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FIGURE 20
Piping Size Process
1
2
3
4
5
6
Which style termination
being used?
Standard or concentric?
See table 12.
Which needs
most elbows?
Intake or
exhaust?
How many elbows?
Count all elbows inside
and outside house.
Desired pipe size?
2”, 2-1/2”, 3”
Use table 14 or 15 to find
max intake or exhaust pipe
length. Includes all vent
pipe and elbows inside
and outside the house.
What is the altitude of
the furnace installation?
7
What is the
furnace capacity?
045, 070, 090 or
110?
NOTE
- It is acceptable to use any pipe size which fits within
the guidelines allowed in table 14.
NOTE
-
All horizontal runs of exhaust pipe must slope back
toward unit. A minimum of 1/4” (6mm) drop for each 12”
(305mm) of horizontal run is mandatory for drainage.
NOTE
- Exhaust pipe MUST be glued to furnace exhaust
fittings.
NOTE
- Exhaust piping should be checked carefully to
make sure there are no sags or low spots.
