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Earlier editions: 20222019

Chapter 12 — HYDRONICS

1221.7 Clearance to Combustibles. Hydronic piping

California Mechanical Code (Title 24, Part 4) · 2025 edition · updated 2026-09-10 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

where the exterior temperature exceeds 250°F (121°C) shall have a clearance of not less 1 inch (25.4 mm) to combustible materials.

272 2025 CALIFORNIA MECHANICAL CODE

CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE

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▸Contents — California Mechanical Code (Title 24, Part 4)
California Mechanical Code (Title 24, Part 4)
  1. Chapter 1 — GENERAL CODE PROVISIONS
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — VENTILATION AIR
  5. Chapter 5 — EXHAUST SYSTEMS
  6. Chapter 6 — DUCT SYSTEMS
  7. Chapter 7 — COMBUSTION AIR
  8. Chapter 8 — CHIMNEYS AND VENTS
  9. Chapter 9 — INSTALLATION OF SPECIFIC APPLIANCES
  10. Chapter 10 — BOILERS AND PRESSURE VESSELS
  11. Chapter 11 — REFRIGERATION
  12. ▸Chapter 12 — HYDRONICS
    Overview
    1. 1201.1 Applicability. This chapter shall apply to hydronic
    2. 1201.2 Insulation. Surfaces within reach of building occupants…
    3. 1201.3 Water Hammer Protection. The piping system
    4. 1201.4 Terminal Units. Terminal units, valves, and flow
    5. 1201.5 Return-Water Low-Temperature Protection.
    6. 1201.6 Heat Transfer Fluid Quality. Heat transfer fluid
    7. 1201.7 Heat Emitters. Heat emitters shall be installed in
    8. 1201.8 Mechanical Devices. Where listed mechanical
    9. 1201.9 Flexible Connectors. Listed flexible connectors
    10. 1201.10 Freeze Protection. Hydronic systems and components sha…
    11. 1202.1 Prohibited Sources. Hydronic systems or parts
    12. 1202.2 Chemical Injection. Additives or chemicals shall
    13. 1202.3 Compatibility. Fluids used in hydronic systems
    14. 1203.1 Heat Source. The heat source shall be sized to the
    15. 1203.2 Dual Purpose Water Heaters. Water heaters utilized for …
    16. 1203.3 Tankless Water Heaters. Tankless water heaters
    17. 1204.1 General. In buildings where potable water and nonpotabl…
    18. 1204.2 Color and Information. Each system shall be identified …
    19. 1204.3 Potable Water. Potable water systems shall be identifie…
    20. 1204.4 Nonpotable Water. Nonpotable water systems
    21. 1204.5 Location of Piping Identification. The background
    22. 1204.6 Flow Directions. Flow directions shall be indicated
    23. 1204.7 Heat Transfer Fluid. Hydronic piping shall be identifie…
    24. 1204.8 Identification of Chemical Additives. In systems
    25. 1205.1 Operating Instructions. Operating and maintenance
    26. 1205.2 Pressure Testing. System piping and components
    27. 1205.3 Flushing. Heating and cooling sources, system piping an…
    28. 1206.1 General. Each closed hydronic system shall be protected…
    29. 1206.2 Discharge Piping. The discharge piping serving a
    30. 1207.1 General. Heating appliances, equipment, safety and
    31. 1207.2 Boilers. Boilers and their control systems shall comply…
    32. 1207.3 Dual Purpose Water Heaters. Water heaters used
    33. 1207.4 Solar Heat Collector Systems. Solar water heating syste…
    34. 1207.5 Heat Pumps. Heat pumps shall comply with UL
    35. 1208.1 General. Circulators and pumps shall be selected for
    36. 1210.2 Expansion and Contraction. Pipe and tubing shall
    37. 1210.3 Hangers and Supports. Pipe and tubing shall be
    38. 1210.4 Oxygen Diffusion Corrosion. PEX and PE-RT tubing in clo…
    39. 1211.1 General. Joints and connections shall be of an
    40. 1211.2 Pipe Bends. Pipe bends shall be formed in accordance wi…
    41. 1208.2 Mounting. The circulator or pump shall be installed
    42. 1208.3 Sizing. The selection and sizing of a circulator or
    43. 1209.1 General. An expansion tank shall be installed in each
    44. 1209.2 Installation. Expansion tanks shall be accessible for
    45. 1209.3 Closed-Type Tanks. Closed-type expansion tanks
    46. 1209.4 Sizing. Expansion tanks shall be sized to accept the
    47. 1210.1 Piping, Tubing, and Fittings. Hydronic pipe and
    48. 1211.4 CPVC/AL/CPVC Plastic Pipe and Joints. Joints
    49. 1211.5 Copper or Copper Alloy Pipe and Tubing.
    50. 1211.3 Chlorinated Polyvinyl Chloride (CPVC) Pipe.
    51. 1211.6 Cross-Linked Polyethylene (PEX) Pipe. Joints
    52. 1211.7 Cross-Linked Polyethylene/Aluminum/Cross-
    53. 1211.8 Ductile Iron Pipe. Joints between ductile iron pipe
    54. 1211.9 Polyethylene (PE) Plastic Pipe/Tubing. Joints
    55. 1211.11 Polyethylene of Raised Temperature (PE-RT).
    56. 1211.12 Polypropylene (PP) Pipe. Joints between
    57. 1211.13 Polyvinyl Chloride (PVC) Pipe. Joints between
    58. 1211.10 Polyethylene/Aluminum/Polyethylene (PE-
    59. 1212.1 General. Valves shall be rated for the operating temper…
