CMC · California Mechanical Code
How are 'Appliance' and 'Appliance, Vented' defined?
Short: The CMC defines an **Appliance** in **§ 203.0** as any device using fuel or electricity to produce light, heat, power, refrigeration, or air conditioning (including vented decorative and electric storage/tankless water heaters). Whether an appliance is a **vented appliance** and which venting **Category I–IV** applies is set out separately in **§ 224.0**, which classifies appliances by vent static pressure and vent-gas temperature.
Last reviewed: July 6, 2026
What the code requires — in plain English
- An Appliance is anything that uses fuel or electricity to produce light, heat, power, refrigeration, or air conditioning; the definition explicitly includes vented decorative appliances and electric storage or tankless water heaters. See § 203.0 .
- The term Appliance, Vented (and the categories that determine venting requirements) is treated separately in the code — the vented appliance categories and criteria are located in § 224.0 (Category I–IV definitions) rather than in § 203.0 .
The single most important point: If a device uses fuel or electricity to produce light, heat, power, refrigeration, or air conditioning, it is an Appliance under the CMC — and whether it is a vented appliance (and which vent category applies) is determined by the vented-appliance definitions and categories in § 224.0.
Requirements in detail
Core definition — "Appliance" (where to find it)
- What counts: devices that use fuel or electricity to produce light, heat, power, refrigeration, or air conditioning. The written definition also lists vented decorative appliances and electric storage or tankless water heaters as examples included in the definition. See § 203.0 .
Where "Appliance, Vented" is defined
- The code separates the general definition (in § 203.0) from the vented-appliance categories: Category I, II, III, and IV Vented Appliances are defined in § 224.0. Those categories use the appliance’s vent static pressure (positive vs nonpositive) and vent gas temperature (tends to avoid or cause condensate) to classify the appliance for venting rules. See § 224.0 .
Decision table — key decision dimensions
| Decision dimension | What to look for | Typical values / outcomes | Code Reference |
|---|---|---|---|
| Is it an Appliance? | Does the device use fuel or electricity to produce light/heat/power/refrigeration/air conditioning? | Yes → Appliance; includes vented decorative, electric storage & tankless water heaters | § 203.0 |
| Is it vented and which category? | Determine vent static pressure (positive vs nonpositive) and vent gas temperature (causes or avoids condensate) | Category I–IV (see descriptions) | § 224.0 |
| Special constructions named in 203.0 | Direct-vent, closed-combustion solid-fuel-burning, etc. | Distinct appliance-type definitions affect installation/venting approach | § 203.0 |
| Where to find installation rules for vented decorative appliances or vented fireplaces | Installation and listing requirements (specific chapters/sections) | See decorative appliance and fireplace sections (e.g., §§ 911–913, 912 for vented gas fireplaces) | § 224.0 and related sections |
Short explanation of the vented categories (from § 224.0)
- Category I — nonpositive vent static pressure; vent gas temperature that avoids excessive condensate. Category II — nonpositive static pressure; vent gas temperature that can cause excessive condensate. Category III — positive vent static pressure; vent gas temperature that avoids condensate. Category IV — positive vent static pressure; vent gas temperature that can cause condensate. See § 224.0 for these distinctions .
Exceptions & special cases
- The general Appliance definition in § 203.0 specifically includes vented decorative appliances and electric storage or tankless water heaters, so those are appliances even if other chapters impose special installation/listing rules .
- The detailed venting classification (Category I–IV) and related venting rules are not in § 203.0 — they are placed in § 224.0 and in the venting-specific chapters. If you need the category-based venting requirements (for connector type, vent material, termination, or condensate protections), consult § 224.0 and the venting chapters referenced by it .
- Some appliances have their own specific rules (for example, vented gas fireplaces have listing and installation requirements in the fireplace sections such as § 912.1 / § 912.3) — those are separate from the general definition and from the vent-category rules and must be followed where applicable .
If you need a numeric threshold or a specific formula (for example: a numeric vent gas temperature value that separates “avoids” vs “causes” condensate), that precise numeric threshold is not supplied in the retrieved text for § 203.0 or § 224.0 in the materials provided here — consult the full text of § 224.0 and the referenced standards/listings for appliance-specific numeric criteria.
