
0.001 = E-03	milli	m
0.000 001 = E-06	micro	µ
0.000 000 001 = E-09	nano	n
0.000 000 000 001 = E-12	pico	p
0.000 000 000 000 001 = E-15	femto	f
0.000 000 000 000 000 001 = E-18	atto	a

USEFUL TABLES

AREAS AND CIRCUMFERENCES OF CIRCLES

DIAMETER		CIRCUMFERENCE		AREA
Inches	mm	Inches	mm	Inches2	mm2
1⁄8	6	0.40	10	0.01227	8.0
1⁄4	8	0.79	20	0.04909	31.7
3⁄8	10	1.18	30	0.11045	71.3
1⁄2	15	1.57	40	0.19635	126.7
3⁄4	20	2.36	60	0.44179	285.0
1	25	3.14	80	0.7854	506.7
11⁄4	32	3.93	100	1.2272	791.7
11⁄2	40	4.71	120	1.7671	1140.1
2	50	6.28	160	3.1416	2026.8
21⁄2	65	7.85	200	4.9087	3166.9
3	80	9.43	240	7.0686	4560.4
4	100	12.55	320	12.566	8107.1
5	125	15.71	400	19.635	12 667.7
6	150	18.85	480	28.274	18 241.3
7	175	21.99	560	38.485	24 828.9
8	200	25.13	640	50.265	32 428.9
9	225	28.27	720	63.617	41 043.1
10	250	31.42	800	78.540	50 670.9

568 2025 CALIFORNIA MECHANICAL CODE

USEFUL TABLES

APPROXIMATE MINIMUM THICKNESS FOR CARBON SHEET STEEL CORRESPONDING

TO MANUFACTURER’S STANDARD GAUGE AND GALVANIZED SHEET GAUGE NUMBERS

CARBON SHEET STEEL			GALVANIZED SHEET
MANUFACTURER’S STANDARD GAUGE NO.	DECIMAL AND NOMINAL THICKNESS EQUIVALENT (inch)	RECOMMENDED MINIMUM THICKNESS EQUIVALENT *(inch)	GALVANIZED SHEET GAUGE NO.	DECIMAL AND NOMINAL THICKNESS EQUIVALENT (inch)	RECOMMENDED MINIMUM THICKNESS EQUIVALENT *(inch)
8	0.1644	0.156	8	0.1681	0.159
9	0.1495	0.142	9	0.1532	0.144
10	0.1345	0.127	10	0.1382	0.129
11	0.1196	0.112	11	0.1233	0.114
12	0.1046	0.097	12	0.1084	0.099
13	0.0897	0.083	13	0.0934	0.084
14	0.0747	0.068	14	0.0785	0.070
15	0.0673	0.062	15	0.0710	0.065
16	0.0598	0.055	16	0.0635	0.058
17	0.0538	0.050	17	0.0575	0.053
18	0.0478	0.044	18	0.0516	0.047
19	0.0418	0.038	19	0.0456	0.041
20	0.0359	0.033	20	0.0396	0.036
21	0.0329	0.030	21	0.0366	0.033
22	0.0299	0.027	22	0.0336	0.030
23	0.0269	0.024	23	0.0306	0.027
24	0.0239	0.021	24	0.0276	0.024
25	0.0209	0.018	25	0.0247	0.021
26	0.0179	0.016	26	0.0217	0.019
27	0.0164	0.014	27	0.0202	0.017
28	0.0149	0.013	28	0.0187	0.016
—	—	—	29	0.0172	0.014
—	—	—	30	0.0157	0.013

For SI units: 1 inch = 25.4 mm

The thickness of the sheets set forth in the code correspond to the thickness shown under these columns. They are the approximate minimum thicknesses

and are based on the following references:

Carbon Sheet Steel—Thickness 0.071 inch (1.803 mm) and over:

ASTM A 568, Table 3, Thickness Tolerances of Hot-Rolled Sheet (Carbon Steel).

Carbon Sheet Steel—Thickness less than 0.071 inch (1.803 mm):

ASTM A 568, Table 23, Thickness Tolerances of Cold-Rolled Sheet (Carbon and High-Strength Low Alloy).

Galvanized Sheet Steel—All thicknesses:

ASTM A 653, Table 4, Thickness Tolerances of Hot-Dip Galvanized Sheet.

Minimum thickness is the difference between the thickness equivalent of each gauge and the maximum negative tolerance for the widest rolled width.

570 2025 CALIFORNIA MECHANICAL CODE

INDEX

© 2024 International Association of Plumbing and Mechanical Officials. All rights reserved. The copyright in this index is separate and distinct from the copyright in the document that it indexes. The licensing provisions set forth for the document are not applicable to this index. This index may not be reproduced in whole or in part by any means without the express written permission of IAPMO.

– A –

ABSORPTION SYSTEM

Cooling system . . . . . . . . . . . . . . . . . . . . . . . Chapter 11 Duct system . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 6

Permit Fees . . . . . . . . . . . . . . . . . . . . . . . . . Table 104.5

ABSORPTION UNIT

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Labeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307.4

Permit Fees . . . . . . . . . . . . . . . . . . . . . . . . . Table 104.5

ACCEPTED ENGINEERING

PRACTICE . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0, 309.1

Oil supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D 112.1

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

HVAC system balancing . . . . . . . . . . . . . . . E 503.6.5.3

Pump head . . . . . . . . . . . . . . . . . . . . . . . . . E 503.4.5.1

Workmanship . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309.1

ACCESS PANELS

Air handling units . . . . . . . . . . . . . . . . . . . . . . . 1106.2.3

Appliances on roofs . . . . . . . . . . . . . . . . . . . . . . . 303.8

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Ducts connected to

duct furnaces . . . . . . . . . . . . . . . . . . . . . . . . . . 905.4

Exhaust systems,

commercial kitchen . . . . . . . . . . . . . 510.1.5, 510.3.1,

510.3.6-510.3.7,

510.7.7, 514.4.9, 514.4.10

Exhaust systems, dryers (multistory) . . . . . . . . .504.4.6

Fire and smoke dampers . . . . . . . . . . . . . . . . . . .606.8 Gas fireplaces, vented . . . . . . . . . . . . . . . . . . . . . .912.3

Wall furnaces . . . . . . . . . . . . . . . . . . . . . . . . . . .907.2.3

ACCESSIBILITY FOR

Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105.1

Operation . . . . . . . . . . . . . . . . . . . . . . . 919.4.1, 919.5.1

Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304.0

ACCESSIBILITY OF

Appliances and equipment . . . . . . . 304.1, 304.3, 304.4

Boilers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1010.0

Cleanouts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 802.5.10

Draft hoods. . . . . . . . . . . . . . . . . . . . . . . . . . . . 802.12.5

Drips, fuel gas piping . . . . . . . . . . . . . . . . . . . . 1310.9.1

Evaporative coolers. . . . . . . . . . . . . . . . . . . . . . . . 932.3

Fire and smoke dampers . . . . . . . . . . . . . . . . . . . 606.8

Floor furnace. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 906.9

Fuel gas meters . . . . . . . . . . . . . . . . . 1308.5.1, D 104.2

Fuel gas piping . . . . . . . . . . . . . . . . . . . . . . . 1310.3.3.1

Fuel gas pressure regulators . . . . . . . . . . . . . .1308.6.2,

1310.5.1

Grease filters. . . . . . . . . . . . . . . . . . . . . . . . . . 509.2.3.2

Lapped flanges . . . . . . . . . . . . . . . . . . . . . . . 1308.4.9.6

Motors and fans, exhaust systems . . . . . . . . . . . . 503.1

Refrigeration equipment . . . . . . . . . . . . . . . . . . . 1105.3

ACCESSIBLE

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Easily, definition. . . . . . . . . . . . . . . . . . . . . . . . . . . 207.0

Readily, definition . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

ACCESSORY DWELLING UNIT

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

ADMINISTRATION

California . . . . . . . . . . . . . . . . . . . . Chapter 1, Division I

General . . . . . . . . . . . . . . . . . . . . . Chapter 1 , Division II

AIR

Balancing . . . . . . . . . . . . . 314.0, 403.10, 407.3, 511.3.1,

E 503.3.1, E 503.6.5.3,

E 605.1.5, E 803.2

Circulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407.4

Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.9

Combustion . . . . . . . . . . . . . . . . . (see Combustion Air)

Dilution . . . . . . . . . . . . . . . . . . . . . . . 203.0, Table 403.7,

701.1, 701.1.1, 701.8, 701.10,

802.6.3.1, 902.2, 902.12, 902.13

Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (see Ducts) Economizer . . . . . . . . . . . . . . . . . (see Economizer, air) Exhaust . . . . . . . . . . . . . . . . . . . . . . . (see Air, exhaust) Filters. . . . . . . . . . . . . . . . . . . . . . . . . . . (see Filters, air) Furnace . . . . . . . . . . . . . . . . . (see Furnaces, warm air) Heaters. . . . . . . . . . . . . . . . . . . . . . . . . (see Heater, air)

Makeup . . . . . . . . . . . . . . . 203.0, 401.1, 403.7, 504.4.1,

505.10, 511.3, 517.1.2, 517.1.3,

517.6.1, 517.6.2, 519.6, 701.1,

701.3, 930.5.4, 1106.2.8, 1106.6,

1106.11.11.1, 1220.5, E 503.4.6.9,

E 503.5.11.3, I 801.1.4

Moving Systems . . . . . . . . . . . . . 203.0, 609.1, I 801.1.6, Outside 203.0, Table 310.3,

311.1, 311.3, Chapter 4,

908.3.2, 932.1, 1105.1,

E 502.10.2, E 805.0

Pollution control

devices. . . . . . . . . . . . . . . . . . . 203.0, 512.3, 512.3.5,

513.1.1, 513.3.3

INDEX

Recirculation. . . . . . . . . . . . . . . . . . 403.3, 403.5, 403.7,

403.9, 404.3, 407.4.5, 512.3.5

Replacement . . . . . . . . . . . . . . . . . . . (see Air, makeup)

Return . . . . . . . . . . . . . 203.0, 311.0, 402.3, 403.2.2.1.2,

403.2.2.2.2, 404.3.2, 517.1.2,

604.4, 905.6, 1105.1, Appendix E

Supply . . . . . . . . . . 203.0, Chapter 4, 914.5, 1104.2.3.2

Transfer . . . . . . . . . . . . . . . . . 203.0, 403.7, E 503.4.6.9,

E 503.4.6.11, E 503.5.11.1,

E 503.11.2.2, I 801.1.4

Variable Air Volume . . . . . . . . . . . . . . . . . . . . . . . . 407.5

Ventilation . . . . . . . . . . . . . . . . . . . . Chapter 4, 701.9.3,

902.2, 914.5.2, 915.3.1.1,

925.4, Appendix E

AIRBORNE INFECTION ISOLATION ROOMS . . . 414.0, 417.0

Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321.7, 416.0

AIR CIRCULATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407.4

AIR CONDITIONED

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Zone isolation . . . . . . . . . . . . . . . . . . . . . . E 503.4.6.3.4

AIR CONDITIONING

Air Conditioning and Heating Systems [OSHPD] . . 320.0

Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 903.0

Coils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 903.2.6

Gas fired type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 903.2

General requirements . . . . . . . . . . . . . . . . . . Chapter 3

Refrigerant port protection . . . . . . . . . . . . . . . . . 1105.11

System test . . . . . . . . . . . . . . . . . . . . . . . . . . . . E 805.0

System water use . . . . . . . . . . . . . . . . . . . . . . . E 403.0

AIR-HANDLING UNIT

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 6

Exposed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 904.9.1

Permit Fees . . . . . . . . . . . . . . . . . . . . . . . . . Table 104.5

System test . . . . . . . . . . . . . . . . . . . . . . . . . . . . E 805.0

AIR, EXHAUST

Cross Contamination. . . . . . . . . . . . . . . . . . . . . . 603.10

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Grease filters. . . . . . . . . . . . . . . . . . . . . . . . . . 509.2.3.1

Openings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.3.2

Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.7

Volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511.2.2

AIR RELIEF

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

AIR TERMINAL DEVICE

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

ALARMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416.0, 418.5

ALTERNATE MATERIALS AND METHODS

CONSTRUCTION EQUIVALENCY . . . . . . . . . . . . . . 302.2

ALTERNATIVE ENGINEERING DESIGN

Design and installation . . . . . . . . . . . . . . . . . . . . . 302.3

Design approval. . . . . . . . . . . . . . . . . . . . . . . . . 302.3.4

Design document. . . . . . . . . . . . . . . . . . . . . . . . 302.3.3

Design review . . . . . . . . . . . . . . . . . . . . . . . . . . 302.3.5

Inspection and testing . . . . . . . . . . . . . . . . . . . . 302.3.6

Permit application . . . . . . . . . . . . . . . . . . . . . . . 302.3.1

Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . 302.3.2

AMMONIA . . . . . . . . . . . . . . . . . . . . 1102.1, 1102.2, 1102.3,

Table 1102.3, 1104.4,

1106.2, 1302.3

ANCHORAGE OF

Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303.4

Boilers and pressure vessels . . . . . . . . . . . . . . . . 1001.5

Cooling towers. . . . . . . . . . . . . . . . . . . . . . . . . . . 1120.0

Evaporative condensers . . . . . . . . . . . . . . . . . . . 1120.0

Floor furnace seepage pans . . . . . . . . . . . . . . . . 906.10

Fluid coolers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1120.0

Fuel gas piping. . . . . . . . . . . . . . . . . . . . . . . . . 1310.3.5

Radiant panels. . . . . . . . . . . . . . . . . . . . . . . . . 1217.11.2

Refrigeration equipment

and piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1105.2

ANODELESS RISER

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Factory assembled. . . . . . . . . . . . . . . . . . . 1308.4.4.2.1

Field assembled. . . . . . . . . . . . . . . . . . . . . 1308.4.4.2.2

APPEALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107.0

APPLIANCE FLUE OUTLET

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509.2.2

Test method for fuel-fired equipment . . . . . . . . . C 108.0

APPLIANCES

Access to . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .304.0

Air-conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . .903.0

Air filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .935.0

Approval of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301.2

Clearance . . . . . . . . . .303.1-303.3, 303.10-303.10.1.3,

Table 303.10.1, Table 802.7.3.3

Closed combustion

solid-fuel-burning, definition . . . . . . . . . . . . . . . 203.0

Clothes dryers . . . . . . . . . . . . . . . . . (see Clothes dryer)

Cooking . . . . . . . . . . . . . . . . . . . . . . . Chapter 5, 919.0,

922.0

Decorative, vented. . . . . . . . . 224.0, 911.0, 912.1, 931.0

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Dehumidifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 938.0

