VENTING
21
6.6 Combination Venting
IMPORTANT: Horizontal vent sections require 1/4 in (6 mm) rise
for every 12 in (305 mm) of travel.
IMPORTANT: Natural gas and LP gas vent installations
terminating with a snorkel cap require a minimum of 24 in
(610mm) of vertical venting off the top of the appliance before
the use of an elbow.
Table 6.5, NG & LPG - Minimum Horizontal Vent Terminations
Minimum
Vertical Rise
Minimum
Horizontal Run
Maximum
Horizontal Run
24 in
610 mm
6 in
152 mm
48 in
1219 mm
Table 6.6, NG & LPG - 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
Table 6.7, Recommended Restriction for Combination Venting
Gas Type
Vent Configuration
Baffle Position
Restrictor
NG
Min vert / min horz
Setting (3)
None
NG
Min vert / max horz
Setting (1)
None
NG
Max vert / max horz
Setting (5)
Install restrictor
LP
Min vert / min horz
Setting (2)
None
LP
Min vert / max horz
Setting (5)
None
LP
Max vert / max horz
Setting (5)
Install restrictor
24”
(610mm)
6”
(152mm)
48”
(1219mm)
90° ELBOW
HORIZONTAL
TERMINATION CAP
Figure 6.3, Combination Venting - Natural and LP Gas (V/H)