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Chapter 5 — WATER HEATERS

509.3 Design and Construction. Venting systems shall

California Plumbing Code (Title 24, Part 5) · 2019 edition · updated 2026-09-10 · California

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

be designed and constructed to convey flue, vent, or both gases to the outdoors. [NFPA 54:12.1]

509.3.1 Appliance Draft Requirements. A venting system shall satisfy the draft requirements of the appliance in accordance with the manufacturer’s instructions.

[NFPA 54:12.4.1] 509.3.2 Appliance Venting Requirements. Appliances required to be vented shall be connected to a venting system designed and installed in accordance with the provisions of Section 509.4 through Section 509.15.

[NFPA 54:12.4.2] 509.3.3 Mechanical Draft Systems. Mechanical draft systems shall be listed and installed in accordance with both the appliance and the mechanical draft system manufacturer’s installation instructions. [NFPA 54:12.4.3.1] 509.3.3.1 Venting. Appliances requiring venting shall be permitted to be vented by means of mechanical draft systems of either forced or induced draft design. [NFPA 54:12.4.3.2] 509.3.3.2 Leakage. Forced draft systems and portions of induced draft systems under positive pressure during operation shall be designed and installed so as to prevent leakage of flue or vent gases into a building. [NFPA 54:12.4.3.3]

2019 CALIFORNIA PLUMBING CODE 89

WATER HEATERS any other purpose or distributed to any other persons or parti es.

509.3.3.3 Vent Connectors. Vent connectors serving appliances vented by natural draft shall not be connected into any portion of mechanical draft systems operating under positive pressure. [NFPA 54:12.4.3.4] 509.3.3.4 Operation. Where a mechanical draft system is employed, provision shall be made to prevent the flow of gas to the main burners where the draft system is not performing so as to satisfy the operating requirements of the appliance for safe performance. [NFPA 54:12.4.3.5] 509.3.3.5 Exit Terminals. The exit terminals of mechanical draft systems shall be not less than 7 feet (2134 mm) above finished ground level where located adjacent to public walkways and shall be located as specified in Section 509.8 and Section 509.8.1 of this code. [NFPA 54:12.4.3.6] 509.3.4 Ventilating Hoods and Exhaust Systems. Ventilating hoods and exhaust systems shall be permitted to be used to vent appliances installed in commercial applications. [NFPA 54:12.4.4.1]

509.3.4.1 Automatically Operated Appli-ances. Where automatically operated appliances, other than commercial cooking appliances, are vented through a ventilating hood or exhaust system equipped with a damper or with a power means of exhaust, provisions shall be made to allow the flow of gas to the main burners where the damper is open to a position to properly vent the appliance and where the power means of exhaust is in operation.

i-ances.** Where automatically operated appliances, other than commercial cooking appliances, are vented through a ventilating hood or exhaust system equipped with a damper or with a power means of exhaust, provisions shall be made to allow the flow of gas to the main burners where the damper is open to a position to properly vent the appliance and where the power means of exhaust is in operation.

[NFPA 54:12.4.4.2] 509.3.5 Circulating Air Ducts and Furnace Plenums. Venting systems shall not extend into or pass through a fabricated air duct or furnace plenum. [NFPA 54:12.4.5.1] 509.3.6 Above-Ceiling or Nonducted Air Han- dling System. Where a venting system passes through an above-ceiling air space or other nonducted portion of an air-handling system, it shall conform to one of the following requirements: (1) The venting system shall be a listed special gas vent,

other system serving a Category III or Category IV

TABLE 509.4 TYPE OF VENTING SYSTEM TO BE USED

[NFPA 54: TABLE 12.5.1]

(1) The venting system shall be a listed special gas vent,

other system serving a Category III or Category IV appliance, or other positive pressure vent, with joints sealed in accordance with the appliance or vent manufacturer’s instructions. (2) The vent system shall be installed such that no fit tings or joints between sections are installed in the

(2) The vent system shall be installed such that no fit tings or joints between sections are installed in the above-ceiling space. (3) The venting system shall be installed in a conduit or

enclosure with joints between the interior of the enclo

APPLIANCES TYPE OF VENTING
SYSTEM		 LOCATION OF
REQUIREMENTS
Listed Category I
appliances

 Type B gas vent
 Section 509.6
Listed appliances
equipped with draft
hood

 Chimney

 Section 509.5
Appliances listed for
use with Type B gas
vent

 Single-wall metal
pipe
Listed chimney lin-
ing system for gas
venting
Special gas vent
listed for
appliances
 Section 509.7
Section 509.5.3
Section 509.4.3
Listed vented wall fur-
naces

 Type B-W gas vent

 Section 509.6(2),
Section 509.6.1.2
Category II appliances
Category III appliances
Category IV appliances

 As specified or
furnished by
manufacturers of
listed appliances
Section 509.4.1
and Section
509.4.3
Appliances that can be
converted to use solid
fuel
Unlisted combination
gas- and oil-burning
appliances
Combination gas- and
solid-fuel-burning
appliances
Appliance listed for use
with chimneys only
Unlisted appliances
Chimney
 Section 509.5
Listed combination
gas- and oil-burning
appliances

 Type L vent
Chimney
 Section 509.6
Section 509.5
Decorative appliances
in vented fireplace
 Chimney
UMC Section
911.2

