CMC · California Mechanical Code
What labeling is required for fuel‑burning and electric heating appliances?
The CMC requires every fuel‑burning and electric heating appliance to have a permanent, factory‑applied, legible nameplate showing specific identification and rating data—fuel input in Btu/h (for fuel appliances), electrical ratings and output in Btu/h (for electric heaters), listing mark, clearance info, and that electric heaters be shipped with installation instructions and wiring temperature ratings over 140°F.
Last reviewed: July 6, 2026
What the code requires — 2–4 sentences
Appliances must carry a permanent, legible, factory‑applied nameplate that lists specific identification, rating and safety information. The labeling requirements for fuel‑burning appliances are set out in § 307.1 and for electric heating appliances in § 307.2.
The single most important rule: every fuel‑burning or electric heating appliance must have a permanent, legible factory nameplate showing the specific items listed in the applicable section (see § 307.1 and § 307.2).
Requirements in detail
At a glance — required nameplate items
The code requires distinct items on the nameplate for fuel‑burning vs. electric heating appliances. Below is a decision‑focused table you can use when inspecting or specifying equipment.
| What must appear on the appliance nameplate | Fuel‑Burning appliances | Electric heating appliances | Code Reference |
|---|---|---|---|
| Manufacturer name or trademark | ✓ | ✓ | § 307.1, § 307.2 |
| Approved fuel input rating (Btu/h or kW) | ✓ (Btu/h (kW)) | — (electric uses output rating) | § 307.1 |
| Model number (or equivalent) | ✓ | ✓ | § 307.1, § 307.2 |
| Serial number | ✓ | ✓ | § 307.1, § 307.2 |
| Lighting / operation / shutdown instructions | ✓ | — (see installation instructions requirement) | § 307.1 |
| Type of fuel approved | ✓ | — | § 307.1 |
| Electrical rating (V, A or W; phases) | — | ✓ (volts, amperes or watts; number of phases) | § 307.2 |
| Output rating (Btu/h or kW) | — | ✓ (Btu/h (kW)) | § 307.2 |
| Ratings of field‑replaceable electrical components | — | ✓ | § 307.2 |
| Symbol of an approved agency (listing mark) | ✓ | ✓ | § 307.1, § 307.2 |
| Required clearances from combustible surfaces (on or adjacent mounting surfaces) | ✓ | ✓ | § 307.1, § 307.2 |
| Installation instructions accompanying the appliance | — | ✓ (must accompany appliance; include required clearances from combustibles not covered by mounting/adjacent surfaces and temperature rating for field wiring >140°F) | § 307.2 |
Notes:
- The code uses the defined term “Labeled” to mean a mark of an acceptable product‑evaluation organization; the nameplate requirement is consistent with that concept.
- The appliance nameplate must be permanent, legible, and factory‑applied as stated in the sections. § 307.1 and § 307.2 require a “permanent and legible factory‑applied nameplate.”
Fuel‑Burning Appliances — specific items (quick list)
Per § 307.1, the fuel‑burning appliance nameplate must include:
- Manufacturer name/trademark, approved fuel input rating (expressed in Btu/h (kW)), model, serial number, lighting/operation/shutdown instructions, type of fuel approved, the symbol of an approved agency, and required clearances from combustible surfaces.
Electric Heating Appliances — specific items (quick list)
Per § 307.2, the electric heater nameplate must include:
- Manufacturer name/trademark, model, serial number, electrical rating (volts, amperes or watts and number of phases), output rating (Btu/h (kW)), electrical rating of each field‑replaceable electrical component, symbol of an approved agency, and required clearances from combustible surfaces. The appliance must also be accompanied by clear and complete installation instructions including required clearances from combustibles (other than mounting/adjacent surfaces) and the temperature rating of field‑installed wiring connections exceeding 140°F (60°C).
Exceptions & special cases
- The text of § 307.1 and § 307.2 requires a factory‑applied nameplate; the code does not provide a provision for substituting only an aftermarket or field‑applied label in place of the factory nameplate.
- The code lists required content but does not specify minimum font size, exact physical location on the appliance, or the label material. Where the code is silent, the Authority Having Jurisdiction may determine acceptability based on permanence and legibility. (The sections require "permanent and legible factory‑applied nameplate" but do not set format limits.)
- For appliances that are part of packaged equipment (e.g., heat pumps, electric cooling appliances), see § 307.3 for additional nameplate items (refrigerant amount, refrigerant designation, factory test pressures, etc.).
Common mistakes
- Omitting the fuel input rating in Btu/h (kW) on fuel‑burning appliance nameplates. The code specifically requires the approved fuel input rating to be expressed in Btu/h (kW). § 307.1
- Listing only electrical volts but not amperes (or watts) or the number of phases on electric appliances — § 307.2 requires volts, amperes (or watts), and for polyphase equipment the number of phases.
