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Earlier editions: 20222019

Chapter 11 — REFRIGERATION

1103.3 Higher Flammability Refrigerants. Group A3

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.

and B3 refrigerants shall not be used except where approved by the Authority Having Jurisdiction.

Exceptions:

(1) Laboratories with more than 100 square feet (9.29 m [2] ) of space per person.

(2) Industrial occupancies.

(3) Listed self-contained systems containing not more than 0.331 pounds (0.150 kg) of Group A3 refrigerant, provided that the equipment is installed in accordance with the listing and the manufacturer’s installation instructions. [ASHRAE 15:7.5.3]

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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
    Overview
    1. 1101.1 Applicability. Part I governs the design, installation,
    2. 1101.2 Equipment. Equipment for refrigerant recovery,
    3. 1102.1 General. Refrigeration systems using a refrigerant
    4. 1102.2 Ammonia Refrigeration Systems. Refrigeration
    5. 1102.3 Refrigerants. The refrigerant used shall be of a type
    6. 1103.1 Classification of Refrigerants. Refrigerants shall
    7. 1103.2 Classification of Refrigeration Systems.
    8. 1103.3 Higher Flammability Refrigerants. Group A3
    9. 1104.1 System Selection. Refrigeration systems shall be
    10. 1104.2 Refrigerant Concentration Limit (RCL). The
    11. 1104.3 Institutional Occupancies. The RCL value
    12. 1104.4 Industrial Occupancies and Refrigerated
    13. 1104.5 Flammable Refrigerants. The total of Group A2,
    14. 1104.6 Group A2L Refrigerants for Human Comfort.
    15. 1104.7 Applications for Human Comfort and for Non-
    16. 1104.8 Refrigerant Type and Purity. Refrigerants shall
    17. 1105.3 Access. An unobstructed readily accessible opening and …
    18. 1105.4 Illumination and Service Receptacles. In addition to th…
    19. 1105.5 Ventilation of Rooms Containing Condensing
    20. 1104.9 Changing Refrigerants. Changes of refrigerant in
    21. 1105.1 Human Comfort. Cooling systems used for human
    22. 1105.2 Supports and Anchorage. Supports and anchorage for refr…
    23. 1105.6 Prohibited Locations. Refrigeration systems or
    24. 1105.7 Condensate. Condensate from air-cooling coils
    25. 1105.8 Defrost. Where defrost cycles are required for portions…
    26. 1105.9 Overflows. Where condensate or defrost liquids are
    27. 1105.10 Condensate, Defrost, and Overflow Dis-
    28. 1105.11 Refrigerant Port Protection. Air conditioning
    29. 1105.12 Storage. Refrigerants and refrigerant oils not
    30. 1106.1 Where Required. Refrigeration systems shall be
    31. 1106.2 Refrigeration Machinery Room, General
    32. 1106.3 Normal Operation. A part of the refrigeration
    33. 1106.7 Maximum Temperature. Ventilation or mechanical cooling …
    34. 1106.8 Refrigerant Parts in Air Duct. Joints and refrigerant-c…
    35. 1106.9 Dimensions. Refrigeration machinery rooms shall
    36. 1106.10 Exits. Exits shall comply with the building code for
    37. 1106.11 Machinery Room, A2L and B2L. When required
    38. 1106.4 Natural Ventilation. When a refrigerating system
    39. 1106.5 Combustion Air. No open flames that use combustion air …
    40. 1106.6 Ventilation Intake. Makeup air intakes to replace
    41. 1107.1 General. In cases specified in the rules of Section
    42. 1108.1 General. Equipment, piping, ducts, vents, or similar
    43. 1108.2 Electrical. Electrical equipment and installations shall
    44. 1108.3 Emergency Shutoff. A clearly identified emergency shuto…
    45. 1108.4 Installation, Maintenance, and Testing. Detection and a…
    46. 1108.5 Emergency Pressure Control System. Where
    47. 1109.1 Materials. Materials used in the construction and
    48. 1109.2 Joints. Iron or steel pipe joints shall be of approved
    49. 1109.3 Penetration of Piping. Refrigerant piping shall not
    50. 1109.4 Location of Refrigeration Piping. Refrigerant
    51. 1109.5 Underground Piping. Refrigerant piping placed
    52. 1109.6 Support. In addition to the requirements of Section
