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Maximum Allowable Exhaust Vent Pipe Length
Winter Design Temperatures
ºF (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- 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 6A through Table 6B or Table 5.
NOTE - If insulation is required in an unconditioned space, it must be located on the pipe closest to the furnace. See Figure 17.
NOTE - Concentric terminations are the equivalent of 5' and should be considered when measuring pipe length.
Page 16 of 74
(in ft.) without Insulation in Unconditioned Space For Winter Design
3
Temperatures Single - Stage High Efficiency Furnace
Vent Pipe
1
Diameter
PVC
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.
070
090
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
N/A
N/A
10
Table 5.
Issue 2346
Unit Input Size
110
PP
PVC
PP
2
2
N/A
N/A
N/A
48
30
30
N/A
56
N/A
35
47
47
N/A
N/A
N/A
29
30
30
N/A
34
N/A
19
26
26
N/A
N/A
N/A
19
30
27
N/A
22
N/A
10
16
16
135
PVC
PP
2
N/A
N/A
N/A
N/A
N/A
N/A
52
52
N/A
N/A
N/A
N/A
N/A
N/A
30
30
N/A
N/A
N/A
N/A
N/A
N/A
18
18
508364-01
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