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TABLE 23
MINIMUM VENT PIPE LENGTHS
SLP98DF
MODEL
MIN. EQUIV.
VENT LENGTH
EXAMPLE
070, 090, 110
15 ft.*
5 ft. plus 2 elbows of 2”, 2-1/2” or
3” diameter pipe
*Any approved termination may be added to the minimum equivalent length
listed.
NOTE
- It is acceptable to use any pipe size which fits within
the guidelines allowed in table 24.
NOTE
- The exhaust collar on all models is sized to ac
commodate 2” Schedule 40 vent pipe. Contact the Ap
plication Department for more information concerning
sizing of vent systems which include multiple pipe sizes.
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.
Use the following steps to correctly size vent pipe diameter.
IMPORTANT
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze-ups
and may block the terminations.
FIGURE 24
Piping Size Process
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?
2”, 2-1/2”, 3”
Use table 24 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?
070, 090, 110?