CMC · California Mechanical Code
Room heaters and related space heating appliances — application and venting
In short: pick only **listed** heaters and follow the manufacturer’s instructions. Unvented (vent‑free) gas heaters are tightly limited by **§ 915.3** — they are generally not allowed as primary heat, are restricted in bedrooms and bathrooms to small, listed ODS wall units (with strict input limits), and are prohibited in Group R residences. Solid‑fuel heaters must meet **UL 1482** (**§ 915.4**). Always confirm combustion air, clearances, and AHJ approval.
Last reviewed: July 6, 2026
What the code requires — plain English
Room heaters must be listed to the standard appropriate for their type (vented, unvented, electric, or solid‑fuel) and installed per their listing and manufacturer instructions. The California Mechanical Code controls application and venting for room heaters in § 915.0, and sets specific limits and prohibitions for gas‑fired and solid‑fuel room heaters in § 915.3 and § 915.4.
The most important rule: unvented (vent‑free) gas room heaters are tightly restricted — they are not to be used as a primary heat source, are prohibited in many occupancies/locations, and limited to small, listed, oxygen‑sensing wall units when any exceptions are granted. See § 915.3.
Requirements in detail
1) Which heaters must be listed (and to what standard)
- Vented room heaters must be listed to ANSI Z21.86/CSA 2.32 or CSA/ANSI Z21.88/CSA 2.33. § 915.1.1.
- Unvented room heaters must be listed to CSA/ANSI Z21.11.2. § 915.1.2.
- Electric room heaters must comply with UL 2021. § 915.2.
- Solid‑fuel room heaters must comply with UL 1482. § 915.4.
2) Unvented (vent‑free) gas room heater limits and prohibitions
- Unvented room heaters shall not be installed as primary heat sources unless the Authority Having Jurisdiction (AHJ) specifically permits it. § 915.3.1.
- Unvented room heaters are not permitted where the room lacks the required indoor air volume defined in § 701.4 (i.e., combustion air / room size constraints apply). § 915.3.1.
- Unvented fuel‑burning room heaters are explicitly prohibited in Group R occupancies (per HCD adoption notes). § 915.3.1 (HCD note).
- Unvented heaters shall not be installed in bathrooms or bedrooms, except where the AHJ approves specific listed wall‑mounted units with an ODS (oxygen depletion safety) shutoff and input limits (see Exceptions). § 915.3.1.1.
3) Bathroom / bedroom exceptions (decision thresholds)
- Allowed only where approved by the AHJ and the appliance is a listed wall‑mounted unvented room heater equipped with an oxygen depletion safety shutoff (ODS) and combustion & ventilation air is provided as specified in § 902.2. § 915.3.1.1.
- Bathroom maximum input: 6000 Btu/h (1.76 kW). § 915.3.1.1 Exception (1).
- Bedroom maximum input: 10,000 Btu/h (3 kW). § 915.3.1.1 Exception (2).
4) Clearance and placement rules
- A heater must be located so it does not create a hazard to walls, floors, curtains, furniture, doors, or free movement in the room, and must be installed in accordance with its listing and the manufacturer’s instructions. § 915.3.3.
- For unlisted room heaters the code gives minimum clearances (decision dimensions): see table below. § 915.3.3.
Decision table — key thresholds and dimensions
| Decision / Dimension | Value(s) | Code Reference |
|---|---|---|
| Bathroom limit for an approved wall‑mounted, ODS unvented heater | 6000 Btu/h (1.76 kW) | § 915.3.1.1 Exception (1) |
| Bedroom limit for an approved wall‑mounted, ODS unvented heater | 10,000 Btu/h (3 kW) | § 915.3.1.1 Exception (2) |
| Clearance — circulating type (unlisted) sides & rear | 12 inches (305 mm) | § 915.3.3(1) |
| Clearance — radiating type (unlisted) sides & rear | 18 inches (457 mm) | § 915.3.3(2) |
| Clearance — front for radiating type using metal/asbestos/ceramic to direct radiation | 36 inches (914 mm) | § 915.3.3(2) |
| When double‑back construction applies — permitted reduced rear clearance (unlisted) | Rear 12 in (305 mm); sides 18 in (457 mm) | § 915.3.3(2) |
| Wall‑mounted heater on combustible wall | Only permitted if listed for such installation | § 915.3.4 |
| Solid‑fuel room heater standard | UL 1482 | § 915.4 |
Notes: where a heater is listed, its listing and the manufacturer's instructions control required clearances; the code directs installers to the listing/manufacturer rather than prescribing every possible clearance for listed appliances. § 915.3.3.
Exceptions & special cases
- Authority Having Jurisdiction (AHJ) exceptions: the AHJ may allow unvented units as non‑primary heat sources in some applications, but the unit must be listed and the AHJ’s approval is required. § 915.3.1.
- Group R (residential) restriction: per the California HCD note in the CMC, unvented fuel‑burning room heaters shall not be installed, used, maintained, or permitted to exist in a Group R occupancy. This is a strict state adoption note and overrides permissive allowances for unvented heaters in typical homes. § 915.3.1 (HCD 1 & HCD 2 note).
- Wall‑mounted combustibles: wall‑mounted heaters must be listed for installation on combustible walls or they must not be attached to combustible walls. § 915.3.4.
Common mistakes
- Installing an unvented heater as the primary heat source (prohibited unless AHJ specifically permits). § 915.3.1.
- Installing unvented heaters in Group R dwellings — code adoption from HCD forbids this. § 915.3.1 (HCD note).