Common mistakes
- Assuming every device with a flue is automatically a “vented appliance” category without checking vent static pressure and vent gas temperature — the vented category (I–IV) is what determines venting rules, and those criteria are in § 224.0, not in the § 203.0 appliance definition .
- Treating direct-vent appliances the same as naturally vented appliances — Direct Vent is a separate appliance type (all combustion air from outdoors and all flue gases discharged outdoors) and has different installation implications; it’s defined in § 203.0 .
- Overlooking that the Appliance definition explicitly calls out vented decorative appliances and electric storage/tankless water heaters as included examples — some readers assume only large heating equipment is an “appliance.” See § 203.0 .
Worked example — concrete scenario
Scenario: You are reviewing a proposed water-heating unit for a single-family house.
The unit is an on-demand (tankless) electric water heater (no combustion).
- Does it meet the Appliance definition? Yes — it uses electricity to produce heat. It is explicitly included as an example in the Appliance definition. Classification: Appliance under § 203.0.
- Is it a vented appliance? No — because it is electric and does not produce combustion products that require venting. No vent-category classification in § 224.0 applies.
The unit is a natural-draft gas water heater (combustion).
- It is an Appliance (fuel used to produce heat) per § 203.0 .
- To determine whether it is a Category I/II/III/IV Vented Appliance, you must assess the appliance’s vent static pressure (natural-draft is normally nonpositive) and whether its vent gas temperature is likely to cause condensate. Based on those two facts you would place it in Category I or II under § 224.0 and then follow the venting rules that apply to that category. The exact category assignment and venting requirements are determined under § 224.0 and the applicable venting chapters — those specific criteria are in § 224.0, not in § 203.0 .
Related provisions (CMC sections)
- § 203.0 — Definitions for Appliance and related appliance-type definitions (Direct Vent, Closed Combustion Solid-Fuel-Burning, etc.) .
- § 224.0 — Vented appliance categories (Category I–IV) and vented-appliance definitions; see for classification used in venting rules .
- § 911.0 – 913.0 (Decorative appliances / Factory-built fireplaces) — installation and listing rules for decorative and vented fireplaces (see vented decorative appliance references) .
- Other venting and appliance-installation sections referenced by the vented categories and appliance-specific chapters — consult the chapters that follow § 224.0 for material/installation/termination rules (see index entries in the retrieved code text) .
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 3.3.101 High relevance — show source text
Valve, Pressure-Relief. A pressure-actuated valve held closed by a spring or other means and designed automatically to relieve pressure in excess of its setting.
Valve, Riser. A valve at the base of a vertical riser that isolates that riser.
Valve, Service. A valve is serving horizontal piping extending from a riser to a station outlet or inlet. Valve, Source. A single valve at the source that controls a number of units that makes up the source. Valve, Zone. A valve that controls the gas or vacuum to a particular area. Vent. See Plumbing Vent; Dry Vent; Wet Vent. Vent Connector, Gas. That portion of a gas venting system that connects a listed gas appliance beginning at the draft hood or flue collar to a gas vent and is installed entirely within the space or area in which the appliance is located. Vent Offset. An arrangement of two or more fittings and pipe installed for the purpose of locating a vertical section of vent pipe in a different but parallel plane with respect to an adjacent section of vertical vent pipe. [NFPA 54:3.3.101] Vent Pipe. See Plumbing Vent. Vent Stack. The vertical vent pipe installed primarily for the purpose of providing circulation of air to and from any part of the drainage system. Vent System. See Plumbing Vent System. Vented Appliance. Category I Vented Appliance. An appliance that operates with a nonpositive vent static pressure and with a vent gas temperature that avoids excessive condensate production in the vent. [NFPA 54:3.3.4.10.1] Category II Vented Appliance. An appliance that operates with a nonpositive vent static pressure and with a vent gas temperature that can cause excessive condensate production in the vent. [NFPA 54:3.3.4.10.2] Category III Vented Appliance. An appliance that operates with a positive vent static pressure and with a vent gas temperature that avoids excessive condensate production in the vent. [NFPA 54:3.3.4.10.3]
Category IV Vented Appliance. An appliance that operates with a positive vent static pressure and with a vent gas temperature that can cause excessive condensate production in the vent. [NFPA 54:3.3.4.10.4]
Vented Flow Control Device. A device installed upstream from the hydromechanical grease interceptor having an orifice that controls the rate of flow through the interceptor, and an air intake (vent) downstream from the orifice, which allows air to be drawn into the flow stream.
