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Use the following steps to correctly size vent pipe diam-
eter.
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?
What is the altitude of
the furnace installation?
7
What is the
furnace capacity?
See max and min length
tables. Include all vent pipe
and elbows inside and
outside the hpouse
FIGURE 22
IMPORTANT
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze-ups and
may block the terminations.