- Ignoring the listing/manufacturer instructions for listed appliances and using the generic clearance numbers for unlisted appliances instead. § 915.3.3.
- Mounting a wall heater on combustible wall surfaces without a unit listed for that purpose. § 915.3.4.
- Assuming any unvented heater can be placed in a bathroom or bedroom — the code forbids this except for the specific listed, low‑input, ODS wall units and only with required combustion/ventilation air provisions. § 915.3.1.1.
Worked example — apply the rule with numbers
Scenario: A small commercial office (non‑Group R) wants to install a listed wall‑mounted unvented gas room heater in a bedroom‑type sleeping room where AHJ approval is possible.
- Check occupancy: because this is not a Group R residential dwelling, the HCD Group R prohibition does not automatically forbid the heater — AHJ approval is still required. § 915.3.1 (HCD note applies to Group R).
- Choose unit: select a listed wall‑mounted, ODS‑equipped unvented heater. § 915.3.1.1 requires that the unit be listed and have an ODS.
- Verify input rating: for a bedroom exception the unit’s input must not exceed 10,000 Btu/h (3 kW). If the chosen unit is 9,500 Btu/h and has ODS, the input threshold is satisfied. § 915.3.1.1 Exception (2).
- Combustion/ventilation air: confirm combustion and ventilation air will be provided as required in § 902.2 (the exception references that requirement as a condition of allowance). § 915.3.1.1 (exception language).
- Clearances & mounting: verify the wall‑mount installation is permitted on the wall construction (unit must be listed for mounting on combustible walls if wall is combustible). § 915.3.4.
If any of these checks fail (unit not listed, input >10,000 Btu/h, inadequate combustion air, or Group R residential application), the installation would violate the CMC.
Related provisions (select)
- § 915.1 — Application / listing requirements for room heaters (vented vs unvented).
- § 915.2 — Electric room heater standard (UL 2021).
- § 915.3.1.1 — Unvented room heater location prohibitions and exceptions (bathroom/bedroom, ODS requirements, input limits).
- § 915.3.3 — Clearance, listing, and manufacturer instruction requirements for room heaters.
- § 915.3.4 — Wall‑mounted room heaters on combustible walls.
- § 915.4 — Solid‑fuel type room heaters (UL 1482).
- Chapter 8 (e.g., § 802.2) — Appliances not required to be vented (includes room heaters listed for unvented use). See § 802.2.1(8).
- For combustion/ventilation air requirements referenced in exceptions: § 902.2 (exception text in § 915.3.1.1 references combustion/ventilation air be provided as specified in § 902.2).
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 10.8.6 High relevance — show source text
[NFPA 54:10.8.6] 914.7 Relief Openings. The design of the installation shall include adequate provisions to permit the direct gas-fired heating and forced ventilation appliances to operate at their rated airflow without overpressurizing the space served by the heater by taking into account the structure’s designed infiltration rate, properly designed relief openings, or an interlocked powered exhaust system, or a combination of these methods. [NFPA 54:10.8.7] 914.7.1 Infiltration Rate. The structure’s designed infiltration rate and the size of relief opening(s) shall be determined by engineering methods. [NFPA 54:10.8.7.1] 914.7.2 Louver or Gravity Dampers. Louver or counterbalanced gravity damper relief openings shall be permitted. Where motorized dampers or closeable louvers are used, they shall be proved to be in their open position prior to main burner operation. [NFPA 54:10.8.7.2] 914.8 Purging. Inlet ducting, when used, shall be purged with at least four air changes prior to an ignition attempt.
[NFPA 54:10.8.8]
915.0 Room Heaters.
915.1 Application. Room heaters shall be listed in accordance with Section 915.1.1 or Section 915.1.2. [NFPA 54:10.21.1]
915.1.1 Vented Room Heaters. Vented room heaters
shall be listed in accordance with ANSI Z21.86/CSA 2.32 or CSA/ANSI Z21.88/CSA 2.33. [NFPA 54:10.21.1.1]
915.1.2 Unvented Room Heaters. Unvented room
heaters shall be listed in accordance with CSA/ANSI
Z21.11.2. [NFPA 54:10.21.1.2]
915.2 Electric Room Heaters. Electric room heaters shall comply with UL 2021.
915.3 Gas-Fired Room Heaters. Gas-fired room heaters shall comply with Section 915.3.1 through Section 915.3.4. 915.3.1 Prohibited Installations. Unless specifically permitted by the Authority Having Jurisdiction, unvented room heaters shall not be installed as primary heat sources. Unvented room heaters shall not be permitted in spaces that do not have the required volume of indoor air as defined in Section 701.4.
[HCD 1 & HCD 2] Unvented fuel-burning room heaters shall not be installed, used, maintained, or permitted to exist in a Group R Occupancy.
915.3.1.1 Unvented Room Heaters. Unvented
room heaters shall not be installed in bathrooms or
bedrooms.
Exceptions:
(1) Where approved, one listed wall-mounted unvented room heater equipped with an oxygen depletion safety shutoff system shall be permitted to be installed in a bathroom, provided that the input rating does not exceed 6000 Btu/h (1.76 kW) and combustion and ventilation air is provided as specified in Section 902.2.
CMC § 802.1.2 High relevance — show source text
802.1.2 Prohibited Discharge. Appliance vents shall not discharge into a space enclosed by screens having openings less than [1] ⁄ 4 of an inch (6.4 mm) mesh.
802.2 Connection to Venting Systems. Except as permitted in Section 802.2.1 through Section 802.2.7, all appliances shall be connected to venting systems. [NFPA 54:12.3.1]
802.2.1 Appliances Not Required to be Vented. The following appliances shall not be required to be vented:
(1) Listed ranges.
