VENTING
27
7.8 Rear Venting
IMPORTANT: Horizontal vent sections require 1/4 in (6 mm) rise
for every 12 in (305 mm) of travel.
7.8.1 Natural Gas Installations
7.8.1.1 Horizontal Terminations
Table 7.6, NG - Minimum / Maximum Horizontal Venting
Minimum Horizontal Length (H
MIN
)
Maximum Horizontal Length (H
MAX
)
6 in
152 mm
48 in
1219 mm
7.8.1.2 Combination Venting
Table 7.7, NG - Minimum / Maximum Vertical Terminations
Horizontal to Vertical
Venting
Minimum Vertical
Length
Maximum Vertical
Length
90° elbow
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 7.6, NG Rear Vent Combination Venting (H/V)
REAR VENTING DIAGRAM (VERTICAL & HORIZONTAL TERMINATIONS)
(A)
Stand-off Brackets
(B)
Stand-off Heat Shields
(C)
90
°
Elbow
(D)
Vertical Vent Heat Shield (not
applicable)
(E)
Horizontal Vent Heat Shield (not
applicable)
(F)
Termination Cap
NG - 90° ELBOW + 3ft (914mm) V
MIN
/ 50ft (15.2m) V
MAX
NG - 6” (152mm) H
MIN
/ 48” (1219mm) H
MAX
H
MIN
H
MAX
V
MIN
V
MAX
A
B
C
F
A
B
F
