Lennox Allied Air A95UH1D Installation Instructions Manual page 18

Use Figure 24 to correctly size vent pipe diameter.
Furnace capacity?
1
Which termination?
2
Which needs most
3
elbows?
How many?
4
Desired pipe size?
5
What is the altitude?
6
Use Table 5 or
Table 6 to find max
7
pipe length.
Figure 24.
Page 18 of 60
045, 070,
090, 110,
135
Standard or
Concentric?
See Table 3
Intake or
Exhaust?
2", 2-1/2"
or 3"
Issue 1917 507270-03