(2) Built-in domestic cooking units listed and marked for optional venting.
(3) Listed hot plates.
(4) Listed Type 1 clothes dryers exhausted in accordance with Section 504.4.
(5) A single listed booster-type (automatic instantaneous) water heater, when designed and used solely for the sanitizing rinse requirements of a dishwashing machine, provided that the appliance is installed with the draft hood in place and unaltered, if a draft hood is required, in a commercial kitchen having a mechanical exhaust system. [Where installed in this manner, the draft hood outlet shall not be less than 36 inches (914 mm) vertically and 6 inches (152 mm) horizontally from any surface other than the appliance.]
(6) Listed refrigerators.
(7) Counter appliances.
(8) Room heaters listed for unvented use.
(9) Direct gas-fired makeup-air heaters.
(10)Other appliances listed for unvented use and not provided with flue collars.
(11)Specialized appliances of limited input such as laboratory burners or gas lights. [NFPA 54:12.3.2]
802.2.2 Maximum Input Rating. Where any or all of the appliances in Section 802.2.1(5) through Section 802.2.1(11) are installed so the aggregate input rating exceeds 20 Btu/h/ft [3] (207 W/m [3] ) of room or space in which it is installed, one or more shall be provided with venting systems or other approved means for conveying the vent gases to the outdoors so that the aggregate input rating of the remaining unvented appliances does not exceed 20 Btu/h/ft [3] (207 W/m [3] ). [NFPA 54:12.3.2.1]
802.2.3 Adjacent Room or Space. Where the calculation includes the volume of an adjacent room or space, the room or space in which the appliances are installed shall be directly connected to the adjacent room or space by a doorway, archway, or other opening of comparable size that cannot be closed. [NFPA 54:12.3.2.2]
802.2.4 Ventilating Hoods. The use of ventilating hoods and exhaust systems to vent appliances shall be limited to industrial appliances and appliances installed in commercial applications. [NFPA 54:12.3.3]
802.2.5 Well-Ventilated Spaces. The flue gases from industrial-type appliances shall not be required to be vented to the outdoors where such gases are discharged into a large and well-ventilated industrial space. [NFPA 54:12.3.4]
802.2.6 Direct Vent Appliances. Listed direct vent appliances shall be installed in accordance with the manufacturer’s installation instructions. [NFPA 54:12.3.5.1]
CMC § 12.4.5.2 High relevance — show source text
(2) The vent system shall be installed such that no fittings or joints between sections are installed in the above-ceiling space.
(3) The venting system shall be installed in a conduit or enclosure with joints between the interior of the enclosure and the ceiling space sealed. [NFPA 54:12.4.5.2] 802.4 Type of Venting System to be Used. The type of venting system to be used shall be in accordance with Table 802.4. [NFPA 54:12.5.1]
802.4.1 Plastic Piping. Where plastic piping is used to vent an appliance, the appliance shall be listed for use with such venting materials and the appliance manufacturer’s installation instructions shall identify the specific plastic piping material. The plastic pipe venting materials shall be labeled in accordance with the product standards specified by the appliance manufacturer or shall be listed and labeled in accordance with UL 1738. [NFPA 54:12.5.2]
802.4.2 Plastic Vent Joints. Plastic pipe and fittings used to vent appliances shall be installed in accordance with the appliance manufacturer’s installation instructions. Plastic pipe venting materials listed and labeled in accordance with UL 1738 shall be installed in accordance
with the vent manufacturer’s installation instructions. Where primer is required, it shall be of a contrasting color.
[NFPA 54:12.5.3]
802.4.3 Special Gas Vents. Special gas vents shall be listed and labeled in accordance with UL 1738 and installed in accordance with the special gas vent manufacturer’s installation instructions. [NFPA 54:12.5.4]
802.5 Masonry, Metal, and Factory-Built Chimneys. Chimneys shall be installed in accordance with Section 802.5.1 through Section 802.5.3.
802.5.1 Factory-Built Chimneys. Factory-built chimneys shall be listed in accordance with UL 103, UL 959, or UL 2561. Factory-built chimneys used to vent appliances that operate at positive vent pressure shall be listed for such application. [NFPA 54:12.6.1.1]
802.5.1.1 Decorative Shrouds. Decorative shrouds addressed in Section 802.5.4.3 shall comply with UL 103 for factory-built residential chimneys, UL 127 for factory-built fireplaces, or UL 1482 for solid-fuel room heaters.
802.5.2 Metal Chimneys. Metal chimneys shall be built and installed in accordance with NFPA 211. [NFPA 54:12.6.1.2]
802.5.3 Masonry Chimneys. Masonry chimneys shall be built and installed in accordance with NFPA 211 and lined with one of the following:
(1) Approved clay flue lining.
(2) A chimney lining system listed and labeled in accordance with UL 1777.
(3) Other approved material that resists corrosion, erosion, softening, or cracking from vent gases at temperatures up to 1800°F (982°C).