- Failing to provide installation instructions with electric heaters that state required clearances from combustibles and the temperature rating of field wiring over 140°F (60°C) as required by § 307.2.
- Assuming a listing mark alone replaces the other required nameplate data — the listing symbol is required in addition to the other specific content. § 307.1, § 307.2.
Worked example — concrete scenario
Scenario A — Fuel‑burning warm‑air furnace installed in a small commercial space:
- Furnace data: manufacturer "Acme Heat", model "FH‑100", serial "A12345", approved fuel input 100,000 Btu/h (29.3 kW), approved fuel: natural gas, required clearances: 6 in back, 18 in front to service panel, listing mark present, lighting/operation/shutdown instructions included on nameplate.
What the nameplate must show (per § 307.1): Manufacturer, 100,000 Btu/h (29.3 kW) fuel input rating, model, serial, lighting/operation/shutdown instructions, approved fuel type, listing agency symbol, required clearances from combustibles. Confirm presence of each item against § 307.1.
Scenario B — Electric duct heater for an air handler:
- Heater data: manufacturer "VoltHeat", model "EDH‑480‑3", serial "V98765", electrical rating 480 V, 3‑phase, 60 A, output rating 50,000 Btu/h (14.65 kW), contains two field‑replaceable contactors rated 480 V / 40 A each, listing mark present, installation instructions packaged with unit state clearances and wiring‑temperature requirements (field wiring expected to exceed 140°F (60°C)).
What the nameplate must show (per § 307.2): Manufacturer, model, serial, 480 V, 60 A, 3‑phase, output 50,000 Btu/h (14.65 kW), electrical rating of each field‑replaceable component (480 V / 40 A), listing mark, required clearances; installation instructions must accompany the appliance and state the temperature rating of field wiring > 140°F (60°C). Verify all items per § 307.2.
Related provisions
- § 307.0 — Labeling (introductory heading that establishes the labeling sub‑chapter).
- § 306.1 — Automatic control devices and related safety shutoff requirements for heating appliances (useful when verifying instructions and controls).
- § 307.3 — Heat pump and electric cooling appliances (additional nameplate items for refrigerant, factory test pressures, etc.).
- § 1002.2.1 — Listing & labeling for oil‑burning boilers (applies where separate boiler standards call out specific listing/labeling standards).
- § 1002.3 — Electric boilers: listing and labeling standard references.
If you need, I can extract the exact text fragments from each cited § for use in inspection checklists or label templates.
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 306.2 High relevance — show source text
Forced-air and gravity-type warm air furnaces shall be equipped with a listed air outlet temperature limit control that cannot be set for temperatures exceeding 250°F (121°C). Such controls shall be located in the bonnet or plenum, within 2 feet (610 mm) of the discharge side of the heating element of gravity furnaces or in accordance with the conditions of listing.
Electric duct heaters shall be equipped with an approved automatic reset air outlet temperature limit control that will limit the outlet air temperature to not exceed 200°F (93°C). The electric elements of the heater shall be equipped with fusible links or a manual reset temperature limit control that will prevent outlet air temperature in excess of 250°F (121°C).
306.2 Building Automation Systems. [OSHPD 1] Building automation systems shall provide for localized con- trol in the event of network failure. This capability shall be specified in the construction documentation.
307.0 Labeling.
307.1 Fuel-Burning Appliances. Fuel-burning heating appliances shall bear a permanent and legible factory-applied nameplate on which shall appear:
(1) The name or trademark of the manufacturer.
(2) The approved fuel input rating of the appliance, expressed in Btu/h (kW).
(3) The model number or equivalent.
(4) The serial number.
(5) Instructions for the lighting, operation, and shutdown of the appliance.
(6) The type of fuel approved for use with the appliance.
(7) The symbol of an approved agency certifying compliance of the equipment with recognized standards.
(8) Required clearances from combustible surfaces on which or adjacent to which it is permitted to be mounted.
307.2 Electric Heating Appliances. Electric heating appliances shall bear a permanent and legible factory-applied nameplate on which shall appear:
(1) The name or trademark of the manufacturer.
(2) The model number or equivalent.
(3) The serial number.
(4) The electrical rating in volts, amperes (or watts), and, for other than single phase, the number of phases.
(5) The output rating in Btu/h (kW).
(6) The electrical rating in volts, amperes, or watts of each field-replaceable electrical component.
(7) The symbol of an approved agency certifying compliance of equipment with recognized standards.
(8) Required clearances from combustible surfaces on which or adjacent to which it is permitted to be mounted.
An appliance shall be accompanied by clear and complete installation instructions, including required clearances from combustibles other than mounting or adjacent surfaces, and temperature rating of field-installed wiring connections exceeding 140°F (60°C). 307.3 Heat Pump and Electric Cooling Appliances. Heat pumps and electric cooling appliances shall bear a permanent and legible factory-applied nameplate on which shall
appear:
(1) The name or trademark of the manufacturer.
