507028-05G / 31-5000694
Issue 2128
Page 16 of 66
Maximum Allowable Exhaust Vent Pipe Length
3
(in ft.) without Insulation in Unconditioned Space For Winter Design
Temperatures Single - Stage High Efficiency Furnace
Winter Design Temperatures
1
ºF (ºC)
Vent Pipe
Diameter
Unit Input Size
070
090
110
135
32 to 21
(0 to -6)
PVC
2
PP
PVC
2
PP
PVC
2
PP
PVC
2
PP
1-1/2 in.
20
N/A
N/A
N/A
N/A
N/A
N/A
N/A
2 in.
31
28
50
48
30
30
N/A
N/A
2-1/2 in.
24
N/A
42
N/A
56
N/A
N/A
N/A
3 in.
18
18
35
35
47
47
52
52
20 to 1
(-7 to -17)
1-1/2 in.
20
N/A
N/A
N/A
N/A
N/A
N/A
N/A
2 in.
18
16
32
29
30
30
N/A
N/A
2-1/2 in.
13
N/A
24
N/A
34
N/A
N/A
N/A
3 in.
8
8
19
19
26
26
30
30
0 to -20
(-18 to -29)
1-1/2 in.
15
N/A
N/A
N/A
N/A
N/A
N/A
N/A
2 in.
12
10
22
19
30
27
N/A
N/A
2-1/2 in.
7
N/A
15
N/A
22
N/A
N/A
N/A
3 in.
N/A
N/A
10
10
16
16
18
18
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- 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.
Table 5.