Exception: Masonry chimney flues lined with a chimney lining system specifically listed for use with listed appliances with draft hoods, Category I appliances, and
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CHIMNEYS AND VENTS
CMC § 914.5 High relevance — show source text
914.5 Air Supply . . . . . . . . . . . . . . . . . . . 207
914.6 Atmospheric Vents, Gas Reliefs, or Bleeds . . . . . . . . . . . . . 207
914.7 Relief Openings . . . . . . . . . . . . . . 207
914.8 Purging . . . . . . . . . . . . . . . . . . . . . 207
915.0 Room Heaters . . . . . . . . . . . . . . . 207
915.1 Application . . . . . . . . . . . . . . . . . . 207
915.2 Electric Room Heaters . . . . . . . . . 207
915.3 Gas-Fired Room Heaters . . . . . . . 207
xxxvi
915.4 Solid-Fuel Type Room Heaters . . 208
916.0 Unit Heaters . . . . . . . . . . . . . . . . . 208
916.1 Application . . . . . . . . . . . . . . . . . . 208
916.2 Support . . . . . . . . . . . . . . . . . . . . 208
916.3 Clearance for Suspended-Type Unit Heaters . . . . . . . . . . . . . . . . . 208
916.4 Combustion and Circulating Air. . . 208
916.5 Ductwork. . . . . . . . . . . . . . . . . . . . 208
916.6 Installation in Commercial
Garages and Aircraft Hangars . . . 208
916.7 Oil-Fired Unit Heaters. . . . . . . . . . 208
917.0 Food Service Appliance, FloorMounted . . . . . . . . . . . . . . . . . . . . 208
917.1 Application . . . . . . . . . . . . . . . . . . 208
917.2 Clearance for Listed Appliances. . . 208
917.3 Mounting on Combustible Floors . . . . . . . . . . . . . . . . . . . . . . 208
917.4 Installation on Noncombustible
Floors . . . . . . . . . . . . . . . . . . . . . . 209
917.5 Combustible Material
Adjacent to Cooking Top . . . . . . . 209
917.6 Use with Casters . . . . . . . . . . . . . 209
917.7 Level Installation. . . . . . . . . . . . . . 209
917.8 Ventilation. . . . . . . . . . . . . . . . . . . 209
918.0 Food Service Appliances, Counter Appliances . . . . . . . . . . . 209
918.1 Application . . . . . . . . . . . . . . . . . . 209
918.2 Vertical Clearance . . . . . . . . . . . . 209
918.3 Clearance for Listed Appliances. . . 209
918.4 Clearance for Unlisted
Appliances . . . . . . . . . . . . . . . . . . 209
919.0 Household Cooking Appliances. . . 209
CMC § 509.2.1 High relevance — show source text
** Where any or all of the appliances in Section 509.2.1(1) and Section 509.2.1(2) are installed so the aggregate input rating exceeds 20 (Btu/h)/ft [3] (207 W/m [3] ) of room or space in which it is installed, one or more shall be provided with venting systems or other approved means for conveying the vent gases to the outdoors so that the aggregate input rating of the remaining unvented appliances does not exceed 20 (Btu/h)/ft [3] (207 W/m [3] ). [NFPA 54:12.3.2.1] 509.2.3 Adjacent Room or Space. Where the calculation includes the volume of an adjacent room or space, the room or space in which the appliances are installed shall be directly connected to the adjacent room or space by a doorway, archway, or other opening of comparable size that cannot be closed. [NFPA 54:12.3.2.2]
509.2.4 Ventilating Hoods. The use of ventilating hoods and exhaust systems to vent appliances shall be limited to industrial appliances and appliances installed in commercial applications. [NFPA 54:12.3.3] 509.2.5 Well-Ventilated Spaces. The flue gases from industrial-type appliances shall not be required to be vented to the outdoors where such gases are discharged into a large and well-ventilated industrial space. [NFPA 54:12.3.4]
509.2.6 Direct-Vent Appliances. Listed direct vent appliances shall be installed in accordance with the manufacturer’s installation instructions. [NFPA 54:12.3.5.1]
509.2.6.1 Through-the-Wall Vent Termination. Through-the-wall vent terminations for listed directvent appliances shall be in accordance with Section 509.8.1. [NFPA 54:12.3.5.2]
509.2.7 Appliances with Integral Vents. Appliances incorporating integral venting means shall be installed in accordance with Section 509.8. [NFPA 54:12.3.6] 509.3 Minimum Safe Performance. Venting systems shall be designed and constructed to convey all flue and vent gases to the outdoors. [NFPA 54:12.1] 509.3.1 Appliance Draft Requirements. A venting system shall satisfy the draft requirements of the appliance in accordance with the manufacturer’s instructions.
[NFPA 54:12.4.1]
509.3.2 Appliance Venting Requirements. Appliances required to be vented shall be connected to a venting system designed and installed in accordance with the provisions of Section 509.4 through Section 509.15.
[NFPA 54:12.4.2] 509.3.3 Mechanical Draft Systems. Mechanical draft systems shall be listed in accordance with UL 378 and installed in accordance with both the appliance and the mechanical draft system manufacturer’s installation instructions. [NFPA 54:12.4.3.1]
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WATER HEATERS
CMC § 902.10 High relevance — show source text
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
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INDEX
STEAM AND HOT-WATER SYSTEMS (Hospitals) . . . .319.0
CMC § 902.2. High relevance — show source text
(2) Where approved, one listed wall-mounted unvented room heater equipped with an oxygen depletion safety shutoff system shall be permitted to be installed in a bedroom, provided that the input rating does not exceed 10 000 Btu/h (3 kW) and combustion and ventilation air is provided as specified in Section 902.2. [NFPA 54:10.21.2]
(3) Portable oil fired unvented heating appliances used as supplemental heating in storage occupancies, utility occupancies, and in accordance with the fire code.
[HCD 1 & HCD 2] Unvented fuel-burning room heaters shall not be installed, used, maintained, or permitted to exist in a Group R Occupancy.
