Allied A93UH1E - Page 33

508107-01 Issue 2041 Page 33 of 58
Maximum Allowable Exhaust Vent Pipe Length (in ft.) without Insulation in Unconditioned Space for Winter Design
Temperatures Single - Stage High E󰀩ciency Furnace
Winter Design
Temperatures
1
ºF (ºC)
Vent Pipe
Diameter
Unit Input Size
030 045 070 090 110
32° to 21°
(0 to -6)
PVC
2
PP PVC
2
PP PVC
2
PP PVC
2
PP PVC
2
PP
1-1/2 in. N/A N/A 25 N/A 25 N/A N/A N/A N/A N/A
2 in. N/A N/A 18 16 31 28 50 48 30 30
2-1/2 in. N/A N/A 13 N/A 24 N/A 42 N/A 56 N/A
3 in. N/A N/A 9 9 18 18 35 35 47 47
20° to 1°
(-7 to -17)
1-1/2 in. N/A N/A 15 N/A 20 N/A N/A N/A N/A N/A
2 in. N/A N/A 9 8 18 16 32 29 30 30
2-1/2 in. N/A N/A 5 N/A 13 N/A 24 N/A 34 N/A
3 in. N/A N/A N/A N/A 8 8 19 19 26 26
0° to -20°
(-18 to -29)
1-1/2 in. N/A N/A 10 N/A 15 N/A N/A N/A N/A N/A
2 in. N/A N/A 5 3 12 10 22 19 30 27
2-1/2 in. N/A N/A N/A N/A 7 N/A 15 N/A 22 N/A
3 in. N/A N/A N/A N/A N/A N/A 10 10 16 16
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
NOTE - Concentric terminations are the equivalent of 5’ 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 11 and Table 12.
NOTE - If insulation is required in an unconditioned space, it must be located on the pipe closest to the furnace. See Figure 29.
Table 13.
Conditioned
Space
Unconditioned
Space
Exhaust
Pipe
Intake
Pipe
Conditioned
Space
Pipe Insulation
Figure 29. Insulating Exhaust Pipe in an Unconditioned Space