507961-01G / 31-5000653
Page 18 of 57
Issue 2128
NOTE:
All horizontal runs of exhaust pipe must slope back toward
unit. A minimum of 1/4” (6 mm) drop for each 12” (305 mm) 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 sages or low spots.
Figure 23. Exhaust Pipe
Horizontal Application
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze-ups and
may block the terminations.
IMPORTANT
Table 4. Minimum Vent Pipe Lengths
Capacity
Min. Vent Length*
045, 070, 090, 110, 135
15 ft. or
5 ft. plus 2 elbows or
10 ft. plus 1 elbow
*Any approved termination may be added to the minimum
length listed.
Use the following steps to correctly size vent pipe diameter.
045, 070,
090, 110,
135 btuh
Standard or
Concentric?
See Table 3
Intake or
Exhaust?
1-1/2”, 2”,
2-1/2”
or 3”
Furnace capacity?
1
Which termination?
2
Which needs most
elbows?
3
How many?
4
Desired pipe size?
5
What is the altitude?
6
Use Table 6 to find
max pipe length.
7
Figure 24.