915.3.2 Installations in Institutions. Room heaters shall not be installed in the following occupancies:
(1) Residential board and care
(2) Health care [NFPA 54:10.21.3] 915.3.3 Clearance. A room heater shall be placed so as not to cause a hazard to walls, floors, curtains, furniture, doors where open, and to the free movements of persons within the room. Heaters designed and marked, “For use in noncombustible fireplace only,” shall not be installed elsewhere. Listed room heaters shall be installed in accordance with their listings and the manufacturer’s installation instructions. In no case shall the clearances be
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INSTALLATION OF SPECIFIC APPLIANCES
(1) A listed unit heater shall be installed with clearances from combustible material at the back and one side of not less than 6 inches (152 mm). Where the flue gases are vented horizontally, the 6 inch (152 mm) clearance shall be measured from the draft hood or
vent instead of the rear wall of the unit heater. A unit
heater listed for reduced clearances shall be installed in accordance with its listing and the manufacturer’s installation instructions.
(2) Floor-mounted-type unit heaters installed on combustible floors shall be listed for such installation.
(3) Combustible floors under unlisted floor-mounted unit heaters shall be protected in an approved man ner.
(4) Clearances for servicing shall be in accordance with the manufacturer’s instructions.
916.4 Combustion and Circulating Air. Combustion and circulating air shall be provided in accordance with Section 701.0. [NFPA 54:10.24.4]
916.5 Ductwork. A unit heater shall not be attached to a warm air duct system unless listed and marked for such installation. [NFPA 54:10.24.5] 916.6 Installation in Commercial Garages and Air- craft Hangars. Unit heaters installed in garages for more than three motor vehicles or in aircraft hangars shall be installed in accordance with Section 303.11 and Section 303.12. [NFPA 54:10.24.6]
916.7 Oil-Fired Unit Heaters. Oil-fired unit heaters shall comply with UL 731 and installed in accordance with the manufacturer’s installation instructions.
917.0 Food Service Appliance, Floor-Mounted. 917.1 Application. Floor-mounted food service appliances shall be listed in accordance with ANSI Z83.11/CSA 1.8.
CMC § 2.32 High relevance — show source text
shall be listed in accordance with ANSI Z21.86/CSA 2.32 or CSA/ANSI Z21.88/CSA 2.33. [NFPA 54:10.21.1.1]
915.1.2 Unvented Room Heaters. Unvented room
heaters shall be listed in accordance with CSA/ANSI
Z21.11.2. [NFPA 54:10.21.1.2]
915.2 Electric Room Heaters. Electric room heaters shall comply with UL 2021.
915.3 Gas-Fired Room Heaters. Gas-fired room heaters shall comply with Section 915.3.1 through Section 915.3.4. 915.3.1 Prohibited Installations. Unless specifically permitted by the Authority Having Jurisdiction, unvented room heaters shall not be installed as primary heat sources. Unvented room heaters shall not be permitted in spaces that do not have the required volume of indoor air as defined in Section 701.4.
[HCD 1 & HCD 2] Unvented fuel-burning room heaters shall not be installed, used, maintained, or permitted to exist in a Group R Occupancy.
915.3.1.1 Unvented Room Heaters. Unvented
room heaters shall not be installed in bathrooms or
bedrooms.
Exceptions:
(1) Where approved, one listed wall-mounted unvented room heater equipped with an oxygen depletion safety shutoff system shall be permitted to be installed in a bathroom, provided that the input rating does not exceed 6000 Btu/h (1.76 kW) and combustion and ventilation air is provided as specified in Section 902.2.
(2) Where approved, one listed wall-mounted unvented room heater equipped with an oxygen depletion safety shutoff system shall be permitted to be installed in a bedroom, provided that the input rating does not exceed 10 000 Btu/h (3 kW) and combustion and ventilation air is provided as specified in Section 902.2. [NFPA 54:10.21.2]
(3) Portable oil fired unvented heating appliances used as supplemental heating in storage occupancies, utility occupancies, and in accordance with the fire code.
[HCD 1 & HCD 2] Unvented fuel-burning room heaters shall not be installed, used, maintained, or permitted to exist in a Group R Occupancy.
915.3.2 Installations in Institutions. Room heaters shall not be installed in the following occupancies:
(1) Residential board and care
(2) Health care [NFPA 54:10.21.3] 915.3.3 Clearance. A room heater shall be placed so as not to cause a hazard to walls, floors, curtains, furniture, doors where open, and to the free movements of persons within the room. Heaters designed and marked, “For use in noncombustible fireplace only,” shall not be installed elsewhere. Listed room heaters shall be installed in accordance with their listings and the manufacturer’s installation instructions. In no case shall the clearances be
2025 CALIFORNIA MECHANICAL CODE 207
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
INSTALLATION OF SPECIFIC APPLIANCES
CMC § 1207.0 High relevance — show source text
(3) Discharge pipe shall discharge independently by gravity through an air gap into the drainage system or outside of the building with the end of the pipe not exceeding 2 feet (610 mm) and not less than 6 inches (152 mm) above the ground and pointing downwards. (4) Discharge in such a manner that does not cause personal injury or structural damage. (5) No part of such discharge pipe shall be trapped or subject to freezing. (6) The terminal end of the pipe shall not be threaded. (7) Discharge from a relief valve into a water heater pan shall be prohibited.
(8) The discharge termination point shall be readily visible.
1207.0 Heating Appliances and Equipment. 1207.1 General. Heating appliances, equipment, safety and operational controls shall be listed for its intended use in a hydronic heating system and installed in accordance with the manufacturer’s installation instructions.
