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Alternate Vertical Vent Termination (Single Pipe)
Standard Horizontal Vent Termination (Single Pipe)
Standard Horizontal Vent Termination (Single Pipe)—
Above Highest Anticipated Snow Level
Direct Vent (Dual Pipe) Piping
The inlet air screens provided in the installation instruction packet
are available for the installer to use in the inlet of the combustion
air pipe to prevent animals from building nests in the combustion
air pipe. Installation of screens, while strongly recommended, is
not required and will not affect performance of the furnace.
Direct vent installations require both a combustion air intake and
a vent/flue pipe. The pipes may be run horizontally and exit
through the side of the building or run vertically and exit through
the roof of the building.
The pipes may be run through an existing unused chimney;
however, they must extend a minimum of 12" (30.5 cm) above the
top of the chimney. The space between the pipes and the
chimney must be closed with a weathertight, corrosion resistant
flashing. Both the combustion air intake and vent/flue pipe
terminations must be in the same atmospheric pressure zone.
See “Termination Locations,” or “Concentric Vent Termination” in
this section for specific details on termination constructions. For
details concerning connection of pipes to the furnace, refer to the
“Standard Furnace Connections” or “Alternate Furnace
Connections” in this section.
Vent/Flue and Combustion Air Pipe Lengths and Diameters
Refer to the following chart for applicable length, elbows and
pipe diameter for construction of the vent/flue and combustion
air intake pipe systems of a direct vent (dual pipe) installation.
The number of elbows tabulated represents the number of
elbows and/or tees in each vent/flue and combustion air intake
pipe. Elbows and/or tees used in the terminations must be
included when determining the number of elbows in the piping
systems.
If the combustion air intake pipe is to be installed above a
finished ceiling or other area where dripping of condensate will
be objectionable, insulation of the combustion air pipe may be
required. Use
¹⁄₂
" (1.3 cm) thick closed-cell foam insulation where
required.
A. 45º or 90º medium radius elbows
B. 12" (30.5 cm) minimum to roof or
highest anticipated snow level
A. Inside building
B. Wall
C. Outside building
D. Tee, 45º or 90º elbow
turned down
E. 12" (30.5 cm) minimum to roof or
highest anticipated snow level
F. 12" (30.5 cm) minimum from wall
G. Coupling
H. Elbow or coupling
A
B
A
B
C
D
G
H
E
F
A. 12" (30.5 cm) minimum from wall
B. Tee, 45º or 90º elbow turned down
C. 12" (30.5 cm) minimum to roof or highest anticipated snow level
A
B
C
