User note: Code change proposals to this chapter will be considered by the IRC – Plumbing and Mechanical Code
    Development Committee during the 2015 (Group A) Code Development Cycle. See explanation on page iv.


    M2101.1 General.

    Hydronic piping shall conform to Table M2101.1. Approved piping, valves, fittings and connections shall be installed in accordance with the manufacturer’s instructions. Pipe and fittings shall be rated for use at the operating temperature and pressure of the hydronic system. Used pipe, fittings, valves or other materials shall be free of foreign materials.

    TABLE M2101.1


    Acrylonitrile butadiene styrene(ABS) plastic pipe1, 5ASTM D 1527;ASTM F 2806;ASTM F 2969Solvent cement joints
    Brass pipe1ASTM B 43Brazed, welded, threaded, mechanical and flanged fittings
    Brass tubing1ASTM B 135Brazed, soldered and mechanical fittings
    Chlorinated poly (vinyl chloride) (CPVC) pipe and tubing1, 2, 3ASTM D 2846Solvent cement joints, compression joints and threaded adapters
    Copper pipe1ASTM B 42,B 302Brazed, soldered and mechanical fittings threaded, welded and flanged
    Copper tubing (type K, L or M)1, 2ASTM B 75,B 88, B 251,B 306Brazed, soldered and flared mechanical fittingsJoints embedded in concrete
    Cross-linked polyethylene (PEX)1, 2, 3ASTM F 876, F 877(See PEX fittings)Install in accordance with manufacturer’s instructions
    Cross-linked polyethylene/aluminum/cross-linked polyethylene-(PEX-AL-PEX) pressure pipe1, 2ASTM F 1281 orCAN/ CSA B137.10Mechanical, crimp/insertInstall in accordance with manufacturer’s instructions
    PEX fittingsASTM F 877ASTM F 1807ASTM F 1960ASTM F 2098ASTM F 2159ASTM F 2735Copper-crimp/insert fittings, cold expansion fittings, stainless steel clamp, insert fittingsInstall in accordance with manufacturer’s instructions
    Polybutylene (PB) pipe and tubing1, 2, 3ASTM D 3309Heat-fusion, crimp/insert and compressionJoints in concrete shall be heat-fused
    Polyethylene/aluminum/polyethylene (PE-AL-PE) pressure pipe1, 2, 3ASTM F 1282CSA B 137.9Mechanical, crimp/insert
    Polypropylene (PP)1, 2, 3ISO 15874ASTM F 2389Heat-fusion joints, mechanical fittings, threaded adapters, compression joints
    Raised temperature polyethylene (PE-RT)1, 2, 3ASTM F 2623ASTM F 2769Copper crimp/insert fitting stainless steel clamp, insert fittings
    Raised temperature polyethylene (PE-RT) fittings1, 2, 3ASTM F 1807ASTM F 2159ASTM F 2735ASTM F 2769ASTM F 2098Copper crimp/insert fitting stainless steel clamp, insert fittings
    Steel pipe1, 2ASTM A 53,A 106Brazed, welded, threaded, flanged and mechanical fittingsJoints in concrete shall be welded. Galvanized pipe shall not be welded or brazed.
    Steel tubing1ASTM A 254Mechanical fittings, welded

    For SI: °C = [(°F)-32]/1.8.

    1. a.Use code:

      1. 1.Above ground.

      2. 2.Embedded in radiant systems.

      3. 3.Temperatures below 180°F only.

      4. 4.Low temperature (below 130°F) applications only.

      5. 5.Temperatures below 160°F only.

    2. b.Standards as listed in Chapter 44.

    M2101.2 System drain down.

    Hydronic piping systems shall be installed to permit draining of the system. Where the system drains to the plumbing drainage system, the installation shall conform to the requirements of Chapters 25 through 32 of this code.

    Exception: The buried portions of systems embedded underground or under floors.

    M2101.3 Protection of potable water.

    The potable water system shall be protected from backflow in accordance with the provisions listed in Section P2902.

    M2101.4 Pipe penetrations.

    Openings through concrete or masonry building elements shall be sleeved.

    M2101.5 Contact with building material.

    A hydronic piping system shall not be in direct contact with any building material that causes the piping material to degrade or corrode.

    M2101.6 Drilling and notching.

    Wood-framed structural members shall be drilled, notched or altered in accordance with the provisions of Sections R502.8, R602.6, R602.6.1 and R802.7. Holes in load bearing members of cold-formed steel light-frame construction shall be permitted only in accordance with Sections R505.2.6, R603.2.6 and R804.2.6. In accordance with the provisions of Sections R505.3.5, R603.3.4 and R804.3.3, cutting and notching of flanges and lips of load-bearing members of cold-formed steel light-frame construction shall not be permitted. Structural insulated panels (SIPs) shall be drilled and notched or altered in accordance with the provisions of Section R610.7.

    M2101.7 Prohibited tee applications.

    Fluid in the supply side of a hydronic system shall not enter a tee fitting through the branch opening.

    M2101.8 Expansion, contraction and settlement.

    Piping shall be installed so that piping, connections and equipment shall not be subjected to excessive strains or stresses. Provisions shall be made to compensate for expansion, contraction, shrinkage and structural settlement.

    M2101.9 Piping support.

    Hangers and supports shall be of material of sufficient strength to support the piping, and shall be fabricated from materials compatible with the piping material. Piping shall be supported at intervals not exceeding the spacing specified in Table M2101.9.

    TABLE M2101.9


    CPVC ≤ 1-inch pipe or tubing35a
    CPVC ≥ 11/4 inches410a
    Copper or copper alloy pipe1210
    Copper or copper alloy tubing610
    PB pipe or tubing2.674
    PE pipe or tubing2.674
    PE-RT ≤ 1 inch2.6710a
    PE-RT ≥ 11/4 inches410a
    PEX tubing2.674
    PP < 1-inch pipe or tubing2.674
    PP > 11/4 inches410a
    Steel pipe1215
    Steel tubing810

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

    1. a.For sizes 2 inches and smaller, a guide shall be installed midway between required vertical supports. Such guides shall prevent pipe movement in a direction perpendicular to the axis of the pipe.

    M2101.10 Tests.

    Hydronic piping systems shall be tested hydrostatically at a pressure of one and one-half times the maximum system design pressure, but not less than 100 pounds per square inch (689 kPa). The duration of each test shall be not less than 15 minutes and not more than 20 minutes.