CMC · California Mechanical Code

Insulation requirements and identification of hydronic piping

Q: What exact wording and color do I put on hydronic piping?

Use an orange background with black uppercase lettering reading “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.” Each outlet must also be posted with that phrase — § 1204.7 .

Q: How often must pipe identification appear?

Every 20 ft (6096 mm) but not less than once per room, and visible from floor level — § 1204.5 .

Hydronic pipes must be insulated so any part a person can touch stays at or below 140°F and insulation must continue through sleeves; chilled water piping needs insulation and a vapor seal to prevent condensation. Hydronic piping must be labeled orange with “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK,” sized per pipe diameter and repeated every 20 feet or at least once per room. These rules are from CMC **§ 1201.2** and **§ 1204.0**; I could not retrieve the text for **§ 1217.10** in the provided files.

Ask a question free See coverage

Last reviewed: July 6, 2026

What the code requires — plain English

Insulation: Piping surfaces reachable by building occupants must not exceed 140°F (60°C) and insulation/manufacturing coverings must be suitable for the system temperature and environment; insulation must continue full size through sleeves and meet plenum fire/smoke tests where installed in plenums — § 1201.2.
Identification: Hydronic (heat‑transfer fluid) piping must be labeled with an orange background and the words “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK”; minimum color‑field lengths and letter sizes are given by pipe outside diameter, and ID must be repeated every 20 ft (6096 mm) but at least once per room — § 1204.0 (see Table § 1204.3 and § 1204.5).

The single most important rule: make piping safe to touch (≤ 140°F) and unmistakable to identify — insulating and labeling are mandatory under § 1201.2 and § 1204.0.

Requirements in detail

Key insulation rules (CMC)

Maximum reachable surface temperature: 140°F (60°C). Insulation, coverings, and jackets must be rated for the system operating temperature and installation environment. Where piping passes through sleeves the insulation must be continuous full size through the sleeve. § 1201.2.
Plenum installations: insulation, jackets and lap‑seal adhesives (and pipe coverings/linings) installed in a plenum must have a flame‑spread index ≤ 25 and smoke‑developed index ≤ 50 when tested to ASTM E84 or UL 723. § 1201.2.
Chilled water / chilled piping: piping, valves, fittings and manifolds that carry chilled water must be insulated and vapor‑sealed to prevent surface condensation; exception applies where the supply is above the space dew‑point or per manufacturer’s instructions — § 1217.4.

Key identification rules (CMC)

Color and marking method: identify systems by colored pipe or band, paint, wraps or other compatible materials — § 1204.2.
Hydronic systems: use orange background with black uppercase lettering and the words “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.” Each outlet shall be posted with black uppercase lettering with that phrase — § 1204.7.
Frequency & visibility: color field and required information shall be shown every 20 feet (6096 mm) but not less than once per room, and shall be visible from floor level — § 1204.5.
Flow direction: must be indicated on the system — § 1204.6.
Chemical additives: where additives are used, maintain on‑site documentation (concentrations, maintenance, log, SDS) — § 1204.8.

Decision‑relevant dimensions and values

Issue / measurement	Required value(s)	Code Reference
Max reachable surface temperature	140°F (60°C)	§ 1201.2
Plenum flame & smoke limits	Flame‑spread ≤ 25; smoke ≤ 50 (ASTM E84 / UL 723)	§ 1201.2
Hydronic pipe ID color	Orange background, black uppercase lettering: “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.”	§ 1204.7
ID frequency	Every 20 ft (6096 mm) or at least once per room; visible from floor	§ 1204.5
Minimum color‑field length & letter size — sample rows	1/2"–1-1/4": 8" field, 1/2" letters; 1-1/2"–2": 8" field, 3/4" letters; 2-1/2"–6": 12" field, 1-1/4" letters	Table § 1204.3 (see § 1204.3)
Chilled water piping	Insulated and vapor sealed to prevent condensation (exception if water > space dew point)	§ 1217.4
Sleeve penetrations	Insulation must continue full size through sleeves	§ 1201.2

(See the Code Reference column to link each decision to the controlling CMC text; Table values are from § 1204.3.)

Exceptions & special cases

Radiant cooling supply piping: piping that serves radiant cooling and is above the space dew point may be exempt from insulation (see exception to § 1217.4). Always confirm manufacturer recommendations.
Plenums: if pipe insulation/jackets are located in a plenum they must meet the stricter flame/smoke limits in § 1201.2 (ASTM E84 / UL 723).
Snow/ice melt slabs: the CMC requires manufacturer‑recommended slab insulation and a minimum R‑value of 5 between poured concrete snow‑melt slabs and compacted grade — see § 1220.4.7 (related hydronic insulation requirement).

Note: The CMC sets the safety and ID rules above; separate energy‑efficiency insulation thickness tables and minimums (for energy code compliance) are in the California Energy Code / Title 24 Part 6 and referenced standards — consult those for thickness/R‑value calculations beyond safety and condensation control.

Common mistakes

Labeling with the wrong color (yellow or green) or omitting the required wording for hydronic (heat‑transfer) systems — hydronic piping must be orange with the specific caution text per § 1204.7.
Using too‑small letters or too‑short color fields (not following Table § 1204.3).
Failing to continue insulation through sleeves (insulation must remain full size through sleeves per § 1201.2).
Not insulating chilled water piping or failing to vapor‑seal — which leads to condensation and possible property damage; § 1217.4 requires insulation + vapor seal unless exception applies.
Installing non‑plenum‑rated insulation or adhesives in plenums (must meet ASTM E84/UL 723 limits).

Worked example

Scenario: You install a 2‑inch OD hydronic supply pipe that is accessible in a mechanical room and connects to a radiant heating loop. The supply water temperature is 150°F.

