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Maximum Allowable Exhaust Vent Pipe Length
Winter Design Temperatures
(ºC)
32 to 21
(0 to -6)
20 to 1
(-7 to -17)
0 to -20
(-18 to -29)
Refer to 99% Minimum Design Temperature table provided in the current edition of the ASHRAE Fundamentals Handbook.
1
Poly-Propylene vent pipe (PP) by Duravent and Centrotherm
2
Vent length in table is equivalent length. Each elbow is equivalent to 5ft of straight pipe and should be included when measuring
3
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 6 or Table 7A through Table 7C.
NOTE - If insulation is required an unconditioned space, it must be located on the pipe closed to the furnace.
507962-01G / 31-5000654
(in ft.) without Insulation in Unconditioned Space for Winter Design
3
ºF
1
Vent Pipe
Diameter
1-1/2 in.
2 in.
2-1/2 in.
3 in.
1-1/2 in.
2 in.
2-1/2 in.
3 in.
1-1/2 in.
2 in.
2-1/2 in.
3 in.
Conditioned
Space
Figure 27. Insulating Exhaust Pipe in an Unconditioned Space
Temperatures
070
PVC
PP
PVC
2
20
N/A
33
30
26
N/A
21
21
20
N/A
19
17
14
N/A
9
9
13
N/A
12
10
7
N/A
N/A
N/A
Table 8.
Conditioned
Space
Pipe Insulation
Unconditioned
Space
Issue 2149
Unit Input Size
090
PP
PVC
2
N/A
N/A
46
42
37
N/A
30
30
N/A
N/A
28
25
21
N/A
16
16
N/A
N/A
19
16
13
N/A
8
8
Exhaust
Pipe
Intake
Pipe
110
PP
2
N/A
N/A
30
30
36
N/A
29
29
N/A
N/A
27
24
20
N/A
14
14
N/A
N/A
18
15
12
N/A
7
7
Page 23 of 51
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