Allied A96UH1E - Vent Pipe Lengths; IMPORTANT; Table 4. Minimum Vent Pipe Lengths; Figure 24.

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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*
030, 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.
030, 045,
070, 090,
110, 135
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 5 to find
max pipe length.
7
Figure 24.