(2) The model number or equivalent.
(3) The serial number.
(4) The amount of refrigerant.
(5) The refrigerant designation.
(6) The factory test pressures or pressures applied.
(7) The electrical rating in volts, amperes, and, for other than single phase, the number of phases.
(8) The output rating in Btu/h (kW).
(9) The electrical rating in volts, amperes, or watts of each field replaceable electrical component.
(10)The symbol of an approved agency certifying compliance of the equipment with recognized standards.
CMC § 305.6 High relevance — show source text
(3) Where a drainage pan pipe is installed, the material of the piping shall be rated for the temperature rating of the water heater and shall be approved for use with the liquid being discharged.
(4) Discharge from a relief valve into a drainage pan shall be prohibited. 305.6 Outdoor Locations. Appliances installed in outdoor locations shall be in accordance with the following:
(1) Listed for outdoor installation.
(2) Provided with approved protection from the outdoor elements that can affect the operation, durability, or safety of such appliances and in accordance with the manufacturer’s installation instructions.
(3) Outdoor cooking appliances shall comply with Section 922.0.
306.0 Automatic Control Devices.
306.1 General. Heating appliances shall be equipped with a listed device or devices that will shut off the fuel supply to the main burner or burners in the event of pilot or ignition failure. Liquefied petroleum gas-air-burning heating appli
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GENERAL REGULATIONS
ances shall be equipped with a listed automatic device or devices that will shut off the flow of gas to the pilot in the event of ignition failure.
Exception: The listed shutoff devices shall not be required on range or cooking tops, log lighters, lights, or other openburner manually operated appliances, or listed appliances not requiring such devices and specific industrial appliances as approved by the Authority Having Jurisdiction.
Heating appliances whose manual fuel controls are not readily accessible from the main portion of the building being heated shall be equipped with remote controls.
Forced-air and gravity-type warm air furnaces shall be equipped with a listed air outlet temperature limit control that cannot be set for temperatures exceeding 250°F (121°C). Such controls shall be located in the bonnet or plenum, within 2 feet (610 mm) of the discharge side of the heating element of gravity furnaces or in accordance with the conditions of listing.
Electric duct heaters shall be equipped with an approved automatic reset air outlet temperature limit control that will limit the outlet air temperature to not exceed 200°F (93°C). The electric elements of the heater shall be equipped with fusible links or a manual reset temperature limit control that will prevent outlet air temperature in excess of 250°F (121°C).
306.2 Building Automation Systems. [OSHPD 1] Building automation systems shall provide for localized con- trol in the event of network failure. This capability shall be specified in the construction documentation.
307.0 Labeling.
307.1 Fuel-Burning Appliances. Fuel-burning heating appliances shall bear a permanent and legible factory-applied nameplate on which shall appear:
(1) The name or trademark of the manufacturer.
(2) The approved fuel input rating of the appliance, expressed in Btu/h (kW).
(3) The model number or equivalent.
(4) The serial number.
(5) Instructions for the lighting, operation, and shutdown of the appliance.
(6) The type of fuel approved for use with the appliance.
(7) The symbol of an approved agency certifying compliance of the equipment with recognized standards.
(8) Required clearances from combustible surfaces on which or adjacent to which it is permitted to be mounted.
CMC § 1001.3 High relevance — show source text
1001.3 Air for Combustion and Ventilation. Air for combustion and ventilation shall be provided in accordance with Chapter 7.
1001.4 Drainage. For heating or hot-water-supply boiler applications, the boiler room shall be equipped with a floor drain or other approved means for disposing of the accumulation of liquid wastes incident to cleaning, recharging, and routine maintenance. No steam pipe shall be directly connected to a part of a plumbing or drainage system, nor shall a water having a temperature above 140°F (60°C) be discharged under pressure directly into a part of a drainage system. Pipes from boilers shall discharge by means of indirect waste piping as determined by the Authority Having Jurisdiction or the boiler manufacturer’s instructions.
1001.5 Mounting. Equipment shall be set or mounted on a level base capable of supporting and distributing the weight contained thereon. Boilers, tanks, and equipment shall be securely anchored to the structure. Equipment requiring vibration isolation shall be installed as designed by a registered design professional and approved by the Authority Having Jurisdiction.
1001.5.1 Floors. Boilers shall be mounted on floors of noncombustible construction unless listed for mounting on combustible flooring. 1001.6 Chimneys or Vents. Boilers shall be connected to a chimney or vent, as provided for other fuel-burning equipment in Chapter 8 of this code.
