48
Table 14 – Maximum Allowable Exposed Vent Lengths Insulation Table -- Ft. / M
Maximum Length of Uninsulated and Insulated Vent Pipe-Ft (M)
Modulating
Furnace High
Heat Input
Winter Design
Temp ° F (° C)
Pipe
Length in
Ft. & M
No Insulation
3/8-in. (9.5 mm)
1/2-in. (12.7 mm)
Pipe Diameter-inches (mm)
Pipe Diameter-inches (mm)
Pipe Diameter-inches (mm)
1.5
2.0
2.5
3.0
4.0
1.5
2.0
2.5
3.0
4.0
1.5
2.0
2.5
3.0
4.0
(38)
(51)
(64)
(76) (102) (38)
(51)
(64)
(76)
(102) (38)
(51)
(64)
(76)
(102)
60000
20 (-10)
Ft.
34.0
29.0
28.0
23.0
N/A
55.0
88.0
79.0
69.0
N/A
55.0 104.0 93.0
81.0
N/A
M
10.4
8.8
8.5
7.0
N/A
16.8
26.8
24.1
21.0
N/A
16.8
31.7
28.3
24.7
N/A
0 (-20)
Ft.
14.0
9.0
7.0
0.0
N/A
55.0
49.0
43.0
34.0
N/A
55.0
60.0
52.0
42.0
N/A
M
4.3
2.7
2.1
0.0
N/A
16.8
14.9
13.1
10.4
N/A
16.8
18.3
15.8
12.8
N/A
-20 (-30)
Ft.
5.0
0.0
0.0
0.0
N/A
41.0
32.0
26.0
18.0
N/A
50.0
40.0
33.0
24.0
N/A
M
1.5
0.0
0.0
0.0
N/A
12.5
9.8
7.9
5.5
N/A
15.2
12.2
10.1
7.3
N/A
-40 (-40)
Ft.
0.0
0.0
0.0
0.0
N/A
30.0
21.0
16.0
8.0
N/A
37.0
28.0
22.0
13.0
N/A
M
0.0
0.0
0.0
0.0
N/A
9.1
6.4
4.9
2.4
N/A
11.3
8.5
6.7
4.0
N/A
60600
20 (-10)
Ft.
34.0
29.0
28.0
23.0
N/A
55.0
88.0
79.0
69.0
N/A
55.0 104.0 93.0
81.0
N/A
M
10.4
8.8
8.5
7.0
N/A
16.8
26.8
24.1
21.0
N/A
16.8
31.7
28.3
24.7
N/A
0 (-20)
Ft.
14.0
9.0
7.0
0.0
N/A
55.0
49.0
43.0
34.0
N/A
55.0
60.0
52.0
42.0
N/A
M
4.3
2.7
2.1
0.0
N/A
16.8
14.9
13.1
10.4
N/A
16.8
18.3
15.8
12.8
N/A
-20 (-30)
Ft.
5.0
0.0
0.0
0.0
N/A
41.0
32.0
26.0
18.0
N/A
50.0
40.0
33.0
24.0
N/A
M
1.5
0.0
0.0
0.0
N/A
12.5
9.8
7.9
5.5
N/A
15.2
12.2
10.1
7.3
N/A
-40 (-40)
Ft.
0.0
0.0
0.0
0.0
N/A
30.0
21.0
16.0
8.0
N/A
37.0
28.0
22.0
13.0
N/A
M
0.0
0.0
0.0
0.0
N/A
9.1
6.4
4.9
2.4
N/A
11.3
8.5
6.7
4.0
N/A
80000
20 (-10)
Ft.
35.0
39.0
39.0
33.0
25.0
35.0 118.0 107.0 92.0
76.0
35.0 130.0 125.0 109.0 90.0
M
10.7
11.9
11.9
10.1
7.6
10.7
36.0
32.6
28.0
23.2
10.7
39.6
38.1
33.2
27.4
0 (-20)
Ft.