    60. 1212.2 Where Required. Valves shall be installed in
    61. 1212.3 Heat Exchanger. Isolation valves shall be installed
    62. 1212.4 Pressure Vessels. Isolation valves shall be installed
    63. 1212.5 Pressure Reducing Valves. Isolation valves shall
    64. 1212.6 Equipment, Components, and Appliances.
    65. 1212.7 Expansion Tank. Isolation valves shall be installed
    66. 1212.8 Flow Balancing Valves. Where flow balancing
    67. 1212.9 Mixing or Temperature Control Valves. Where
    68. 1212.10 Thermosiphoning. An approved type check valve
    69. 1212.11 Air Removal Device or Air Vents. Isolation valves
    70. 1212.12 District Energy and Central Utility Systems.
    71. 1213.1 Water Temperature Controls. A heat source or system of …
    72. 1211.14 Steel Pipe and Tubing. Joints between steel pipe
    73. 1211.15 Stainless Steel Pipe and Joints. Joining methods for s…
    74. 1211.16 Joints Between Various Materials. Joints
    75. 1213.2 Operating Steam Controls. A steam heat source or
    76. 1213.3 Occupied Spaces. A temperature-sensing device
    77. 1213.4 Simultaneous Operation. Radiant heating and cooling sys…
    78. 1213.5 Temperature Reading. A temperature gauge or
    79. 1214.1 Balancing. A means for balancing distribution
    80. 1214.2 Low-Water Control. Direct-fired heat sources
    81. 1214.3 Flow-Sensing Devices. A direct-fired heat source,
    82. 1214.4 Automatic Makeup Fluid. Automatic makeup
    83. 1214.5 Differential Pressure Regulation. Provisions
    84. 1214.6 Air-Removal Device. Provision shall be made for
    85. 1214.7 Air-Separation Device. To assist with the removal
    86. 1214.8 Secondary Loops. Secondary loops that are isolated from…
    87. 1215.1 General. Based on the system design, the heat-distribut…
    88. 1215.2 Installation. Heat-distribution units shall be
    89. 1215.3 Balancing. System loops shall be installed so that
    90. 1215.4 Heat Transfer Fluid. The ignitable flash point of
    91. 1216.1 Steam Traps. For other than one-pipe steam systems, eac…
    92. 1216.2 Sloping for Two-Pipe System. Two-pipe steam
    93. 1216.3 Sloping for One-Pipe System. One-pipe steam
    94. 1216.4 Automatic Air Vents. Steam automatic air vents
    95. 1216.5 Condensate Flow. System piping shall be installed
    96. 1216.6 Steam-Distribution Piping. Where multi-row elements are…
    97. 1217.1 Installation. Radiant heating and cooling systems
    98. 1217.2 Radiant Under-Floor Heating. Floor finished surface tem…
    99. 1217.3 Radiant Cooling Systems. Radiant cooling systems shall …
    100. 1217.4 Chilled Water Supply/Distribution Piping.
    101. 1217.5 Tube Placement. Hydronic radiant system tubing
    102. 1217.6 Tube Length. The maximum loop length of continuous tubi…
    103. 1217.7 Tube Identification. For the purpose of system balancin…
    104. 1217.8 Poured Floor Structural Concrete Slab Sys-
    105. 1217.9 Joist Systems and Subfloors. Where tubing is
    106. 1217.10 Wall and Ceiling Panels. Where radiant tubing is
    107. 1217.11 Radiant Heating and Cooling Panels. Radiant
    108. 1218.1 General. Systems utilizing heat exchangers shall
    109. 1219.1 General. Domestic hot-water heat exchangers,
    110. 1220.1 Use of Chemical Additives and Corrosive Flu-
    111. 1220.2 Types of Tube Fasteners. Tubing that is embedded within…
    112. 1220.3 Spacing of Tube Fasteners. The maximum spacing between …
    113. 1220.4 Snow and Ice Melt Controls. An automatic operating cont…
    114. 1220.5 Hydronic Makeup Air Units. Hydronic makeup
    115. 1221.1 General. Piping, fittings, and connections shall be
    116. 1221.2 Embedded Piping Materials and Joints. Piping embedded i…
    117. 1221.3 Pressure Testing. Piping to be embedded in concrete sha…
    118. 1221.4 System Drainage. Hydronic piping systems shall
    119. 1221.5 Condensate Drainage. Condensate drains from
    120. 1221.6 Hydronic Fluid Disposal. Hydronic system fluids
    121. 1221.7 Clearance to Combustibles. Hydronic piping
  13. Chapter 13 — FUEL GAS PIPING
  14. Chapter 14 — PROCESS PIPING
  15. Chapter 15 — SOLAR ENERGY SYSTEMS
  16. Chapter 16 — STATIONARY POWER PLANTS
  17. Chapter 17 — GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE…
  18. Chapter 18 — REFERENCED STANDARDS
  19. Appendix A — RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SY…
  20. Appendix B — PROCEDURES TO BE FOLLOWED TO PLACE GAS EQUIPMENT …
  21. Appendix C — INSTALLATION AND TESTING OF OIL (LIQUID) FUEL-FIR…
  22. Appendix D — FUEL SUPPLY: MANUFACTURED/MOBILE HOME PARKS AND R…
  23. Appendix E — SUSTAINABLE PRACTICES
  24. Appendix F — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
  25. Appendix G — EXAMPLE CALCULATION OF OUTDOOR AIR RATE
  26. Appendix H — PROFESSIONAL QUALIFICATIONS
  27. Appendix I — INDOOR HORTICULTURAL FACILITIES
  28. Appendix J — CLEAN AIR DELIVERY

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