What the CMC requires, step by step:

Surface temperature: Because the pipe is reachable and the system temperature (150°F) could create a surface hotter than the limit, you must insulate so that surfaces within reach do not exceed 140°F — § 1201.2. Choose insulation and thickness rated for 150°F operating temperature and the room environment.
Sleeve continuity: Where that 2‑inch pipe passes through any sleeve or penetration, extend the insulation full size through the sleeve — § 1201.2.
Labeling: Identify the pipe as hydronic using an orange band and black uppercase lettering: “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.” For a 2‑inch OD pipe, consult Table § 1204.3: the row “1‑1/2 to 2 inches” requires a minimum color field length of 8 inches and minimum letter height of 3/4 inch. Place the marking such that it is visible from floor level and repeat it every 20 ft and at least once per room — § 1204.3 and § 1204.5.
Condensation control (if chilled water): If the piping were chilled water instead, you would need insulation + vapor seal to prevent condensation (unless the water is above the space dew point) — § 1217.4.

This example follows the exact CMC provisions for surface temperature, sleeve continuity, identification sizing and marking frequency.

Related provisions (CMC)

Insulation specifics and general hydronics chapter: § 1201.2.
Identification of piping and labeling rules: § 1204.0 (and § 1204.3, § 1204.5, § 1204.6, § 1204.7, § 1204.8).
Radiant systems — condensation and chilled‑water insulation rules: § 1217.4 and related radiant provisions § 1217.3 – § 1217.7.
Snow/ice melt slab insulation: § 1220.4.7 (minimum R‑5 where in contact with soil).
Testing and documentation (pressure testing, maintenance, SDS): § 1205.2 and § 1204.8.

Important note about § 1217.10: I could not locate the text of § 1217.10 in the materials returned by the file search. The document index shows a cross‑reference to 1217.10.1, but the section content itself was not retrieved; therefore I cannot quote or interpret § 1217.10 specifically here. If you need the specific language or application of § 1217.10, please upload the section or I can search again if you want me to.

Code references

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

CMC § 1.8 High relevance — show source text
For SI units: °C = (°F-32)/1.8 Note:
- Ethylene glycol shall not be used in one- and two-unit residential systems. In existing systems, where ethylene glycol is used, there shall be no direct or permanent potable water connections. Where a temporary potable water connection is required, a backflow preventer shall be installed.
»

1201.0 General.

1201.1 Applicability. This chapter shall apply to hydronic piping systems that are part of heating, cooling, ventilation, refrigeration, and air conditioning systems. Such piping systems include steam, hot water, radiant heating and cooling, chilled water, steam condensate, condenser water, ground source heat pump systems, snow and ice melting systems, ambient temperature loops (ATL), and district ambient temperature loops. The regulations of this chapter shall govern the construction, location, and installation of hydronic piping systems. 1201.2 Insulation. Surfaces within reach of building occupants shall not exceed 140°F (60°C). Where sleeves are installed, the insulation shall continue full size through them.

Coverings and insulation used for piping shall be of material approved for the operating temperature of the system and the installation environment. Where installed in a plenum, the insulation, jackets, and lap-seal adhesives, including pipe coverings and linings, shall have a flamespread index not to exceed 25 and a smoke-developed index not to exceed 50 where tested in accordance with ASTM E84

or UL 723.

1201.3 Water Hammer Protection. The piping system shall be designed to prevent water hammer.

1201.4 Terminal Units. Terminal units, valves, and flow control devices shall be installed in accordance with the man ufacturer’s installation instructions.

1201.5 Return-Water Low-Temperature Protection. Where a minimum return-water temperature to the heat source is specified by the manufacturer, the heating system shall be designed and installed to meet or exceed the minimum return-water temperature during the normal operation of the heat source.

1201.6 Heat Transfer Fluid Quality. Heat transfer fluid used in closed loop hydronic systems shall be in accordance with IAPMO/ANSI H1001.1.

1201.6.1 Ethylene Glycol. Ethylene glycol shall not be used in one- and two-unit residential systems. In existing systems, where ethylene glycol is used, there shall be no direct or permanent potable water connections. Where a temporary potable water connection is required, a backflow preventer shall be installed.

1201.7 Heat Emitters. Heat emitters shall be installed in

accordance with the manufacturer’s installation instructions.

1201.8 Mechanical Devices. Where listed mechanical devices are used, the manufacturer’s installation instructions as to the location and method of installation shall be followed.

1201.9 Flexible Connectors. Listed flexible connectors shall be installed in readily accessible locations. 1201.10 Freeze Protection. Hydronic systems and components shall be designed, installed, and protected from freez

ing. The percent of glycol by volume shall be determined based on the freezing point of the solution and type of mixture in accordance with Table 1201.10 or the manufacturer’s specifications.

For SI units: °C = (°F-32)/1.8 Note:

CMC § 1210.2 High relevance — show source text

2,Note||||X|X|||||||||||||||||||| |1210.2||||||||||X|X|X||X|X|||||||||| |1211.7,Note||||X|X|||||||||||||||||||| |1217.8.2.1|||||||||||||||||||||X|||| |1217.10.1|||||||||||||||||||||X|||| |1220.4.7.1|||||||||||||||||||||X||||

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

2025 CALIFORNIA MECHANICAL CODE 255

256 2025 CALIFORNIA MECHANICAL CODE

CHAPTER 12

HYDRONICS

TABLE 1201.10 PERCENT GLYCOL MIXTURES	Col2	Col3
FREEZING POINT, °F	FREEZING POINT, °F	FREEZING POINT, °F
(% BY VOLUME)	ETHYLENE GLYCOL*	PROPYLENE GLYCOL
20	16	18
30	3	8
40	-12	-7
50	-35	-28

For SI units: °C = (°F-32)/1.8 Note:

Ethylene glycol shall not be used in one- and two-unit residential systems. In existing systems, where ethylene glycol is used, there shall be no direct or permanent potable water connections. Where a temporary potable water connection is required, a backflow preventer shall be installed.

1201.0 General.

1201.1 Applicability. This chapter shall apply to hydronic piping systems that are part of heating, cooling, ventilation, refrigeration, and air conditioning systems. Such piping systems include steam, hot water, radiant heating and cooling, chilled water, steam condensate, condenser water, ground source heat pump systems, snow and ice melting systems, ambient temperature loops (ATL), and district ambient temperature loops. The regulations of this chapter shall govern the construction, location, and installation of hydronic piping systems. 1201.2 Insulation. Surfaces within reach of building occupants shall not exceed 140°F (60°C). Where sleeves are installed, the insulation shall continue full size through them.

