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Maximum Allowable Exhaust Vent Pipe Length
Winter Design Temperatures
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 7A through Table 7D or Table 8A through Table
8B.
NOTE - If insulation is required an unconditioned space, it must be located on the pipe closed to the furnace.
(in ft.) without Insulation in Unconditioned Space for Winter Design
3
Temperatures Single - Stage High Efficiency Furnace
Vent Pipe
ºF (ºC)
1
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
Conditioned
Space
Figure 27. Insulating Exhaust Pipe in an Unconditioned Space
045
PVC
PP
2
20
N/A
18
16
13
N/A
9
9
15
N/A
9
8
5
N/A
1
1
10
N/A
5
3
1
N/A
N/A
N/A
Table 12.
Space
Pipe Insulation
Unconditioned
Space
Page 30
Unit Input Size
070
PVC
PP
PVC
2
20
N/A
N/A
31
28
50
24
N/A
42
18
18
35
20
N/A
N/A
18
16
32
13
N/A
24
8
8
19
15
N/A
N/A
12
10
22
7
N/A
15
2
2
10
Exhaust
Pipe
Intake
Pipe
090
PP
2
N/A
48
N/A
35
N/A
29
N/A
19
N/A
19
N/A
10
31-5000729 Rev. 0
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