508148-01
Issue 2128
Page 40 of 75
Conditioned
Space
Unconditioned
Space
Exhaust
Pipe
Intake
Pipe
Conditioned
Space
Pipe Insulation
Figure 27. Insulating Exhaust Pipe in an Unconditioned Space
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
045
070
090
110
135
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.
22
N/A
25
N/A
N/A
N/A
N/A
N/A
N/A
N/A
2 in.
21
18
33
30
46
42
30
30
N/A
N/A
2-1/2 in.
16
N/A
26
N/A
37
N/A
36
N/A
N/A
N/A
3 in.
12
12
21
21
30
30
29
29
42
42
20 to 1
(-7 to -17)
1-1/2 in.
12
N/A
20
N/A
N/A
N/A
N/A
N/A
N/A
N/A
2 in.
11
9
19
17
28
25
27
24
N/A
N/A
2-1/2 in.
7
N/A
14
N/A
21
N/A
20
N/A
N/A
N/A
3 in.
N/A
N/A
9
9
16
16
14
14
23
23
0 to -20
(-18 to -29)
1-1/2 in.
8
N/A
13
N/A
N/A
N/A
N/A
N/A
N/A
N/A
2 in.
6
4
12
10
19
16
18
15
N/A
N/A
2-1/2 in.
N/A
N/A
7
N/A
13
N/A
12
N/A
N/A
N/A
3 in.
N/A
N/A
N/A
N/A
8
8
7
7
13
13
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 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 19A through Table 19C.
NOTE
Table 20.