1002.0 Standards.
1002.1 General. Pressure vessels shall be constructed and designed in accordance with the ASME Boiler & Pressure Vessel Code (BPVC) Section VIII.1. Boilers shall be constructed, designed, and installed in accordance with one of the following: (1) ASME BPVC Section I (2) ASME BPVC Section IV (3) NFPA 85 1002.2 Oil-Burning Boilers. Oil-burning boilers shall comply with Section 1002.2.1 and Section 1002.2.2. 1002.2.1 Listing & Labeling. Oil-burning boilers shall be listed and labeled in accordance with UL 726.
1002.2.2 Installation. Tanks, piping, and valves for oil-burning boilers shall be installed in accordance with NFPA 31.
1002.3 Electric Boilers. Electric boilers shall be listed and
labeled in accordance with UL 834.
1002.4 Solid-Fuel-Fired Boilers. Solid-fuel-fired boilers shall comply with UL 2523 and shall be installed in accordance with the manufacturer’s installation instruc tions.
1002.5 Dual Purpose Water Heaters. Water heaters utilized for combined space- and water-heating applications shall comply with the standards referenced in Table 1203.2, and shall be installed in accordance with the manufacturer’s
installation instructions.
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BOILERS AND PRESSURE VESSELS
1003.0 Detailed Requirements.
1003.1 Safety Requirements. The construction of boilers and pressure vessels and the installation thereof shall be in accordance with minimum requirements for safety from structural and mechanical failure and excessive pressures as established by the Authority Having Jurisdiction in accordance with nationally recognized standards.
CMC § 305.6 High relevance — show source text
305.6 Outdoor Locations . . . . . . . . . . . . . 55
306.0 Automatic Control Devices . . . . . . . 55
306.1 General. . . . . . . . . . . . . . . . . . . . . . 55
306.2 Building Automation Systems . . . . 56
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TABLE OF CONTENTS
307.0 Labeling . . . . . . . . . . . . . . . . . . . . . 56
307.1 Fuel-Burning Appliances . . . . . . . . 56
307.2 Electric Heating Appliances . . . . . . 56
307.3 Heat Pump and Electric Cooling Appliances . . . . . . . . . . . . . . . . . . . 56
307.4 Absorption Units . . . . . . . . . . . . . . . 56
308.0 Improper Location. . . . . . . . . . . . . . 57
308.1 General. . . . . . . . . . . . . . . . . . . . . . 57
309.0 Workmanship . . . . . . . . . . . . . . . . . 57
309.1 Engineering Practices. . . . . . . . . . . 57
309.2 Concealing Imperfections . . . . . . . . 57
309.3 Installation Practices. . . . . . . . . . . . 57
310.0 Condensate Wastes and Control . . 57
310.1 Condensate Disposal . . . . . . . . . . . 57
310.2 Condensate Control . . . . . . . . . . . . 57
310.3 Condensate Waste Pipe Material and Sizing. . . . . . . . . . . . . . . . . . . . 57
Table 310.3 Minimum Condensate Pipe Size. . . 57
310.4 Appliance Condensate Drains . . . . 58
310.5 Point of Discharge . . . . . . . . . . . . . 58
310.6 Condensate Waste from
Air-Conditioning Coils . . . . . . . . . . . 58
310.7 Female Plastic Connections . . . . . . 58
311.0 Heating or Cooling Air System . . . . 58
311.1 Source . . . . . . . . . . . . . . . . . . . . . . 58
311.2 Air Filters . . . . . . . . . . . . . . . . . . . . 58
311.3 Prohibited Sources . . . . . . . . . . . . . 58
311.4 Return-Air Limitations . . . . . . . . . . . 58
311.5 California Energy Code Requirements for Residential
Air Filtration . . . . . . . . . . . . . . . . . . 59
312.0 Plumbing Connections . . . . . . . . . . 59
312.1 General. . . . . . . . . . . . . . . . . . . . . . 59
CMC § 303.7 High relevance — show source text
303.7 Liquefied Petroleum Gas (LP-Gas) Facilities . . . . . . . . . . . . . . 53
303.8 Appliances on Roofs. . . . . . . . . . . . 53
303.9 Avoiding Strain on Gas Piping . . . . 53
303.10 Clearance to Combustible
Materials . . . . . . . . . . . . . . . . . . . . . 53
303.11 Installation in Commercial
Garages . . . . . . . . . . . . . . . . . . . . . 54
303.12 Installation in Aircraft Hangars . . . . 54
304.0 Accessibility for Service . . . . . . . . . 54
304.1 General. . . . . . . . . . . . . . . . . . . . . . 54
304.2 Sloped Roof . . . . . . . . . . . . . . . . . . 54
304.3 Access to Appliances on Roofs . . . 54
304.4 Appliances in Attics and Under-Floor Spaces . . . . . . . . . . . . 54
305.0 Location . . . . . . . . . . . . . . . . . . . . . 55
305.1 Installation in Residential Garages . . 55
305.2 Pit Location. . . . . . . . . . . . . . . . . . . 55
305.3 Flood Hazard Areas . . . . . . . . . . . . 55
305.4 Elevator Shaft . . . . . . . . . . . . . . . . . 55
305.5 Drainage Pan . . . . . . . . . . . . . . . . . 55
305.6 Outdoor Locations . . . . . . . . . . . . . 55
306.0 Automatic Control Devices . . . . . . . 55
306.1 General. . . . . . . . . . . . . . . . . . . . . . 55