Venting System. A continuous open passageway from the flue collar or draft hood of an appliance to the outdoors for the purpose of removing flue or vent gases. [NFPA 54:3.3.95.7]
Vent, Gas. A listed factory-made vent pipe and vent fittings for conveying flue gases to the outdoors.
Type B Gas Vent. A factory-made gas vent listed by a nationally recognized testing agency for venting listed or approved appliances equipped to burn only gas.
Type BW Gas Vent. A factory-made gas vent listed by a nationally recognized testing agency for venting listed or approved gas-fired vented wall furnaces.
CMC § 907.0 High relevance — show source text
907.0, 911.3, 1009.4
Required . . . . . . . . . . . . . . . . . . . . . . . . . . .901.2, 904.1
Required separately
on every trap . . . . . . . . . . . . . . . .901.2, 1002.1, 1002.2 Sizing . . . . . . . . . . . . . .Table 702.1, 703.0, Table 703.2,
904.0, 908.1.1, 908.1.2,
908.2.2, 910.4, C 401.0,
Table C 401.1, C 601.2
Special . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .909.0
Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224.0, 906.1,
907.0, C 401.2, C 601.2
Sump . . . . . . . . . . . . . . . . . . . .710.7, 710.10, 710.13.3,
810.1, Table 810.1
System, definition . . . . . . . . . . . . . . . . . . . . . . . . .224.0
Termination . . . . . . . . . . . . . . . . . .905.4, 906.0, 906.2.1
Testing . . . . . . . . . . . . . . . . . . . . . . . . . .712.0, 1504.10 Trap seal protection . . . . . . . . . . . . . . . . . .901.3, 1002.0
Undiminished in
size through roof . . . . . . . . . . . . . . . . . . .905.4, 907.1 Unit loading . . . . . . . . . . . . . . . . . . . . . . . . .Table 703.2
Wet, Horizontal . . . . . . . . . . . . . . . . . . . . . . . . . . .908.2
Wet, Vertical . . . . . . . . . . . . . . . . . . . . . . . . . . . . .908.1
Yoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .227.0, 907.0
VENTED APPLIANCE, DEFINITION . . . . . . . . . . . . . .224.0
Category I Vented Appliance, definition . . . . . . . . .224.0 Category II Vented Appliance, definition . . . . . . . .224.0 Category III Vented Appliance, definition . . . . . . . .224.0 Category IV Vented Appliance, definition . . . . . . .224.0 VENTILATING HOODS . . . . . . . . . . . . . . . .509.2.4, 509.3.4
VERTICAL-TO-HORIZONTAL
CMC § 905.4 High relevance — show source text
Undiminished in
size through roof . . . . . . . . . . . . . . . . . . .905.4, 907.1 Unit loading . . . . . . . . . . . . . . . . . . . . . . . . .Table 703.2
Wet, Horizontal . . . . . . . . . . . . . . . . . . . . . . . . . . .908.2
Wet, Vertical . . . . . . . . . . . . . . . . . . . . . . . . . . . . .908.1
Yoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .227.0, 907.0
VENTED APPLIANCE, DEFINITION . . . . . . . . . . . . . .224.0
Category I Vented Appliance, definition . . . . . . . . .224.0 Category II Vented Appliance, definition . . . . . . . .224.0 Category III Vented Appliance, definition . . . . . . . .224.0 Category IV Vented Appliance, definition . . . . . . .224.0 VENTILATING HOODS . . . . . . . . . . . . . . . .509.2.4, 509.3.4
VERTICAL-TO-HORIZONTAL
DRAINAGE FITTINGS . . . . . . . . . . . . . . . . . . . . . . .706.4
VERTICAL WET VENTING . . . . . . . . . . . . .(see Wet vents) VIOLATION, NOTICES OF . . . . . . . . . . . . . . . . . . . . . .106.2
VITRIFIED CLAY PIPE . . . . . . . . .701.2, Table 701.2, 705.8,
811.2, Table 1101.4.6
– W –
WALL, EXTENSION THROUGH . . . . .312.1, 509.6.1, 509.8
WALL-HUNG FIXTURES,
INSTALLATION OF . . . . . . . . . . . . . . . . . . . . .402.4, 402.6
WASH FOUNTAINS . . . . . . . . . . . . . . . . . . . . . 417.1.1, 417.1.2
WASH RACKS, AUTO . . . . . . . . . . . . . . . . . . . . . . . . . 1011.0
WASTES
Anesthetic gas disposal . . . . . . . . . . . . . . . . . . . .1301.2 Chemical . . . . . . . . . . . . . . . . . . . .205.0, 811.0, 903.2.2
Clear water . . . . . . . . . . . . . . . . . . . . . . . . .205.0, 812.0
Condensate . . . . . . . . . . . . . . . . . . . . . . . . .807.2, 814.0
CMC § 3.3.3 High relevance — show source text
Anchors. See Supports.
