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Earlier editions: 20222019

Chapter 8 — CHIMNEYS AND VENTS

802.15 Obstruction of Flow. Devices that retard the flow

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.

of vent gases shall not be installed in a vent connector, chimney, or vent. The following shall not be considered as obstructions:

(1) Draft regulators and safety controls specifically listed for installation in venting systems and installed in accordance with the manufacturer’s installation instructions.

(2) Approved draft regulators and safety controls designed and installed in accordance with engineering methods.

(3) Listed heat reclaimers and automatically operated vent dampers installed in accordance with the manufacturers’ installation instructions.

(4) Vent dampers serving listed appliances installed in accordance with Section 803.1 or Section 803.2 or engineering methods.

(5) Approved economizers, heat reclaimers, and recuperators installed in venting systems of appliances not required to be equipped with draft hoods, provided the appliance manufacturer’s instructions cover the installation of such a device in the venting system and performance in accordance with Section 802.3 and Section

802.3.1 is obtained. [NFPA 54:12.16]

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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
    Overview
    1. 801.1 Applicability. The requirements of this chapter shall
    2. 801.2 Venting of Gas Appliances. Low-heat and
    3. 801.3 Appliances Fueled by Other Fuels. Appliances
    4. 802.1 Listing. Type B and Type B-W gas vents shall comply with…
    5. 802.2 Connection to Venting Systems. Except as permitted in Se…
    6. 802.3 Minimum Safe Performance. Venting systems shall
    7. 802.4 Type of Venting System to be Used. The type of
    8. 802.5 Masonry, Metal, and Factory-Built Chimneys.
    9. 802.6 Gas Vents. The installation of gas vents shall meet
    10. 802.7 Single-Wall Metal Pipe. Single-wall metal pipe shall
    11. 802.8 Through-the-Wall Vent Termination. Throughthe-wall vent …
    12. 802.9 Condensation Drain. Provision shall be made to
    13. 802.10 Vent Connectors for Category I Appliances.
    14. 802.11 Vent Connectors for Category II, Category III,
    15. 802.12 Appliances Requiring Draft Hoods. Vented
    16. 802.13 Manually Operated Dampers. A manually operated damper s…
    17. 802.14 Automatically Operated Vent Dampers. An
    18. 802.15 Obstruction of Flow. Devices that retard the flow
    19. 803.1 Additional Requirements to Single Appliance
    20. 803.2 Additional Requirements to Multiple-Appliance
  9. Chapter 9 — INSTALLATION OF SPECIFIC APPLIANCES
  10. Chapter 10 — 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 — 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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