Direct vent . . . . . . . . . . . . . . . . . . . . 203.0, 311.3, 701.1,

701.11, 802.2.6, 802.2.6.1,

Table 802.4, 802.5.11.1, 802.8.1

Table 802.8.1, 802.8.2, 802.12,

902.12, 907.2.2, 912.2, 912.3

572 2025 CALIFORNIA MECHANICAL CODE

INDEX

Downdraft . . . . . . . . . . . . . . . . . . . . . . . . 405.4.1, 518.0

Electric cooling . . . . . . . . . . . . . . . . 307.3, 903.1, 1115.5

Electric heating . . . . . . . . . . . . . . . . 203.0, 307.2, 903.1,

905.9, 915.2, 925.6,

939.0, 1217.11.1

Fan-assisted

combustion system . . . . . . . . . . . . . 203.0, 802.6.2.1,

802.10.2, 802.12,

F 102.2, F 102.3

Floor furnaces . . . . . . . . . (see Furnaces, floor furnace)

Food service . . . . . . . . . . . . . . . . . . . . . . 802.3.4, 917.0,

918.0, 1312.1.2

Gas input . . . . . . . . . . . . . . . . 1308.3.1, Table 1308.3.1

Heating . . . . . . . . . . . . . . . . . . . . . . . Table 104.5, 306.1

Table 803.1.2(6), 803.1.10,

Table 803.2(7), Table 803.2(9),

903.2.4, 915.3.1.1,

1207.0, Table 1308.3.1

Household cooking . . . . . . . . . . . . . . . . . . . . . . . . 919.0

Illuminating . . . . . . . . . . . . 923.0, Table 923.2.1, 1312.9

In attics and

under-floor space . . . . . . . . . . . . . . . . 304.4–304.4.4,

904.4.1, 904.11

In garages . . . . . . . . . . . . . . . . . . . . . . . . 305.1-305.1.2,

905.8, 916.6, 925.5

In manufactured housing . . . . . . . . . . . . . 911.3.2, 929.0

Kilns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 930.0

Labeling of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307.0

Listed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303.1

Location of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.0

Low-heat . . . . . . . . . . . . . . . . . . . 203.0, 801.2, 802.5.4,

Table 802.7.3.3,

802.7.3.5, 802.10.1.3,

Table 802.10.1.3, 803.1.11

Medium-heat. . . . . . . . . . . . . . . 203.0, 801.2, 802.5.4.1,

Table 802.7.3.3, 802.10.1.4,

Table 802.10.1.4, 802.10.13.1

Movement of . . . . . . . . . . . . . . . . . . . . . 303.5, 1312.1.3

Oil-burning. . . . . . . . . . . . 301.5, Table 802.4, 802.5.8.3,

802.14.1, 904.12, 906.14,

907.5, 916.7, 920.3, 1002.2,

D 113.6, D 115.0, E 503.4

On roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . 304.3, 303.8

Open-top broiler units . . . . . . . . . . . . (see Broiler units)

Outdoor cooking. . . . . . . . . . . . . . . . . . . . 922.0, 1312.9

Pit location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .305.2

Protection against

flood damage . . . . . . . . . . . . . . . . . . . . . . . . . . 305.3

Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306.1, 508.1,

508.5.1.3-508.5.1.5,

802.12, 917.2, 917.5,

919.0, 920.0, Table 1308.3.1

Refrigeration . . . . . . . . . Table 104.5, 933.0, Chapter 11

Refrigerators . . . . . . . . . . . . . . . . . . (see Refrigerators)

Room heaters. . . . . . . . . . . . . . . . . . (see Heater, room)

Solid-fuel burning . . . . . . . . . . . 303.10.1.3, 508.1, 517.0

Table 802.4, 802.5.1.1,

902.10, 904.12, 915.4, 1002.4

Support . . . . . . . . . . . . . . . . . . . . 303.4, 303.8.1, 303.9,

303.1, 902.8, 902.8.1,

904.4.1.1, 904.4.1.2,

906.7, 916.2, 925.2

Unit heaters . . . . . . . . . . . . . . . . . . . . . . . . (see Heater)

Unlisted. . . . . . . . . . . . . . . . 303.3, 303.10, Table 802.4,

802.7.3.5, 902.1, 902.5,

904.2, 918.4, 923.2

Venting of . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 8

APPROVED

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

APPROVED TESTING AGENCY . . . . . . . .203.0, 302.2.1.1,

1003.2, Table 1003.2.1

AUTHORITY HAVING JURISDICTION

Appeals decisions . . . . . . . . . . . . . . . . . . . . . . . . . 107.1

Authority to disconnect

of gas piping . . . . . . . . . . . . . . . . . . . . . . . . . . 1306.0

Authority to render gas service . . . . . . . . . . . . . . 1305.0

Condemn equipment. . . . . . . . . . . . . . . . . . . . . . . 106.6

Connection approval . . . . . . . . . . . . . . . . . . . . . . . 105.4

Cooperation of other

officials and officers . . . . . . . . . . . . . . . . . . . . . . 103.1

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Disconnect utilities in

emergencies, to. . . . . . . . . . . . . . . . . . . . . . . . . 106.5

Duties and powers . . . . . . . . . . . . . . . . . . . . . . . . 103.0

Inspections . . . . . . . . . . . . . . . . . . . . . . . . 105.0, 1013.0

Issues permits. . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.4

Liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.2

Limitations of authority. . . . . . . . . . . . . . . . . . . . . . 107.2

Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106.2

Powers and duties. . . . . . . . . . . . . . . . . . . . . . . . . 103.0

Right of entry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.4

Stop orders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106.4

Temporary connection . . . . . . . . . . . . . . . 105.4, 1307.1

Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . 105.3, 302.2.1

AUTOMATIC

CONTROL DEVICES . . . . . . . . . . . . . . . . . . . . . . . . 306.0

AUTOMATIC, BOILERS . . . . . . . . . . . . . . . (see Boiler types,

automatic)

INDEX

AZEOTROPE

Allowable quantities . . . . . . . . . . . . . . . . . . Table 1102.3

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

– B –

BAFFLE PLATE . . . . . . . . . . . . . . . . . . . . 204.0, 509.2.2.1,

509.2.2.3, 513.2.4.2, 515.1.1.4

BALANCING, HVAC . . . . . . . . . . . . . . . . . . . 314.0, E 502.3

E 503.6.5.3–E 503.6.5.3.2

BLEED LINES . . . . . . . . . . . . . . . . . . . . . . . 902.15, 1308.14

BOARD OF APPEALS . . . . . . . . . . . . . . . . . . . . . . . . . 107.0

BOILER

Clearance for access. . . . . . . . . . . . . . . . . . . . . . 1010.0

Clearance for connectors . . . . . . . . . . . . Table 802.7.3.3

Closet or alcove installation . . . . . . . . . . . . . . . . . 303.2

Combustion regulators . . . . . . . . . . . . . . . . . . . . 1009.0

Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1003.2

Control diagram. . . . . . . . . . . . . . . . . . . . . . . . . . 1012.1

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0

General requirements. . . . . . . . . . . . . . . . . . Chapter 10

In hydronic systems . . . . . . . . . . . . . . . . . . . . . . . 1207.2

Inspections and tests. . . . . . . . . . . . . . . . . . . . . . 1013.0

Low-water cutoff . . . . . . . . . . . . . . . . . . . . . . . . . 1008.0

Mounting of. . . . . . . . . . . . . . . . . . . . . . 1001.5, 1001.5.1

Operation and maintenance . . . . . . . . . . . . . . . . 1014.0

Permit Fees . . . . . . . . . . . . . . . . . . . . . . . . . Table 104.5

Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1005.0

Room . . . . . . . . . . . . . . . . . . . . . 204.0, 1001.2 , 1001.2.1

Venting of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1001.6

BOILER TYPES

Automatic . . . . . . . . . . . 204.0, 1003.2.1, Table 1003.2.1

1003.3, 1003.4

Central heating. . . . . . . . . . . . . . . . . . . . . . 303.2, 904.0

Condensing . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207.2.1

Electric . . . . . . . . . . . . . . . . . . . . . . 1002.3, E 503.5.7.3

High-pressure, definition . . . . . . . . . . . . . . . . . . . . 204.0

Low-pressure hot-water-heating,

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0

Low-pressure steam-heating,

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0

Miniature Boiler. . . . . . . . . . . . . . . . . . . . . 204.0, 1013.4

Noncondensing. . . . . . . . . . . . . . . . . . . . . . . . . 1207.2.2

Oil burning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1002.2

Package . . . . . . . . . . . . . . . . . . . 204.0, 1010.4, 1705.2,

Table E 503.7.1(6)

Power . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0, 1002.1,

Table 1003.2.1, 1010.2,

1010.3, 1013.4

Solid fuel . . . . . . . . . . . . . . . . . . . . . . 1002.4, 1003.2.1,

Table 1203.2

Steam and hot water. . . . . . . . . . . . . . . . . 204.0, 904.2,

Table 904.3.2, 904.5,

904.7, Table 1003.2.1,

1003.3, 1008.1, 1010.3,

1010.4, 1012.1, 1216.3,

1216.5, C 105.1

BONDING CONDUCTOR

OR JUMPER . . . . . . . . . . . . . . . . . . . . . . . . . . .204.0, 1311.0

BRAZED JOINTS . . . . . . . . . .(see Joints and connections)

BREECHING

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0

BRINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1105.3, 1108.1,

1109.9, 1116.5

BROILER UNITS

Open top unit . . . . . . . . . . . . . . . . 921.0, Table 1308.3.1

BUILDING

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0

BUILDING AUTOMATION SYSTEMS . . . . . . . . . . . . . . 306.2

BUILDING CODE

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0

BUILDING OFFICIAL

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0

BUILDING STRUCTURAL MEMBERS . . . . . . 316.9, 603.3

BURNER ASSEMBLIES . . . . . . . . . . . . . . . . . . . . . . . 910.0

BURNER, CONVERSION . . . . . . . . . . . . . . Table 802.7.3.3,

802.10.1.2, 802.12,

802.12.1, 909.0, C 105.1

– C –

CARBON MONOXIDE SENSING . . . . . . . . . . . . . . . 403.7.2

CAS NUMBER

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

CENTRAL HEATING PLANT

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

CHIMNEY

Cleanouts . . . . . . . . . . . . . . . . . . . .802.5.7.2, 802.5.10

Connection . . . . . . . . . . . . . . . . . . . . . . . . . . .802.10.11

Decorative shrouds . . . . . . . . . . . . .802.5.1.1, 802.5.4.3

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

Existing . . . . . . . . . . . . . . . . . . . . . . . .802.5.7, 802.5.7.3

Factory-built . . . . . . . . .802.5.1, 802.10.1.3, 802.10.1.4

Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .802.5.4.2

Inspection . . . . . . . . . . . . . . . . . . . . . .802.5.6, 802.5.7

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . .Chapter 8

Location . . . . . . . . . . . . . . . . . . . . . . . . . .Table 402.4.1

Masonry . . . . . . . . . . . . . . . . .802.5.3, 802.5.11, 802.6,

Table 803.1.2(3), Table 803.1.2(4),

Table 803.1.2(6), 803.1.6,

803.1.9, 803.1.10, Table 803.2(3),

Table 803.2(4), Table 803.2(6)-Table 803.2(9),

803.2.19, 803.2.20, Appendix F

574 2025 CALIFORNIA MECHANICAL CODE

INDEX

Metal . . . . . . . . . . . . . . . . . . . . . . . . .802.5.2, 802.10.11

Serving appliances . . . . . . . . . . . . . . . . . . . . . .802.5.8

Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .802.5.5

Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .802.5.9

Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . .802.5.4

Venting systems . . . . . . . . . . . . . . . .802.5.5, 802.6.2.4

CHIMNEY CLASSIFICATIONS

High-heat appliances-type . . . . . . . . . . . . . . . . . . 205.0

Low-heat appliances-type. . . . . . . . . . . . . . . . . . . 205.0

Medium-heat

appliances-type. . . . . . . . . . . . . . . . . . . . . . . . . 205.0

Residential appliances-type . . . . . . . . . . . . . . . . . . 205.0

CHLORINATED POLYVINYL

CHLORIDE (CPVC) PIPE OR TUBING

Condensate waste piping . . . . . . . . . . . . . . . . . . . 310.3

Ground source loop . . . . . . . . . . . . . . . . . . Table 1703.2

Hangers and supports. . . . . . . . . . . . . . . . . Table 313.6

Hydronics. . . . . . . . . . . . . . . . . . . . . . . . . . Table 1210.1

Joining

and connections . . . . . . (see Joints and connections)