Anodeless Riser. An assembly of steel-cased plastic pipe used to make the transition between plastic piping installed underground and metallic piping installed aboveground.
[NFPA 54:3.3.3]
Appliance. A device that utilizes fuel or electricity as an energy source to produce light, heat, power, refrigeration, or air conditioning. This definition also includes vented decorative appliances and electric storage or tankless water heaters.
Appliance, Closed Combustion Solid-Fuel-Burn- ing. A heat-producing appliance that employs a combustion chamber that has no openings other than the flue collar, fuel-charging door, and adjustable openings provided to control the amount of combustion air that enters
the combustion chamber.
Appliance, Direct Vent. Appliances that are constructed and installed so that all air for combustion is derived directly from the outdoors and all flue gases are discharged to the outdoors. [NFPA 54:3.3.4.2]
Appliance, Electric Heating. A device that produces heat energy to create a warm environment by the application of electric power to resistance elements, refrigerant compressors, or dissimilar material junctions. Appliance, Fan-Assisted Combustion System. An appliance equipped with an integral mechanical means to either draw or force products of combustion through the combustion chamber or heat exchanger.
[NFPA 54:3.3.95.2]
Appliance, Low-Heat. A fuel-burning appliance that produces a continuous flue gas temperature, at the point of entrance to the flue, of not more than 1000°F (538°C).
Appliance, Medium-Heat. A fuel-burning appliance that produces a continuous flue gas temperature, at the point of entrance to the flue, of more than 1000°F (538°C) and less than 2000°F (1093°C).
Appliance, Portable Heating. A heating appliance designed for environmental heating that may have a self
32 2025 CALIFORNIA MECHANICAL CODE
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DEFINITIONS
200 000 Btu/h (58.6 kW), or an operating temperature exceeding 210°F (99°C) that provides hot water to be used externally to itself.
Boiler, Low-Pressure Hot-Water-Heating. A boiler furnishing hot water at pressures not exceeding 160 psig (1103 kPa) and at temperatures not exceeding 250°F (121°C).
Boiler, Low-Pressure Steam-Heating. A boiler furnishing steam at pressures not exceeding 15 psig (103 kPa).
Boiler, Miniature. A power boiler having an internal shell diameter of 16 inches (406 mm) or less, a gross volume of 5 cubic feet (0.14 m [3] ) or less, a heating surface of 20 square feet (1.86 m [2] ) or less (not applicable to electric boilers), and not exceeding 100 psig (689 kPa).
Boiler, Package. A class of boiler defined herein and shall be a boiler equipped and shipped complete with fuel-burning equipment, automatic controls and accessories, and mechanical draft equipment.
Boiler, Power. A boiler in which steam is generated at pressures exceeding 15 psig (103 kPa).
CMC § 223.0 High relevance — show source text
223.0 – U –
UMC. [HCD 1, HCD 2, OSHPD 1, 1R, 2, 3, 4, 5 & 6] The most recent edition of Uniform Mechanical Code published by the International Association of Plumbing and Mechanical Officials.
Unconditioned Space. An area, room, or space not being heated or cooled by any equipment.
Unit Heater. A heating appliance designed for nonresidential space heating and equipped with an integral means for circulation of air.
