Allied A97UH2E - Page 39

508433-01 Issue 2345 Page 39 of 70
Maximum Allowable Exhaust Vent Pipe Length
3
(in ft.) without Insulation in Unconditioned Space for Winter
Design Temperatures
Winter Design Temperatures
1
ºF
(ºC)
Vent Pipe
Diameter
Unit Input Size
030 045 070 090 110
PVC
2
PP PVC
2
PP PVC
2
PP PVC
2
PP PVC
2
PP
32 to 21
(0 to -6)
1-1/2 in. N/A N/A 22 N/A 20 N/A N/A N/A N/A N/A
2 in. 13 12 21 18 33 30 46 42 30 30
2-1/2 in. 10 N/A 16 N/A 26 N/A 37 N/A 36 N/A
3 in. 6 6 12 12 21 21 30 30 29 29
20 to 1
(-7 to -17)
1-1/2 in. N/A N/A 12 N/A 20 N/A N/A N/A N/A N/A
2 in. 6 4 11 9 19 17 28 25 27 24
2-1/2 in. N/A N/A 7 N/A 14 N/A 21 N/A 20 N/A
3 in. N/A N/A N/A N/A 9 9 16 16 14 14
0 to -20
(-18 to -29)
1-1/2 in. N/A N/A 8 N/A 13 N/A N/A N/A N/A N/A
2 in. N/A N/A 6 4 12 10 19 16 18 15
2-1/2 in. N/A N/A N/A N/A 7 N/A 13 N/A 12 N/A
3 in. N/A N/A N/A N/A N/A N/A 8 8 7 7
1
Refer to 99% Minimum Design Temperature table provided in the current edition of the ASHRAE Fundamentals Handbook.
2
Poly-Propylene vent pipe (PP) by Duravent and Centrotherm
3
Vent length in table is equivalent length. Each elbow is equivalent to 5ft. of straight pipe and should be included when measuring
total length.
NOTE - Concentric terminations are the equivalent of 5ft. and should be considered when measuring pipe length.
NOTE - Maximum uninsulated vent lengths listed may include the termination (vent pipe exterior to the structure) and cannot exceed
5 linear feet or the maximum allowable intake or exhaust vent length listed in Table 13A through Table 13C.
NOTE - If insulation is required in an unconditioned space, it must be located on the pipe closest to the furnace. See Figure 27.
Table 14.
Conditioned
Space
Unconditioned
Space
Exhaust
Pipe
Intake
Pipe
Conditioned
Space
Pipe Insulation
Figure 27. Insulating Exhaust Pipe in an Unconditioned Space