CIRCULATORS . . . . . . . . . . . . . . . . . 205.0, 1208.0, 1214.5

CLASSIFICATION OF

Air . . . . . . . . . . . . . . . . . . . . . 203.0, Table 402.1, 403.9

Chimney, definition . . . . . . . . . . . . . . . . . . . . . . . . 205.0

Occupancy, definition. . . . . . . . . . . . . . . . . . . . . . . 217.0

Product-conveying ducts. . . . . . . . . . . . . . . . . . . . 505.8

Refrigerants. . . . . . . . . . . . . . . . . . . . . 1103.1, 1103.1.1,

Table 1102.3

Refrigeration systems . . . . . . . . . . . . . . . . . . . . . 1103.2

CLEAN AIR DELIVERY . . . . . . . . . . . . . . . . . . .Appendix J

Carbon dioxide detection . . . . . . . . .J 301.1.3, J 301.1.4

Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .J 301.1.2

Demand Control Ventilation (DCV) . . . . . . . . . . .J 301.0

Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .J 201.1.1

CLEARANCES FOR

Air-conditioning appliances,

gas type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 903.2.4

Air heaters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.4

Appliances . . . . . . . . . . . . . . . . . 303.3, 303.8, 303.8.4,

303.8.4.1, 303.10, 304.1,

303.10.1, 304.3.1.1, 516.2.1,

701.6.2, Table 303.10.1

Boilers. . . . . . . . . . . . . . . . . . . . . . . . . . . . 303.2, 904.3,

1010.0, Table 904.3.2

Broilers units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 921.2

Clothes dryers, gas type . . . . . . . . . . . . . . . . . . 908.3.1

Connectors. . . . . . . . . . . . . . . 802.10.4, Table 303.10.1,

Table 802.7.3.3

Cooking appliances. . . . . . . . 919.4.1, 919.4.2, 919.5.2,

Draft hoods and controls . . . . . . . . . . . . . . . . . 802.12.6

Ducts, commercial kitchen

exhaust . . . . . . . . . . . . . .303.10.1.1, 507.4, 507.4.2.3,

507.4.6.3, 510.7.3,

510.9.1, 510.9.2

Ducts, furnaces. . . . . . . . . . . . . . . . . . . . . . . . . . . 905.2

Ducts, product conveying,

exhaust. . . . . . . . . . . . . . . . . . . . . 303.10.1.2, 506.10,

Equipment on roofs . . . . . . . . . . . . . . . . 303.8, 303.8.4,

303.8.4.1, 304.2, 304.3.1.1

Fans, commercial

kitchen exhaust . . . . . . . . . . . . . . . . . . . . . . . . 510.7.3

Floor furnace . . . . . . . . . . . . . . . . . . . . . . 906.8, 906.12

Food service appliances. . . . . . . . . . 917.2, 918.0-918.4

Furnaces, central heating . . . . . . . . . . 904.3, 904.4.1.2,

Table 904.3.2

Gas-fired toilets. . . . . . . . . . . . . . . . . . . . . . . . . . . 928.1

Gas fireplaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . 912.3

Grease removal devices,

commercial kitchen exhaust . . . . . . . . . . 507.4, 507.4.1,

509.2.2.3

Hoods . . . . . . . . . . . . . . . . . . 506.10.2, 507.4-507.4.2.3,

603.13.6

Illuminating appliances . . . 923.1-923.2.1, Table 923.2.1

Infrared heaters. . . . . . . . . . . . . . . . . . . . . . . . . . . 925.3

Kilns . . . . . . . . . . . . . . . . . . . . . . . . . . 603.13.6, 930.5.1

Listed equipment and appliances . . . . . . . . . . . . . 303.1

Piping, fuel gas . . . . . . . . . . . . . . . . . . . . . . . . . D 110.1

Piping, hydronics . . . . . . . . . . . . . . . . . . . . . . . . . 1221.7

Pool heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 926.3

Prohibited use . . . . . . . . . . . . . . . . . . . . . . 512.1, 701.12

Reduction of . . . . . . . . . . . . 506.10.3, 506.11, 506.11.6,

507.4.2-507.4.2.3, 507.4.3.3

Refrigerators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 927.2

Room heaters. . . . . . . . . . . . . . . . . . . . . . . . . . . 915.3.3

Seepage pans. . . . . . . . . . . . . . . . . . . . . . . . . . . 906.10

Unit heaters. . . . . . . . . . . . . . . . . . . . . . . 916.3, 916.3.1

Unlisted appliances . . . . . . . . . . . . . . . . . 303.3, 303.10

CLOSED COMBUSTIBLE CONSTRUCTION

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

CLOSET OR ALCOVE INSTALLATIONS

Air conditioners . . . . . . . . . . . . . . . . . . . . . . . . 603.13.4

Central heating

furnaces and boilers. . . . . . . . . . . . . . . . 303.2, 904.2

Clothes dryers . . . . . . . . . . . . . . . . . . . 504.4.1, 908.3.1

CLOTHES DRYER

Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 908.3.1

Commercial use. . . . . . . . . . . . . . . . . . . . . . . . . 504.4.3

Common exhaust. . . . . . . . . . . . . . . . . . . . . . . . 504.4.4

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

Domestic type . . . . . . . . . . . . . . . . . . . . . . . . . . 504.4.2

Electric type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 908.2

Exhaust duct . . . . . . . . . . . . . . . . . . . . . . 504.4-504.4.6

INDEX

For multiple family use . . . . . . . . . . . . . . . . . . . . 908.3.3

For public use . . . . . . . . . . . . . . . . . . . . . . . . . . 908.3.3

Makeup air. . . . . . . . . . . . . . . . . . . . . . . . 504.4.1, 701.3

Termination . . . . . . . . . . . . . . . . . . . . . . . 502.2.1, 504.4

Transition ducts. . . . . . . . . . . . . . . . . . . . . . . . 504.4.2.2

Type 1 . . . . . . . . . . . . . 205.0, 504.4.1, 504.4.2, 908.3.1

Type 2 . . . . . . . . . . . 205.0, 504.4.1, 504.4.3.1, 908.3.1

Unlisted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 908.3.1

CODE

Conflicts between . . . . . . . . . . . . . . . . . . . . . . . . . 102.1

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

Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101.3

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

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

COMPRESSOR

Flammable

gas-air mixture. . . . . . . . . . . . . . 1310.14.1, 1310.14.5

Positive displacement . . . . . . . . . . 205.0, 1111.2, 1112.2,

Refrigeration system . . . . . . . . . . . . . . . 1105.2, 1105.3,

1105.6, 1111.2, 1112.2

CONCEALED SPACES

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

Fuel gas piping in . . . . . . . . . . . . . . . . . . . . . . . 1310.4.1

Hazardous process piping in . . . . . . . . . . . . . . 1406.2.1

Lighting units in

commercial kitchen hoods . . . . . . . . 512.2.3, 512.2.4

Used as ducts. . . . . . . . . . . . . . . . . . . . . . . . . . . . 602.1

CONDENSATE

Cleanouts for condensate drain . . . . . . . . . . . . . 310.3.1

Control . . . . . . . . . . . . . . . . . . . . . . . . . . 310.2, 1105.10

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

Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310.1

From air

conditioning equipment . . . . . . . . 310.1, 310.2, 310.5

From air cooling coils . . . . . . . . . . . . . . . . 310.2, 1105.7

From appliances . . . . . . . . . . . . . . . . . . . . . . . . . . 310.4

From category II and

category IV appliances . . . . . . . . . . . . . . . . . . . 802.9

From fuel gas piping . . . . . . . . . . . . . . 1310.9, 1310.9.1

From refrigeration coils . . . . . . . . . . . . . . . . . . . . . 904.7

Point of discharge . . . . . . . . . . . . . . . . . . . . . . . . . 310.5

Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310.1.1

Waste pipe sizing . . . . . . . . . . . . . . . 310.3, Table 310.3

CONDENSER

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

CONDENSING APPLIANCE

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

CONDENSING UNIT

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

CONDITIONED SPACE

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

CONFINED SPACE

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

CONFLICTS BETWEEN CODES . . . . . . . . . . . . . . . . 102.1

CONNECTORS

Appliances, category I . . . . . . . . . . . . . . . . . . . . 802.10,

802.10.1–802.10.1.3,

Table 802.10.1.3

Appliances, category II, III, and IV . . . . . . . . . . . 802.11

Appliance fuel connector. . . . . . . . . . . . . 203.0, 1312.1,

1312.1.1, 1312.3,

1312.5.2, 1312.5.3

Boilers . . . . . . . . . . . . . . . . . . . . . . . . . . Table 802.7.3.3

Chimney . . . . . . . . . . . . . . . 205.0, 802.5.5, 802.10.1.3,

Table 303.10.1, Table 802.10.1.3

Clearances . . . . . . . . . . Table 303.10.1, Table 802.7.3.3

Flexible connectors. . . . . . . . . . . . . . 1312.5.2, 1312.5.3

Gas vent . . . . . . . . . . 224.0, 802.2, 802.3.3.3, 802.5.5,

802.10—802.10.13,

802.11, 803.2–803.2.3,

803.2.11, 803.2.14,

803.2.21 803.2.23,

Table 303.10.1, Table 802.7.3.3,

Table 802.10.1.3, Table 803.2.1

576 2025 CALIFORNIA MECHANICAL CODE

INDEX

Incinerators . . . . . . . . . . . . . . . . . . . . . Table 802.10.1.3

Multiple appliances . . . . . . . . . . . . . . . . . . . . . . . . 803.2

Vibration Isolation . . . . . . . . . . . . . . . . . . . . . . 510.9.1.1

CONSTRUCTION DOCUMENTS

Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205.0

For Permits . . . . . . . . . . . . . . . . . . . . . . . 103.3, 104.3.1

CONTAINERS FOR

Grease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509.2.4.1

Liquid petroleum gas (LP-Gas) . . . . . . . . . . . . . D 104.3

Oil tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D 113.6.2

Refrigerants . . . . . . . . . . (see Refrigerants, containers)

CONTINUOUS ENCLOSURE . . . . . . . . . . . . . . 205.0, 510.7

COOLING

Air system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311.0

Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 904.8

Evaporative cooling system . . . . . . . . . . . . 207.0, 932.0 System, definition . . . . . . . . . . . . . . . . . . . . . . . . . 205.0

Towers . . . . . . . . . . . . . . . . . . . . . . . Chapter 11 (Part II)

Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205.0, 904.9

COPPER OR COPPER

ALLOY PIPE AND TUBING . . . . . . . . . . . . . . . . . . . 1211.4

CORRUGATED STAINLESS STEEL

TUBING (CSST)

Bonding of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1311.2

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

Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1310.3.5

Test pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1313.3

CREMATORIES

Factory built . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 925.3

CROSS-LINKED POLYETHYLENE (PEX)

PIPING OR TUBING

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Ground source loop. . . . . . . Table 1703.2, Table 1703.3

Hydronics . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1,

Table 1220.4.2

Joining and connections. . . . . . . . . . . . . . . . (see Joints

and connections)

Oxygen diffusion . . . . . . . . . . . . . . . . . . . . . . . . . 1210.4

CROSS-LINKED POLYETHYLENE-ALUMINUM-CROSS-

LINKED POLYETHYLENE (PEX-AL-PEX)

PIPING OR TUBING

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Hydronics . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1

Joining and connections. . . . . . . . . . . . . . . . (see Joints

and connections)

– D –

DAMPERS

Automatically

operated . . . . . . . 606.8, 802.14, 802.14.1, E 502.10.2

Backdraft. . . . . . . . . . . . . . . . . . . 504.1.1, 504.4, 1106.6

Balancing. . . . . . . . . . . . . . . . . . . . . . . . . . . . .E 502.3.1

Ceiling radiation . . . . . . . . . . . . . . . . . . . . . 206.0, 606.3

Combination fire and smoke . . . . . . . . . . . 206.0, 606.4

Corridor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 606.5

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.0

Economizers . . . . . . . . . . . . . . . . . . . . . . . . E 503.5.1.1

Fire . . . . . . . . . . . . . . . . . 206.0, 508.3.5.3, 508.3.5.3.1,

511.4.2, 516.2.6,

606.2, 606.8, 932.1

Fire and smoke, access to . . . . . . . . . . . . . . . . . . 606.8

Freedom from interference . . . . . . . . . . . . . . . . . . 606.9

Heating, ventilation,

and air conditioning . . . . . . . . . . . . . . . . . . . E 502.12

HVAC system tests of . . . . . . . . . . . . . . . . . . . . E 805.0

Identification of . . . . . . . . . . . . . . . . . . . . . . . . . . . 606.8

In ducts, commercial

kitchen exhaust . . . . . . . . . . . . . . . . . . 512.1, 512.1.1

In duct furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . 905.7

Manually operated . . . . . . . . . . . . . . 802.13, E 502.10.2

Maximum leakage . . . . . . . . . . . . . . . . . . E 503.4.6.4.2

Motorized, nonrecirculating

air heating. . . . . . . . . . . . . . . . . . 914.7, E 503.4.6.4.1

Multiple arrangements . . . . . . . . . . . . . . . . . . . . . 606.7

Return air . . . . . . . . . . . . . . . . E 503.5.1.3, E 805.5.1.2,

E 805.5.2, E 805.12.1.1

Smoke. . . . . . . . . . . . . . . . . . . . . . . 206.0, 606.1, 606.8

Supply air . . . . . . . . . . . . . E 503.4.6.4.1, E 503.4.6.4.2

Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1003.4

Vent . . . . . . . . . . . . . 802.13, 802.14, 802.14.1, C 109.1

Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.0

DECORATIVE

APPLIANCES, VENTED . . . . . . . . . . . . (see Appliances)

DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 2

DEPARTMENT

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.0

DESIGN

Requirements for Ethylene Oxide (ETO)

Sterilization Areas . . . . . . . . . . . . . . . . . . . . . 418.0

DESIGN FLOOD ELEVATION . . . . . . . . . . . . . . . . . . . 206.0

DEVICES

Automatic control . . . . . . . . . . . . . . . . . . . . . . . . . 306.0

Detection. . . . . . . . . . . . . . . . . . . . . . . . . 206.0, 514.2.3

Draft control, fuel gas vent . . . . . . . . . . . . . . . . 802.12.2

Grease removal . . . . . . . . . . . . . . 209.0, 507.4, 507.4.1,

509.0, 513.1.2,

514.4.2, 517.5, 517.7.1

Pressure limiting . . . . . . . . . 218.0, 904.5, 926.4, 1111.0

Pressure relief . . . . . . . . . . . . . . . . 218.0, 904.7, 1112.0,

1113.0, 1115.4, 1206.1

Quick-disconnect . . . . . . . . . . . 219.0, 1312.3.2, 1312.7

DISTRICT HEATING PLANT

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.0

INDEX

DRAFT CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . 802.12

DRAFT HOODS . . . . . . . . . . . . . . . . 206.0, 802.5.5, 802.6.2

DRAINAGE

Boiler rooms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1001.4

Cooling tower . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1121.0

Hydronic piping system . . . . . . . . . . . . . . . . . . . . 1221.4

DRAINAGE PANS . . . . . . . . . . . . . . . . 305.5, 310.2, 1105.7

DUCTLESS MINI-SPLIT SYSTEMS . . . . . . . . . . . . . . 934.0

DUCT(S) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 6

Air Dispersion . . . . . . . . . . . . . . . . . . . . 602.5.3, 603.12

Clothes dryers. . . . . . . . . . . . . . . . . . . . . 504.4, 504.4.2

Combustion air . . . . . . . . . . . . . . 701.6.1, 701.11, 701.12

Combustibles within . . . . . . . . . . . . . . . . . . . . . . . 602.2

Construction of

(product conveying). . . . . . . . . . . . . . . . . . . . . . 506.2

Cross contamination . . . . . . . . . . . . . . . . . . . . . . 603.10

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.0

Domestic range vents . . . . . . . . . . . . . . . . . . . . . . 504.3

Ducts [OSHPD] . . . . . . . . . . . . . . . . . . . . . . . . . . 409.0

Environmental air. . . . . . . . . . . . . . . . . . . . 206.0, 504.0

Exhaust, commercial kitchen . . . . . . . . . . . . . . . . 510.0

Existing metal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.2

Factory-made air. . . . . . . . . . . . . 603.4, 603.4.1, 603.7

Fire protection required . . . . . . . . . . . . . . . . . . . . . 506.8

Flexible air ducts and connectors. . . . . . . . . . . . . . 603.4,

603.4.1.1, 603.7.2

For kilns . . . . . . . . . . . . . . . . . 603.13.6, 930.5.3, 930.6

Furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.0, 905.0

Gravity ventilation . . . . . . . . . . . . . . . . . . . . . . . 930.5.3

Grease type . . . . . . . . . . . . . . . . . . . . . . . . 206.0, 510.0

Gypsum wallboard . . . . . . . . . . . . . . . . . . . . . . . 602.5.2

In under floor or crawl spaces. . . . . . . . . . . . . . . . 603.2

Inspection and cleaning of . . . . . . . . . . . 514.2, 514.4.2

Insulation of . . . . . . . . . . . . . . . . . . 605.0, 605.2, 605.3,

E 502.4.1, E 503.4.7.1,

Table E 503.7.2–Table E 503.7.3(2)