Coverings and insulation used for piping shall be of material approved for the operating temperature of the system and the installation environment. Where installed in a plenum, the insulation, jackets, and lap-seal adhesives, including pipe coverings and linings, shall have a flamespread index not to exceed 25 and a smoke-developed index not to exceed 50 where tested in accordance with ASTM E84

or UL 723.

CMC § 2.5 High relevance — show source text
(1) 85°F (29°C) in general occupied applications.

(2) 90°F (32°C) in bathrooms, foyers, distribution areas such as hallways and indoor swimming pools.

(3) 88°F (31°C) in industrial spaces.

(4) 95°F (35°C) in radiant panel perimeter areas, i.e., up to 2.5 feet (762 mm) from outside walls.

The radiant heating system temperature shall not exceed the maximum temperature rating of the materials used in its construction.

1217.3 Radiant Cooling Systems. Radiant cooling systems shall be designed to minimize the potential for condensation. To prevent condensation on any cooled radiant surface, the supply water temperature for a radiant cooling system shall be above the space dewpoint temperature, or in accordance with the manufacturer’s recommendation.

1217.3.1 Minimum Floor Temperatures. The minimum floor surface temperature shall not be less than 66°F (19°C) in general occupied applications.

1217.4 Chilled Water Supply/Distribution Piping. Chilled water piping, valves, fittings, and manifolds shall be insulated and vapor sealed to prevent surface condensation.

Exception: Piping, valves, fittings, and manifolds used to supply radiant cooling systems and where the water temperature is above the space dewpoint temperature shall not require insulation.

1217.5 Tube Placement. Hydronic radiant system tubing shall be installed in accordance with the manufacturer’s installation instructions and with the tube layout and spacing in accordance with the system design. Except for distribution mains, the individual loop lengths shall be installed with a variance of not more than ±10 percent from the design.

1217.6 Tube Length. The maximum loop length of continuous tubing from a supply-and-return manifold shall not exceed the lengths specified by the manufacturer or, in the absence of manufacturer’s specifications, the lengths specified in Table 1217.6. Actual loop lengths shall be determined by spacing, flow rate, and pressure drop requirements as specified in the system design.

TABLE 1217.6

MAXIMUM LENGTH OF CONTINUOUS TUBING FROM

A SUPPLY-AND-RETURN MANIFOLD ARRANGEMENT

NOMINAL TUBE SIZE
(inches) MAXIMUM LOOP LENGTH
(feet)

1/4 125

5/16 200

3/8 250

1/2 300

5/8 400

3/4 500

1 750

For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm

1217.7 Tube Identification. For the purpose of system balancing, each individual loop shall have a tag or label securely affixed to the manifold to indicate the length of the loop and the room(s) and area(s) served.

TABLE 1217.6

MAXIMUM LENGTH OF CONTINUOUS TUBING FROM

A SUPPLY-AND-RETURN MANIFOLD ARRANGEMENT

«

«

For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm

2025 CALIFORNIA MECHANICAL CODE 267

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

HYDRONICS

»

»

»

»
CMC § 1215.0 High relevance — show source text
HYDRONIC SPACE HEATING . . . . . . . . . . . . . . . . . 1215.0

HYDRONICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 12

Auxiliary systems . . . . . . . . . . . . . . . . . . . . . . . . 1220.0

Appliances and equipment . . . . . . . . . . . . . . . . . 1207.0

Boilers . . . . . . . . . . . . . . . . . . 1207.2, 1207.2.1, 1207.2.2

Circulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1208.0

Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1221.7

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0

Embedded piping and joints . . . . . . . . . . . . . . . . 1221.2

Expansion tanks . . . . . . . . . . . . . . . . . . . . . . . . . 1209.0

Hangers and supports. . . . . . . . . . . . . . . . . . . . . 1210.3

Heat emitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1201.7

Heat pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207.5

Heat sources . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203.1

Heat transfer fluid . . . . . . . . . . . . . . . . . . 1201.3, 1204.7

Identification of piping . . . . . . . . . . . . . . . . . . . . . 1204.0

Installation . . . . . . . . . . . . . . . . . . . . . . . 1205.0, 1221.0

Insulation. . . . . . . . . 1201.2, 1217.8.2, 1217.10, 1220.4.7

Joints and connections . . . . . . . . . . . . . . . . . . . . 1211.0

Materials . . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1

Protection of potable water supply . . . . . . . . . . . 1202.0

Radiant heating and cooling . . . . . . . . . . . . . . . . 1217.0

Snow melt systems . . . . . . . . . . . . . . . . 1220.4, 1220.0,

1217.8.2, Table 1220.4.2
CMC § 1220.3 High relevance — show source text
(5) Insulation sheets with integrated knobs for holding the specific type of tube and intended for this application.

(6) Other fasteners recommended by the manufacturer. 1220.3 Spacing of Tube Fasteners. The maximum spacing between tube fasteners within a concrete area shall not exceed the spacing specified by the manufacturer or, in the absence of manufacturer’s specifications, 2.5 feet (762 mm). 1220.4 Snow and Ice Melt Controls. An automatic operating control device that controls the supply hydronic fluid temperature to the snow and ice melt area shall be installed in the system. Snow and ice melt systems shall be protected from freezing with a mixture of propylene glycol or ethylene glycol, and water or other approved fluid. Automotive antifreeze shall not be used.

1220.4.1 Tube Placement. Snow and ice melt tubing shall be installed in accordance with the manufacturer’s installation instructions and with the tube layout and spacing in accordance with the system design. Except for distribution mains, tube spacing and the individual loop lengths shall be installed with a variance of not more than ±10 percent from the design.

2025 CALIFORNIA MECHANICAL CODE 269

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

HYDRONICS

«

«

«

1220.4.7 Insulation. Where a poured concrete snow melt system is installed in contact with the soil, insulation recommended by the manufacturer for such application and with a minimum R-value of 5 shall be placed between the concrete and the compacted grade; and be extended as close as practicable to the outside edges of the concrete.

1220.4.7.1 California Energy Code Insulation Requirements for Heated Slab Floors. See California Energy Code Section 110.8(g) and Table 110.8-A for additional insulation requirements for heated slab floors – a higher level of insulation is required for Climate Zone 16, and more detailed requirements for installing insulation are specified in all climate zones.