    53. 1109.7 Pipe Enclosure. Refrigerant piping and tubing
    54. 1109.8 Visual Inspection. Refrigerant piping and joints
    55. 1109.9 Condensation. Piping and fittings that convey
    56. 1109.10 Identification. Piping shall be in accordance with
    57. 1110.1 More than 6.6 Pounds of Refrigerant. Systems
    58. 1110.2 More than 110 Pounds of Refrigerant. Systems
    59. 1110.3 Support. Stop valves installed in copper refrigerant
    60. 1110.4 Access. Stop valves required by Section 1110.0 shall
    61. 1110.5 Identification. Stop valves shall be identified by tagg…
    62. 1111.1 Where Required. Pressure-limiting devices complying wit…
    63. 1111.2 Setting. Pressure limiting devices shall be set in
    64. 1111.3 Location. Stop valves shall not be installed between
    65. 1111.4 Emergency Stop. Activation of a pressure-limiting
    66. 1112.1 General. Refrigeration systems shall be protected by
    67. 1112.2 Positive Displacement Compressor. A positive
    68. 1112.3 Liquid-Containing Portions of Systems. Liquid-containin…
    69. 1112.4 Evaporators. Heat exchanger coils located downstream, o…
    70. 1112.5 Hydrostatic Expansion. Pressure rise resulting
    71. 1112.6 Actuation. Pressure-relief devices shall be direct
    72. 1112.7 Stop Valves Prohibited. Stop valves shall not be
    73. 1112.8 Location. Pressure-relief devices shall be connected
    74. 1112.9 Materials. The seats and discs of pressure-relief
    75. 1112.10 Pressure-Relief Valve Setting. Pressure-relief
    76. 1112.11 Discharge from Pressure-Relief Devices.
    77. 1112.12 Discharge Piping. The piping used for pressure-relief …
    78. 1112.13 Rating of Pressure-Relief Device. The rated
    79. 1112.14 Rating of Rupture Members and Fusible
    80. 1113.1 General. Pressure vessels shall be provided with
    81. 1113.2 Type of Protection. Pressure vessels with an internal g…
    82. 1113.3 Discharging into Lowside of System. For pressure-relief…
    83. 1113.4 Parallel Pressure-Relief Devices. Two or more
    84. 1113.5 Discharge Capacity. The minimum required discharge capa…
    85. 1113.6 Three-Way Valve. Pressure vessels of 10 cubic feet
    86. 1114.1 General. Systems containing other than Group A1 or
    87. 1114.2 Design Requirements. Flaring devices shall be
    88. 1114.3 Testing. Flaring systems shall be tested to demonstrate…
    89. 1115.1 General. In addition to labels required elsewhere in
    90. 1115.2 Volume and Type. A condenser, receiver, absorber,
    91. 1115.3 Permanent Sign. In a refrigeration machinery
    92. 1115.4 Marking of Pressure-Relief Devices. Pressurerelief valv…
    93. 1115.5 Nameplate. Each self-contained system and each
    94. 1116.1 Factory Tests. Refrigerant-containing parts of unit
    95. 1116.2 Field Tests. Refrigerant-containing parts of a system t…
    96. 1116.3 Test Gases. Tests shall be performed with dry nitrogen …
    97. 1116.4 Declaration. A dated declaration of test shall be
    98. 1116.5 Brine Systems. Brine-containing portions of a system sh…
    99. 1117.1 Inside Dimensions 6 Inches or Less. Pressure
    100. 1117.2 Inside Dimensions More than 6 Inches. Pressure vessels …
    101. 1117.3 Pressure Vessels for 15 psig or Less. Pressure
    102. 1118.1 General. Refrigeration systems shall be operated and
    103. 1119.1 Applicability. Cooling towers, evaporative condensers, …
    104. 1120.1 General. Cooling towers, evaporative condensers,
    105. 1121.1 General. Drains, overflows, and blow-down provisions sh…
    106. 1122.1 General. Chemical treatment systems shall comply
    107. 1122.2 Automated Control of Cycles of Concentra-
    108. 1123.1 General. Cooling towers, evaporative condensers,
    109. 1124.1 General. Electrical systems shall be in accordance
    110. 1125.1 General. Equipment containing refrigerants as a part
    111. 1126.1 General. Cooling towers, evaporative condensers,
    112. 1127.1 General. Cooling towers, evaporative coolers and
  12. Chapter 12 — HYDRONICS
  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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