1207.2 Boilers. Boilers and their control systems shall comply with Section 1002.0. 1207.2.1 Condensing Boilers. A condensing boiler, in which the heat exchanger and venting system are designed to operate with condensing flue gases, shall be permitted to be connected directly to the panel heating system without a protective mixing device. 1207.2.2 Noncondensing Boilers. Where the heat exchanger and venting system are not designed to operate with condensed flue gases, the boiler shall be permitted to connect directly to the panel heating system where protected from flue gas condensation. The operating temperature of the boiler shall be more than the fluid temperature in accordance with the manufacturer’s instructions. The minimum return-water temperature to the heat source shall comply with Section 1201.5.
1207.3 Dual Purpose Water Heaters. Water heaters used for combined space- and water-heating applications shall be in accordance with the standards referenced in Table 1203.2, and shall be installed in accordance with the manufacturer’s instal lation instructions. Water used as the heat transfer fluid in the hydronic heating system shall be isolated from the potable water supply and distribution in accordance with Section 312.1, Section 1202.0, and Section 1218.0.
1207.3.1 Temperature Limitations. Where a combined space- and water-heating application requires water for space heating at temperatures exceeding 140°F (60°C), a thermostatic mixing valve in accordance with ASSE 1017 shall be installed to temper the water supplied to the potable water distribution system to a temperature of 140°F (60°C) or less. 1207.4 Solar Heat Collector Systems. Solar water heating systems used in hydronic panel radiant heating systems shall be installed in accordance with the Uniform Solar, Hydronics and Geothermal Code (USHGC). 1207.5 Heat Pumps. Heat pumps shall comply with UL 1995 or UL 60335-2-40. Air source heat pumps shall also comply with AHRI 210/240. In addition, ground-source heat pumps shall comply with AHRI/ASHRAE/ISO 13256-1 for water-to-air heat pumps and AHRI/ASHRAE/ISO 13256-2 for water-to-water heat pumps. Heat pumps shall be fitted with a means to indicate that the compressor is locked out.
CMC § 503.4.6.4 Medium relevance — show source text
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
CMC § 925.5 Medium relevance — show source text
925.5 Installation in Commercial
Garages and Aircraft Hangars . . . 212
925.6 Electric Radiant Heaters. . . . . . . . 212
926.0 Pool Heaters. . . . . . . . . . . . . . . . . 212
926.1 Application . . . . . . . . . . . . . . . . . . 212
926.2 Location . . . . . . . . . . . . . . . . . . . . 212
926.3 Clearance . . . . . . . . . . . . . . . . . . . 212
926.4 Temperature or PressureLimiting Devices . . . . . . . . . . . . . . 212
926.5 Bypass Valves . . . . . . . . . . . . . . . 212
926.6 Venting . . . . . . . . . . . . . . . . . . . . . 212
927.0 Refrigerators. . . . . . . . . . . . . . . . . 212
927.1 Application . . . . . . . . . . . . . . . . . . 212
927.2 Clearance . . . . . . . . . . . . . . . . . . . 212
927.3 Venting or Ventilating Kits Approved for Use with a Refrigerator. . . . . . . . . . . . . . . . . . 212
928.0 Gas-Fired Toilets . . . . . . . . . . . . . 212
928.1 Clearance . . . . . . . . . . . . . . . . . . . 212
928.2 Installation on Combustible
Floors . . . . . . . . . . . . . . . . . . . . . . 212
928.3 Vents . . . . . . . . . . . . . . . . . . . . . . 212
929.0 Appliances for Installation in Manufactured Housing . . . . . . . 212
2025 CALIFORNIA MECHANICAL CODE
929.1 General. . . . . . . . . . . . . . . . . . . . . 212
930.0 Small Ceramic Kilns . . . . . . . . . . . 212
930.1 General. . . . . . . . . . . . . . . . . . . . . 212
930.2 Installation . . . . . . . . . . . . . . . . . . 212
930.3 Fuel-Gas Controls . . . . . . . . . . . . 212
930.4 Electrical Equipment. . . . . . . . . . . 212
930.5 Installations Inside Buildings . . . . 213
930.6 Exterior Installations . . . . . . . . . . . 213
931.0 Outdoor Open Flame Decorative Appliances . . . . . . . . . 213
931.1 General. . . . . . . . . . . . . . . . . . . . . 213
932.0 Evaporative Cooling Systems. . . . 213
932.1 General. . . . . . . . . . . . . . . . . . . . . 213
932.2 Location . . . . . . . . . . . . . . . . . . . . 213
CMC § 378-2006 Medium relevance — show source text
STANDARD NUMBER STANDARD TITLE APPLICATION REFERENCED
SECTIONUL 378-2006 Draft Equipment (with revisions through September 17, 2013) Fuel Gas, Appliances 509.3.3, 509.13,
509.14.1UL 399-2017 Drinking Water Coolers (with revisions through July 31, 2020) Fixtures 415.1 UL 430-2015 Waste Disposers (with revisions through September 14, 2021) Appliances 419.1 UL 441-2016 Gas Vents (with revisions through August 28, 2019) Fuel Gas, Vents 509.1 UL 467-2013 Grounding and Bonding Equipment (with revisions through
June 7, 2017)Miscellaneous 1211.2.5 UL 499-2014 Electric Heating Appliances (with revisions through October
22, 2021)Appliances Table 501.1(1) UL 641-2010 Type L Low-Temperature Venting Systems (with revisions
through April 23, 2018)Fuel Gas 509.1 UL 723-2018 Test for Surface Burning Characteristics of Building Materials Miscellaneous 701.2(2), 903.1(2),