306.2 Building Automation Systems . . . . 56
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TABLE OF CONTENTS
307.0 Labeling . . . . . . . . . . . . . . . . . . . . . 56
307.1 Fuel-Burning Appliances . . . . . . . . 56
307.2 Electric Heating Appliances . . . . . . 56
307.3 Heat Pump and Electric Cooling Appliances . . . . . . . . . . . . . . . . . . . 56
307.4 Absorption Units . . . . . . . . . . . . . . . 56
308.0 Improper Location. . . . . . . . . . . . . . 57
308.1 General. . . . . . . . . . . . . . . . . . . . . . 57
309.0 Workmanship . . . . . . . . . . . . . . . . . 57
309.1 Engineering Practices. . . . . . . . . . . 57
309.2 Concealing Imperfections . . . . . . . . 57
309.3 Installation Practices. . . . . . . . . . . . 57
CMC § 0.35 High relevance — show source text
Mechanical Ventilation = [(0.35 – Summer ) × Volume ] / 60
Where:
Mechanical Ventilation = required mechanical ventilation rate to supplement summer infiltration, CFM
Summer = summer design infiltration rate, ACH Volume = volume of conditioned space, ft [3 ] (m [3] )
For SI units: 1 cubic foot = 0.0283 m [3], 1 cubic foot per minute = 0.00047 m [3] /s, 1 cubic foot per minute = 0.4719 L/s
[ASHRAE 90.2-2007:6.6.1]
E 502.6.1 Combustion Air. Combustion air for fossil fuel heating equipment shall comply with this code or with one of the following:
(1) Natural gas and propane heating equipment, NFPA 54
(2) Oil heating equipment, NFPA 31
(3) Solid fuel burning equipment, NFPA 211
[ASHRAE 90.2-2007:6.6.2] E 502.7 Electric Heating Systems. Electric heating systems shall be installed in accordance with the following requirements. [ASHRAE 90.2-2007:6.7] E 502.7.1 Wall, Floor, or Ceiling Electric-Resis- tance Heating. Where wall, floor, or ceiling electricresistance heating units are used, the structure shall be zoned and heaters installed in each zone in accordance with the heat loss of that zone. Where living and sleeping zones are separate, the number of zones shall be not less than two. Where two or more heaters are installed in one room, they shall be controlled by one thermostat.
[ASHRAE 90.2-2007:6.7.1]
E 502.7.2 Electric Central Warm Air Heating. Where electric central warm air heating is to be installed, an electric heat pump or an off-peak electric heating system with thermal storage shall be used.
Exceptions:
(1) Electric resistance furnaces where the ducts are located inside the conditioned space, and not less than two zones are provided where the living and sleeping zones are separate.
(2) Packaged air-conditioning units with supplemental electric heat. [ASHRAE 90.2-2007:6.7.2] E 502.8 Bath Ceiling Units. Bath ceiling units providing a combination of heat, light, or ventilation shall be provided with controls permitting separate operation of the heating function. [ASHRAE 90.2-2007:6.8] E 502.9 HVAC Equipment, Rated Combinations. HVAC system equipment and system components shall be furnished with the input(s), the output(s), and the value of the appropriate performance descriptor of HVAC products in accordance with federal law or in accordance with Table E 502.9, as applicable. These shall be based on newly produced equipment or components. Manufacturer’s instructions shall be furnished with and attached to the equipment. The manufacturer of electric-resistance heating equipment shall furnish full-load energy input over the range of voltages at which the equipment is intended to operate. [ASHRAE 90.2-2007:6.9] **E 502.10 Controls.
CMC § 100 High relevance — show source text
It includes but is not limited to burning oil or liquid fuel. Fuel Burner System. The fuel burner and a conveyance system or piping system for the purpose of introducing the appropriate fuel into the combustion chamber zone. Fuel-Burning Equipment/Appliance. An oil or fuel burner of any type including all oil or liquid fuel burners, oil or liquid fuel-fired units, dual, or multi-fuel burners and heating and cooking appliances with their fuel burner system and with their tank or fuel storage system, piping system, vent connectors, vent flues, fans, blowers, valves, control devices, combustion air, wiring, controls, and related devices including all accessories and appurtenances for safe and proper operation of the appliance. Fuel Oil. Hydrocarbon oil as specified by ASTM D396, or the Canadian Government Specification Board, 3-GP-28, and having a flashpoint of not less than 100°F (38°C). Fuel-Piping System. Method of conveying liquid, vapor, steam, gases, or slurry from one point to another, including accessories, appurtenances, and equipment necessary for its proper operation. Indirect-Fired Appliance. An oil or fuel-burning appliance in which products of combustion (flue gases) are not mixed in the appliance with the air or other medium being heated.