1220.4.8 Testing and Flushing. Testing of snow and ice melt systems shall be in accordance with Section 1205.2 and flushing shall be in accordance with Section 1205.3.

1220.5 Hydronic Makeup Air Units. Hydronic makeup air units that are affected by freezing shall be protected against freezing by a hydronic solution.

1221.0 Piping Installation.

1221.1 General. Piping, fittings, and connections shall be installed in accordance with the conditions of their approval and manufacturer’s installation instructions.

1221.2 Embedded Piping Materials and Joints. Piping embedded in concrete shall be steel pipe, Type L copper tubing or plastic pipe or tubing rated at not less than 80 psi at 180°F (552 kPa at 82°C). Joints of pipe or tubing that are embedded in a portion of the building, such as concrete or plaster shall be installed in accordance with Section 1221.2.1 through Section 1221.2.3.

1221.2.1 Steel Pipe. Steel pipe shall be welded by electrical arc or oxygen/acetylene method.

1221.2.2 Copper Tubing. Copper tubing shall be joined by brazing with filler metals having a melting point not less than 1000°F (538°C).
CMC § 150.0 High relevance — show source text
Exception to Section 150.0(i)2A, B, and C: Where supplementary heat is locked out above 35°F by another control device in accordance with Section 150.0(h)7.

2025 CALIFORNIA ENERGY CODE 161

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

SINGLE-FAMILY RESIDENTIAL BUILDINGS— MANDATORY FEATURES AND DEVICES

Exception 1 to Section 150.0(i)2: Systems compliant with Exception 1 to Section 150.0(h)7.

Exception 2 to Section 150.0(i)2: Room air-conditioner heat pumps.

(j) Insulation for piping and tanks.
1. Water piping, solar water-heating system piping, and space-conditioning system line insulation thickness and conductivity. Piping shall be insulated as follows: A. All domestic hot water piping shall be insulated as specified in Section 609.12 of the California Plumbing Code . B. Piping for space-conditioning systems, solar water-heating system collector loop, and distribution piping for steam and hydronic heating system shall meet the requirements of Section 120.3(a). Exception 1 to Section 150.0(j)1: Factory-installed piping within space-conditioning equipment certified under Section 110.1 or 110.2.
Exception 2 to Section 150.0(j)1: Piping that penetrates framing members shall not be required to have pipe insulation for the distance of the framing penetration. Piping that penetrates metal framing shall use grommets, plugs, wrapping or other insulating material to assure that no contact is made with the metal framing. Insulation shall butt securely against all framing members. Exception 3 to Section 150.0(j)1: Piping installed in interior or exterior walls shall not be required to have pipe insulation if all of the requirements are met for compliance with quality insulation installation (QII) as specified in the Reference Residential Appendix RA3.5. Exception 4 to Section 150.0(j)1: Piping surrounded with a minimum of 1 inch of wall insulation, 2 inches of crawlspace insulation, or 4 inches of attic insulation shall not be required to have pipe insulation. 2. Insulation protection. Pipe insulation shall meet the insulation protection requirements of Section 120.3(b).

(k) Residential lighting.
1. Luminaire requirements. A. Luminaire efficacy. All installed luminaires and light sources shall comply with Reference Joint Appendix JA8 and shall be certified and marked as required by JA8. Exception 1 to Section 150.0(k)1A: Integrated device lighting. Lighting integral to exhaust fans, kitchen range hoods, bath vanity mirrors, garage door openers, and ceiling fan kits that are subject to DOE’s Appliance and Equipment Standards Program. Exception 2 to Section 150.0(k)1A: Navigation lighting rated less than 5 watts, such as night lights, step lights, and path lights. Exception 3 to Section 150.0(k)1A: Lighting with an efficacy of 45 lumens per watt or greater and located internal to drawers, cabinetry, or linen closets. Exception 4 to Section 150.0(k)1A: Light sources as follows: i. LED light sources installed outdoors; ii. Inseparable solid state lighting (SSL) luminaires containing colored light sources that are installed to provide decorative lighting; iii.
CMC § 0.34 Medium relevance — show source text
32 to 0.34|250|4.5|5.0|5.0|5.0|5.0| |251 to 350|0.29 to 0.32|200|3.0|4.0|4.5|4.5|4.5| |201 to 250|0.27 to 0.30|150|2.5|2.5|2.5|3.0|3.0| |141 to 200|0.25 to 0.29|125|1.5|1.5|2.0|2.0|2.0| |105 to 140|0.22 to 0.28|100|1.0|1.0|1.5|1.5|1.5|

For SI units: °C=(°F-32)/1.8, 1 inch = 25 mm, 1 British thermal unit inch per hour square foot degree Fahrenheit = [0.1 W/(m•K)]

Notes: 1 For insulation outside the stated conductivity range, the minimum thickness ( T ) shall be determined as follows: T = r {(1 + t / r ) [K] [/] [k ] – 1}

Where:

T = minimum insulation thickness (inches). r = actual outside radius of pipe (inches). t = insulation thickness listed in this table for applicable fluid temperature and pipe size. K = conductivity of alternate material at mean rating temperature indicated for the applicable fluid temperature [Btu•in/(h•ft [2] - °F)] [W/(m•K)]. k = the upper value of the conductivity range listed in this table for the applicable fluid temperature. 2 These thicknesses are on energy efficiency considerations only. Additional insulation is sometimes required relative to safety issues/surface temperature. 3 For piping smaller than 1 1 ⁄ 2 inches (40 mm) or less and located in partitions within conditioned spaces, reduction of these thicknesses by 1 inch (25.4 mm) shall be permitted (before thickness adjustment required in footnote 1) but not to thicknesses below 1 inch (25.4 mm). 4 For direct-buried heating and hot water system piping, reduction of these thicknesses by 1 1 ⁄ 2 inch (40 mm) shall be permitted (before thickness adjustment required in footnote 1) but not to thicknesses below 1 inch (25.4 mm). 5 Table E 503.7.3(1) is based on steel pipe. Nonmetallic pipes schedule 80 thickness or less shall use the table values. For other nonmetallic pipes having thermal resistance more than that of steel pipe, reduced insulation thicknesses are permitted where documentation is provided showing that the pipe with the proposed insulation has no more heat transfer per foot (mm) than a steel pipe of the same size with the insulation thickness shown in Table E 503.7.3(1).