1101.4UL 732-2018 Oil-Fired Storage Tank Water Heaters (with revisions through
August 9, 2018)Fuel Gas, Appliances Table 501.1(1) UL 749-2018 Household Dishwashers Appliances 414.1 UL 778-2016 Motor-Operated Water Pumps (with revisions throughJune
29, 2021)Appliances 1101.14 UL 921-2020 Commercial Dishwashers Appliances 414.1 UL 959-2010 Medium Heat Appliance Factory-Built Chimneys (with revisions
through August 28, 2019)Fuel Gas, Appliances 509.5.1 UL 1453-2016 Electric Booster and Commercial Storage Tank Water Heaters
(with revisions through May 18, 2018)Appliances Table 501.1(1) UL 1479-2015 Fire Tests of Penetration Firestops (with revisions through May
18, 2021)Miscellaneous 1404.3, 1405.3 UL 1738-2010 Venting Systems for Gas-Burning Appliances, Categories II,
III, and IV (with revisions through August 26, 2021)Fuel Gas, Appliances 509.4.1, 509.4.2,
509.4.3UL 1777-2015 Chimney Liners (with revisions through April 11, 2019) Chimney Liners 509.5.3(2) UL 2523-2009 Solid Fuel-Fired Hydronic Heating Appliances, Water Heaters,
and Boilers (with revisions through March 16, 2018)Fuel Gas, Appliances Table 501.1(1) UL 2561-2016 1400 Degree Fahrenheit Factory-Built Chimneys (with revisions
through April 19, 2018)Fuel Gas, Appli-
ances509.5. CMC § 911.2 Medium relevance — show source text
911.2 Prohibited Installations . . . . . . . . . 206
911.3 Installation . . . . . . . . . . . . . . . . . . 206
911.4 Fireplace Screens. . . . . . . . . . . . . 206
912.0 Gas Fireplaces, Vented . . . . . . . . 206
912.1 Application . . . . . . . . . . . . . . . . . . 206
912.2 Reserved . . . . . . . . . . . . . . . . . . . 206
912.3 Installation . . . . . . . . . . . . . . . . . . 206
912.4 Combustion and Circulating Air . . . 206
913.0 Factory-Built Fireplaces and Fireplace Stoves. . . . . . . . . . . . . . 206
913.1 Factory-Built Fireplaces . . . . . . . . 206
913.2 Fireplace Stoves. . . . . . . . . . . . . . 206
913.3 Fireplace Accessories . . . . . . . . . 206
914.0 Non-Recirculating Direct Gas-Fired Industrial Air Heaters. . . 206
914.1 Application . . . . . . . . . . . . . . . . . . 206
914.2 Prohibited Installations . . . . . . . . . 206
914.3 Installation . . . . . . . . . . . . . . . . . . 206
914.4 Clearance from Combustible
Materials . . . . . . . . . . . . . . . . . . . . 207
914.5 Air Supply . . . . . . . . . . . . . . . . . . . 207
914.6 Atmospheric Vents, Gas Reliefs, or Bleeds . . . . . . . . . . . . . 207
914.7 Relief Openings . . . . . . . . . . . . . . 207
914.8 Purging . . . . . . . . . . . . . . . . . . . . . 207
915.0 Room Heaters . . . . . . . . . . . . . . . 207
915.1 Application . . . . . . . . . . . . . . . . . . 207
915.2 Electric Room Heaters . . . . . . . . . 207
915.3 Gas-Fired Room Heaters . . . . . . . 207
xxxvi
915.4 Solid-Fuel Type Room Heaters . . 208
916.0 Unit Heaters . . . . . . . . . . . . . . . . . 208
916.1 Application . . . . . . . . . . . . . . . . . . 208
916.2 Support . . . . . . . . . . . . . . . . . . . . 208
916.3 Clearance for Suspended-Type Unit Heaters . . . . . . . . . . . . . . . . . 208
916.4 Combustion and Circulating Air. . . 208
916.5 Ductwork. . . . . . . . . . . . . . . . . . . . 208
916.6 Installation in Commercial
Garages and Aircraft Hangars . . . 208
CMC § 915.3.3 Medium relevance — show source text
(2) Radiating type room heaters other than those of the circulating type described in Section 915.3.3(1) shall have clearance at sides and rear of not less than 18 inches (457 mm), except that heaters that make use of metal, asbestos, or ceramic material to direct radiation to the front of the heater shall have a clearance of 36 inches (914 mm) in front and, where constructed with a double back of metal or ceramic, shall be permitted to be installed with a clearance of 18 inches (457 mm) at sides and 12 inches (305 mm) at rear. Combustible floors under unlisted room heaters shall be protected in an approved manner.
915.3.4 Wall-Mounted Room Heaters. Wall mounted room heaters shall not be installed in or attached
to walls of combustible material unless listed for such installation. [NFPA 54:10.21.4]
915.4 Solid-Fuel Type Room Heaters. Solid-fuel type room heaters shall comply with UL 1482.
916.0 Unit Heaters.
916.1 Application. Unit heaters shall be listed in accordance with ANSI Z83.8/CSA 2.6 and installed in accordance with the manufacturer’s installation instructions. [NFPA 54:10.24.1]
916.2 Support. Suspended-type unit heaters shall be safely and adequately supported, with due consideration given to their weight and vibration characteristics. Hangers and brackets shall be of noncombustible material. [NFPA 54:10.24.2]
916.3 Clearance for Suspended-Type Unit Heaters. Suspended-type unit heaters shall comply with the following requirements:
(1) Unit heaters shall be installed with clearances from combustible material of not less than 18 inches (457 mm) at the sides, 12 inches (305 mm) at the bottom, and 6 inches (152 mm) above the top where the unit heater has an internal draft hood, or 1 inch (25.4 mm) above the top of the sloping side of a vertical draft hood. A unit heater listed for reduced clearances shall be installed in accordance with its listing and the manufacturer’s installation instructions.
