VENTING
25
7.9 Rear Venting
IMPORTANT: Horizontal vent sections require ¼ in (6 mm) rise
for every 12 in (305 mm) of travel.
7.9.1 Natural Gas Applications
7.9.1.1 Horizontal Terminations
Table 7.6, NG - Minimum / Maximum Horizontal Venting
Minimum Horizontal Length
Maximum Horizontal Length
6 in
152 mm
48 in
1219 mm
7.9.1.2 Combination Venting
Table 7.7, NG - Minimum / Maximum Vertical Terminations
Horizontal to Vertical
Venting
Minimum Vertical
Length
Maximum Vertical
Length
90° elbow off
appliance back
3 ft
914 mm
50 ft
15.2 m
Table 7.8, NG - Max Vertical / Max Horizontal Combination
Maximum
Vertical Rise
Maximum
Horizontal Run
Total Length
25 ft
7.6 m
25 ft
7.6 m
50 ft
15.2 m
Maximum number of 90° elbows: 5
Figure 7.8, Rear Vent Natural Gas Combination Venting
STAND-OFF
BRACKETS
MIN:
6 in (152mm)
MAX:
48 in (1219mm)
TERMINATION
CAP
90° ELBOW
TERMINATION
CAP
STAND-OFF
BRACKETS
MIN: 3 ft (914mm)
MAX: 50 ft (15.2 m)
Figure 7.9, Rear Vent Horizontal Termination - Natural Gas
Figure 7.10, Rear Vent Combination Venting
