Page 32
TABLE 15
Maximum Allowable Exhaust Vent Pipe Length (in ft.)
3
Without Insulation In Unconditioned Space For
Winter Design Temperatures Single - Stage High Efficiency Furnace
Winter
Design
Temp
1
°F (°C)
Vent
Pipe
Diam
Unit Input Size
030
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
PVC
2
PP
1-1/2 in
N/A
N/A
25
N/A
20
N/A
N/A
N/A
N/A
N/A
N/A
N/A
2 in
18
16
31
28
50
48
30
30
2-1/2 in
13
N/A
24
N/A
42
N/A
56
N/A
3 in
9
9
18
18
35
35
47
47
42
42
20 to 1
(-7 to -17)
1-1/2 IN
15
N/A
20
N/A
N/A
N/A
N/A
N/A
N/A
N/A
2 in
9
8
18
16
32
29
30
30
2-1/2 in
5
N/A
13
N/A
24
N/A
34
N/A
3 in
1
1
8
8
19
19
26
26
23
23
0 to -20
(-18 to -29)
1-1/2 in
10
N/A
15
N/A
N/A
N/A
N/A
N/A
N/A
N/A
2 in
5
3
12
10
22
19
30
27
2-1/2 in
1
N/A
7
N/A
15
N/A
22
N/A
3 in
N/A
N/A
2
2
10
10
16
16
13
13
1Refer 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.
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 ex
-
ceed 5 linear feet or the maximum allowable intake or exhaust vent length listed in table TABLE 13 which ever is less.
NOTE - If insulation is required in an unconditioned space, it must be located on the pipe closest to the furnace. See FIGURE 31.
3 Vent length in the table is equivalent length. Each elbow is equivalent to 5ft of straight pipe and should be included when mea
-
suring total length.
Conditioned
Space
Unconditioned
Space
Exhaust
Pipe
Intake
Pipe
Conditioned
Space
Pipe Insulation
FIGURE 31
Summary of Contents for ML196UH030XE36B
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