7
MAXIMUM ALLOWABLE EXPOSED VENT LENGTHS INSULATION TABLE -- FT. / M
Two Stage
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)
40000*
20 (-10)
Ft.
40.0
35.0
35.0
N/A
N/A
50.0 104.0 94.0
N/A
N/A
50.0 122.0 110.0
N/A
N/A
M
12.2
10.7
10.7
N/A
N/A
15.2
31.7
28.7
N/A
N/A
15.2
37.2
33.5
N/A
N/A
0 (-20)
Ft.
19.0
14.0
12.0
N/A
N/A
50.0
61.0
54.0
N/A
N/A
50.0
74.0
65.0
N/A
N/A
M
5.8
4.3
3.7
N/A
N/A
15.2
18.6
16.5
N/A
N/A
15.2
22.6
19.8
N/A
N/A
-20 (-30)
Ft.
9.0
3.0
1.0
N/A
N/A
50.0
41.0
35.0
N/A
N/A
50.0
51.0
43.0
N/A
N/A
M
2.7
0.9
0.3
N/A
N/A
15.2
12.5
10.7
N/A
N/A
15.2
15.5
13.1
N/A
N/A
-40 (-40)
Ft.
3.0
0.0
0.0
N/A
N/A
39.0
29.0
23.0
N/A
N/A
48.0
37.0
30.0
N/A
N/A
M
0.9
0.0
0.0
N/A
N/A
11.9
8.8
7.0
N/A
N/A
14.6
11.3
9.1
N/A
N/A
60000
20 (-10)
Ft.
30.0
51.0
51.0
45.0
N/A
30.0 135.0 138.0 120.0
N/A
30.0 135.0 162.0 141.0
N/A
M
9.1
15.5
15.5
13.7
N/A
9.1
41.1
42.1
36.6
N/A
9.1
41.1
49.4
43.0
N/A
0 (-20)
Ft.
30.0
24.0
23.0
16.0
N/A
30.0
93.0
82.0
69.0
N/A
30.0 111.0 98.0
83.0
N/A
M
9.1
7.3
7.0
4.9
N/A
9.1
28.3
25.0
21.0
N/A
9.1
33.8
29.9
25.3
N/A
-20 (-30)
Ft.
18.0
11.0
9.0
1.0
N/A
30.0
65.0
56.0
44.0
N/A
30.0
79.0
68.0
55.0
N/A
M
5.5
3.4
2.7
0.3
N/A
9.1
19.8
17.1
13.4
N/A
9.1
24.1
20.7
16.8
N/A
-40 (-40)
Ft.
10.0
3.0
0.0
0.0
N/A
30.0
48.0
40.0
29.0
N/A
30.0
59.0
50.0
38.0
N/A
M
3.0
0.9
0.0
0.0
N/A
9.1
14.6
12.2
8.8
N/A
9.1
18.0
15.2
11.6
N/A
80000
20 (-10)
Ft.
20.0
64.0
64.0
56.0
47.0
20.0
70.0 173.0 150.0 125.0 20.0
70.0 175.0 177.0 147.0
M
6.1
19.5
19.5
17.1
14.3
6.1
21.3
52.7
45.7
38.1
6.1
21.3
53.3
53.9
44.8
0 (-20)
Ft.
20.0
32.0
30.0
22.0
11.0
20.0
70.0 104.0 87.0
67.0
20.0
70.0 124.0 104.0 82.0
M
6.1
9.8
9.1
6.7
3.4
6.1
21.3
31.7
26.5
20.4
6.1
21.3
37.8
31.7
25.0
-20 (-30)
Ft.
20.0
17.0
14.0
6.0
0.0
20.0
70.0
71.0
57.0
40.0
20.0
70.0
86.0
71.0
52.0
M
6.1
5.2
4.3
1.8
0.0
6.1
21.3
21.6
17.4
12.2
6.1
21.3
26.2
21.6
15.8
-40 (-40)
Ft.
15.0
7.0
5.0
0.0
0.0
20.0
61.0
52.0
40.0
24.0
20.0
70.0
64.0
50.0
33.0
M
4.6
2.1
1.5
0.0
0.0
6.1
18.6
15.8
12.2
7.3
6.1
21.3
19.5
15.2
10.1
100000
20 (-10)
Ft.
N/A
25.0
79.0
70.0
59.0
N/A
25.0 110.0 186.0 155.0 N/A
25.0 110.0 219.0 182.0
M
N/A
7.6
24.1
21.3
18.0
N/A
7.6
33.5
56.7
47.2
N/A
7.6
33.5
66.8
55.5
0 (-20)
Ft.
N/A
25.0
40.0
31.0
19.0
N/A
25.0 110.0 109.0 86.0
N/A
25.0 110.0 131.0 104.0
M
N/A
7.6
12.2
9.4
5.8
N/A
7.6
33.5
33.2
26.2
N/A
7.6
33.5
39.9
31.7
-20 (-30)
Ft.
N/A
23.0
21.0
13.0
0.0
N/A
25.0
91.0
74.0
54.0
N/A
25.0 110.0 90.0
68.0
M
N/A
7.0
6.4
4.0
0.0
N/A
7.6
27.7
22.6
16.5
N/A
7.6
33.5
27.4
20.7
-40 (-40)
Ft.
N/A
13.0
10.0
1.0
0.0
N/A
25.0
68.0
53.0
35.0
N/A
25.0
83.0
66.0
46.0
M
N/A
4.0
3.0
0.3
0.0
N/A
7.6
20.7
16.2
10.7
N/A
7.6
25.3
20.1
14.0
120000
20 (-10)
Ft.
N/A
N/A
15.0
85.0
73.0
N/A
N/A
15.0 100.0 190.0 N/A
N/A
15.0 100.0 224.0
M
N/A
N/A
4.6
25.9
22.3
N/A
N/A
4.6
30.5
57.9
N/A
N/A
4.6
30.5
68.3
0 (-20)
Ft.
N/A
N/A
15.0
41.0
29.0
N/A
N/A
15.0 100.0 109.0 N/A
N/A
15.0 100.0 131.0
M
N/A
N/A
4.6
12.5
8.8
N/A
N/A
4.6
30.5
33.2
N/A
N/A
4.6
30.5
39.9
-20 (-30)
Ft.
N/A
N/A
15.0
20.0
7.0
N/A
N/A
15.0
94.0
71.0
N/A
N/A
15.0 114.0 88.0
M
N/A
N/A
4.6
6.1
2.1
N/A
N/A
4.6
28.7
21.6
N/A
N/A
4.6
34.7
26.8
-40 (-40)
Ft.
N/A
N/A
15.0
7.0
0.0
N/A
N/A
15.0
69.0
48.0
N/A
N/A
15.0
85.0
62.0
M
N/A
N/A
4.6
2.1
0.0
N/A
N/A
4.6
21.0
14.6
N/A
N/A
4.6
25.9
18.9
* Not all families have these models.
* 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 1 or 3.
† Insulation thickness based on R value of 3.5 per in.
59TP5A