G2427.6 (503.6) Gas Vents
A gas vent shall terminate in accordance with one of the following:
- Gas vents that are 12 inches (305 mm) or less in size and located not less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate above the roof in accordance with Figure G2427.6.4.
- Gas vents that are over 12 inches (305 mm) in size or are located less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate not less than 2 feet (610 mm) above the highest point where they pass through the roof and not less than 2 feet (610 mm) above any portion of a building within 10 feet (3048 mm) horizontally.
- As provided for direct-vent systems in Section G2427.2.1.
- As provided for appliances with integral vents in Section G2427.2.2.
- As provided for mechanical draft systems in Section G2427.3.3.
|ROOF SLOPE||H (minimum) ft|
|Flat to 6/12||1.0|
|Over 6/12 to 7/12||1.25|
|Over 7/12 to 8/12||1.5|
|Over 8/12 to 9/12||2.0|
|Over 9/12 to 10/12||2.5|
|Over 10/12 to 11/12||3.25|
|Over 11/12 to 12/12||4.0|
|Over 12/12 to 14/12||5.0|
|Over 14/12 to 16/12||6.0|
|Over 16/12 to 18/12||7.0|
|Over 18/12 to 20/12||7.5|
|Over 20/12 to 21/12||8.0|
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.
FIGURE G2427.6.4 (503.6.5)
TERMINATION LOCATIONS FOR GAS VENTS WITH LISTED CAPS 12 INCHES OR LESS IN SIZE NOT LESS THAN 8 FEET FROM A VERTICAL WALL
The sizing of natural draft venting systems serving one or more listed appliances equipped with a draft hood or appliances listed for use with Type B gas vent, installed in a single story of a building, shall be in accordance with one of the following methods:
- The provisions of Section G2428.
- For sizing an individual gas vent for a single, draft-hood-equipped appliance, the effective area of the vent connector and the gas vent shall be not less than the area of the appliance draft hood outlet, nor greater than seven times the draft hood outlet area.
- For sizing a gas vent connected to two appliances with draft hoods, the effective area of the vent shall be not less than the area of the larger draft hood outlet plus 50 percent of the area of the smaller draft hood outlet, nor greater than seven times the smaller draft hood outlet area.
- Approved engineering practices.
In those localities where solid and liquid fuels are used extensively, gas vents shall be permanently identified by a label attached to the wall or ceiling at a point where the vent connector enters the gas vent. The determination of where such localities exist shall be made by the code official. The label shall read: