NOTE - In Direct Vent installations, combustion air is tak-
en from outdoors and ue gases are discharged outdoors.
Intake and exhaust pipe sizing --
-
-
NOTE - The exhaust collar on all models is sized to ac-
commodate 2” Schedule 40 vent pipe. In horizontal ap-
plications, any transition to exhaust pipe larger than 2”
must be made in vertical runs of the pipe. Therefore a 2”
elbow must be added before the pipe is transitioned to
any size larger than 2”. This elbow must be added to the
elbow count used to determine acceptable vent lengths.
Contact the Application Department for more information
concerning sizing of vent systems which include multiple
pipe sizes.
Horizontal Installation Offset Requirements
NOTE -
ward unit. A minimum of 1/4” (6mm) drop for each 12” (305mm
of horizontal run is mandatory for drainage.
NOTE - Exhaust piping should be checked carefully to make
sure there are no sags or low spots.
Exhaust Pipe
Horizontal
Gas Furnace
12” Min.
12” Max.
FIGURE 20
TABLE 20
MINIMUM VENT PIPE LENGTHS
-
1
2
3
4
5
6
Which style termination
being used?
Standard or concentric?
Which needs
most elbows?
Intake or
exhaust?
How many elbows?
Count all elbows inside
and outside house.
Desired pipe size?
determine
max intake or exhaust pipe
length. Includes all vent
pipe and elbows inside
What is the altitude of
the furnace installation?
7
What is the
furnace capacity?
FIGURE 21
IMPORTANT
Do not use screens or perforated metal in exhaust
or intake terminations. Doing so will cause freeze-
ups and may block the terminations.
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