474 2025 CALIFORNIA MECHANICAL CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

APPENDIX E

TABLE E 503.7.3(2) MINIMUM PIPE INSULATION THICKNESS FOR COOLING SYSTEMS (CHILLED WATER, BRINE, AND REFRIGERANT) [1,2,3,4 ]

[ASHRAE 90.1: TABLE 6.8.3-2]
CMC § 25921.1 Medium relevance — show source text
Reference: Sections 25921 and 25921.1, Public Resources Code.

HISTORY:
1. Amendment of subsections (a), (b) (4), (b) (6) and (f) filed 8-10-81; designated effective 9-22-81 (Register 81, No. 33).
QUALITY ASSURANCE (RESERVED)

Sec. 12-13-1556.

Authority: Section 25218 (e), Public Resources Code.

Reference: Section 25921.1, Public Resources Code.

HISTORY:
1. Repealer filed 8-10-81; designated effective 9-22-81 (Register 81, No. 33).
IDENTIFICATION

Sec. 12-13-1557.

(a) Except as specified in subsection (b), Item 3, of this section, no insulation shall be sold in California on or after September 22, 1981, unless the insulating material, container, bundle or similar packaging material bears a visible Commission approved statement certifying that a representative sample of the insulation material has been tested and approved by an approved laboratory and complies with the requirements of this article.

(b) The Commission-approved statement shall consist of either:
1. A design or statement approved by the Executive Director, or
2. An identification of the manufacturer and any statement that the material meets the quality standards of the State of California.
3. A statement that the material meets the quality standards of the State of California included in the bill of lading shall meet the requirements of this section only if the product is being shipped in bulk, or the container or product is not otherwise labeled by the manufacturer and the product is being sold to its ultimate user.
(c) Any representation of thermal performance which appear on any label, literature, advertising or any other writing intended for the public shall be consistent with the certification testing results and derating required by this article.

(d) Any insulation with facings and membranes for which the flame spread exceeds 25 when tested with facings and membranes exposed to the flame during the ANSI/ASTM E84-79 test must be clearly labeled with a statement that the product may be highly combustible if used in an exposed application. This subsection shall not apply to any product meeting the requirements of Sections 2602.1-2602.6 of the 1994 Uniform Building Code.

Authority: Section 25218(e), Public Resources Code.

Reference: Section 25921, Public Resources Code.

HISTORY:
1. Amendment of subsections (a) and (c) filed 8-10-81; designated effective 9-22-81 (Register 81, No. 33).
INSPECTIONS

Sec. 12-13-1558.

After September 22, 1981, the Commission may, upon the consent of the owner or lessee, or upon securing a search warrant, have access, during normal working hours, to the premises of manufacturers, distributors and retailers of insulating material sold for installation within the state for the purpose of determining compliance with the standards promulgated pursuant to Chapter 10.5 of the California Public Resources Code . Such access shall be for the purposes of obtaining representative samples of subject insulation and inspecting records and documents pertaining to tests by approved testing labs.

Authority: Section 25218 (e), Public Resources Code.

Reference: Section 25926, Public Resources Code.

HISTORY:
CMC § 1310.10 Medium relevance — show source text
1310.10, 1312.10

Overhead heaters in commercial

garages and aircraft hangars . . . . . . . . . 905.8, 925.5

INSULATION OF

Ducts . . . . . . . . . . . . . . . . . . . 506.11.2, 506.11.3, 605.0,

E 502.4.1, E 503.4.7,

Table E 503.7.2,

Hoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.3.4

Hydronic systems. . . . . . . . . . . . . . . . . 1201.2, 1220.4.7,

1217.8.2, 1217.8

HVAC system piping. . . . . . . . . . E 502.5, E 503.4.7.1.2,

Table E 502.5,

Table E 503.7.3(1)

INTERLOCK

Air heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.7

Cooking equipment

ventilation . . . . . . . . . . . . . . . . . . . . . . 517.1.3, 517.6.2

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.0

Exhaust. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503.1

Gas mixing machines. . . . . . . . . . . . . . . . . . . 1310.14.5

Inspection of safety . . . . . . . . . . . . . . . . . . . . . . 516.6.4

Mechanical air supply . . . . . . . . . . . . . . . . . . . . . 701.9.2

Motorized louvers . . . . . . . . . . . . . . . . . . . . . . . 701.10.2

Recirculating systems . . . . . . . . . . . . . . . . . . . . . . 516.3 Stack dampers . . . . . . . . . . . . . . . . . . . . . . . . . . 1003.4

– J –

JOINTS AND CONNECTIONS . . . . . . . . . . . . . . . . . 1109.2,

1109.8, 1211.0,

1308.4.8–1308.4.9.6

Brazed joint . . . . . . . . . . . . . . . . . . . . . . . 212.0, 1211.4 Copper or copper alloy pipe or tubing . . . . . . . 1109.2, 1211.4, 1211.16.1

