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Chapter 10 — BOILERS AND PRESSURE VESSELS

1004.1 General.1004.0 Expansion Tanks. An expansion tank shall be installed in a

California Mechanical Code (Title 24, Part 4) · 2019 edition · updated 2026-09-10 · California

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

hot-water-heating system as a means for controlling increased pressure caused by thermal expansion. Expansion tanks shall be of the closed or open type and securely fastened to the structure. Tanks shall be rated for the pressure of the system. Supports shall be capable of carrying twice the weight of the tank filled with water without placing a strain on connecting piping.

Hot-water-heating systems incorporating hot water tanks or fluid relief columns shall be installed to prevent freezing under normal operating conditions.

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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
    Overview
    1. 1001.0 General.1001.1 Applicability. The requirements of this …
    2. 1001.2 Boiler Rooms and Enclosures. Boiler rooms and
    3. 1001.3 Air for Combustion and Ventilation. Air for
    4. 1001.4 Drainage. For heating or hot-water-supply boiler
    5. 1001.5 Mounting. Equipment shall be set or mounted on a
    6. 1001.6 Chimneys or Vents. Boilers shall be connected to
    7. 1002.1 General.1002.0 Standards. Pressure vessels shall be con…
    8. 1002.2 Oil-Burning Boilers. Oil-burning boilers shall
    9. 1002.3 Electric Boilers. Electric boilers shall be listed and
    10. 1002.4 Solid-Fuel-Fired Boilers. Solid-fuel-fired boilers
    11. 1002.5 Dual Purpose Water Heater. Water heaters utilized for c…
    12. 1003.1 Safety Requirements.1003.0 Detailed Requirements. The c…
    13. 1003.2 Controls. Required electrical, mechanical, safety,
    14. 1004.4 Minimum Capacity of Closed-Type Tank. The
    15. 1003.3 Gauges. Steam boilers shall be provided with a
    16. 1003.4 Stack Dampers. Stack dampers on boilers fired
    17. 1003.5 Welding. Welding on pressure vessels shall be done
    18. 1004.1 General.1004.0 Expansion Tanks. An expansion tank shall…
    19. 1004.2 Open-Type Expansion Tanks. Open type expansion tanks sh…
    20. 1004.3 Closed-Type Systems. Closed-type systems shall
    21. 1005.2 Discharge Piping. The discharge piping serving a
    22. 1005.5 Vacuum Relief Valve. Hot-water heating systems
    23. 1008.0 Low-Water Cutoff.1008.1 General. Hot water boilers and …
    24. 1005.3 Splash Shield. Where the operating temperature
    25. 1005.4 Hazardous Discharge. Where the discharge from
    26. 1010.1 General. 1010.0 Clearance for Access. Where boilers are…
    27. 1010.2 Power Boilers. Power boilers having a steam-generating …
    28. 1010.3 Steam-Heating Boilers, Hot Water Boilers, andPower Boil…
    29. 1012.1 General.1012.0 Operating Adjustments and Instructions. …
    30. 1013.1 General.1013.0 Inspections and Tests. An installation f…
    31. 1011.1 General. 1011.0 Boilers, Stokers, and Steam Generators.…
    32. 1013.2 Operating Permit. It shall be unlawful to operate a
    33. 1013.3 Maintenance Inspection. The Authority Having
    34. 1013.4 Power and Miniature Boilers. Power boilers and
    35. 1013.6 Automatic Steam-Heating Boilers. Automatic
    36. 1013.7 Unfired Pressure Vessels. Unfired pressure vessels shal…
    37. 1014.1 General. Pressure Vessels. Boilers and pressure vessels…
  11. Chapter 11 — REFRIGERATION
  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 — REFERENCED STANDARDS
  18. Appendix A — RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SY…
  19. Appendix B — PROCEDURES TO BE FOLLOWED TO PLACE GAS EQUIPMENT …
  20. Appendix C — INSTALLATION AND TESTING OF OIL (LIQUID) FUEL-FIR…
  21. Appendix D — FUEL SUPPLY: MANUFACTURED/MOBILE HOME PARKS AND R…
  22. Appendix E — SUSTAINABLE PRACTICES
  23. Appendix F — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
  24. Appendix G — EXAMPLE CALCULATION OF OUTDOOR AIR RATE

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