Demand Duo
™
H
-
Series Installation and Operation Manual
23
Twin Pipe Termination Clearances
Direct Vent
(Twin Pipe)
1
Combustion air and exhaust vent directly through
separate penetrations.
Twin Pipe Overview
Exhaust
Combustion
air
For illustration purposes only. Listed equivalent length is based on worst case scenario of 3 X 90°
elbows or 18 equivalent ft.
Twin Pipe Vertical Termination
of Multiple Water Heaters
12 in. (0.30 m) minimum
12 in. (0.30 m)
minimum above
combustion air
opening
Roof
12 in. (0.30 m)
above grade or
anticipated snow
level
12 in. (0.30 m)
minimum
Combustion
Air
Exhaust
Figure 22
Figure 23
Intake
Ground/Grade/Snow Level
60 in.
min
Indicates area in
which intake
cannot be located.
12 in.
min
12 in.
min
12 in.
min
12 in.
min
12 in.
min
Intake
Exhaust
Intake