Joints and seams . . . . . . . . . . . . . . . . . . . . . . . . . 603.9

Leakage test . . . . . . . . . . . . . . . . . . . 603.9.2 , 603.9.2.1

Manifold (common duct) . . . . . . . . . . . . . . . . . . . . 511.4

Material of . . . . . . . . . . . . . . . . . . 506.1, 510.5.1, 602.0

Metal . . . . . . . . . . . . . . . . . 506.1, 602.5, 603.3, 603.7.1

Non-grease type. . . . . . . . . . . . . . . . . . . . . 519.4, 519.5

Nonmetallic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 602.5

Openings. . . . . . . . . . . . . . . . 510.3, 510.3.3–510.3.3.2,

510.3.4.2, 511.1.5

Other grease . . . . . . . . . . . . . . . . . . . . . . 510.5, 602.5.4

Plastic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 603.5

Product-conveying . . . . . . . . . . . . . . . . . 206.0, 502.2.2,

506.0, Table 506.2(1),

Table 506.2(2)

Protection of. . . . . . . . . . . . . . . . . . . . . . . . 506.9, 603.6

Return duct sizing . . . . . . . . . . . . . . . . . . . . . . . 601.2.1

Smoke Detectors . . . . . . . . . . . . . . . . . . . . . . . . 609.1.1

Solid-fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517.0

Support systems . . . . . . . . . . .504.4.5, 506.7–506.8.4,

510.1.6, 510.1.7, 510.3.3.3,

510.5.1, 603.3, 603.7

Termination . . . . . . . . . . . . . . . . . . 222.0, 502.2, 510.9,

519.5, 701.11

Underground. . . . . . . . . . . . . . . . . . . . . . . 510.8, 603.11

– E –

ECONOMIZER, AIR . . . . . . . . . . . . . E 503.5.1, E 503.5.1.2,

Table E 503.5.1.2

ECONOMIZER, WATER . . . . . . . . . . E 503.5.2, E 503.5.2.1,

Table E 503.5.2

ECONOMIZERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407.6

ELECTRIC HEATING APPLIANCES

Air conditioners . . . . . . . . . . . . . . . . . . . . . . . . . . . 903.1

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Duct heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 905.9

Room heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 915.2

ELECTRICAL CODE

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207.0

ENCLOSED PARKING GARAGES . . . . . . . . . . . . . . 403.7.2

Alternative Exhaust Ventilation. . . . . . . . . . . . . 403.7.2.1

Exhaust Systems Operation. . . . . . . . . . . . . . . 403.7.2.4

Minimum Exhaust Rate . . . . . . . . . . . . . . . . . . 403.7.2.2

ENCLOSURE OF DUCTS,

COMMERCIAL KITCHEN EXHAUST

Clearances . . . . . . . . . . . . . . 507.4.6.3, 507.4.8, 510.7.3

Continuous. . . . . . . . . . . . . . . . . . . . . . . . . 205.0, 510.7

Ducts within . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510.7.8

Fire doors required . . . . . . . . . . . . . . . . . . . . . . . 510.7.7

Grease, factory built . . . . . . . . . . . . . . . . 208.0, 507.4.4,

507.4.6, 507.4.6.3

Grease duct, field-applied. . . . . . . . . . . . 208.0, 507.4.5,

507.4.6, 507.4.6.3

Product conveying ducts . . . . . . . . . . . . . . . . . . . . 505.8

ENCLOSURES

For equipment on roof. . . . . . . . . . . . . . . . . . . . . . 303.8

For boilers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1001.2

ENERGY STAR, DEFINITION . . . . . . . . . . . . . . . . . . E 201.1

ENFORCEMENT (SFM) . . . . . . . . . . . . . . . . . . . . . . . 1.11.2.1

ENFORCING AGENCY

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207.0

SFM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.11.2

ENGINE, GAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1602.0

EQUIPMENT

Clearances. . . . . . . . . 303.10, 303.10.1, Table 303.10.1

Converted equipment . . . . . . . . . . . . . . . . . . . . . . 902.3

578 2025 CALIFORNIA MECHANICAL CODE

INDEX

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207.0

Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301.3

Identification of . . . . . . . . . . . . . . . . . . . . . . . . . . . 303.6

Improper location . . . . . . . . . . . . . . . . . . . . . . . . . 308.0

Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303.2

On roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . 303.8, 304.0

Protection against flood damage. . . . . . . . . . . . . . 305.3

Service and access. . . . . . . . . . . . . . . . . . . . . . . . 304.0

Types of Fire Extinguishing Equipment. . . . . . . . . 513.2

ESSENTIAL MECHANICAL PROVISIONS . . . . . . . . . . 321.0

ETO STERILIZATION AREAS . . . . . . . . . . . . . . . . . . . . 418.0

EVAPORATIVE

Condenser . . . . . . . . . . . . . . . . . 1119.1, 1120.1, 1123.1

Cooler. . . . . . . . . . . . . . . . . . . . . . 207.0, 932.3, E 403.2

Cooler, portable, definition . . . . . . . . . . . . . . . . . . 218.0

Cooling system . . . . . . . . . . . . . . . . 207.0, 406.0, 932.0

EVAPORATOR

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207.0

EXCESS FLOW VALVE . . . . . . . . . . . . . . . . . . . . . . . . 207.0,

1309.0, 1406.2.1.5

EXHAUST

Bathroom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405.3

Clothes dryer . . . . . . . . . . . . . . 504.4, 504.4.2–504.4.5

Commercial kitchen. . . . . . . . . . . . . . Chapter 5 (Part II)

Discharge, type I

and type II system . . . . . . . . . . . . . . . . . 519.5, 510.9,

Ducts . . . . . . . . . . . . . . . . . . . . . . . 504.0, 506.0, 510.0,

Chapter 6, 1106.8

Independent system . . . . . . . . . . . . . . . . 504.2, 517.3.1

Kitchen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405.4

Mechanical . . . . . . . . . . . . . . . . . . . 405.3, 405.4, 403.7,

Chapter 5, 1105.5.2,

1106.0, Table 403.7

Product conveying. . . . . . . . . . . . . . 218.0, 505.0, 506.0

Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . 403.7.1, 405.3.1,

405.4.1, E 503.5.11.2.1,

E 503.5.11.3, Table 403.7

Refrigeration

machinery room . . . . . . . . . . . . . . . . 1105.5.2, 1106.0

Separation from

other exhaust . . . . . . . . . . . . . . . . . . . . 504.2, 517.3.1

Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414.1

Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 502.0

Ventilator openings. . . . . . . . . . . . . 311.3, 502.1, 1106.6

EXISTING BUILDINGS . . . . . . . . . . . . . . . . . . . . . . . 302.1.3

EXISTING MECHANICAL SYSTEMS . . . . . . . . . . . . . 102.2

EXPANSION TANKS

Closed-type . . . . . . . . . . . . . . . . . . . . . . 1004.3, 1209.3

Minimum capacity . . . . . . . . . . 1004.4, Table 1004.4(1),

Table 1004.4(2)

Open-type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1004.2

Where required. . . . . . . . . . . . . . . . . . . . 1004.1, 1209.1

– F –

FAMILY

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208.0

FANS . . . . . . . . . . . . . . . . . . . . . . . . . 503.0, 510.9.1.2, 511.0

FEES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.5

For investigations . . . . . . . . . . . . . . . . . . . . . . . . 104.5.1

For permits . . . . . . . . . . . . . . . . . . . . 104.5, Table 104.5

For plan review. . . . . . . . . . . . . . . . . . . . . . . . . . 104.3.2

For re-inspection . . . . . . . . . . . . . . . . . . . . . . . . 105.2.6

Mechanical permit fees . . . . . . . . . . . . . . . . Table 104.5

Refunds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.5.3

FILTERS

Air . . . . . . . . . . . . . . . . . . . . . . . . . . 311.0, 408.2, 408.3,

408.4, 408.5, 602.2

Filter Efficiencies . . . . . . . . . . . . . . Table 4-B, Table 4-C

Grease . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209.0, 509.1

Hospitals, for . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408.2

In recirculating systems. . . . . . . . . . . . . . . . . . . . . 516.3

MERV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401.3

Outpatient Facilities . . . . . . . . . . . . . . . . . . . . . . . 408.4

Return air . . . . . . . . . . . . . . . . . . . . . E 603.1.1, E 603.3

Residential Air Filtration . . . . . . . . . . . . . . . . . . . . . 311.5

Skilled Nursing Facilities, Intermediate Care

Facilities, and Correctional Treatment Centers . . . . 408.3

FIRE

Code, definition. . . . . . . . . . . . . . . . . . . . . . . . . . . 208.0

Damper . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.0, 606.0

Doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510.7.7

Extinguishing equipment . . . . . . . . 513.0, 513.12, 517.7

Fire-resistive

construction, definition . . . . . . . . . . . . . . . . . . . 208.0

Partition, definition . . . . . . . . . . . . . . . . . . . . . . . . 208.0

Resistance rating, definition . . . . . . . . . . . . . . . . . 208.0

Wall, definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . 208.0

FIREPLACE

Decorative appliance for . . . . . . . . . . . . . . . . . . . .911.0

Factory-built . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .913.0

Gas vents . . . . . . . . . . . . . . . . . . . . . . . .912.0, E 602.1

Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .911.4

Stove, definition . . . . . . . . . . . . . . . . . . . . . . . . . . .208.0

Venting . . . . . . . . . . . . . . . . . . . . . . .802.0, 911.4, 912.0

Wood burning . . . . . . . . . . . . . . . . . . . . . . . . . .E 602.1

FITTINGS

Fuel gas piping . . . . . . . . . . . . . . . 1308.4.4, 1308.4.8,

1308.4.7.4, 1310.4.1

Fuel gas vent . . . . . . . . . . . . . . . . . . . .803.2.8, 803.2.9

Hydronic piping . . . . . . . . . . . . . . .1210.0, Table 1210.1

Refrigeration piping . . . . . . . . . . . . . .1109.1.1, 1109.1.2

FLAMMABLE VAPORS

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .208.0

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .902.9

INDEX

FLOOD RESISTANT CONSTRUCTION

Coastal high hazard area . . . . . . . . . . . .205.0, 305.3.1

Design flood elevation . . . . . . . . . . . . . . . . . . . . . .206.0

Flood hazard area . . . . . . . . . . . . . . . . . . . . . . . . .208.0

Flood hazard resistance . . . . . . . . . . . . . . . . . . . .305.3

FLOOR FURNACE . . . . . . . . .(see Furnaces, floor furnace)

FUEL

Appliance . . . . . . . . . . . . . . . . . . . . . .(see Appliances)

Appliance, connectors, definition . . . . . . . . . . . . .203.0

Shutoff . . . . . . . . . . . . . . . . . . . . .513.4, 513.8, C 102.0,

Table 1003.2.1

Solid-fuel cooking . . . . . . . . . . . . .221.0, 508.6, 510.10,

511.1, 511.5, 513.12, 517.0

Temporary connection . . . . . . . . . . . . . . . . . . . . . .105.4

FUEL APPLIANCE CONNECTOR

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

FUEL GAS

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209.0

FUEL GAS MIXING

BLOWERS AND MACHINES . . . . . . . . . . . . . . 1310.14.3,

1310.14.4, 1310.14.5

FUEL GAS PIPING

Cathodic protection . . . . . . . . . . . . . . . . . . . . . . D 105.0

Change in direction . . . . . . . . . . . . . . . . . . . . . 1310.8.3

Concealed location . . . . . . . . . . . . . . . . . . . . . . . 1310.3

Detection of leaks . . . . . . . . . . . . . . . . . . . . . . . . 1313.4

Electrical bonding and grounding. . . . . . . . . . . . . 1311.0

Inspection and testing . . . . . . . . . . . . . . 1303.0, 1313.0

Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1310.0

Interconnections . . . . . . . . . . . . . . . . . . . . . . . . . 1308.2

Joints and fittings . . . . . . . . . . . . . . 1308.4.4–1308.4.8,

1313.2.1, 1313.2.2

Materials. . . . . . . . . . . . . . . . . . . . . . . . 1308.4, D 109.0

Obstruction of flow. . . . . . . . . . . . . . . . . . . . . . . 1310.12

Pressure regulators . . . . . . . . . . . . . . . . . . . . . . 1308.14

Purging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1313.6 Sizing . . . . . . . . . . . . . 1308.3, 1314.0, 1315.0, D 108.0, Table 1315.2(1)–Table 1315.2(36) Supports. . . . . . . . . . . . . . . . 1310.3.5, Table 1310.3.5.1

Underground

installations . . . . . . . . 1308.4.2.4, 1308.4.3.4, 1310.0,

D 101.2, D 109.3, D 110.3

Venting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1308.6.4

FUEL GAS TUBING

Cathodic protection . . . . . . . . . . . . . . . . . . . . . . D 105.0 Change in direction . . . . . . . . . . . . . . . . . . . . . 1310.8.3

Concealed location . . . . . . . . . . . . . . . . . . . . . . . 1310.4

Detection of leaks . . . . . . . . . . . . . . . . . . . . . . . . 1313.4

Electrical bonding and grounding. . . . . . . . . . . . . 1311.0 Inspection and testing . . . . . . . . . . . . . . 1303.0, 1313.0

Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1310.0

Interconnections . . . . . . . . . . . . . . . . . . . . . . . . . 1308.2

Joints and fittings . . . . . . . . . . . . . . 1308.4.4–1308.4.8,

1313.2.1, 1313.2.2

Materials. . . . . . . . . . . . . . . . . . . . . . . . 1308.4, D 109.0

Obstruction of flow. . . . . . . . . . . . . . . . . . . . . . . 1310.12

Purging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1313.6 Sizing . . . . . . . . . . . . . 1308.3, 1314.1, 1315.0, D 108.0,

Table 1315.2(1)–Table 1315.2(36)

Supports. . . . . . . . . . . . . . . . 1310.3.5, Table 1310.3.5.1

Underground installations . . . . . . . . . . . . . . 1308.4.2.4,

1308.4.3.4, 1310.1,

D 101.2, D 109.3, D 110.3

Venting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1308.6.4

FURNACES

Approximate gas input . . . . . . . . . . . . . . Table 1308.3.1

Automatic control required . . . . . . . . . . . . . . . . . . 608.6

Central heating furnaces . . . . . . . . . . . . . . 303.2, 904.0 Clearance for servicing . . . . . . . . . . . . . . . . . . . 304.4.3,

905.9.2, 906.12

Clearances . . . . . . . . . . . . . . . 303.10, 303.10.1, 904.3,

904.4.1.2, 905.2, 906.8,

Table 303.10.1, Table 904.3.2

Downflow-type,

heating, definition . . . . . . . . . . . . . . . . . . . . . . .208.0

Duct furnace . . . . . . . . . . . . . . . . . . . . . . .206.0, 905.0

Enclosed furnace, definition . . . . . . . . . . . . . . . . .208.0

Floor furnace . . . . . . . . . . . . . . . . . . . . . . .208.0, 906.0

Forced-air heating, definition . . . . . . . . . . . . . . . . .208.0

Furnace plenums . . . . . . . . . . .802.3.5, 903.2.4, 904.8

Gravity-type, floor

furnace, definition . . . . . . . . . . . . . . . . . . . . . . . 209.0

Horizontal-type furnace . . . . . . . . . . . . . . 208.0, 904.10

Oil-fired central furnace. . . . . . . . . . . . . . . . . . . . 904.12

Seepage pan, floor furnace. . . . . . . . . . . . . . . . . 906.10

Solid fuel furnace . . . . . . . . . . . . . . . . . . . . . . . . 904.10

Upflow-type, heating . . . . . . . . . . . . . . . . 208.0, 904.10

Wall furnace, vented. . . . . . . . 224.0, 907.0, Table 802.4

Warm air . . . . . . . . . . . . . . 225.0, 608.6, 608.7, C 105.1

FUSIBLE LINK

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208.0

FUSIBLE PLUG

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208.0

– G –

GALVANIZED STEEL

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209.0

GAS CONVENIENCE OUTLET . . . . . . . . . . . . . . . . . 1312.8

GAS ENGINE, STATIONARY . . . . . . . . . . . . . . . . . . 1602.0

GAS ENGINES,

AIR CONDITIONERS . . . . . . . . . . . . . . . . . . . . . . 903.2.3

GAS VENT CONNECTOR . . . . . . . . . . . . . (see Connectors,

gas vent)

580 2025 CALIFORNIA MECHANICAL CODE

INDEX

GAS VENT,

SURROUNDING SPACE . . . . . . . . . . . . . . . . . . . 802.5.11

GAS-FIRED

Air conditioners

and heat pumps . . . . . . . . . . . . . . . . . . . . . . . . 903.2

Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 903.2.1

Clothes dryers. . . . . . . . . . . . . . . . . . . . . . . . . . . . 908.3

Household cooking appliances . . . . . . . . . . . . . . . 919.3

Industrial air heaters . . . . . . . . . . . . . . . . . . . . . . . 914.0

Packaged terminal . . . . . . . . . . . . . . . . . . . . . . . . 903.3

Room heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 915.3

Toilets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 928.0

GAS FIREPLACE, VENTED . . . . . . . . . . . . . . . . . . . . 912.0

GAS TURBINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1602.2

GASEOUS HYDROGEN SYSTEMS . . . . . . . . . . . . . . 936.0

GAUGES, STEAM BOILERS . . . . . . . . . . . . . . . . . . 1003.3

GENERATORS

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209.0

Emergency Diesel-Powered . . . . . . . . . . . . . . . . . 324.0

Engine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1602.0

Steam. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 917.2, 1011.0

GEOTHERMAL ENERGY SYSTEMS . . . . . . . . . Chapter 17

Ambient Temperature Loops . . . . . . Chapter 17 (Part V)

Closed-loop systems . . . . . . . . . . . . Chapter 17 (Part II)

Decommissioning and abandonment . . . . . . . . . 1709.0

Design of systems. . . . . . . . . . . . . . . . . . . . . . . . 1703.0

Direct exchange systems . . . . . . . . Chapter 17 (Part IV)

General . . . . . . . . . . . . . . . . . . . . . . Chapter 17 (Part I)

Groundwater systems . . . . . . . . . . . . . . . . . . . . . 1702.0

Heat pumps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1704.0

Heat transfer fluid. . . . . . . . . . . . . . . . . . . . . . . . 1701.11

Installation practices . . . . . . . . . . . . . . . . . . . . . . 1707.0

Open-loop systems. . . . . . . . . . . . . Chapter 17 (Part III)

Specific system components design . . . . . . . . . . 1706.0

System start-up. . . . . . . . . . . . . . . . . . . . . . . . . . 1708.0

Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1705.0

GRAVITY

Definition, heating system. . . . . . . . . . . . . . . . . . . 209.0

Type floor furnace. . . . . . . . 209.0, 306.1, Table 904.3.2

Venting system. . . . . . . . . . . . . . . 224.0, 930.5.3, 930.6

GREASE

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209.0

Ducts . . . . . . . . . . . . . . . . . . . . . 209.0, 510.1.3, 510.1.7

Ducts, four stories or more . . . . . . . . . . . . . . . . . 517.4.2

Drip trays. . . . . . . . . . . . . . . . . . . . . . 509.2.4, 509.2.4.1

Filter mesh type, definition . . . . . . . . . . . . . . . . . . 209.0

Filters . . . . . . . . . . . . . 209.0, 509.1, 509.2.3, 509.2.3.4,

509.2.4, 509.2.5, 516.3.2

Laden vapors. . . . . . . . . . . . . . . . 507.2, 508.3.1, 508.5,

511.2.2, 511.4.6,

513.1.2, 516.1

Receptacle. . . . . . . . . . . . . . . . . . . . 511.1.2.1, 511.1.3.1,

511.1.3.2

Removal devices . . . . . . . . . . . . . . 209.0, 507.4, 509.0,

513.1, 513.2.5,

516.1, 517.5

Vapors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.3.1

GRILLES AND LOUVERS . . . . . . . . . . . . . . . . . . . . . 701.10

GROUNDING ELECTRODE . . . . . . . . . . . . . . 209.0, 1311.0

– H –

HANGERS AND SUPPORTS

Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .303.4

Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . .506.7, 510.1.6,

510.1.7, 603.3

Fuel gas piping . . . . . . . . . . . . . . . . . . .313.7, 1310.3.5,

Table 1310.3.5.1

Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . .916.2, 925.2

Hydronics system piping . . . . . . . . . . . . . . . . . . .1210.3

In ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313.5

Piping and tubing . . . . . . . . . . . . . . .313.0, Table 313.3

Refrigeration equipment . . . . . . . . . . . . . . . . . . .1105.2

HEALTH FACILITIES . . . . . . . . . . . . . . . . . . . . . . . . . . .318.1

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .210.0

HEATED SLAB FLOORS . . . . . . . . . . .1217.8.2.1, 1220.4.7.1

HEAT RECOVERY VENTILATION

(HRV) AND ENERGY RECOVERY

VENTILATION (ERV) SYSTEMS . . . . . . . . . . . . . . .504.5

HEAT PUMPS

Auxiliary Heat Control . . . . . . . . . . . . . . . . . E 503.4.6.6

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0

Hydronic (water loop) . . . . . . E 503.5.5.2.3, E 503.5.7.5

In low-rise buildings . . . . . . . . . . . . . E 502.0, E 502.7.2

Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 903.2

Labeling . . . . . . . . . . . . . . . . . . . . . . 307.3, E 503.4.4.1

Minimum efficiency . . . . . . . . . . . . . . . . . Table E 502.9,

Table E 503.7.1(2),

Table E 503.7.1(4)

Nameplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307.3

Other than

low-rise buildings, HVAC. . . . . . . . . . . . . . . E 503.3.1

Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E 805.3

HEATER

Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.0

Aircraft hangars. . . . . . . . . . . . . . . . . . . . . . . . . . 303.12 Clearances . . . . . . . . . . . . . . . . . . . . . (see Clearances)

Direct gas-fired industrial air . . . . . . . . . . . . . . . . . 914.0

Duct, electric. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306.1

Efficiency . . . . . . . . . . . . . . . . . . . . . . Table E 503.7.1(5)

Infrared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 925.3

Pool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 926.0

Radiant room, definition . . . . . . . . . . . . . . . . . . . . 220.0

INDEX

Room . . . . . . . . . . . . . . . . . . . . . . 220.0, 802.2.1, 915.0

Sauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 939.0

Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223.0, 916.0

Wall. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225.0

Water. . . . . . . . . . . . . . . . . . . . . 225.0, 802.2.1, 1203.2,

1203.3, Table 1203.2

HEATING

Air system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311.0 Appliances. . . . . . . . . . . . . . . (see Appliances, heating)

Equipment, industrial,

definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.0

Gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209.0

Plant, central, definition. . . . . . . . . . . . . . . . . . . . . 205.0

Plant, district, definition. . . . . . . . . . . . . . . . . . . . . 206.0

System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0, 311.0

HEATING DEGREE DAY

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0

HIGH-RISE BUILDING

Existing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.11.3.4

Fees. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.11.4

New Construction. . . . . . . . . . . . . . . . . . . . . . . . 1.11.3.3

HOODS

Airflow rate. . . . . . . . . . . . . . . . . . . . . . 508.5, 508.5.2.2

Canopy-type. . . . . . . . . . . . . . . . . . . . . 508.5.1, 930.5.2 Capacity . . . . . . . . . . . . . . . . . . . . . 508.5.1.1, 508.5.2.2 Ceiling Technology. . . . . . . . . . . . . . . . . . . . . . . 508.2.2 Clearance . . . . . . . . . . . . . (see Clearances for, hoods) Commercial cooking . . . . . . . . . . . . . . . . . . . . . . . 508.0 Compensating. . . . . . . . . . . . . . . . . . . . . . . 210.0, 511.3 Construction. . . . . . . . . . . . . . . . . 508.3, 519.2, 508.3.2

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0

Draft . . . . . . . . . . . . . . . . . . . . . . . 206.0, 802.12, 905.5

Eyebrow-type. . . . . . . . . . . . . . . . . . . . . . . . . . . 508.3.3

Exhaust outlet. . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.7

Fixed baffle . . . . . . . . . . . . . . . . . . . . . . . 210.0, 513.2.5

For dishwashing machines . . . . . . . . . . . 519.1, 519.3.1

For kilns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 930.5.2

Grease removal devices in . . . . . . . . . . . . . . . . . . 509.0

Inspection and cleaning . . . . . . . . . 514.2, 514.3, 514.4

Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.3.4

Integrated supply-air plenums . . . . . . . . . . . . . . 508.3.5 Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.5.3

Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.1

Noncanopy-type. . . . . . . . . . . . . . . . . . . . . . . . . 508.5.2 Product conveying. . . . . . . . . . . . . . . . . . . . . . . . . 506.0 Seams, joints and penetration . . . . . . . . . . . . . . 508.3.2

Size. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.5

Solid-fuel. . . . . . . . . . . . . . . . . . . . . . . . . . . 508.6, 517.3

Type I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0, 508.3 Type II. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0, 519.0

Ultraviolet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.2.1

Ventilating . . . . . . . . . . . . . . . . . . . . . . 802.2.1, 802.2.4,

802.3.4, 802.12, 921.2

HOT PLATES . . . . . . . . . . . . . . . . . . . . . . . . . . 918.2–918.4,

HYDRONIC SPACE HEATING . . . . . . . . . . . . . . . . . 1215.0

HYDRONICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 12

Auxiliary systems . . . . . . . . . . . . . . . . . . . . . . . . 1220.0

Appliances and equipment . . . . . . . . . . . . . . . . . 1207.0

Boilers . . . . . . . . . . . . . . . . . . 1207.2, 1207.2.1, 1207.2.2

Circulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1208.0

Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1221.7

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0

Embedded piping and joints . . . . . . . . . . . . . . . . 1221.2

Expansion tanks . . . . . . . . . . . . . . . . . . . . . . . . . 1209.0

Hangers and supports. . . . . . . . . . . . . . . . . . . . . 1210.3

Heat emitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1201.7

Heat pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207.5

Heat sources . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203.1

Heat transfer fluid . . . . . . . . . . . . . . . . . . 1201.3, 1204.7

Identification of piping . . . . . . . . . . . . . . . . . . . . . 1204.0

Installation . . . . . . . . . . . . . . . . . . . . . . . 1205.0, 1221.0

Insulation. . . . . . . . . 1201.2, 1217.8.2, 1217.10, 1220.4.7

Joints and connections . . . . . . . . . . . . . . . . . . . . 1211.0

Materials . . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1

Protection of potable water supply . . . . . . . . . . . 1202.0

Radiant heating and cooling . . . . . . . . . . . . . . . . 1217.0

Snow melt systems . . . . . . . . . . . . . . . . 1220.4, 1220.0,

1217.8.2, Table 1220.4.2

Safety devices. . . . . . . . . . . . . . . . . . . . . . . . . . . 1206.0

Steam systems . . . . . . . . . . . . . . . . . . . . . . . . . . 1216.0

Testing . . . . . . . . . . . . . . . . . . . . . . . . . . 1205.2, 1221.3

Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1212.0

Water heaters . . . . . . . . . . . . . . . . . . . . 1203.2, 1203.3,

1207.3, Table 1203.2

– I –

IDLH

Definition,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.0

Refrigeration . . . . . . . . . . . . . . . . 1106.2.5, 1106.11.10.3

INCINERATORS

Commercial and

industrial type . . . . . . . . . . . . . . . . . . . . . . . . . . 924.0

Fume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208.0, 512.3

Residential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 924.3

INDOOR HORTICULTURAL FACILITIES . . . . . . Appendix I

Carbon dioxide detection systems . . . . . . . . . . . . I 601.0

Chemical storage. . . . . . . . . . . . . . . . . . . . . . . . I 1301.0

Classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . I 301.0

Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 1001.0

Fire protection . . . . . . . . . . . . . . . . . . . . . . . . . . . I 501.0

Flammable solvents. . . . . . . . . . . . . . . . . . . . . . . I 701.0

Fumigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 1601.0

Particulate and odor control. . . . . . . . . . . . . . . . . I 901.0

Ventilation and exhaust system . . . . . . . . . . . . . . I 801.0

582 2025 CALIFORNIA MECHANICAL CODE

INDEX

INDUSTRIAL HEATING EQUIPMENT

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.0

INSANITARY LOCATION

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.0

INSPECTIONS

Chimneys. . . . . . . . . . . . . . . . . . . . . . . 802.5.6, 802.5.7

Commercial kitchen

exhaust system, schedule of . . . . . . . . . . Table 514.3

Evaporative cooler . . . . . . . . . . . . . . . . . . . . . . . . 932.3

Fire-extinguishing equipment . . . . . . . . . . . . . . . . 514.2 Fuel gas piping . . . . . . . . . . . . . 1303.0, 1304.0, 1313.1

Reinspections . . . . . . . . . . . . . . . . . . . . . . . . . . 105.2.6

Requests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105.2.3

INSTALLATIONS OF

Appliances in manufactured housing . . . . . . . . . . 929.0 Appliances in garages. . . . . . . . . . . . . . . . . . . . . . 305.1 Appliances in repair garages . . . . . . . . . . . . . . 303.11.2

Ducts. . . . . . . . . . . . . . . . . . . . . . . . . . . . 510.5.3, 603.0

Equipment and appliances . . . . . . . . . . . . . . . . . . 303.0 Gas piping . . . . . . . . . . . . . . . . . . . . . . . 1310.0, 1310.3,

1310.10, 1312.10

Overhead heaters in commercial

garages and aircraft hangars . . . . . . . . . 905.8, 925.5

INSULATION OF

Ducts . . . . . . . . . . . . . . . . . . . 506.11.2, 506.11.3, 605.0,

E 502.4.1, E 503.4.7,

Table E 503.7.2,

Hoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.3.4

Hydronic systems. . . . . . . . . . . . . . . . . 1201.2, 1220.4.7,

1217.8.2, 1217.8

HVAC system piping. . . . . . . . . . E 502.5, E 503.4.7.1.2,

Table E 502.5,

Table E 503.7.3(1)

INTERLOCK

Air heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.7

Cooking equipment

ventilation . . . . . . . . . . . . . . . . . . . . . . 517.1.3, 517.6.2

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.0

Exhaust. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503.1

Gas mixing machines. . . . . . . . . . . . . . . . . . . 1310.14.5

Inspection of safety . . . . . . . . . . . . . . . . . . . . . . 516.6.4

Mechanical air supply . . . . . . . . . . . . . . . . . . . . . 701.9.2

Motorized louvers . . . . . . . . . . . . . . . . . . . . . . . 701.10.2

Recirculating systems . . . . . . . . . . . . . . . . . . . . . . 516.3 Stack dampers . . . . . . . . . . . . . . . . . . . . . . . . . . 1003.4

– J –

JOINTS AND CONNECTIONS . . . . . . . . . . . . . . . . . 1109.2,

1109.8, 1211.0,

1308.4.8–1308.4.9.6

Brazed joint . . . . . . . . . . . . . . . . . . . . . . . 212.0, 1211.4 Copper or copper alloy pipe or tubing . . . . . . . 1109.2, 1211.4, 1211.16.1

CPVC piping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1211.3

Embedded piping and joints . . . . . . . . . . . . . . . . 1221.2

Expansion joint. . . . . . . . . . . . . . . . . . . . . . . . . 1313.2.2

Flared. . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.0, 1211.4,

1308.4.7.4, 1308.4.7.5

Mechanical joint . . . . . . . . . . . . . . 212.0, 1109.7, 1211.6,

1211.7, 1211.9, 1211.10,

1211.13, 1211.14,

1308.4.8.3

PE pipe or tubing . . . . . . . . . . . . . . . . . . . . . . . . . 1211.9

PE-AL-PE pipe or tubing . . . . . . . . . . . . . . . . . . 1211.10

PE-RT piping or tubing. . . . . . . . . . . . . . . . . . . . 1211.11

PEX pipe or tubing. . . . . . . . . . . . . . . . . . . . . . . . 1211.6

PEX-AL-PEX pipe or tubing . . . . . . . . . . . . . . . . . 1211.7

Plastic piping, joints, and fittings . . . . . . . . . . . 1211.16.2

PP piping or tubing. . . . . . . . . . . . . . . . . . . . . . . 1211.12

Press-Connect, definition . . . . . . . . . . . . . . . . . . . 212.0

PVC piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1211.13 Soldered joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.0

Solvent cement

plastic pipe . . . . . . . . . . . . . . . . . . . . . 1211.3, 1211.13

Steel pipe or tubing . . . . . . . . . . . . . . . . 1109.2, 1211.14

Threaded joint . . . . . . . . . . . . . . . . . . . . 1211.3, 1211.14

Various materials . . . . . . . . . . . . . . . . . . . . . . . . 1211.16

Welded joint. . . . . . . . . . . . . . . . . . . . . . . 212.0, 1211.14

JUMPER, BONDING

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0

Fuel gas piping. . . . . . . . . . . . . . . . . . . . . . . . . . . 1311.2

– K –

KILNS, SMALL CERAMICS . . . . . . . . . . . . . . . . . . . . 930.0

KITCHEN HOODS, COMMERCIAL . . . . . . . . . . . . . . 508.0

– L –

LABELED

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

LABELS AND INSTRUCTIONS

For appliances. . . . . . . . . . . . . . . . . . . . . . . . . . . . 307.0

For heating appliances . . . . . . . . . . . . . . . . . . . . . 307.0

For hydronic systems . . . . . . . . . . . . . . . . . . . . . 1204.0

For refrigerating systems . . . . . . . . . . . . . . . . . . . 1115.0

For type I hoods. . . . . . . . . . . . . . . . . . . . . . . . . 508.5.3

LABORATORIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410.0

LADDER, PERMANENT . . . . . . . . . . . . . . . . . . . . 304.3.1.2

LEAKS

Fuel gas . . . . . . . . . . . . . . . . . . . . . . . . . 1313.4, 1313.5

LINE CONTACT INSTALLATION

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

LIQUEFIED PETROLEUM GAS (LP-GAS)

Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303.7.1

Automatic control devices . . . . . . . . . . . . . . . . . . . 306.0

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209.0

INDEX

Gas Facilities . . . . . . . . . . . . . . . . 214.0, 303.7, 1312.11

Shutoff devices. . . . . . . . . . . . . . . . . . . . . . . . . . D 110.4

Supply connections . . . . . . . . . . . . . . . D 101.2, D 106.1

LIQUID-FUELED ENGINES AND GAS TURBINES . . . . 1602.2

LISTED

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

LISTED AND LISTING

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

LISTING AGENCY

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

LOCATION OF

Appliances in garages . . . . . . . . 305.1.1, 305.1.2, 905.8

Appliances subject to

mechanical damage . . . . . . . . . . . . . . . . . . . . 305.1.1

Boilers, central heating . . . . . . . . . . . . . . . . . . . . . 904.2

Draft hoods and controls . . . . . . . . . . . . . 802.12, 905.5

Evaporative cooling systems. . . . . . . . . . . . . . . . . 932.2

Pool heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 926.2

Refrigerating equipment . . . . . . . . . . . . . . . . . . . 1106.1

Wall furnaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 907.3

LOUVERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.0

LOUVERS, GRILLES,

AND SCREENS . . . . . . . . . . . . . . . . . . . . . . . . . . . 701.10

LOW-PRESSURE

HOT-WATER-HEATING BOILER

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0

LOW-PRESSURE STEAM-HEATING BOILER

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.0

LOW-WATER CUTOFF . . . . . . . . . . . . . . . . . . . . . . . 1008.0

LOWER FLAMMABILITY LIMIT (LFL)

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

Product conveying ducts . . . . . . . . . . . . . . 505.1, 505.3

Refrigeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1104.4

– M –

MACHINERY

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215.0

MACHINERY ROOM, REFRIGERATION

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215.0

Detectors and alarms . . . . . . . . . . . . . . . . . . . . 1106.2.9

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)

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

MOTORS, FANS, AND FILTERS . . . . . . . . . . . . . . . . . 503.0

MULTIPLE-ZONE SYSTEM . . . . . . . . . . . . . . . . . . . . . 404.0

– N –

NATURAL VENTILATION

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216.0

Floor area to be ventilated. . . . . . . . . . . . . . . . 402.2.1.2

Indoor air quality for

low-rise residential buildings . . . . . . . . . . . . . E 605.1

Indoor air quality for

residential occupancies . . . . . . . . . . . . . . . . . 405.1.1

Location and size openings. . . . . . . . . . . . . . . 402.2.1.6

Refrigeration systems . . . . . . . . . . . . . . . . . . . . . 1106.3

Systems . . . . . . . . . . . . . . . . . . . . . . . . 402.2, 402.2.1.2

NEONATAL INTENSIVE CARE UNITS

Formula preparation area . . . . . . . . . . . . . . . . . . . 419.1

Treatment Area/Room . . . . . . . . . . . . . . . . . . . . . . 419.2

584 2025 CALIFORNIA MECHANICAL CODE

INDEX

NONCOMBUSTIBLE MATERIAL

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216.0

NON-GREASE DUCTS . . . . . . . . . . . . . . . . . . . . . . . . 519.4

NUISANCE

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216.0

– O –

OCCUPATION CLASSIFICATION

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

ODOROUS ROOMS . . . . . . . . . . . . . . . . . . . . . . . . . . . 413.0

OIL BURNING BOILERS . . . . . . . . . . . . . (see Boiler types,

oil burning)

OPEN TOP BROILER UNIT . . . . . . . . . . . . . . . . . . . . . 921.0

OPENINGS

Air heaters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.7

Attics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E 502.11

Ducts. . . . . . . . . . . . . . . . . . . . . . . 506.6, 510.1.4, 510.3

Exhaust and intake . . . . . . . . . . . . . . . . . 305.3.2, 925.4

For access . . . . . . . . . . . . . . . . . . . . . . . 506.3, 510.1.4,

514.1.2, 1406.2.1.4

For combustion air. . . . . . . . . . . . . . . . . . 701.6, C 109.1

Furnaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 906.9

Illuminating appliances . . . . . . . . . . . . . . . . . . . . . 923.4

Ratproofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316.10

Relief. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.7

Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 802.1.2

Ventilation . . . . . . . . . . . 402.2.1.2, 402.2.1.3, 402.2.1.4,

402.2.1.5, 402.2.1.1, 402.2.1.6,

402.2.3, 802.1.2, 802.10.3,

1105.5.1, 1106.3, E 605.1.1

OSHPD 1R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301.7

OUTDOOR AIR INTAKES and EXHAUST OUTLETS . . 407.2

Building Pressurization . . . . . . . . . . . . . . . . . . . . . 407.8

Hazardous Exhaust Outlets. . . . . . . . . . . . . . . 407.2.2.1

OUTDOOR AIR RATE

Calculation. . . . . . . . . . . . . . . . . . . . . . . . . . Appendix H

OUTLETS

Appliance flue . . . . . . . . . . . . . . . . . . . . 203.0, 802.10.5

Draft hood . . . . . . . . . . . . 802.10.2.1, 802.10.5, 803.1.1

Exhaust. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.7

Fuel gas piping . . . . . . . . . . . . 1305.2, 1306.3, 1310.10,

1312.8, 1314.4

OVER PRESSURE PROTECTION

Fuel gas piping . . . . . . . . . . . . . . . . . 1308.6.1, 1310.6.1

OVERHEAD HEATERS

In garages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 925.5

– P –

PENALTIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106.2, 106.3

PERMISSIBLE EXPOSURE

LIMIT (PEL)

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

PERMITS

Application. . . . . . . . . . . . . . . . . . . . . . . . . 103.3, 104.3,

302.3.1, 1402.0

Construction documents . . . . . . . . . . . . . . . . . . 104.3.1

Exempt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.2

Expiration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.4.3

Fees . . . . . . . . . . . . . . . . . . . . . . . . . 104.5, Table 104.5

For alteration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.1

Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105.0

Investigation fees . . . . . . . . . . . . . . . . . . . . . . . . 104.5.2

Issuance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.4

Mechanical systems . . . . . . . . . . . . . . . . . . . . . . . 104.0

Retention of plans . . . . . . . . . . . . . . . . . . . . . . . 104.4.6

Suspension or revocation of. . . . . . . . . . . . . . . . 104.4.5

To operate boiler or

pressure vessel . . . . . . . . . . . . . . . . . . . . . . . . 1013.2

Validity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.4.2

Work without . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.5.1

PERMITS AND INSPECTIONS . . . . . . . . . . . . 104.0, 105.0,

302.3.1, 302.3.6

PHARMACIES . . . . . . . . . . . . . . . . . . . . . . 505.12, 505.12.1

PHARMACEUTICAL COMPOUND EXHAUST

DISCHARGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507.7

PILOT

Boilers. . . . . . . . . . . . . . 1006.1, 1007.1, C 106.0, C 107.0

Continuous, definition . . . . . . . . . . . . . . . . . . . . . . 205.0

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Intermittent, definition. . . . . . . . . . . . . . . . . . . . . . . 211.0

Interrupted, definition . . . . . . . . . . . . . . . . . . . . . . . 211.0

PIPE INSULATION REQUIREMENTS . . . . . . . . . . . 1217.10.1

PIPING

Fuel gas . . . . . . . . . . . . . . . . . . . . . . . . . 1308.0, 1310.0

Hangers, supports and anchors . . . . . . . 313.0, 1105.2,

1109.6, 1210.3,

1310.3.5, 1310.3.5.1,

Table 313.3, Table 1310.3.5.1

Hydronics . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1

Identification . . . . . . . . . . . . . . . . . . . . . 1109.10, 1204.0

Joints and connections. . . . . . . . . . . . . . . . . (see Joints

and connections)

Protection of . . . . . . . . . . . . . . . . . . . . . 316.0, 1109.4.1,

1310.1.3, 1310.1.4

Trenching, excavation,

and backfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317.0

Underground . . . . . . . . . . . . . 1109.5, 1109.5.1, 1310.1.6

PIPING TYPES

Double-wall. . . . . . . . Table 803.1.2(1), Table 803.1.2(2),

Table 803.2(1), Table 803.2(2)

Single-wall metal . . . . . . . . . . . . 802.7, Table 803.1.2(5)

PLANS

Approval by Authority

Having Jurisdiction . . . . . . . . . . . . . . . . . . . . . . . 104.3

INDEX

Retention of . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.4.6

Review fees . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.3.2

PLENUMS

Applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 601.1 Closure systems . . . . . . . . . . . . . . . . . . . . . . . . . . 603.9

Combustibles within . . . . . . . . . . . . . . . . . . . . . . . 602.2

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Furnace. . . . . . . . . . . . . . . . . . . . . . . . 802.3.5, 903.2.4,

603.13.4, 904.3, 604.1

Heating and cooling system . . . . . . . . 605.1, E 503.3.1

Hood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 516.6.3

Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . E 503.4.7.1.1

Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . E 503.4.7.2.1

Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 602.1

Metal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 602.5

Serving type II hoods . . . . . . . . . . . . . . . . . . . . . 510.1.7 Supply-air. . . . . . . . . . . . . . . . . . . . . 508.3.5, 508.3.5.3,

508.3.5.3.3, 608.0,

E 503.4.7.1.1

Use of under-floor as supply plenum. . . . . . . . . . . 608.0 Where dampers are required . . . . . . . . . . . . . . . . 701.12

PLUMBING CODE

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

POLYETHYLENE (PE) PIPE OR TUBING

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Fuel gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1308.4.4, Table 1315.2(19)–Table 1315.2(23),

Table 1315.2(34)–Table 1315.2(36)

Hydronics . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1

Joining and connections . . . . . . . . . . . . . . . . . . . . (see Joints

and connections)

POLYETHYLENE-ALUMINUM-POLYETHYLENE

(PE-AL-PE) PIPE OR TUBING

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Ground source loop. . . . . . . Table 1703.2, Table 1703.3

Hydronics . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1 Joining and connections. . . . . . . . . . . . . . . . (see Joints and connections)

POLYETHYLENE OF RAISED

TEMPERATURE (PE-RT) PIPE OR TUBING

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Ground source loop . . . . . . . . . . . . . . . . . Table 1703.2,

