802.7 Single-Wall Metal Pipe. Single-wall metal pipe

shall be constructed of galvanized sheet steel not less than 0.0304 of an inch (0.7722 mm) thick or of other approved, noncombustible, corrosion-resistant material. [NFPA 54:12.8.1] 802.7.1 Cold Climate. Uninsulated single-wall metal pipe shall not be used outdoors for venting appliances in regions where the 99 percent winter design temperature is below 32°F (0°C). [NFPA 54:12.8.2] 802.7.2 Termination. The termination of single-wall metal pipe shall meet the following requirements: (1) Single-wall metal pipe shall terminate at least 5 feet

(1524 mm) in vertical height above the highest con

(1) Single-wall metal pipe shall terminate at least 5 feet

(1524 mm) in vertical height above the highest connected appliance draft hood outlet or flue collar. (2) Single-wall metal pipe shall extend at least 2 feet

(610 mm) above the highest point where it passes

802.7.3.3 Clearances. Minimum clearances from single-wall metal pipe to combustible material shall be in accordance with Table 802.7.3.3. Reduced clearances from single-wall metal pipe to combustible material shall be as specified for vent connectors in Table 303.10.1. [NFPA 54:12.8.4.4] 802.7.3.4 Combustible Exterior Wall. Singlewall metal pipe shall not pass through a combustible exterior wall unless guarded at the point of passage by a ventilated metal thimble not smaller than the following: (1) For listed appliances with draft hoods and appli ances listed for use with Type B gas vents, the

(2) Single-wall metal pipe shall extend at least 2 feet

(610 mm) above the highest point where it passes through a roof of a building and at least 2 feet (610 mm) higher than any portion of a building within a horizontal distance of 10 feet (3048 mm). (See Figure 802.5.4) (3) An approved cap or roof assembly shall be attached

to the terminus of a single-wall metal pipe. [NFPA

(2) For unlisted appliances having draft hoods, the

thimble shall be a minimum of 6 inches (152 mm) larger in diameter than the metal pipe. (3) For residential and low-heat appliances, the

thimble shall be a minimum of 12 inches (305

(3) An approved cap or roof assembly shall be attached

to the terminus of a single-wall metal pipe. [NFPA 54:12.8.3] 802.7.3 Installation with Appliances Permitted by Section 802.4. Single-wall metal pipe shall not be used as a vent in dwellings and residential occupancies.

[NFPA 54:12.8.4.1]

(1) For listed appliances with draft hoods and appli ances listed for use with Type B gas vents, the thimble shall be a minimum of 4 inches (102 mm) larger in diameter than the metal pipe. Where there is a run of not less than 6 feet (1829 mm) of metal pipe in the opening between the draft hood outlet and the thimble, the thimble shall be a minimum of 2 inches (51 mm) larger in diameter than the metal pipe. (2) For unlisted appliances having draft hoods, the

thimble shall be a minimum of 6 inches (152

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(3) For residential and low-heat appliances, the

thimble shall be a minimum of 12 inches (305 mm) larger in diameter than the metal pipe. Exception: In lieu of thimble protection, combustible material in the wall shall be removed a sufficient distance from the metal pipe to provide the specified clearance from such metal pipe to combustible material. Any material used to close up such opening shall be noncombustible. [NFPA 54:12.8.4.6] 802.7.3.5 Roof Thimble. Where a single-wall metal pipe passes through a roof constructed of combustible material, a noncombustible, nonventilating thimble shall be used at the point of passage. The thimble shall extend not less than 18 inches (457 mm) above and 6 inches (152 mm) below the roof

802.7.3.1 Limitations. Single-wall metal pipe shall be used for runs directly from the space in which the appliance is located through the roof or exterior wall to the outer air. A pipe passing through a roof shall extend without interruption through the roof flashing, roof jacket, or roof thimble. [NFPA 54:12.8.4.2] 802.7.3.2 Attic or Concealed Space. Singlewall metal pipe shall not originate in an unoccupied attic or concealed space and shall not pass through an attic, inside wall, concealed space, or floor.