Labeled. Having attached a label, symbol, or other identifying mark of an organization acceptable to the Authority Having Jurisdiction and concerned with product evaluation that maintains periodic inspection of production of labeled equipment or materials and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner. Premixing. A power burner in which all or nearly all of the air for combustion is mixed with the gas as primary air. Pump, Oil or Fuel Transfer. An oil or fuel pump, automatically or manually operated, that transfers oil or fuel through continuous piping from a supply tank to an oil or fuel-burning appliance or to an auxiliary tank, and that is not designed to stop pumping automatically in case of total breakage of the oil or fuel supply line between the pump and the appliance. Tank, Auxiliary. A tank having a capacity of not over 60 gallons (227 L) listed for installation in the supply piping between a burner and its main fuel supply tank. It shall be permitted to be included as an integral part of an automatic pump or a transfer pump, or it shall be permitted to be a separate tank.
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APPENDIX C
Tank, Gravity. A supply tank from which the oil or fuel is delivered directly to the burner by gravity.
Tank, Integral. A tank that is furnished by the manufacturer as an integral part of an oil or fuel-burning appliance.
Tank Storage. A separate tank that is not connected to the oil or fuel-burning appliance.
Tank Supply. A separate tank connected directly or by a pump to the oil or fuel-burning appliance.
Tank, Vacuum or Barometric. A tank not exceeding 5 gallons (19 L) capacity that maintains a definite level of oil or fuel in a sump or similar receptacle by barometric feed. Fuel is delivered from the sump to the burner by gravity.
CMC § 3305.1 Medium relevance — show source text
3305.1 Listed. Temporary heating devices shall be listed and labeled. The installation, maintenance and use of temporary heating devices shall be in accordance with the listing and the manufacturer’s instructions.
3305.1.1 Oil-fired heaters. Oil-fired heaters shall comply with Section 605.
3305.1.2 LP-gas heaters. Fuel supplies for liquefied-petroleum gas-fired heaters shall comply with Chapter 61 and the Interna- tional Fuel Gas Code .
3305.1.3 Refueling. Refueling operations for liquid-fueled equipment or appliances shall be conducted in accordance with Section 5705. The equipment or appliance shall be allowed to cool prior to refueling.
3305.1.4 Installation. Clearance to combustibles from temporary heating devices shall be maintained in accordance with the labeled equipment. When in operation, temporary heating devices shall be fixed in place and protected from damage, dislodgement or overturning in accordance with the manufacturer’s instructions.
3305.1.5 Supervision. The use of temporary heating devices shall be supervised and maintained only by competent personnel.
3305.2 Smoking. Smoking shall be prohibited except in approved areas. Signs shall be posted in accordance with Section 310. In approved areas where smoking is permitted, approved ashtrays shall be provided in accordance with Section 310.
3305.3 Burning of combustible debris, rubbish and waste. Combustible debris, rubbish and waste material shall not be disposed of by burning on the site unless approved.
3305.4 Open burning. Open burning shall comply with Section 307.
3305.5 Cutting and welding. Welding, cutting, open torches and other hot work operations and equipment shall comply with Chapter 35.
3305.6 Electrical. Temporary wiring for electrical power and lighting installations used in connection with the construction, alteration or demolition of buildings, structures, equipment or similar activities shall comply with the California Electrical Code .
3305.7 Cooking. Cooking shall be prohibited except in approved designated cooking areas separated from combustible materials by a minimum of 10 feet (3048 mm). Signs with a minimum letter height of 3 inches (76 mm) and a minimum brush stroke of [1] / 2 inch (13 mm) shall be posted in conspicuous locations in designated cooking areas and state:
DESIGNATED COOKING AREA
COOKING OUTSIDE OF A DESIGNATED
COOKING AREA IS PROHIBITED
3305.8 Portable generators. Portable generators used at construction and demolition sites shall comply with Section 1204.
3305.9 Hot work operations. The site safety director shall ensure hot work operations and permit procedures are in accordance with Chapter 35.
3305.10 Safeguarding roofing operations. Roofing operations utilizing heat-producing systems or other ignition sources shall be conducted in accordance with Sections 3305.10.1 and 3305.10.2 and Chapter 35.
3305.10.1 Asphalt and tar kettles. Asphalt and tar kettles shall be operated in accordance with Section 303.
3305.10.2 Fire extinguishers for roofing operations. Fire extinguishers shall comply with Section 906. There shall be not less than one multiple-purpose portable fire extinguisher with a minimum 3-A 40-B:C rating on the roof being covered or repaired.
