507266-04B
Page 26 of 56
Issue 1904
Maximum Allowable Exhaust Vent Pipe Length (in ft.) without Insulation in Unconditioned Space for Winter Design
Temperatures
Winter Design Temperatures1 ºF (ºC)
Vent Pipe
Diameter
Unit Input Size
070
090
110
32 to 21
(0 to -6)
PVC
2
PP
PVC
2
PP
PVC
2
PP
2 in.
33
30
46
42
30
30
2-1/2 in.
26
N/A
37
N/A
36
N/A
3 in.
21
21
30
30
29
29
20 to 1
(-7 to -17)
2 in.
19
17
28
25
27
24
2-1/2 in.
14
N/A
21
N/A
20
N/A
3 in.
9
9
16
16
14
14
0 to -20
(-18 to -29)
2 in.
12
10
19
16
18
15
2-1/2 in.
7
N/A
13
N/A
12
N/A
3 in.
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
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
NOTE
Table 6.
Conditioned
Space
Unconditioned
Space
Exhaust
Pipe
Intake
Pipe
Conditioned
Space
Pipe Insulation
Figure 33. Insulating Exhaust Pipe in an Unconditioned Space
