§27-884 Types of Gas Vents

(a) Type B gas vents. Type B gas vents conforming to the requirements of section 27-855 of article one of this subchapter may be used to vent gas-fired equipment. Type B gas vents may be used for single-story or multi-story installations when they conform to the requirements of section 27-855 of article one of this subchapter and the gas equipment used in multi-story installations shall be accepted for such use. Type B gas vents shall be used to vent only listed gas appliances with draft hoods and other gas appliances listed for use with Type B gas vents. However, Type B gas vents shall not be used for venting:

(1) vented wall furnaces listed for use with Type BW gas vents only;

(2) incinerators;

(3) appliances which may be converted readily to the use of solid or liquid fuels;

(4) combination gas-oil burning appliances;

(5) appliances listed for use with chimneys only.

(b) Type B-W gas vents. Type B-W gas vents conforming to the requirements of section 27-855 of article one of this subchapter shall be used to vent gas-fired vented recessed heaters. Type B-W gas vents may be used with single-story or multi-story installations when they conform to the requirements of section 27-855 of article one of this subchapter and the gas equipment used in multi-story installations shall be accepted for such use. Type BW vents shall be used with listed vented gas wall furnaces having a capacity not greater than that of the listed Type BW gas vent.

(c) Single-wall metal vents. Single-wall metal vents may be used to vent gas-fired equipment and shall be constructed of not less than 16 oz. sheet copper, or No. 20 galvanized sheet gauge steel, or of other equivalent noncombustible corrosion-resistive material. Single-wall metal gas vents may pass through the roof or exterior wall to the outdoor air, but shall not pass through any attic or other concealed space nor through any intermediate floor construction.

(d) Connection to a common vent. Connection of gas-fired equipment on more than one floor level to a common vent, except as provided for in subdivisions (a) and (b) of this section, shall be prohibited.

(e) Ventilating hoods. Ventilating hoods and exhaust systems may be used to vent kitchen, laboratory, and commerical equipment.