Table 1703.3

Hydronics . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1,

Table 1220.4.2

Joining and connections. . . . . . . . . . . . . . . . (see Joints and connections) Oxygen diffusion . . . . . . . . . . . . . . . . . . . . . . . . . 1210.4 POLYPROPYLENE (PP) PIPE OR TUBING

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Ground source loop . . . . . . . . . . . . . . . . . Table 1703.2,

Table 1703.3

Hydronics . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1

Joining and connections. . . . . . . . . . . . . . . . (see Joints

and connections)

POLYVINYL CHLORIDE (PVC) PIPE OR TUBING

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Ground source loop. . . . . . . Table 1703.2, Table 1703.3

Hydronics . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1

PORTABLE

Cooling unit . . . . . . . . . . . . . . . . . . . . . . . . 104.2, 218.0

Evaporative cooler . . . . . . . . . . . . . . . . . . . 104.2, 218.0

Fire extinguishers . . . . . . . . . . . . . . . . . . . 513.2, 513.11

Heating appliance . . . . . . . . . . . . . . . . . . . 104.2, 203.0

Ventilating equipment. . . . . . . . . . . . . . . . . 104.2, 218.0

POSITIVE DISPLACEMENT COMPRESSOR

Refrigeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1112.2

POWER BOILER PLANT

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

PRESSURE

Design, definition . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Field test, definition . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Imposing element, definition . . . . . . . . . . . . . . . . . 218.0

Limiting devices. . . . . . . . . . . . . . . . . . . . . 218.0, 904.5,

926.4, 1111.0, 1308.9.6

Relief devices . . . . . . . . . . . . . . . . 218.0, 904.7, 1112.0,

1113.0, 1115.4, C 109.1

Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D 113.6.2

Test, definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.0

Vessel . . . . . . . . . . . . . . . . . . . . . . . .218.0, Chapter 10,

1113.0, 1117.0

Vessel, refrigerant . . . . . . . . . . . . .218.0, 1113.0, 1117.0

PRESSURE-RELIEF VALVE

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.0

Discharge . . . . . . . . . . 1005.2, 1112.10, 1112.11, 1206.2

Hydronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1206.0

Pressure vessels . . . . . . . . . . . . . . . . . . 1005.0, 1113.0,

Refrigeration system. . . . . 1111.2, 1112.0, 1113.0, 1115.4

Steam and hot

water boilers (low pressure) . . . . . . . . . . . . . . . 904.7

PROFESSIONAL QUALIFICATIONS . . . . . . . .Appendix H

HVAC technicians . . . . . . . . . . . . . . . . . . . . . .H 102.5.3

Hydronic systems . . . . . . . . . . . . . . . . . . . . . .H 102.4.2

Infection control . . . . . . . . . . . . . . . . . . . . . . . . .H 102.5

Mechanical inspectors . . . . . . . . . . . . . . . . . .H 102.2.1

Mechanical plan examiners . . . . . . . . . . . . . .H 102.2.2

Residential mechanical service technicians . . .H 102.3

Solar water heaters . . . . . . . . . . . . . . . . . . . .H 102.4.1

Water management . . . . . . . . . . . . . . . . . . . . . .H 102.5

PROTECTION

Fire . . . . . . . . . . . . . . . . . . . . .506.8, 507.4.3.1, 510.3.7,

512.3.3, 513.2.1, 516.2.3,

516.5, 1108.1, 1406.2.1.4

586 2025 CALIFORNIA MECHANICAL CODE

INDEX

Overpressure . . . . . . . . . . . . . . . . . . . .1308.7, 1310.6.1

Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301.6

Piping, materials, and structures . . . . . . . . . . . . . .316.0

PROTECTIVE ENVIRONMENT ROOMS . . . . . . . . . . . 415.0

PURGE

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .218.0

Fuel gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1313.6

– R –

RADIANT HEATING AND COOLING . . . . . . . . . . . . .1217.0

RADIANT ROOM HEATER

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .220.0

RANGE

Commercial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .920.1

Domestic . . . . . . . . . . . . . . . . . . . . . . . . . .504.3, 919.0

Oil burning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .920.3

Ventilation of . . . . . . . . . . . . . . . . . . . . . . . . . . . . .504.3

RATPROOFING . . . . . . . . . . . . . . . . . . . . . . . . . . . . .316.10

RECIRCULATING SYSTEMS

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .220.0

Exhaust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .516.0

Labeling . . . . . . . . . . . . . . . . . . . . . . . .516.2.4, 516.2.5 Listing . . . . . . . . . . . . . . . . . . .516.2.2, 516.2.5, 516.2.9

Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .403.5

REFRIGERANTS

Ammonia . . . . . . . . . . . . . . . . . .1102.1, 1104.4, 1104.5,

1106.1.4, 1106.5, 1106.0, 1114.1,

Table 1102.3, Table E 503.7.1(7)

Amount of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1104.2

Applications for human comfort . . . . . . . . . . . . . .1104.7

Azeotrope, definition . . . . . . . . . . . . . . . . . . . . . . .203.0 Changing of . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1104.9

Classification of . . . . . . . . . . . . . . . . . . . . . . . . . .1103.0

Concentration limit . . . . . . . . . . . . . . . . . . . . . . . .1104.2

Containers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1109.0

Emergency purge . . . . . . . . . . . . . . . . . . . . . . . .1106.0

Flammable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1104.5

For human comfort . . . . . . . . . . . . . . . . .1104.7, 1104.8

In institutional occupancies . . . . . . . . . . . . . . . . .1104.3

In nonindustrial occupancies . . . . . . . . . . . . . . . .1104.7

Parts in ducts. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1106.8

Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1109.0

Port protection . . . . . . . . . . . . . . . . . . . . . . . . . . 1105.11

Pressure vessel . . . . . . . . . . . . . . . 218.0, 1113.0, 1117.0

Purity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1104.8 Mixing of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1104.8.4

Reclaimed . . . . . . . . . . . . . . . . . . . . . . . 220.0, 1104.8.3

Recovered . . . . . . . . . . . . . . . . . . . . . . . 220.0, 1104.8.1

Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1101.2

Recycled . . . . . . . . . . . . . . . . . . . . . . . . 220.0, 1104.8.2 Refrigerant designation, definition . . . . . . . . . . . . 220.0 Requirements for . . . . . . . . . . . . . . . . . . . . . . . . . 1104.0 Safety classification, definition . . . . . . . . . . . . . . . 220.0

Storage of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1105.12

Types used . . . . . . . . . . . . 1102.3, 1104.8, Table 1102.3

Zeotropic, definition. . . . . . . . . . . . . . . . . . . . . . . . 228.0

REFRIGERATION EQUIPMENT

Access. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1105.3

Coils . . . . . . . . . . . . . . . . . 310.6, 903.2.6, 904.8, 905.7

Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1108.0

Identification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1115.0

Illumination and

service receptacles . . . . . . . . . . . . . . . . . . . . . 1105.4

Location of . . . . . . . . . . . . . . . . . . . . . . . 1104.2, 1105.0

Refrigeration recovery . . . . . . . . . . . . . . . . . . . . . 1101.2 Supports and anchorage. . . . . . . . . . . . . . . . . . . 1105.2

Testing of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1116.0 Valves. . . . . . . . . (see Valves, for refrigeration systems)

REFRIGERATION

MACHINERY ROOMS

A2L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1106.11

B2L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1106.11

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220.0

General . . . . . . . . . . . . . . . . . . . . . . . . . . 1106.0, 1106.2

REFRIGERATION SPACES

Concentration limit. . . . . . . 1102.3, 1104.2, Table 1102.3

Industrial occupancies. . . . . . . . . . . . . . . . . . . . . 1104.4

Institutional occupancies . . . . . . . . . . . . . . . . . . . 1104.3

Nonconnecting spaces . . . . . . . . . . . . . . . . . . . 1104.2.2

Refrigerated spaces . . . . . . . . . . . . . . . . . . . . . . 1104.4

Ventilated spaces . . . . . . . . . . . . . . . . . . . . . . . 1104.2.3

Volume calculation . . . . . . . . . . . . . . . . . . . . . . 1104.2.1

REFRIGERATION SYSTEM CLASSIFICATION

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220.0

High-probability systems. . . . . . . . . . . . . . . . . . 1103.2.1

Higher flammability refrigerants. . . . . . . . . . . . . . 1103.3

Low-probability . . . . . . . . . . . . . . . . . . . . . . . . . 1103.2.2

REFRIGERATION SYSTEMS

Absorption . . . . . . . . . . . . . . . . . . . . . . . . . 220.0, 307.4

Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 933.0

Attic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1105.3, 1105.9

Classification of . . . . . . . . . . . . . . . . . . . . . . . . . . 1103.2

Condensation . . . . . . . . . 310.6, 1105.7, 1105.10, 1109.9

Containing

hazardous fluids. . . . . . . . . . . . . . . . . . . . . . . . 1125.0

Defrost. . . . . . . . . . . . . . . . . . . . . . . . . . 1105.8, 1105.10

Discharge piping. . . . . . . . . . . . 1112.10, 1112.11, 1114.1

Duct furnaces used with . . . . . . . . . . . . . . . . . . . . 905.7

Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1108.2

Emergency shutoff. . . . . . . . . . . . . . . . . . . . . . . . 1108.3

Flaring device . . . . . . . . . . . . . . . . . . . . . 1114.1–1114.3

High probability. . . . . . . . . . . . . . . . . . . . . . . . . 1103.2.1

Highside, definition . . . . . . . . . . . . . . . . . . . . . . . . 210.0

Human comfort . . . . . . . . . . . . . . . . . . . . . . . . . . 1105.1

Labeling. . . . . . . . . . . . . . . . . . . . . . 307.3, 307.4, 1115.3

INDEX

Low probability . . . . . . . . . . . . . . . . . . . . . . . . . 1103.2.2

Lowside, definition. . . . . . . . . . . . . . . . . . . . . . . . . 214.0

Machinery room. . . . . . . . . . . . . . . . . . . . 220.0, 1106.0,

1107.0, 1115.3

Maintenance and operation . . . . . . . . . . . . . . . . . 1118.0

Mechanical. . . . . . . . . . . . . . . . . . . . . . . . . 220.0, 933.3

Mechanical system, definition . . . . . . . . . . . . . . . . 220.0

Mechanical ventilation . . . . . . . . . . . . . . . . . . . . . 1107.0

Permissible . . . . . . . . . . . . . . . . . . . . . . . . Table 1104.1

Pressure-limiting devices . . . . . . . . . . . . . . . . . . . 1111.0

Pressure-relief devices . . . . . . . . . . . . . . 1112.0, 1112.9,

1112.10, 1112.11

1113.4, 1113.5, 1115.4

Probability . . . . . . . . . . . . . . . 1103.2, 1103.2.1, 1103.2.2

Protection from

mechanical damage . . . . . . . . . . . . . . . . . . . 1109.4.1

Requirements for . . . . . . . . . . . . . . . . . . . . . . . . . 1104.0

Self-contained mechanical

refrigeration systems . . . . . . . . . . . . . . . . . . . . . 933.3

Self-contained refrigerators

and freezers . . . . . . . . . . . . . . . . . . . . . . . . . . . 933.1

Unit coolers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 933.2

Ventilation of room . . . . . . . . . . . . . . . . . . 1105.5, 1107.0

REFRIGERATORS

Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 927.2

Factory-built . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 933.1

Ventilating kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 927.3

REGULATOR VENT PIPING . . . . . . . . . . . . . . . . 1308.4.4.1

REGULATORS

Combustion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1009.0

Gas appliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . 923.5

Gas-pressure regulators . . . . . . . . . . . . . . . . . . . 1007.0

Vent piping . . . . . . . . . . . . . . . . . . . . . . . . . . 1308.4.4.1

RETURN DUCT SIZING . . . . . . . . . . . . . . . . . . . . . . . 601.2.1

RISER HEAT PIPE

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220.0

ROOFTOP TERMINATIONS

Chimneys. . . . . . . . . . . . . . . . . . . . . . . 802.5.4, 802.7.2,

803.1.10, 803.2.20

Fans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511.1.3.1

Gas vents . . . . . . . . . . . . . . . . . . . . . . 802.6.1, 802.7.2,

803.1.10, 803.2.20

ROOM HEATERS . . . . . . . . . . . . . . . . . . . . . . . 220.0, 915.0

ROOM

Boiler . . . . . . . . . . . . . . . . . 204.0, 303.2, 1001.2, 1001.4

Equipment . . . . . . . . . . . . . . . . . . . . . . . . 303.2, 305.1.3

HPM storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0

Machinery . . . . . . . . . . . . 1106.0, 1107.0, 1108.0, 1115.3

Used for ventilation . . . . . . . . . . . . . . . . . . . . . 402.2.1.6

RUPTURE MEMBERS . . . . . . . . . . . . . . . 220.0, 1112.10.1,

1112.13, 1113.3, 1115.4.1

– S –

SAFE TEMPERATURES

Alternate Source of Power . . . . . . . . . . . . . . . . . . 325.0

SCOPE AND ADMINISTRATION . . . . . . . . . . . . . Chapter 1

SEDIMENT TRAPS . . . . . . . . . . . . . . . . . . 1310.9.2, 1312.9

SEEPAGE PAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 906.10

SELF-CONTAINED . . . . . . . . . . . . . . . . . . . . . 221.0, 517.1.2

SENSITIVE AREAS OR ROOMS [OSHPD] . . . . . . . . . 322.0

SHAFT

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221.0

Fuel gas piping. . . . . . . . . . . . . . . . . . . . . . . . . 1310.3.4

Refrigeration systems . . . . . . . . . . . . . . 305.4, 1109.4.1

Stair and shaft vents . . . . . . . . . . . . . . . . . . E 503.4.6.4

SHAFT ENCLOSURE

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221.0

SHUTOFF

Automatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 609.0

Fuel. . . . . . . . . . . . . . . . . . . . . . . 513.4, 513.8, C 102.0,

Table 1003.2.1

SMOKE DAMPERS . . . . . . . . . . . . . . . . 206.0, 606.0 , 606.8

SMOKE DETECTORS . . . . . . . . . . . . . . 221.0, 609.0 , 609.2

SNOWMELT SYSTEMS . . . . . . . . . . . . . . 1220.4, 1220.4.1,

1217.8.2, Table 1220.4.2

SOLAR ENERGY SYSTEMS . . . . . . . . . . . . . . . . . . . . 1502.0

SOLID-FUEL

Boilers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1002.4

Burning appliances . . . . . . . . . . . . . . . . . . . . . . . 902.10 Chimney, combination

gas- and solid-fuel. . . . . . . . . . . . . . . . . . . . 802.5.8.2 Cooking operations . . . . . . . . . . . . . . . . . . . . . . . . 517.0

Furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 904.11

Room heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 915.4

Venting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 801.3

SPARK ARRESTERS

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221.0

Solid-fuel cooking operations . . . . . . . . . . . . . . . 517.1.6

SPECIFIC APPLIANCES,

INSTALLATION OF . . . . . . . . . . . . . . . . . . . . . . Chapter 9

STANDARDS

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221.0

General . . . . . . . . . . . . . . . . . . . . . . . . . . 301.2, 302.1.2

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

588 2025 CALIFORNIA MECHANICAL CODE

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

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

TESTING AND BALANCING (MECHANICAL SYSTEMS)

AIRBORNE INFECTION ISOLATION ROOMS . . .417.0

THERMAL RECOVERY UNIT

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .222.0

TOILETS, GAS FIRED . . . . . . . . . . . . . .928.0, Table 802.4

TYPES OF

Chimneys . . . . . . . . . . . . . . . . . . . . . . . .(see Chimney)

– U –

UMC

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223.0

UNCONSTITUTIONAL . . . . . . . . . . . . . . . . . . . . . . . . .101.4

UNDER-FLOOR SPACE . . . . . . . . . . . . . . . . . .304.4, 608.0

UNIT HEATER . . . . . . . . . .223.0, 916.0, Table E 503.7.1(5)

UNSAFE EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . .102.5

UNUSUALLY TIGHT CONSTRUCTION

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223.0

– V –

VALIDITY OF PERMITS . . . . . . . . . . . . . . . . . . . . . .104.4.2

VALVE TYPES

Bleed lines for diaphragm-type . . . . . . . . . . . . . .902.15 Companion or block, definition . . . . . . . . . . . . . . .224.0

Pressure relief . . . . . . . . . . . . . . . . . . . . . .224.0, 904.7,

926.4, 1112.0,

1113.0, 1115.4, C 109.1

Safety or relief . . . . . . . . . . . . .1005.0, 1009.0, C 109.1

Shutoff . . . . . . . . . .904.7, 1006.0, 1308.12, 1310.10.1.1,

1310.11, 1312.3.1, 1312.3.2,

1312.5.3, 1312.6, 1406.2.1.5,

C 109.1, D 103.0, D 104.3,

D 110.4, D 112.3

Stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224.0, 1112.6

VALVES

For fuel gas piping . . . . . . . . . . . .1308.4.1, 1308.4.7.5,

1308.10.1, 1308.12, 1309.1,

1310.3.3.1, 1310.10.1.1,

1310.11, 1310.14.6,

1312.3.1, 1312.3.2,

1312.5.3, 1312.6, 1312.9,

1313.1.4, 1313.1.5,

D 103.0, D 104.3, D 110.4,

D 112.3, D 113.3

For hydronics . . . . . . . . . . . . . . . . . . . . . . . . . . . .1212.0

For mobile home parks . . . .D 103.0, D 104.3, D 110.4,

D 112.3, D 113.3

For recreational vehicle park . . . . . . .D 103.0, D 104.3,

D 110.4, D 112.3, D 113.3

For refrigeration systems . . . . . . . . . . . .1105.3, 1109.0,

1110.0, 1112.6,

1112.9, 1113.6

VENT

Appliances not requiring vents . . . . . . . . . . . . . .802.2.1 Caps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .802.7.4(3)

Clearance . . . . . . . . . . . . . . .802.7.3.4, Table 303.10.1,

Table 802.7.3.3

Dampers . . . . . . . . . . . . . . . . .802.13, 802.14, 802.14.1

Direct vent . . . . . . . . . . . . . . . . . . . . . . . . . . . . .802.2.6

General requirements . . . . . . . . . . . . . . . . . . . . . .802.0

Insulation shield . . . . . . . . . . . . . . . . . . . . . . . .802.6.1.1

Integral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .802.2.7

Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .802.1

Mechanical draft . . . . . . . . . . . . . . . .802.3.3–802.3.3.4

Obstruction of flow . . . . . . . . . . . . . . . . . . . . . . .802.15

Plastic piping . . . . . . . . . . . . . . . . . . . . . . . . . . .802.4.1 Special . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .802.4.3

Termination . . . . . . . . . . . . . . . . . . . . .802.6.1, 802.7.2,

802.8

Wall penetration . . . . . . . . . . . . . . . . . . . . . . . . . .802.8

VENT, ATTIC . . . . . . . . . . . . . . . . . . .802.10.1.1, 802.10.1.2

INDEX

VENT, GAS . . . . . . . . . . . . . . .224.0, 802.4, 802.6, 802.6.2,

802.6.2.1, 802.6.2.2

VENT, GAS CONNECTORS . . . . . . . . . . .(see Connectors,

gas vent) VENT DAMPERS . . . . . . . . . . . . . . . . . . . . .(see Dampers)

VENT SIZING

Category I appliances . . . . . . . . . . . . .802.6.2.1, 803.0

Multiple appliances . . . . . . . . . . . . . . . . . . . . . . .803.2,

Table 803.2(1)–Table 803.2(9)

Multistory . . . . . . . . . . . . . . . . . . . . .802.6.3, 802.6.3.2,

803.2.16

Single appliance . . . . .802.7.4(1)(b), 802.10.2.1, 803.1,

Table 803.1.2(1)–Table 803.1.2(6)

VENTED

Decorative appliances . . . . . . . . . . . . . . . .224.0, 911.0,

Table 802.4

Equipment not

required to be . . . . . . . . . . . . . . . . . . . . . . . . .802.2.1

Fireplaces . . . . . . . . . . . . . . . . . . . . . . .912.0, E 602.0,

Table 1308.3.1

Wall furnace . . . . . . . . . . . . . .224.0, 907.2, Table 802.4

VENTED APPLIANCE CATEGORIES

Category I . . . . . . . . . . . . . . . .224.0, 701.1.1, 802.6.2.1,

802.6.3, 802.10, 802.10.1.1,

802.10.3.2, 803.0,

Appendix F, Table 802.4,

Table 803.1.2(1)–Table 803.1.2(4),

Table 803.2(1)–Table 803.2(4)

Category II . . . . . . . . . . . . . . . . . . . . .224.0, 802.6.2.3,

802.9, 802.11, Table 802.4

Category III . . . . . . . . . . . . . . . . . . . . .224.0, 802.6.2.3,

802.9.1, Table 802.4

Category IV. . . . . . . . . . . . . . . . . . . . . 224.0, 802.6.2.3,

802.9, 802.11, Table 802.4

VENTILATED SPACES . . . . . . . . . . . . . . . . . . . . . . 802.2.5

VENTILATING

Ceiling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.0, 607.0

Equipment . . . . . . . . . . . . . . . . . . . . . . 513.4.2, 514.1.2

Hoods . . . . . . . . . . . . . . . . . . . . . . . . . 802.2.4, 802.3.4,

919.5.2, 921.2

Kits for use in refrigerators. . . . . . . . . . . . . . . . . . . 927.3

Portable, equipment, definition . . . . . . . . . . . . . . . 218.0

VENTILATION

Air balance . . . . . . . . . . . . . . . . . . . . . . . . 403.10 , 407.3

Air class and recirculation . . . . . . . . . . . . . . 403.9 , 407.4

Mechanical. . . . . . . . . . . . . . . . . . . . . . . . . 402.3, 405.0

Multiple zone systems. . . . . . . . . . . . . . . . . . . . . . 404.0

Natural. . . . . . . . . . . . . . . . . . . . . . . . . 402.2, 402.2.1.2,

405.1.1, E 605.1.1

Obstructions of . . . . . . . . . . . . . . . . . . . . . . . . . . 802.15

Outdoor air intakes . . . . . . . . . . . . . . 402.4 , 403.9, 407.2

Parking garages . . . . . . . . . . . . . . . . . . 403.7.1, 403.7.2

Rates . . . . . . . . . . . . . . . . . . . . . . . . 403.0, Table 402.1

Requirements for Acute Care Hospitals,

Skilled Nursing Facilities, Intermediate Care Facilities, Outpatient Facilities,

Licensed Clinics,Correctional Treatment

Centers and Acute Psychiatric Hospitals . . . . Table 4-A System Details [OSHPD]. . . . . . . . . . . . . . . . . . . . 407.0

Variable Air Volume . . . . . . . . . . . . . . . . . . . . . . . . 407.5

VENTILATION SYSTEM DETAILS [OSHPD] . . . . . . . . . 407.0

VENTILATORS, HEAT

(ENERGY) RECOVERY . . . . . . . . . . . . . . . . 210.0, 504.5

VENTILATING SYSTEMS AND HOODS [OSHPD]

Airborne Infection Isolation Rooms. . . . . . . . . . . . 414.0

Boiler, Mechanical, and Electrical Rooms. . . . . . . 412.0

Kitchen and Dining Areas . . . . . . . . . . . . . . . . . . . 411.0

Laboratory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410.0

Odorous Rooms . . . . . . . . . . . . . . . . . . . . . . . . . . 413.0

Protective Environment Rooms. . . . . . . . . . . . . . . 415.0

VENTING COLLAR

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.0

VENTING SELECTION TABLES

Exterior masonry chimney. . . . . . . . . . Table 803.1.2(6),

Table 803.2(6),

Table 803.2(7),

Table 803.2(8),

Table 803.2(9)

Masonry Chimneys . . . . . . . . . . . . . . . Table 803.1.2(3),

Table 803.1.2(4),

Table 803.2(3),

Table 803.2(4)

Single appliances . . . Table 803.1.2(1)–Table 803.1.2(6) Single-wall metal

pipe or type B

asbestos cement vent . . . . . . . . . . Table 803.1.2(5),

Table 803.2(5)

Two or more

appliances . . . . . . . . . Table 803.2(1)–Table 803.2(9)

Type B double-wall

gas vent . . . . . . . . . . . . . . . . . . . . . . Table 803.1.2(1),

Table 803.1.2(2),

Table 803.2(1),

Table 803.2(2)

VIBRATION ISOLATORS . . . . . . . . . . . . . . . . 602.6, 1001.5

VOLUME DAMPERS

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.0

– W –

WALL

Furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 907.0

Furnace, vented, definition . . . . . . . . . . . . . . . . . . 224.0

Heater, definition. . . . . . . . . . . . . . . . . . . . . . . . . . 225.0

Terminations. . . . . . . . . . . . . . . . . . . . . . . . . . . . 510.9.2

590 2025 CALIFORNIA MECHANICAL CODE

INDEX

WARM AIR F571 - 592URNACE

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225.0

Heating systems . . . . . . . . . . . . . . . . . . . . . . . . . . 311.0 Located in under-floor spaces. . . . . . . . . . . . . . . . 608.0

WATER HEATERS

Accepted standards . . . . . . . . . . . . . . . . 1203.2, 1207.3,

Table 1203.2

Drain pans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.5 Dual purpose . . . . . . . . . . . . . . . . . . . . . 1203.2, 1207.3,

Table 1203.2

For space heating and cooling . . . . . . . . . . . . . . . . 1203.2, Table 1203.2

Tankless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1203.3

WELD, CONTINUOUS

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

Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . .212.0, 1211.14

Pressure Vessels . . . . . . . . . . . . . . . . . . . . . . . . .1003.5

Welded duct connections . . . . . . . . . . . . . . . .510.5.3.2

WORKMANSHIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . .309.0

– Z –

ZONE

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228.0

592 2025 CALIFORNIA MECHANICAL CODE

HISTORY NOTE APPENDIX

CALIFORNIA CODE OF REGULATIONS, TITLE 24, PART 4

HISTORY:

For prior code history, see the History Note Appendix to the California Mechanical Code, 2022 Triennial Edition, effec- tive January 1, 2023.

1. (BSC 01/24, DSA-SS 01/24, DSA-SS 01/24 CWoRE, HCD 02/24, OSHPD 01/24, SFM 01/24) Adoption by reference the 2024 Uniform Mechanical Code with necessary amendments to become the 2025 California Mechanical Code, and repeal of the 2021 edition of the Uniform Mechanical Code. Effective on January 1, 2026.

594 2025 CALIFORNIA MECHANICAL CODE

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No Transfer This license is not transferable by the eBook purchaser unless such transfer is approved in advance by IAPMO, in which case the transferee will be subject to the terms and conditions of this Agreement.

Disclaimer The eBook, or any support given by IAPMO’s technical support staff, are in no way substitutes for assistance from legal, tax, accounting, or other qualified professionals. If legal advice or other expert assistance is required, the services of a competent professional person should be sought.

Limitation of Liability The eBook is provided “as is” and IAPMO does not make any warranty or representation, either express or implied, to the eBook, including its quality, accuracy, performance, merchantability, or fitness for a particular purpose. You assume the entire risk as to the results and performance of the eBook. IAPMO does not warrant, guarantee, or make any representations regarding the use of, or the results obtained with, the eBook in terms of accuracy, correctness or reliability. In no event will IAPMO be liable for indirect, special, incidental, or consequential damages arising out of delays, errors, omissions, inaccuracies, or the use or inability to use the eBook, or for interruption of the eBook, from whatever cause. This will apply even if IAPMO has been advised that the possibility of such damage exists. Specifically, IAPMO is not responsible for any costs, including those incurred as a result of lost profits or revenue, loss of data, the cost of recovering such programs or data, the cost of any substitute program, claims by third parties, or similar costs.

Hold Harmless / Indemnification. You agree to defend, indemnify and hold IAPMO and any third party provider harmless from and against all third party claims and damages (including reasonable attorneys’ fees) regarding your use of the eBook, unless the claims or damages are due to IAPMO’s or any third party provider’s gross negligence or willful misconduct or arise out of an allegation for which IAPMO is obligated to indemnify you.

ou agree to defend, indemnify and hold IAPMO and any third party provider harmless from and against all third party claims and damages (including reasonable attorneys’ fees) regarding your use of the eBook, unless the claims or damages are due to IAPMO’s or any third party provider’s gross negligence or willful misconduct or arise out of an allegation for which IAPMO is obligated to indemnify you.

Termination If you materially breach this License Agreement, we may terminate your right to use the Material immediately upon notice to you.

You agree that, upon termination of the License Agreement, you will either return to us or destroy all copies of the Material in your possession.

Additional Terms This written License Agreement is the exclusive agreement between you and us concerning the eBook and supersedes any and all prior oral or written agreements, negotiations, or other dealings between us concerning the eBook.

This License Agreement may be modified only by a writing signed by the user and IAPMO.

In the event of litigation between the user and IAPMO concerning the eBook, the prevailing party in the litigation and the prevailing party in any ancillary disputes (e.g., discovery disputes) will be entitled to recover attorneys’ fees and expenses from the other party.

This License Agreement is governed by the laws of the State of California applicable to contracts executed and performed entirely in, and by residents of, that state.

This License Agreement is effective immediately upon your installation or use of the eBook.

If you have any questions regarding this License Agreement, please write to the International Association of Plumbing and Mechanical Officials (IAPMO), 4755 East Philadelphia Street, Ontario, California 91761-2816.

This agreement is governed by the laws of the State of California applicable to contracts executed and performed entirely in, and by residents of, that state.