SECTION 3306—FIRE PROTECTION SYSTEMS AND DEVICES
CMC § 901.1 Medium relevance — show source text
901.1 Applicability. . . . . . . . . . . . . . . . . . 199
902.0 General. . . . . . . . . . . . . . . . . . . . . 199
902.1 Nonindustrial Appliances . . . . . . . 199
902.2 Combustion Air from Bedroom
or Bathroom . . . . . . . . . . . . . . . . . 199
902.3 Added or Converted Appliances. . 199
902.4 Type of Gas(es) . . . . . . . . . . . . . . 199
902.5 Safety Shutoff Devices for Unlisted LP-Gas Appliances Used Indoors . . . . . . . . . . . . . . . . 199
902.6 Fuel Input Rate . . . . . . . . . . . . . . . 199
902.7 Use of Air or Oxygen Under Pressure . . . . . . . . . . . . . . . . . . . . 199
902.8 Appliance Support . . . . . . . . . . . . 199
902.9 Flammable Vapors . . . . . . . . . . . . 199
902.10 Solid-Fuel-Burning Appliances . . . 199
902.11 Combination of Appliances and Equipment . . . . . . . . . . . . . . . 199
902.12 Protection of Gas Appliances from Fumes or Gases Other
than Products of Combustion . . . . 199
902.13 Process Air . . . . . . . . . . . . . . . . . . 200
902.14 Gas Appliance Pressure Regulators . . . . . . . . . . . . . . . . . . 200
902.15 Bleed Lines for Diaphragm-Type Valves. . . . . . . . . . . . . . . . . . . . . . 200
903.0 Air-Conditioning Appliances . . . . . 200
903.1 Electric Air Conditioners . . . . . . . . 200
903.2 Gas-Fired Air Conditioners
and Heat Pumps. . . . . . . . . . . . . . 200
903.3 Packaged Terminal Air Conditioners . . . . . . . . . . . . . . . . . 200
904.0 Central Heating Boilers and Furnaces. . . . . . . . . . . . . . . . . . . . 200
904.1 Application . . . . . . . . . . . . . . . . . . 200
2025 CALIFORNIA MECHANICAL CODE
904.2 Location . . . . . . . . . . . . . . . . . . . . 201
904.3 Clearance . . . . . . . . . . . . . . . . . . . 201
904.4 Assembly and Installation. . . . . . . 201
904.5 Temperature or Pressure Limiting Devices . . . . . . . . . . . . . . 202
904.6 Low-Water Cutoff . . . . . . . . . . . . . 202
904.7 Steam Safety and Pressure Relief Valves. . . . . . . . . . . . . . . . . 202
904.8 Refrigeration Coils . . . . . . . . . . . . 202
CMC § 509.2.2 Medium relevance — show source text
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
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
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
CMC § 1106.2.6. Medium relevance — show source text
(1) The space(s) containing the machinery is (are) separated from other occupancies by tight construction with tightfitting doors.
(2) Access is restricted to authorized personnel.
(3) Refrigerant detectors are installed with the sensing location and alarm level as required in refrigeration machinery rooms in accordance with Section 1106.2.6.
(4) Open flames and surfaces exceeding 800°F (427°C) shall not be permitted where a Group A2, B2, A3, or B3 refrigerant, is used.
(5) Electrical equipment that is in accordance with Class 1, Division 2, of NFPA 70 where the quantity of a Group A2, B2, A3, or B3 refrigerant in an independent circuit is capable of exceeding 25 percent of the lower flammability limit (LFL) upon release to the space based on the volume determined in accordance with Section 1104.2.1 through Section 1104.2.3.
(6) Refrigerant containing parts in systems exceeding 100 horsepower (74.6 kW) compressor drive power, except evaporators used for refrigeration or dehumidification, condensers used for heating, control and pressure-relief valves for either, low-probability pumps, and connecting piping, are located in a machinery room or outdoors.
[ASHRAE 15:7.2.2]
1104.5 Flammable Refrigerants. The total of Group A2, B2, A3, and B3 refrigerants, other than Group A2L and B2L refrigerants shall not exceed 1100 pounds (498.9 kg) without approval by the Authority Having Jurisdiction. Institutional Occupancies shall comply with Section 1104.3. Machinery rooms required in accordance with Section 1106.0 based on flammability shall be constructed and maintained in accordance with Section 1106.2.1 through Section 1106.2.6 and Section 1106.11 for Group A2L and B2L refrigerants. 1104.6 Group A2L Refrigerants for Human Comfort. High-probability systems using Group A2L refrigerants for human comfort applications shall comply with this section.