(2) Clearances for servicing shall be in accordance with the manufacturer’s installation instructions. {NFPA 54:10.24.3}
916.3.1 Floor-Mounted-Type Unit Heaters. Floormounted-type unit heaters shall comply with the following requirements:
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208 2025 CALIFORNIA MECHANICAL CODE
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INSTALLATION OF SPECIFIC APPLIANCES
permitted where protected in accordance with Table 303.10.1.
[NFPA 54:10.11.5] 917.6 Use with Casters. Floor-mounted appliances with casters shall be listed for such construction and shall be
installed in accordance with the manufacturer’s installation instructions for limiting the movement of the appliance to prevent strain on the connection. [NFPA 54:10.11.6]
917.7 Level Installation. Floor-mounted food service appliances shall be installed level on a firm foundation.
[NFPA 54:10.11.7]
CMC § 802.14.1 Medium relevance — show source text
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
CMC § 10.11.2 Medium relevance — show source text
** Floor-mounted food service appliances, such as ranges for hotels and restaurants, deep fat fryers, unit broilers, kettles, steam cookers, steam generators, and baking and roasting ovens, shall be installed not less than 6 inches (152 mm) from combustible material except that at least a 2 inch (51 mm) clearance shall be maintained between a draft hood and combustible material. Floor-mounted food service appliances listed for installation at lesser clearances shall be installed in accordance with its listing and the manufacturer’s installation instructions. Appliances designed and marked, “For use only in noncombustible locations,” shall not be installed elsewhere. [NFPA 54:10.11.2] 917.3 Mounting on Combustible Floors. Floor-mounted food service appliances that are listed specifically for installation on floors constructed of combustible material shall be permitted to be installed on combustible floors in accordance with its listing and the manufacturer’s installation instructions. [NFPA 54:10.11.3.1]
917.3.1 Not Listed for Mounting on Combustible Floors. Floor-mounted food service appliances that are not listed for installation on a combustible floor shall be
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such as to interfere with combustion air and accessibility. Unlisted room heaters shall be installed with clearances from combustible material not less than the following:
(1) Circulating type room heaters having an outer jacket surrounding the combustion chamber, arranged with openings at top and bottom so that air circulates between the inner and outer jacket, and without openings in the outer jacket to permit direct radiation, shall have clearance at sides and rear of not less than 12 inches (305 mm).
(2) Radiating type room heaters other than those of the circulating type described in Section 915.3.3(1) shall have clearance at sides and rear of not less than 18 inches (457 mm), except that heaters that make use of metal, asbestos, or ceramic material to direct radiation to the front of the heater shall have a clearance of 36 inches (914 mm) in front and, where constructed with a double back of metal or ceramic, shall be permitted to be installed with a clearance of 18 inches (457 mm) at sides and 12 inches (305 mm) at rear. Combustible floors under unlisted room heaters shall be protected in an approved manner.
915.3.4 Wall-Mounted Room Heaters. Wall mounted room heaters shall not be installed in or attached
to walls of combustible material unless listed for such installation. [NFPA 54:10.21.4]
915.4 Solid-Fuel Type Room Heaters. Solid-fuel type room heaters shall comply with UL 1482.
916.0 Unit Heaters.
916.1 Application. Unit heaters shall be listed in accordance with ANSI Z83.8/CSA 2.6 and installed in accordance with the manufacturer’s installation instructions. [NFPA 54:10.24.1]
916.2 Support. Suspended-type unit heaters shall be safely and adequately supported, with due consideration given to their weight and vibration characteristics. Hangers and brackets shall be of noncombustible material. [NFPA 54:10.24.2]
916.3 Clearance for Suspended-Type Unit Heaters. Suspended-type unit heaters shall comply with the following requirements:
CMC § 510.3.4.2 Medium relevance — show source text
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
CMC § 904.12 Medium relevance — show source text
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
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
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
Frequently asked questions
Can I install a vent‑free gas heater in my single‑family home?
No. The California adoption notes in § 915.3.1 (HCD 1 & HCD 2) state that unvented fuel‑burning room heaters shall not be installed in Group R occupancies, which includes single‑family homes.
What if my heater is “listed” — do I still need to follow these clearance numbers?
Yes. For listed appliances you must follow the listing and the manufacturer’s installation instructions. The code gives default minimum clearances only for unlisted heaters; listed units may have different, tested clearances in their listing. § 915.3.3.
Are there any small unvented heaters allowed in bathrooms?
Only in limited cases: a single listed wall‑mounted unvented heater with an ODS may be allowed in a bathroom if approved by the AHJ, the unit’s input ≤ 6000 Btu/h, and combustion/ventilation air is provided as required. § 915.3.1.1 Exception (1).
What standard applies to a solid‑fuel room heater?
Solid‑fuel type room heaters must comply with UL 1482 per § 915.4.
If a heater is not required to be vented, is it still safe to operate in a small room?
Not necessarily — the CMC prohibits unvented heaters where the room does not meet the required indoor air volume (see § 701.4) and restricts use in many occupancies. Always confirm listing, combustion air, and AHJ approvals. § 915.3.1.
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