22.0
16.0
14.0
7.0
0.0
35.0
69.0
60.0
49.0
35.0
35.0
83.0
72.0
60.0
45.0
M
6.7
4.9
4.3
2.1
0.0
10.7
21.0
18.3
14.9
10.7
10.7
25.3
21.9
18.3
13.7
-20 (-30)
Ft.
11.0
5.0
2.0
0.0
0.0
35.0
46.0
39.0
29.0
16.0
35.0
57.0
48.0
37.0
23.0
M
3.4
1.5
0.6
0.0
0.0
10.7
14.0
11.9
8.8
4.9
10.7
17.4
14.6
11.3
7.0
-40 (-40)
Ft.
4.0
0.0
0.0
0.0
0.0
35.0
33.0
26.0
17.0
4.0
35.0
41.0
34.0
24.0
11.0
M
1.2
0.0
0.0
0.0
0.0
10.7
10.1
7.9
5.2
1.2
10.7
12.5
10.4
7.3
3.4
100000
20 (-10)
Ft.
N/A
47.0
47.0
41.0
32.0
N/A
50.0 110.0 112.0 93.0
N/A
50.0 110.0 132.0 110.0
M
N/A
14.3
14.3
12.5
9.8
N/A
15.2
33.5
34.1
28.3
N/A
15.2
33.5
40.2
33.5
0 (-20)
Ft.
N/A
21.0
19.0
12.0
1.0
N/A
50.0
74.0
61.0
45.0
N/A
50.0
89.0
74.0
57.0
M
N/A
6.4
5.8
3.7
0.3
N/A
15.2
22.6
18.6
13.7
N/A
15.2
27.1
22.6
17.4
-20 (-30)
Ft.
N/A
8.0
6.0
0.0
0.0
N/A
50.0
49.0
38.0
23.0
N/A
50.0
60.0
48.0
32.0
M
N/A
2.4
1.8
0.0
0.0
N/A
15.2
14.9
11.6
7.0
N/A
15.2
18.3
14.6
9.8
-40 (-40)
Ft.
N/A
1.0
0.0
0.0
0.0
N/A
42.0
34.0
24.0
10.0
N/A
50.0
43.0
32.0
18.0
M
N/A
0.3
0.0
0.0
0.0
N/A
12.8
10.4
7.3
3.0
N/A
15.2
13.1
9.8
5.5
120000
20 (-10)
Ft.
N/A
N/A
15.0
49.0
40.0
N/A
N/A
15.0 100.0 111.0 N/A
N/A
15.0 100.0 131.0
M
N/A
N/A
4.6
14.9
12.2
N/A
N/A
4.6
30.5
33.8
N/A
N/A
4.6
30.5
39.9
0 (-20)
Ft.
N/A
N/A
15.0
17.0
6.0
N/A
N/A
15.0
75.0
57.0
N/A
N/A
15.0
90.0
70.0
M
N/A
N/A
4.6
5.2
1.8
N/A
N/A
4.6
22.9
17.4
N/A
N/A
4.6
27.4
21.3
-20 (-30)
Ft.
N/A
N/A
10.0
2.0
0.0
N/A
N/A
15.0
48.0
32.0
N/A
N/A
15.0
59.0
42.0
M
N/A
N/A
3.0
0.6
0.0
N/A
N/A
4.6
14.6
9.8
N/A
N/A
4.6
18.0
12.8
-40 (-40)
Ft.
N/A
N/A
1.0
0.0
0.0
N/A
N/A
15.0
32.0
17.0
N/A
N/A
15.0
41.0
25.0
M
N/A
N/A
0.3
0.0
0.0
N/A
N/A
4.6
9.8
5.2
N/A
N/A
4.6
12.5
7.6
* Pipe length (ft) specified for maximum pipe lengths located in unconditioned spaces. Pipes located in unconditioned space cannot exceed total allowable pipe
length calculated from Table 15 or 17.
† Insulation thickness based on R value of 3.5 per in.
59MN
7A