Gas-fired toilets
 Single-wall metal
pipe
 Section 509.7
Direct-vent appliances

 —
 Section 509.2.6
Appliances with
integral vents		 —
Section 509.2.7

turer’s installation instruction shall identify the specific plastic piping material. [NFPA 54:12.5.2] 509.4.2 Plastic Vent Joints. Plastic pipe and fittings used to vent appliances shall be installed in accordance with the appliance manufacturer’s installation instructions. Where primer is required, it shall be of a contrasting color. [NFPA 54:12.5.3] 509.4.3 Special Gas Vents. Special gas vents shall be listed and installed in accordance with the special gas vent manufacturer’s installation instructions. [NFPA 54:12.5.4]

(3) The venting system shall be installed in a conduit or

enclosure with joints between the interior of the enclosure and the ceiling space sealed. [NFPA 54:12.4.5.2]

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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. 501.0 General.501.1 Applicability. The regulations of this cha…
    2. 503.2 Final Water Heater Inspection. This inspection
    3. 504.2 Vent. Water heaters of other than the direct-vent type
    4. 504.3 Clearance. The clearance requirements for water
    5. 504.4 Pressure-Limiting Devices. A water heater installation s…
    6. 504.5 Temperature-Limiting Devices. A water heater
    7. 504.6 Temperature, Pressure, and Vacuum Relief
    8. 505.2 Safety Devices. Storage-type water heaters and hot
    9. 505.3 Oil-Fired Water Heaters. Oil-fired water heaters
    10. 505.4 Indirect-Fired Water Heaters. Indirect-fired water
    11. 506.0 Air for Combustion and Ventilation.506.1 General. Air fo…
    12. 506.2 Indoor Combustion Air. The required volume of
    13. 506.4 Outdoor Combustion Air. Outdoor combustion air
    14. 506.3 Indoor Opening Size and Location. Openings
    15. 506.8 Louvers, Grilles, and Screens. The required size
    16. 506.5 Combination Indoor and Outdoor CombustionAir. The use of…
    17. 506.9 Combustion Air Ducts. Combustion air ducts shall
    18. 506.6 Engineered Installations. Engineered combustion
    19. 506.7 Mechanical Combustion Air Supply. Where
    20. 507.2 Seismic Provisions. Water heaters shall be
    21. 507.3 Appliance Support. Appliances and equipment shall
    22. 507.4 Ground Support. A water heater supported from the
    23. 507.5 Drainage Pan. Where a water heater is located in an
    24. 507.6 Added or Converted Equipment or Appliances. When additio…
    25. 507.7 Types of Gases. The appliance shall be connected to
    26. 507.8 Safety Shutoff Devices for Unlisted LP-GasAppliance Used…
    27. 507.9 Use of Air or Oxygen Under Pressure. Where air
    28. 507.10 Protection of Gas Appliances from Fumes orGases other t…
    29. 507.11 Process Air. In addition to air needed for combustion i…
    30. 507.12 Flammable Vapors. Appliances shall not be
    31. 507.13 Installation in Residential Garages. Appliances
    32. 507.14 Installation in Commercial Garages. Appliances
    33. 507.15 Installation in Aircraft Hangars. Heaters in aircraft h…
    34. 507.16 Venting of Flue Gases. Appliances shall be vented
    35. 507.17 Extra Device or Attachment. No device or attachment sha…
    36. 507.18 Adequate Capacity of Piping. When additional
    37. 507.19 Avoiding Strain on Gas Piping. Appliances shall
    38. 507.20 Gas Appliance Pressure Regulators. Where the
    39. 507.21 Venting of Gas Appliance Pressure Regula-tors. Venting …
    40. 507.22 Bleed Lines for Diaphragm-Type Valves. Bleed
    41. 507.23 Combination of Appliances and Equipment. A
    42. 507.24 Installation Instructions. The installing agency
    43. 507.25 Protection of Outdoor Appliances. Appliances
    44. 507.26 Accessibility for Service. Appliances shall be
    45. 507.27 Clearance to Combustible Materials. Appliances and thei…
    46. 508.0 Appliances on Roofs.508.1 General. Appliances on roofs s…
    47. 508.2 Installation of Appliances on Roofs. Appliances
    48. 508.3 Appliances on Roofs. Appliances located on roofs
    49. 508.4 Appliances in Attics and Under-Floor Spaces.
    50. 509.2 Connection to Venting Systems. Except as permitted in Se…
    51. 509.3 Design and Construction. Venting systems shall
    52. 509.4 Type of Venting System to be Used. The type of
    53. 509.5 Masonry, Metal, and Factory-Built Chimneys.
    54. 509.6 Gas Vents. The installation of gas vents shall meet
    55. 509.7 Single-Wall Metal Pipe. Single-wall metal pipe
    56. 509.8 Through-the-Wall Vent Termination. A mechanical draft ve…
    57. 509.9 Condensation Drain. Provision shall be made to
    58. 509.11 Vent Connectors for Category II, Category III,
    59. 509.12 Draft Hoods and Draft Controls. Vented appliances shall…
    60. 509.15 Obstructions. Devices that retard the flow of vent
    61. 509.13 Manually Operated Dampers. A manually operated damper s…
    62. 509.14 Automatically Operated Vent Dampers. An
    63. 510.1 Single Appliance Vent Table 510.1.2(1) through
    64. 510.2 Multiple Appliance Vent Table 510.2(1) throughTable 510.…
  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 STANDARD FOR PEX TUBING SYSTEMS FOR …
  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

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