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Earlier editions: 20222019

Chapter 5 — WATER HEATERS

507.9 Use of Air or Oxygen Under Pressure. Where air

California Plumbing Code (Title 24, Part 5) · 2025 edition · updated 2026-09-10 · California

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

or oxygen under pressure is used in connection with the gas supply, effective means such as a backpressure regulator and relief valve shall be provided to prevent air or oxygen from passing back into the gas piping. Where oxygen is used, installation shall be in accordance with NFPA 51. [NFPA 54:9.1.5]

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▸Contents — California Plumbing Code (Title 24, Part 5)
California Plumbing Code (Title 24, Part 5)
  1. Chapter 1 — GENERAL CODE PROVISIONS
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — PLUMBING FIXTURES AND FIXTURE FITTINGS
  5. ▸Chapter 5 — WATER HEATERS
    Overview
    1. 501.1 Applicability. The regulations of this chapter shall gov…
    2. 501.2 California Energy Code Water Heating System
    3. 502.1 General. It shall be unlawful for a person to install,
    4. 503.1 Inspection of Chimneys or Vents. This inspection shall b…
    5. 503.2 Final Water Heater Inspection. This inspection
    6. 504.1 Location. Water heater installations in bedrooms and
    7. 504.2 Vent. Water heaters of other than the direct-vent type
    8. 504.3 Clearance. The clearance requirements for water
    9. 504.4 Pressure-Limiting Devices. A water heater installation s…
    10. 504.5 Temperature Limiting Devices. A water heater
    11. 504.6 Temperature, Pressure, and Vacuum Relief
    12. 504.7 Lead Content. Water heaters shall comply with the
    13. 505.1 Water Heaters. Water heaters deriving heat from
    14. 505.2 Safety Devices. Storage-type water heaters and hot
    15. 505.3 Oil-Fired Water Heaters. Oil-fired water heaters
    16. 505.4 Indirect-Fired Water Heaters. Indirect-fired water
    17. 506.1 General. Air for combustion, ventilation, and dilution o…
    18. 506.2 Indoor Combustion Air. The required volume of
    19. 506.3 Indoor Opening Size and Location. Openings
    20. 506.4 Outdoor Combustion Air. Outdoor combustion air
    21. 506.5 Combination Indoor and Outdoor Combustion
    22. 506.6 Engineered Installations. Engineered combustion
    23. 506.7 Mechanical Combustion Air Supply. Where all
    24. 506.8 Louvers, Grilles, and Screens. The required size
    25. 506.9 Combustion Air Ducts. Combustion air ducts shall
    26. 507.1 Dielectric Insulator. The Authority Having Jurisdiction …
    27. 507.2 Seismic Provisions. Water heaters shall be
    28. 507.3 Appliance Support. Appliances and equipment shall
    29. 507.4 Ground Support. A water heater supported from the
    30. 507.5 Drainage Pan. Where a water heater is located in an
    31. 507.6 Added or Converted Equipment or Appliances.
    32. 507.7 Type of Gas(es). The appliance shall be connected to
    33. 507.8 Safety Shutoff Devices for Unlisted LP-Gas
    34. 507.9 Use of Air or Oxygen Under Pressure. Where air
    35. 507.10 Protection of Gas Appliances from Fumes or
    36. 507.11 Process Air. In addition to air needed for combustion i…
    37. 507.12 Flammable Vapors. Appliances shall not be
    38. 507.13 Installation in Residential Garages. Appliances
    39. 507.14 Installation in Commercial Garages. Appliances
    40. 507.15 Installation in Aircraft Hangars. Heaters in aircraft h…
    41. 507.16 Venting of Flue Gases. Appliances shall be vented