CPVC piping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1211.3
CMC § 120.10 Medium relevance — show source text
4(f)2 Variable Air volume (VAV) 120.10(a), 140.4(c)2, 140.4(d), 140.9(c)4, 141.0(a)2, 141.0(b)3, 160.2(c)7, 170.2(c)4A, 170.2(c)4B, Table 170.2-B, Table 170.2-C, Table 180.2-D Capacity heat pump (VCHP) 150.1(b)3, 170.1(d)2 Exhaust 140.9(c)3 Flow control 140.4(k)6, 160.3(d), 170.2(c)4I Fluid flow 140.4(k)1, 170.2(c)4I Speed 120.6(a), 120.6(b)5 Speed compressor 120.6(a)3, 120.6(a)7, 150.0(m)13, 160.3(b)5L Speed control 140.4(k)6, 140.9(b) Speed drive 120.6(e), 120.9(b), 140.4(c)1, 140.4(k)6, 160.4(e), 170.2(c)4I Speed fan 120.6(a)4, 120.6(a)8, 120.6(b)1, 150.0(o), 160.2(b)2 Ventilation 150.0(o), 160.2(b)2A Vending Machine 140.6(a)3J, K, L Vent Damper 110.2(d), 110.2(f) Vented Attic 150.0(a), 150.0(g), 150.2(b)1J, 160.1(a), 160.1(d), 180.2(b)1 Vented Range Hood 150.0(o), Table 150.0-E, 150.0(v), 160.2(b)2B, Table 160.2-E Ventilated Attic 150.1(c)9, 170.2(c), 180.2(a)1 Ventilation 120.1, 140.4(b)4, 150.0(o), 160.3(d)2 Air 120.1(d), 120.2(e), 130.1(f), 140.4(e), 140.4(m), 140.9(b), 150.0(o), 150.1(b), 150.2(a)2C, 160.2(b)2B, 160.2(c), 160.5(b), 170.1(d), 170.2(c), 180.1(a), 180.3(a) And indoor air quality 120.1, 150.0(o), 160.2(b)2 Cooling 150.1(b)3, 150.1(c)12, 150.2(a), 170.1(d) Dampers 150.0(m)8, 160.3(b) Device 10-103(b), 120.1(d), 160.2(c)5 Doors 120.6(f) Fan 120.6(f), 150.2(b)1L, 180.2(b) Load 140.4(b)4, 170.2(c) Only 120.1(h)

NOMINAL TUBE SIZE (inches)	MAXIMUM LOOP LENGTH (feet)
1/4	125
5/16	200
3/8	250
1/2	300
5/8	400
3/4	500
1	750

CMC § 0.293 Medium relevance — show source text

For SI units: 1000 British thermal units per hour = 0.293 kW

1203.3 Tankless Water Heaters. Tankless water heaters used in space-heating applications shall be rated by the manufacturer for space-heating applications, and the output performance shall be determined by the temperature rise and flow rate of water through the unit. The ratings shall be expressed by the water temperature rise at a given flow rate. Manufacturer’s flow rates shall not be exceeded.

1204.0 Identification of Potable and Nonpotable Water Systems. 1204.1 General. In buildings where potable water and nonpotable water systems are installed, each system shall be clearly identified in accordance with Section 1204.2 through Section 1204.7.

1204.2 Color and Information. Each system shall be identified with a colored pipe or band and coded with paint, wraps, and materials compatible with the piping. 1204.3 Potable Water. Potable water systems shall be identified with a green background with white lettering. The minimum size of letters and length of the color field shall be in accordance with Table 1204.3.

TABLE 1204.3

MINIMUM LENGTH OF COLOR FIELD AND SIZE OF LETTERS

OUTSIDE DIAMETER OF PIPE OR COVERING (inches)	MINIMUM LENGTH OF COLOR FIELD (inches)	MINIMUM SIZE OF LETTERS (inches)
1_/2 to 11/_4	8	1_/_2
11_/_2 to 2	8	3_/_4
21_/_2 to 6	12	11_/_4
8 to 10	24	21_/_2
over 10	32	31_/_2

For SI units: 1 inch = 25.4 mm

TABLE 1203.2

WATER HEATERS

1204.4 Nonpotable Water. Nonpotable water systems shall have a yellow background with black uppercase lettering, with the words: “CAUTION: NONPOTABLE WATER, DO NOT DRINK.” Each nonpotable system shall be identified to designate the liquid being conveyed, and the direction of normal flow shall be clearly shown. The minimum size of the letters and length of the color field shall comply with Table 1204.3.

TABLE 1204.3

MINIMUM LENGTH OF COLOR FIELD AND SIZE OF LETTERS

For SI units: 1 inch = 25.4 mm

1204.5 Location of Piping Identification. The background color and required information shall be indicated every 20 feet (6096 mm) but not less than once per room, and shall be visible from the floor level.

1204.6 Flow Directions. Flow directions shall be indicated

on the system.

1204.7 Heat Transfer Fluid. Hydronic piping shall be identified with an orange background with black uppercase lettering, with the words “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.” Each hydronic system shall be identified to designate the fluid being conveyed. The minimum size of the letters and length of the color field shall comply with Table 1204.3.

Each outlet on the hydronic piping system shall be posted with black uppercase lettering as follows:

“CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.”

CMC § 802.5.6 Medium relevance — show source text
INSPECTIONS

Chimneys. . . . . . . . . . . . . . . . . . . . . . . 802.5.6, 802.5.7

Commercial kitchen

exhaust system, schedule of . . . . . . . . . . Table 514.3

Evaporative cooler . . . . . . . . . . . . . . . . . . . . . . . . 932.3

Fire-extinguishing equipment . . . . . . . . . . . . . . . . 514.2 Fuel gas piping . . . . . . . . . . . . . 1303.0, 1304.0, 1313.1

Reinspections . . . . . . . . . . . . . . . . . . . . . . . . . . 105.2.6

Requests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105.2.3

INSTALLATIONS OF

Appliances in manufactured housing . . . . . . . . . . 929.0 Appliances in garages. . . . . . . . . . . . . . . . . . . . . . 305.1 Appliances in repair garages . . . . . . . . . . . . . . 303.11.2

Ducts. . . . . . . . . . . . . . . . . . . . . . . . . . . . 510.5.3, 603.0

Equipment and appliances . . . . . . . . . . . . . . . . . . 303.0 Gas piping . . . . . . . . . . . . . . . . . . . . . . . 1310.0, 1310.3,

1310.10, 1312.10

Overhead heaters in commercial

garages and aircraft hangars . . . . . . . . . 905.8, 925.5

INSULATION OF

Ducts . . . . . . . . . . . . . . . . . . . 506.11.2, 506.11.3, 605.0,

E 502.4.1, E 503.4.7,

Table E 503.7.2,

Hoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.3.4

Hydronic systems. . . . . . . . . . . . . . . . . 1201.2, 1220.4.7,

1217.8.2, 1217.8

HVAC system piping. . . . . . . . . . E 502.5, E 503.4.7.1.2,

Table E 502.5,

Table E 503.7.3(1)

INTERLOCK

Air heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.7

Cooking equipment

ventilation . . . . . . . . . . . . . . . . . . . . . . 517.1.3, 517.6.2
CMC § 25.4 High relevance — show source text
For SI units: 1 inch = 25.4 mm

TABLE 1203.2

WATER HEATERS

1204.4 Nonpotable Water. Nonpotable water systems shall have a yellow background with black uppercase lettering, with the words: “CAUTION: NONPOTABLE WATER, DO NOT DRINK.” Each nonpotable system shall be identified to designate the liquid being conveyed, and the direction of normal flow shall be clearly shown. The minimum size of the letters and length of the color field shall comply with Table 1204.3.