46 2025 CALIFORNIA MECHANICAL CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
DEFINITIONS
Vented Appliance Categories. Category I. An appliance that operates with a nonpositive vent static pressure and with a vent gas temperature that avoids excessive condensate production in the vent.
[NFPA 54:3.3.4.10.1] Category II. An appliance that operates with a nonpositive vent static pressure and with a vent gas temperature that can cause excessive condensate production in the vent. [NFPA 54:3.3.4.10.2] Category III. An appliance that operates with a positive vent static pressure and with a vent gas temperature that avoids excessive condensate production in the vent.
[NFPA 54:3.3.4.10.3] Category IV. An appliance that operates with a positive vent static pressure and with a vent gas temperature that can cause excessive condensate production in the vent.
[NFPA 54:3.3.4.10.4] Vented Decorative Appliance. A vented appliance whose only function is providing an aesthetic effect of flames. Vented Wall Furnace. A self-contained, vented, fuel gasburning appliance complete with grilles or equivalent, designed for incorporation in or permanent attachment to the structure of a building and furnishing heated air, circulated by gravity or by a fan, directly into the space to be heated through openings in the casing. [NFPA 54:3.3.45.7] Ventilating Ceiling. A suspended ceiling containing many small apertures through which air, at low pressure, is forced downward from an overhead plenum dimensioned by the concealed space between the suspended ceiling and the floor or roof above.
Ventilation System. All of that equipment intended or installed for the purpose of supplying air to or removing air from, any room or space by mechanical means, other than equipment that is a portion of an environmental heating, cooling, absorption, or evaporative cooling system. Venting Collar. The outlet opening of an appliance provided for connection of the vent system. Venting System. The vent or chimney and its connectors, assembled to form a continuous open passageway from an appliance to the outdoors for the purpose of removing products of combustion. This definition also shall include a venting assembly that is an integral part of an appliance. Venting System, Gravity-Type. A system that depends entirely on the heat from the fuel being used to provide the energy required to vent an appliance. Venting System, Power-Type. A system that depends on a mechanical device to provide a positive draft within the venting system. **Volume, Internal Gross.
CMC § 3.3.4.10.4 High relevance — show source text
[NFPA 54:3.3.4.10.4] Vented Decorative Appliance. A vented appliance whose only function is providing an aesthetic effect of flames. Vented Wall Furnace. A self-contained, vented, fuel gasburning appliance complete with grilles or equivalent, designed for incorporation in or permanent attachment to the structure of a building and furnishing heated air, circulated by gravity or by a fan, directly into the space to be heated through openings in the casing. [NFPA 54:3.3.45.7] Ventilating Ceiling. A suspended ceiling containing many small apertures through which air, at low pressure, is forced downward from an overhead plenum dimensioned by the concealed space between the suspended ceiling and the floor or roof above.
Ventilation System. All of that equipment intended or installed for the purpose of supplying air to or removing air from, any room or space by mechanical means, other than equipment that is a portion of an environmental heating, cooling, absorption, or evaporative cooling system. Venting Collar. The outlet opening of an appliance provided for connection of the vent system. Venting System. The vent or chimney and its connectors, assembled to form a continuous open passageway from an appliance to the outdoors for the purpose of removing products of combustion. This definition also shall include a venting assembly that is an integral part of an appliance. Venting System, Gravity-Type. A system that depends entirely on the heat from the fuel being used to provide the energy required to vent an appliance. Venting System, Power-Type. A system that depends on a mechanical device to provide a positive draft within the venting system. Volume, Internal Gross. The volume as determined from internal dimensions of the container, with no allowance for the volume of the internal parts.
225.0 – W –
Wall Heater. See Vented Wall Furnace.
Warm Air Furnace. An environmental heating appliance designed or arranged to discharge heated air through any duct or ducts. This definition shall not include a unit heater.
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Unusually Tight Construction. Construction where:
(1) Walls and ceilings exposed to the outdoors have a continuous water vapor retarder with a rating of 1 perm or less with openings gasketed or sealed.
(2) Weatherstripping is on openable windows and doors.
(3) Caulking or sealants are applied to areas such as joints around window and door frames, between sole plates and floors, between wall-ceiling joints, between wall panels, and at penetrations for plumbing, electrical, and gas lines and at other openings. Use (Material). The placing in action or making available for service by opening or connecting a container utilized for confinement of material, whether a solid, liquid, or gas.
