Article 6 Gas Vent Connectors

Vent connectors for conversion burners without draft hoods, or other gas-fired equipment without draft hoods, shall be constructed of materials having resistance to corrosion and temperature not less than that of no. 24 galvanized sheet gauge steel.

(a) Vent connectors used for gas-fired equipment having draft hoods and for conversion burners having draft hoods, shall be constructed of type B gas vent material or materials having resistance to corrosion and temperature not less than that of no. 26 galvanized sheet gauge steel.

(b) The vent connector between the equipment and the vertical gas vent or chimney shall have the greatest possible initial rise consistent with the headroom available in the equipment area and with the required clearance to combustible material. The horizontal run of the vent connector shall be as short as possible and the equipment shall be located as near the gas vent or chimney as practicable. The maximum length of an uninsulated horizontal run of vent connector shall not exceed seventy-five percent of the height of the gas vent or chimney.

(c) No vent connector shall pass through floor or ceiling construction.

(a) Minimum clearance. Minimum clearances at vent connectors to combustible materials shall not be less than those listed in table 15-10.

(b) Reduced clearances. These clearances may be reduced when the combustible construction is protected as provided in table 15-11.

TABLE 15-10
VENT CONNECTOR CLEARANCE[S]* FOR GAS-FIRED EQUIPMENT

Equipment	Minimum Distances from Combustible Materials (in.)
	Type B Gas Vent Material	Other Than Type B Materials
Boiler	As required by Std.	6
Warm air furnace	As required by Std.	6
Water heater	As required by Std.	6
Room Heater	As required by Std.	6
Floor furnace	As required by Std.	6
Conversion burner (with draft hood)	6	9
Equipment with draft hoods	6	9
Equipment without draft hoods	Not Permitted	18

*Copy in brackets not enacted but probably intended.

TABLE 15-11
REDUCED CLEARANCES FOR VENT CONNECTORS WITH SPECIFIED FORMS OF PROTECTION^a

Specified Form of Protectionb	Reduced Clearances Where the Required Clearance with No Protection is:
	18 in.	9 in.	6 in.
(a) 1/4 in. asbestos millboard spaced out 1 in.c	12	6	3
(b) 28 gage [sic] sheet metal on 1/4 in. asbestos mill board	12	4	2
(c) 28 gage [sic] sheet metal spaced out 1 in.c	9	4	2
(d) 28 gage [sic] sheet metal on 1/8 in. asbestos millboard spaced out 1 in.c	9	4	2
(e) 1 1/2 in. asbestos cement covering on heating appliance	18	9	6
(f) 1/4 in. asbestos millboard on 1 in. mineral fiber bats reinforced with wire mesh or equivalent	6	4	2
(g) 22 gage [sic] sheet metal on 1 in. mineral fiber bats reinforced with wire or equivalent	3	2	2
(h) 1/4 in. asbestos cement board or 1/4 in. asbestos millboard	18	9	4
(i) 1/4 in. cellular asbestos	18	9	3

Notes for Table 15-11:
^a Except for the protection described in (e) above, all clearances should be measured from the outer surface of the appliance to the combustible material disregarding any intervening protection applied to the combustible material.
^b Applied to the combustible material unless otherwise specified and covering all surfaces within the distance specified as the required clearance with no protection. Thicknesses are minimum.
^c Spacers shall be on** noncombustible material.
**As enacted but "of" probably intended.

(a) When passing through combustible constructions, bent connectors constructed of type B gas vent material shall be installed so that the clearances required by the standard are maintained.

(b) Vent connections made of single-wall metal pipe shall not pass through any combustible walls or partitions unless they are guarded at the point of passage by ventilated metal thimbles not smaller than the following:

(1) For equipment conforming to standards -- four inches larger in diameter than the vent connector.

(2) For equipment having draft hoods -- six inches larger in diameter than the vent connector.

(3) For equipment without draft hoods -- twelve inches larger in diameter than the vent connector.

The vent connector shall not be smaller than the size of the flue collar or the draft hood outlet of the gas-fired equipment. Where a single item of equipment has more than one draft hood outlet, the vent connector shall equal the combined area of the draft hood outlets for which it acts as a common connector to the gas vent or chimney.