TABLE 1204.3

MINIMUM LENGTH OF COLOR FIELD AND SIZE OF LETTERS

For SI units: 1 inch = 25.4 mm

1204.5 Location of Piping Identification. The background color and required information shall be indicated every 20 feet (6096 mm) but not less than once per room, and shall be visible from the floor level.

1204.6 Flow Directions. Flow directions shall be indicated

on the system.

1204.7 Heat Transfer Fluid. Hydronic piping shall be identified with an orange background with black uppercase lettering, with the words “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.” Each hydronic system shall be identified to designate the fluid being conveyed. The minimum size of the letters and length of the color field shall comply with Table 1204.3.

Each outlet on the hydronic piping system shall be posted with black uppercase lettering as follows:

“CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.”

1204.8 Identification of Chemical Additives. In systems where chemical additives are used, documentation including the following information shall be readily accessible and maintained onsite:

(1) Concentrations

(2) Maintenance requirements

(3) Maintenance log

(4) Material Safety Data Sheet (SDS)

For SI units: 1000 British thermal units per hour = 0.293 kW

1205.0 Installation, Testing, and Inspection.

1205.1 Operating Instructions. Operating and maintenance information shall be provided to the building owner. 1205.2 Pressure Testing. System piping and components shall be tested with a pressure of not less than one and one-half times the operating pressure but not less than 100 psi (689 kPa). Piping shall be tested with water or air except that plastic pipe

258 2025 CALIFORNIA MECHANICAL CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

HYDRONICS

shall not be tested with air. Test pressures shall be held for a period of not less than 30 minutes with no perceptible drop in pressure. These tests shall be made in the presence of the Authority Having Jurisdiction.

Exceptions: (1) For PEX, PP-R, PP-RCT, PEX-AL-PEX, PE-RT, and PEAL-PE piping systems, testing with air shall be permitted where authorized by the manufacturer’s instructions for the PEX, PP-R, PP-RCT, PEX-AL-PEX, PE-RT, and PE-ALPE pipe and fittings products, and air testing is not prohibited by applicable codes, laws, or regulations outside this code.
CMC § 5.6. Medium relevance — show source text
1. Supply fan variable flow controls shall be tested in accordance with NA7.5.6.
2. Hydronic system variable flow controls shall be tested in accordance with NA7.5.7 and NA7.5.9.
3. Boiler or chillers that require isolation controls as specified by Section 140.4(k)2 or 140.4(k)3 shall be tested in accordance with NA7.5.7.
4. Hydronic systems with supply water temperature reset controls shall be tested in accordance with NA7.5.8.
5. Automatic demand shed controls shall be tested in accordance with NA7.5.10.
6. Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units shall be tested in accordance with NA7.5.11.
7. Automatic fault detection and diagnostics (FDD) for air handling units and zone terminal units shall be tested in accordance with NA7.5.12.
8. Distributed Energy Storage DX AC Systems shall be tested in accordance with NA7.5.13.
9. Thermal Energy Storage (TES) Systems shall be tested in accordance with NA7.5.14.
10. Supply air temperature reset controls shall be tested in accordance with NA7.5.15.
11. Water-cooled chillers served by cooling towers with condenser water reset controls shall be tested in accordance with NA7.5.16.
12. When an energy management control system is installed, it shall functionally meet all of the applicable requirements of Part 6.
13. Occupant sensing zone controls shall be tested in accordance with NA7.5.17.
14. Conductivity controls and overflow alarms for open and closed-circuit cooling towers shall be tested according to NA7.5.18.
(b) When certification is required by Title 24, Part 1, Section 10-103.2, the acceptance testing specified by Section 120.5(a) shall be performed by a certified mechanical acceptance test technician (CMATT). If the CMATT is operating as an employee, the CMATT shall

2025 CALIFORNIA ENERGY CODE 79

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

NONRESIDENTIAL, HOTEL/MOTEL OCCUPANCIES, AND COVERED PROCESSES—MANDATORY REQUIREMENTS

be employed by a certified mechanical acceptance test employer. The CMATT shall disclose on the certificate of acceptance a valid CMATT certification identification number issued by an approved acceptance test technician certification provider. The CMATT shall complete all certificate of acceptance documentation in accordance with the applicable requirements in Section 10-103(a)4.

Note: Authority cited: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code. Reference: Sections 25007, 25008, 25218.5, 25310, 25402(a)-(b), 25402.1, 25402.4, 25402.5, 25402.8 and 25943, Public Resources Code .

SECTION 120.6—MANDATORY REQUIREMENTS FOR COVERED PROCESSES

Nonresidential and hotel/motel buildings shall comply with the applicable requirements of Sections 120.6(a) through 120.6(k), and the applicable requirements of Sections 110.2(a) and 120.3.

(a) Mandatory requirements for refrigerated warehouses.
CMC § 104.1 Medium relevance — show source text
[A] 104.1 General. The building official is hereby authorized and directed to enforce the provisions of this code.

[A] 104.2 Determination of compliance. The building official shall have the authority to determine compliance with this code, to render interpretations of this code and to adopt policies and procedures in order to clarify the application of its provisions. Such interpretations, policies and procedures:
1. Shall be in compliance with the intent and purpose of this code.
2. Shall not have the effect of waiving requirements specifically provided for in this code.
[A] 104.2.1 Listed compliance. Where this code or a referenced standard requires equipment, materials, products or services to be listed and a listing standard is specified, the listing shall be based on the specified standard. Where a listing standard is not specified, the listing shall be based on an approved listing criteria. Listings shall be germane to the provision requiring the listing. Installation shall be in accordance with the listing and the manufacturer’s instructions, and where required to verify compliance, the listing standard and manufacturer’s instructions shall be made available to the building official.