[ASHRAE 15:7.6]
1104.6.1 Refrigerant Concentration Limits. Occupied spaces shall comply with the releasable charge limitations of the equipment listing and ASHRAE 15. Unoccupied spaces with refrigerant containing equipment, not including continuous piping or tubing, shall comply with the releasable charge limitations of the equipment listing or Section 1104.6.4. {ASHRAE 15:7.6.1-7.6.1.2}
1104.6.2 Listing and Installation Requirements. Refrigeration systems shall be listed and shall be installed in accordance with listing, the manufacturer’s instructions, and any markings on the equipment restricting the installation. [ASHRAE 15:7.6.2]
1104.6.2.1 Nameplate. The nameplate required by Section 1115.5 shall include a symbol indicating that a flammable refrigerant is used, as specified by the product listing. [ASHRAE 15:7.6.2.1]
1104.6.2.2 Labeling. A label indicating a flammable refrigerant is used shall be placed adjacent to service ports and other locations where service involving components containing refrigerant is performed, as specified by the product listing.
California Mechanical Code Medium relevance — show source text
Burner, Mechanical Draft Type. A burner that includes a power-driven fan, blower, or other mechanism as the primary means for supplying the air for combustion. Burner, Natural Draft Type. A burner that depends primarily on the natural draft created in the chimney or venting system to induce air required for combustion into the burner. Constant Level Valve. A device for maintaining within a reservoir a constant level of oil or fuel for delivery to a burner. Control Limit. An automatic safety control that is responsive to changes in fluid flow or level, pressure, or temperature and that is normally set beyond the operating range for limiting the operation of the controlled equipment by shutting off the energy supply. Control Safety. Automatic interlock controls, including relays, switches, and other auxiliary equipment used in conjunction with them, to form a safety control system that is intended to prevent unsafe operation of the controlled equipment.
Draft Booster. A power-operated fan, blower, or other device installed in the chimney connector to increase the natural draft developed in the connected chimney. Draft Regulator, Barometric. A device built into a fuel-burning appliance or made part of a chimney connector or vent connector that functions to reduce excessive draft through an appliance to a desired value by admitting ambient air into the appliance chimney, chimney connector, vent, or vent connector. Fuel. Natural, manufactured, or liquefied petroleum gas, or a mixture of these gases; all grades of fuel oil, wood, or any other combustible or flammable material or any mixture of combustible or flammable materials.
Fuel Burner. A device used to convey the appropriate fuel into the combustion chamber zone in close proximity to its primary and secondary air supply to permit a stable controlled heat release compatible with the burner design, listing, and applicable approvals in a boiler, furnace, device or appliance. It includes but is not limited to burning oil or liquid fuel. Fuel Burner System. The fuel burner and a conveyance system or piping system for the purpose of introducing the appropriate fuel into the combustion chamber zone. Fuel-Burning Equipment/Appliance. An oil or fuel burner of any type including all oil or liquid fuel burners, oil or liquid fuel-fired units, dual, or multi-fuel burners and heating and cooking appliances with their fuel burner system and with their tank or fuel storage system, piping system, vent connectors, vent flues, fans, blowers, valves, control devices, combustion air, wiring, controls, and related devices including all accessories and appurtenances for safe and proper operation of the appliance. Fuel Oil. Hydrocarbon oil as specified by ASTM D396, or the Canadian Government Specification Board, 3-GP-28, and having a flashpoint of not less than 100°F (38°C). Fuel-Piping System. Method of conveying liquid, vapor, steam, gases, or slurry from one point to another, including accessories, appurtenances, and equipment necessary for its proper operation. Indirect-Fired Appliance. An oil or fuel-burning appliance in which products of combustion (flue gases) are not mixed in the appliance with the air or other medium being heated.
Labeled. Having attached a label, symbol, or other identifying mark of an organization acceptable to the Authority Having Jurisdiction and concerned with product evaluation that maintains periodic inspection of production of labeled equipment or materials and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner. **Premixing.
Frequently asked questions
Can a field‑applied sticker satisfy the “factory‑applied nameplate” requirement?
No. § 307.1 and § 307.2 require a factory‑applied permanent and legible nameplate. The code does not provide for substituting a field sticker in place of the factory nameplate.
Must the nameplate show both Btu/h and kW?
For fuel‑burning appliances § 307.1 requires the approved fuel input rating expressed in Btu/h (kW) — showing both is the format the section specifies.
Are installation instructions mandatory for electric heaters?
Yes. § 307.2 requires that electric heating appliances be accompanied by clear and complete installation instructions, including required clearances from combustibles and temperature rating of field‑installed wiring connections exceeding 140°F (60°C).
Is the listing agency symbol alone sufficient for compliance?
No. The listing symbol is required but is not a substitute for the other specific nameplate items listed in § 307.1 or § 307.2.
Does the code specify location or font size for the nameplate?
No. The sections require the nameplate to be permanent and legible and factory‑applied, but they do not prescribe exact font size or mounting location; acceptability is subject to the Authority Having Jurisdiction.
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