    42. 507.17 Extra Device or Attachment. No device or attachment sha…
    43. 507.18 Addition to Existing System. When additional
    44. 507.19 Avoiding Strain on Gas Piping. Appliances shall
    45. 507.20 Gas Appliance Pressure Regulators. Where the
    46. 507.21 Bleed Lines for Diaphragm-Type Valves. Bleed
    47. 508.2 Installation of Appliances on Roofs. Appliances
    48. 508.3 Appliances on Roofs. Appliances located on roofs or
    49. 507.22 Combination of Appliances and Equipment.
    50. 507.23 Installation Instructions. The installer shall conform …
    51. 507.24 Protection of Outdoor Appliances. Appliances
    52. 507.25 Accessibility for Service. All appliances shall be
    53. 507.26 Clearance to Combustible Materials. Appliances and thei…
    54. 508.1 General. Appliances on roofs shall be designed or
    55. 508.4 Appliances in Attics and Under-Floor Spaces.
    56. 509.1 Listing. Type B and Type B-W gas vents shall comply
    57. 509.2 Connection to Venting Systems. Except as permitted in Se…
    58. 509.3 Minimum Safe Performance. Venting systems
    59. 509.4 Type of Venting System to be Used. The type of
    60. 509.5 Masonry, Metal, and Factory-Built Chimneys.
    61. 509.6 Gas Vents. The installation of gas vents shall meet
    62. 509.7 Single-Wall Metal Pipe. Single-wall metal pipe
    63. 509.9 Condensation Drain. Provision shall be made to
    64. 509.10 Vent Connectors for Category I Appliances.
    65. 509.8 Through-the-Wall Vent Termination. Throughthe-wall vent …
    66. 509.13 Manually Operated Dampers. A manually operated damper s…
    67. 509.14 Automatically Operated Vent Dampers. An
    68. 509.15 Obstructions. Devices that retard the flow of vent
    69. 510.1 Additional Requirements to Single Appliance
    70. 509.11 Vent Connectors for Category II, Category III,
    71. 509.12 Appliances Requiring Draft Hoods. Vented
    72. 510.2 Additional Requirements to Multiple-Appliance
  6. Chapter 6 — WATER SUPPLY AND DISTRIBUTION
  7. Chapter 7 — SANITARY DRAINAGE
  8. Chapter 8 — INDIRECT WASTES
  9. Chapter 9 — VENTS
  10. Chapter 10 — TRAPS AND INTERCEPTORS
  11. Chapter 11 — STORM DRAINAGE
  12. Chapter 12 — FUEL GAS PIPING
  13. Chapter 13 — HEALTH CARE FACILITIES AND MEDICAL GAS AND MEDICA…
  14. Chapter 14 — FIRESTOP PROTECTION
  15. Chapter 15 — ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS
  16. Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS
  17. Chapter 17 — REFERENCED STANDARDS
  18. Appendix A — RECOMMENDED RULES FOR SIZING THE WATER SUPPLY SYS…
  19. Appendix B — EXPLANATORY NOTES ON COMBINATION WASTE AND VENT S…
  20. Appendix C — ALTERNATE PLUMBING SYSTEMS
  21. Appendix D — SIZING STORM WATER DRAINAGE SYSTEMS
  22. Appendix E — MANUFACTURED/MOBILE HOME PARKS AND RECREATIONAL V…
  23. Appendix F — FIREFIGHTER BREATHING AIR REPLENISHMENT SYSTEMS
  24. Appendix G — SIZING OF VENTING SYSTEMS
  25. Appendix H — PRIVATE SEWAGE DISPOSAL SYSTEMS
  26. Appendix I — INSTALLATION STANDARDS
  27. Appendix J — COMBINATION OF INDOOR AND OUTDOOR COMBUSTION AND …
  28. Appendix K — POTABLE RAINWATER CATCHMENT SYSTEMS
  29. Appendix L — SUSTAINABLE PRACTICES
  30. Appendix M — PEAK WATER DEMAND CALCULATOR
  31. Appendix N — IMPACT OF WATER TEMPERATURE ON THE POTENTIAL FOR …
  32. Appendix O — NON-SEWERED SANITATION SYSTEMS
  33. Appendix P — PROFESSIONAL QUALIFICATIONS
  34. Appendix Q — INDOOR HORTICULTURAL FACILITIES
  35. Appendix R — TINY HOUSES
  36. Appendix S — ONSITE STORMWATER TREATMENT SYSTEMS

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