[A] 104.2.2 Technical assistance. To determine compliance with this code, the building official is authorized to determine compliance with this code, to require the owner or owner’s authorized agent to provide a technical opinion and report.

[A] 104.2.2.1 Cost. A technical opinion and report shall be provided without charge to the jurisdiction.

[A] 104.2.2.2 Preparer qualifications. The technical opinion and report shall be prepared by a qualified engineer, specialist, laboratory or specialty organization acceptable to the building official. The building official is authorized to require design submittals to be prepared by, and bear the stamp of, a registered design professional.

[A] 104.2.2.3 Content. The technical opinion and report shall analyze the properties of the design, operation or use of the building or premises and the facilities and appurtenances situated thereon to identify and propose necessary recommendations.

[A] 104.2.2.4 Tests. Where there is insufficient evidence of compliance with the provisions of this code, the building official shall have the authority to require tests as evidence of compliance. Test methods shall be as specified in this code or by other recognized test standards. In the absence of recognized test standards, the building official shall approve the testing procedures. Such tests shall be performed by a party acceptable to the building official.

[A] 104.2.3 Alternative materials, design and methods of construction and equipment. The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved.

Exception: Performance-based alternative materials, designs or methods of construction and equipment complying with the International Code Council Performance Code . This exception shall not apply to alternative structural materials or to alternative structural designs. [DSA-SS, DSA-SS/CC] The International Code Council Performance Code is not permitted by DSA.

[DSA-SS, DSA-SS/CC & OSHPD 1, 1R, 2, 4 & 5] Alternative system shall satisfy ASCE 7 Section 1.3, unless more restrictive require- ments are established by this code for an equivalent system.

[DSA-SS, DSA-SS/CC] Alternative systems shall also satisfy the California Administrative Code, Section 4-304.
CMC § 160.3 Medium relevance — show source text
Exception 2 to Section 160.3(c)1: Piping that conveys fluids with a design operating temperature range between 60°F and 105°F.

Exception 3 to Section 160.3(c)1: Where the heat gain or heat loss to or from piping without insulation will not increase building source energy use. Exception 4 to Section 160.3(c)1: Piping that penetrates framing members shall not be required to have pipe insulation for the distance of the framing penetration. Metal piping that penetrates metal framing shall use grommets, plugs, wrapping or other insulating material to ensure that no contact is made with the metal framing. 2. Requirements for air distribution system, ducts and plenum. Multifamily common areas shall comply with the applicable requirements of Sections 160.3(c)2A through 160.3(c)2F. A. CMC compliance. All air distribution system ducts and plenums, including, but not limited to, building cavities, mechanical closets, air-handler boxes and support platforms used as ducts or plenums shall meet the requirements of CMC Sections 601.0, 602.0, 603.0, 604.0 and 605.0, and ANSI/SMACNA-006-2006 HVAC Duct Construction Standards Metal and Flexible 3rd Edition, incorporated herein by reference. Connections of metal ducts and the inner core of flexible ducts shall be mechanically fastened. Openings shall be sealed with mastic, tape, aerosol sealant or other duct-closure system that meets the applicable requirements of UL 181, UL 181A or UL 181B. If mastic or tape is used to seal openings greater than [1] / 4 inch, the combination of mastic and either mesh or tape shall be used. B. Portions of supply-air and return-air ducts conveying heated or cooled air located in one or more of the following spaces shall be insulated to a minimum installed level of R-8:

i. Outdoors; or ii. In a space between the roof and an insulated ceiling; or iii. In a space directly under a roof with fixed vents or openings to the outside or unconditioned spaces; or iv. In an unconditioned crawl space; or v. In other unconditioned spaces. Portions of supply-air ducts that are not in one of these spaces, including ducts buried in concrete slab, shall be insulated to a minimum installed level of R-4.2 or be enclosed in directly conditioned space. C. Duct and plenum materials. i. Factory-fabricated duct systems. a. All factory-fabricated duct systems shall comply with UL 181 for ducts and closure systems, including collars, connections and splices, and be labeled as complying with UL 181. UL 181 testing may be performed by UL laboratories or a laboratory approved by the Executive Director. b. All pressure-sensitive tapes, heat-activated tapes and mastics used in the manufacture of rigid fiberglass ducts shall comply with UL 181 and UL 181A. c. All pressure-sensitive tapes and mastics used with flexible ducts shall comply with UL 181 and UL 181B. d. Ductwork and plenums with pressure class ratings shall be constructed to Seal Class A. Joints and seams of duct systems and their components shall not be sealed with cloth back rubber adhesive duct tapes unless such tape is used in combination with mastic and drawbands.

Frequently asked questions

Do hydronic pipes always need insulation, even in conditioned space?

Not always. The CMC requires insulation where needed to keep accessible surface temperatures ≤ 140°F and, for chilled water, to prevent condensation — the code also requires insulation to be suitable for the operating temperature and environment. Check § 1201.2 and § 1217.4.

What exact wording and color do I put on hydronic piping?

Use an orange background with black uppercase lettering reading “CAUTION: HEAT TRANSFER FLUID, DO NOT DRINK.” Each outlet must also be posted with that phrase — § 1204.7.

How often must pipe identification appear?

Every 20 ft (6096 mm) but not less than once per room, and visible from floor level — § 1204.5.

Can I use any insulation material in a plenum?

No. Insulation, jackets and adhesives used in plenums must meet flame‑spread ≤ 25 and smoke ≤ 50 when tested to ASTM E84 or UL 723 — § 1201.2.

Who maintains documentation on chemical additives?

Where chemical additives are used in hydronic systems, documentation (concentrations, maintenance requirements and logs, and SDS) must be readily accessible and maintained on site — § 1204.8.

Ask about the CMC

Get cited, plain-English answers on the California Mechanical Code for your project — any code section, any scenario.

Start Free Trial

Related in the CMC

When are variable‑flow pumps and controls required (energy provisions)?

How to size, mount and install circulators and pumps

Pumps, Controls, Insulation & Identification

California Mechanical Code