224.0 – V –
Vacuum. A pressure less than that exerted by the atmosphere. Valve, Pressure-Relief. A pressure-actuated valve held closed by a spring or other means and designed to automatically relieve pressure in excess of its setting. Valve, Stop. A device in a piping system to shut off the flow of the fluid.
Valve, Three-Way-Type Stop. A manually operated valve with one inlet that alternately can stop flow to either of two outlets.
CMC § 906.10 Medium relevance — show source text
Floor furnace seepage pans . . . . . . . . . . . . . . . . 906.10
Fluid coolers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1120.0
Fuel gas piping. . . . . . . . . . . . . . . . . . . . . . . . . 1310.3.5
Radiant panels. . . . . . . . . . . . . . . . . . . . . . . . . 1217.11.2
Refrigeration equipment
and piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1105.2
ANODELESS RISER
Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0
Factory assembled. . . . . . . . . . . . . . . . . . . 1308.4.4.2.1
Field assembled. . . . . . . . . . . . . . . . . . . . . 1308.4.4.2.2
APPEALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107.0
APPLIANCE FLUE OUTLET
Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0
Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509.2.2
Test method for fuel-fired equipment . . . . . . . . . C 108.0
APPLIANCES
Access to . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .304.0
Air-conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . .903.0
Air filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .935.0
Approval of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301.2
Clearance . . . . . . . . . .303.1-303.3, 303.10-303.10.1.3,
Table 303.10.1, Table 802.7.3.3
Closed combustion
solid-fuel-burning, definition . . . . . . . . . . . . . . . 203.0
Clothes dryers . . . . . . . . . . . . . . . . . (see Clothes dryer)
Cooking . . . . . . . . . . . . . . . . . . . . . . . Chapter 5, 919.0,
922.0
Decorative, vented. . . . . . . . . 224.0, 911.0, 912.1, 931.0
CMC § 9.1 Medium relevance — show source text
SHUTOFF VALVE
APPLICATIONSTANDARDS
Appliance shutoff
valve up to1_/_2 psiCSA/ANSI Z21.15/CSA 9.1
Appliance shutoff
valve up to1_/_2 psiASME B16.44
Appliance shutoff
valve up to1_/_2 psiASME B16.33 marked 125 G
Appliance shutoff
valve up to1_/_2 psiCSA/ANSI LC 4/CSA 6.32
Valve up to1_/_2 psiASME B16.44
Valve up to1_/_2 psiASME B16.33 marked 125 G
Valve up to1_/_2 psiCSA/ANSI LC 4/CSA 6.32
Valve up to 2 psiASME B16.44 labeled 2G
Valve up to 2 psiASME B16.33 marked 125 G
Valve up to 2 psiCSA/ANSI LC 4/CSA 6.32 with
ANSI/ASME B16.44 labeled 2G or
labeled 5G
Valve up to 2 psiCSA/ANSI LC 4/CSA 6.32 with
ANSI/ASME B16.33 marked 125 G
Valve up to 5 psiASME B16.44 labeled 5G
Valve up to 5 psiASME B16.33
Valve up to 5 psiCSA/ANSI LC 4/CSA 6.32 with
ANSI/ASME B16.44 marked 5G
Valve up to 5 psiCSA/ANSI LC 4/CSA 6.32 with
ANSI/ASME B16.33 marked 125 G
Valve up to 125 psiASME B16.33 marked 125 G
Valve up to 125 psiCSA/ANSI LC 4/CSA 6.32 with
ASME B16.33 marked 125 GFor SI Units: 1 pound-force per square inch = 6.8947 kPa
1308.13 Expansion and Flexibility. Piping systems shall be designed to prevent failure from thermal expansion or contraction. [NFPA 54:5.13.1]
CMC § 911.2 Medium relevance — show source text
911.2 Prohibited Installations. Decorative appliances for installation in vented fireplaces shall not be installed in bathrooms or bedrooms unless the bedroom or bathroom has the
required volume in accordance with Section 701.4. [NFPA 54:10.6.2] [OSHPD 1, 1R, 2, 4 & 5] A vented decorative appliance shall not be located in any hospital, skilled nursing facility, intermediate care facility, or correctional treatment
center.
911.3 Installation. A decorative appliance for installation in a vented fireplace shall be installed only in a vented fireplace having a working chimney flue and constructed of noncombustible materials. These appliances shall not be thermostatically controlled. [NFPA 54:10.6.3]
911.3.1 Listed Decorative Appliance. A listed decorative appliance for installation in a vented fireplace shall be installed in accordance with its listing and the manufacturer’s installation instructions. {NFPA 54:10.6.3.1}
911.3.2 Reserved
911.4 Fireplace Screens. A fireplace screen shall be installed with a decorative appliance for installation in a vented fireplace. [NFPA 54:10.6.4]
912.0 Gas Fireplaces, Vented.
912.1 Application. Vented gas fireplaces shall be listed in accordance with ANSI Z21.50/CSA 2.22. [NFPA 54:10.7.1]
912.2 Reserved
912.3 Installation. The installation of vented gas fireplaces shall comply with the following requirements:
(1) [HCD 1 & HCD 2] Any newly installed gas fireplace shall be a direct-vent sealed-combustion type.
(2) Vented gas fireplaces shall be installed in accordance with their listing and the manufacturer’s installation instructions and where installed in or attached to com bustible material shall be specifically listed for such installation.
(3) Panels, grilles, and access doors that are required to be removed for normal servicing operations shall not be attached to the building.
(4) Direct vent gas fireplaces shall be installed with the vent air intake terminal in the outdoors and in accor dance with the manufacturer’s installation instructions.
[NFPA 54:10.7.3] 912.4 Combustion and Circulating Air. Combustion and circulating air shall be provided in accordance with Section 701.0. [NFPA 54:10.7.4]
913.0 Factory-Built Fireplaces and Fireplace Stoves. 913.1 Factory-Built Fireplaces. Factory-built fireplaces shall comply with UL 127 and installed in accordance with the manufacturer’s installation instructions. {NFPA 211:11.1.1} 913.1.1 Gasketed Fireplace Doors. A gasketed fireplace door shall not be installed on a factory-built fireplace, except where the fireplace system has been tested in accordance with UL 127.
913.2 Fireplace Stoves. Fireplace stoves shall comply with UL 737 and installed in accordance with the manufac turer’s installation instructions.
913.3 Fireplace Accessories. Heat exchangers, glass doors assemblies, combustion air vents, and termination caps shall comply with UL 907 and installed in accordance with the manufacturer’s installation instructions.
CMC § 907.2.3 Medium relevance — show source text
907.2.3 Panels, Grilles, and Access Doors. Panels, grilles, and access doors that are required to be removed for normal servicing operations shall not be attached to the building. For additional information on the venting of wall furnaces, see Section 802.0. [NFPA 54:10.25.2.4]
For SI units: 1 inch = 25.4 mm
FIGURE 907.2.1
INSTALLATION OF TYPE B-W GAS VENTS FOR
VENTED WALL FURNACES
[NFPA 54: FIGURE 10.25.2.2]
907.3 Location. Wall furnaces shall be located so as not to cause a hazard to walls, floors, curtains, furniture, or doors. Wall furnaces installed between bathrooms and adjoining rooms shall not circulate air from bathrooms to other parts of the building. [NFPA 54:10.25.3]
2025 CALIFORNIA MECHANICAL CODE 205
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
INSTALLATION OF SPECIFIC APPLIANCES
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910.0 Burner Assemblies.
910.1 Oil Burners. Oil burners shall comply with UL 296 and installed in accordance with the manufacturer’s installa tion instructions.
910.2 Gas Burners. Commercial gas burners shall comply with UL 295 and installed in accordance with the manufac turer’s installation instructions.
911.0 Decorative Appliances for Installation in Vented Fireplaces.
911.1 Application. Decorative appliances for installation in vented fireplaces shall be listed in accordance with ANSI Z21.60/CSA 2.26. [NFPA 54:10.6.1]
911.2 Prohibited Installations. Decorative appliances for installation in vented fireplaces shall not be installed in bathrooms or bedrooms unless the bedroom or bathroom has the
required volume in accordance with Section 701.4. [NFPA 54:10.6.2] [OSHPD 1, 1R, 2, 4 & 5] A vented decorative appliance shall not be located in any hospital, skilled nursing facility, intermediate care facility, or correctional treatment
center.
