Page 30
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
Temperatures
1
°F (°C)
Vent Pipe
Diameter
Unit Input Size
045
070
090
110
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
20
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
36
N/A
3 in
9
9
18
18
35
35
29
29
20 to 1
(-7 to -17)
1-1/2in.
15
N/A
20
N/A
N/A
N/A
N/A
N/A
2 in
9
8
18
16
32
29
27
24
2-1/2 in
5
N/A
13
N/A
24
N/A
20
N/A
3 in
1
1
8
8
19
19
14
14
0 to -20
(-18 to -29)
1-1/2 in
10
N/A
15
N/A
N/A
N/A
N/A
N/A
2 in
5
3
12
10
22
19
18
15
2-1/2 in
1
N/A
7
N/A
15
N/A
12
N/A
3 in
N/A
N/A
2
2
10
10
7
7
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.
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 13 or TABLE 14 which ever is less.
NOTE -
3
Vent length in the table is equivalent length. Each elbow is equivalent to 5ft of straight pipe and should be included when measuring total length.
Conditioned
Space
Unconditioned
Space
Exhaust
Pipe
Intake
Pipe
Conditioned
Space
Pipe Insulation
FIGURE 29