[NFPA 54:12.8.4.3]

clearances shall apply.

142 2019 CALIFORNIA MECHANICAL CODE

CHIMNEYS AND VENTS

with the annular space open at the bottom and closed at the top. The thimble shall be sized in accordance with Section 802.7.3.4. [NFPA 54:12.8.4.5] 802.7.4 Size of Single-Wall Metal Pipe. Single-wall metal piping shall comply with Section 802.7.4.1 through Section 802.7.4.3. [NFPA 54:12.8.5]

802.7.4.1 Sizing of Venting System. A venting system of a single-wall metal pipe shall be sized in accordance with one of the following methods and the appliance manufacturer’s instructions: (1) For a draft hood-equipped appliance, in accor dance with Section 803.0.

(1) For a draft hood-equipped appliance, in accor dance with Section 803.0. (2) For a venting system for a single appliance with

a draft hood, the areas of the connector and the

(2) For a venting system for a single appliance with

a draft hood, the areas of the connector and the pipe each shall not be less than the area of the appliance flue collar or draft hood outlet, whichever is smaller. The vent area shall not exceed seven times the draft hood outlet area. (3) Other approved engineering methods. [NFPA

54:12.8.5(1)]

802.8.2 Direct-Vent Appliance. The vent terminal of a direct-vent appliance with an input of 10 000 Btu/h (3 kW) or less shall be located at least 6 inches (152 mm) from any air opening into a building, an appliance with an input over 10 000 Btu/h (3 kW) but not over 50 000 Btu/h (14.7 kW) shall be installed with a 9 inch (229 mm) vent termination clearance, and an appliance with an input exceeding 50 000 Btu/h (14.7 kW) shall have at least a 12 inch (305 mm) vent termination clearance. The bottom of the vent terminal and the air intake shall be located at least 12 inches (305 mm) above finished ground level. [NFPA 54:12.9.3] 802.8.3 Category I through Category IV and Non-categorized Appliances. Through-the-wall vents for Category II and Category IV appliances and noncategorized condensing appliances shall not terminate over public walkways or over an area where condensate or vapor could create a nuisance or hazard or could be detrimental to the operation of regulators, relief valves, or other equipment. Where local experience indicates that condensate is a problem with Category I and Category III appliances, this provision shall also apply.

Drains for condensate shall be installed in accordance with the appliance and the vent manufacturer’s installation instructions. [NFPA 54:12.9.4] 802.8.4 Annular Spaces. Where vents, including those for direct-vent appliances or combustion air intake pipes, penetrate outside walls of buildings, the annular spaces around such penetrations shall be permanently sealed using approved materials to prevent entry of combustion products into the building. [NFPA 54:12.9.5] 802.8.5 Vent Terminals. Vent systems for Category IV appliances that terminate through an outside wall of a building and discharge flue gases perpendicular to the adjacent wall shall be located not less than 10 feet (3048 mm) horizontally from an operable opening in an adjacent building. Exception: This shall not apply to vent terminals that are 2 feet (610 mm) or more above or 25 feet (7620 mm) or more below operable openings. [NFPA 54:12.9.6]

(3) Other approved engineering methods. [NFPA

54:12.8.5(1)] 802.7.4.2 Non-Round Metal Pipe. Where a single-wall metal pipe is used and has a shape other than round, it shall have an effective area equal to the effective area of the round pipe for which it is substituted, and the internal dimension of the pipe shall be not less than 2 inches (51 mm). [NFPA 54:12.8.5(2)] 802.7.4.3 Venting Capacity. The vent cap or a roof assembly shall have a venting capacity not less than that of the pipe to which it is attached. [NFPA 54:12.8.5(3)] 802.7.5 Support of Single-Wall Metal Pipe. Portions of single-wall metal pipe shall be supported for the design and weight of the material employed. [NFPA 54:12.8.6] 802.7.6 Marking. Single-wall metal pipe shall comply with the marking provisions of Section 802.6.5. [NFPA 54:12.8.7]