911.3 Installation. A decorative appliance for installation in a vented fireplace shall be installed only in a vented fireplace having a working chimney flue and constructed of noncombustible materials. These appliances shall not be thermostatically controlled. [NFPA 54:10.6.3]
911.3.1 Listed Decorative Appliance. A listed decorative appliance for installation in a vented fireplace shall be installed in accordance with its listing and the manufacturer’s installation instructions. {NFPA 54:10.6.3.1}
911.3.2 Reserved
911.4 Fireplace Screens. A fireplace screen shall be installed with a decorative appliance for installation in a vented fireplace. [NFPA 54:10.6.4]
912.0 Gas Fireplaces, Vented.
912.1 Application. Vented gas fireplaces shall be listed in accordance with ANSI Z21.50/CSA 2.22. [NFPA 54:10.7.1]
CMC § 11.5 Medium relevance — show source text
5-foot
level of storage
3.
Locate in
longitudinal flue
space,
staggered
vertical
4.
Shields required
where multiple-
level|1.
Ordinary
temperature,
quick-response
sprinklers,
maximum 8 feet
3 inches
horizontal
spacing
2.
One line of
sprinklers at the
6-foot level and
the 11.5-foot
level of storage
3.
Locate in
longitudinal flue
space,
staggered
vertical
4.
Shields required
where multiple-
level| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Maximum
spacing|Maximum
spacing|100 ft2/head|100 ft2/head| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Area
(square feet)|Ordinary
temperature|Not
Applicable|Not
Applicable| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Area
(square feet)|High
temperature|2,000b|2,000b| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Density
(gpm/ft2)|Density
(gpm/ft2)|0.60|0.60| |**TABLE 5704.3.6.CMC § 3.6.3 Medium relevance — show source text
3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR**
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|IN-RACK SPRINKLER ARRANGEMENT AND DEMAND|Racks
9 to 12 feet|Racks
9 to 12 feet|Not
Applicable|Not
Applicable| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|IN-RACK SPRINKLER ARRANGEMENT AND DEMAND|Racks up to
9 feet deep|Racks up to
9 feet deep|1.
Ordinary
temperature,
quick-response
sprinklers,
maximum 8 feet
3 inches
horizontal
spacing
2.
One line of
sprinklers at the
6-foot level and
the 11.5-foot
level of storage
3.
Locate in
longitudinal flue
space,
staggered
vertical
4.
Shields required
where multiple-
level|1.
Ordinary
temperature,
quick-response
sprinklers,
maximum 8 feet
3 inches
horizontal
spacing
2.
One line of
sprinklers at the
6-foot level and
the 11.5-foot
level of storage
3.
Locate in
longitudinal flue
space,
staggered
vertical
4.
Shields required
where multiple-
level| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Maximum
spacing|Maximum
spacing|100 ft2/head|100 ft2/head| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
**OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET,
Frequently asked questions
What exact language defines "Appliance" in the CMC and where is it found?
The Appliance definition is located in § 203.0 and reads (in part) that an appliance is a device using fuel or electricity to produce light, heat, power, refrigeration, or air conditioning; it explicitly includes vented decorative appliances and electric storage or tankless water heaters.
Where do I find the definition of "Appliance, Vented" and the vent categories?
The vented appliance categories (Category I–IV) and the definition of “vented” appliance concepts are in § 224.0; § 203.0 does not contain the Category I–IV criteria.
Does an electric tankless water heater need venting under the CMC?
No — an electric tankless water heater is an Appliance by definition in § 203.0, but it does not produce combustion products and therefore would not be classified into the vented categories in § 224.0.
Is “Direct Vent” the same as a vented appliance?
No. Direct Vent is a distinct appliance construction where all combustion air is from outdoors and all flue gases go outdoors; it is defined separately in § 203.0 and is treated differently for installation/venting.
If an appliance has a flue, how do I know which vent category applies?
You must determine the appliance’s vent static pressure (positive vs nonpositive) and whether vent gas temperatures will avoid or cause condensate; those criteria are the basis for Category I–IV in § 224.0. The exact assignment and related venting requirements are in § 224.0 and the venting chapters that reference it.
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