51
Table 15 – Maximum Allowable Exposed Vent Lengths in Unconditioned Space Table -- Ft.
Winter
Design
Temp
°F
Unit Size
40,000* BTUH
60,000 BTUH
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Pipe Dia.
in.
1 ½
2
2 ½
1 ½
2
2 ½
1 ½
2
2 ½
1 ½
2
2 ½
3
1 ½
2
2 ½
3
1 ½
2
2 ½
3
20
20
20
20
20
50
45
20
60
50
20
30
30
25
20
75
65
60
20
85
75
65
0
10
5
5
20
25
20
20
30
25
15
15
10
10
20
40
30
25
20
45
40
30
-20
5
20
15
10
20
20
15
10
5
20
25
20
15
20
30
25
20
-40
15
10
5
15
15
10
5
20
15
15
10
20
20
15
10
Winter
Design
Temp
°F
Unit Size
80,000 BTUH
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Pipe Dia.
in.
1 ½
2
2 ½
3
4
1 ½
2
2 ½
3
4
1 ½
2
2 ½
3
4
20
15
40
40
35
30
15
50
90
75
65
15
50
70
70
70
0
15
20
15
10
5
15
50
45
35
30
15
50
50
40
35
-20
15
10
5
15
35
30
20
15
15
40
30
25
15
-40
10
5
15
25
20
15
5
15
30
25
20
10
Winter
Design
Temp
°F
Unit Size
100,000 BTUH
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Pipe Dia.
in.
2
2 ½
3
4
2
2 ½
3
4
2
2 ½
3
4
20
20
50
40
35
20
80
95
80
20
80
105
90
0
20
20
15
10
20
55
45
35
20
65
55
45
-20
15
10
5
20
35
30
20
20
45
35
25
-40
10
5
20
25
20
10
20
30
25
15
Winter
Design
Temp
°F
Unit Size
120,000 BTUH
140,000 BTUH
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Pipe Dia.
in.
2 ½
3
4
2 ½
3
4
2 ½
3
4
2 ½
3
4
2 ½
3
4
2 ½
3
4
20
10
50
40
10
75
95
10
75
105
5
55
50
5
65
105
5
65
125
0
10
20
15
10
55
45
10
65
50
5
25
15
5
65
50
5
65
60
-20
10
10
10
35
25
10
45
30
5
10
5
5
45
30
5
50
40
-40
10
5
10
25
15
10
30
20
5
5
5
30
20
5
35
25
Maximum Allowable Exposed Vent Length in Unconditioned Space (Metric)
Winter
Design
Temp
°C
Unit Size
40,000* BTUH
60,000 BTUH
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Pipe Dia.
mm
38
51
64
38
51
64
38
51
64
38
51
64
76
38
51
64
76
38
51
64
76
-7
6.1
6.1
6.1
6.1
15.2 13.7
6.1
18.3 15.2
6.1
9.1
9.1
7.6
6.1
22.9 19.8 18.3
6.1
25.9 22.9 19.8
-18
3.0
1.5
1.5
6.1
7.6
6.1
6.1
9.1
7.6
4.6
4.6
3.0
3.0
6.1
12.2
9.1
7.6
6.1
13.7 12.2
9.1
-29
1.5
6.1
4.6
3.0
6.1
6.1
4.6
3.0
1.5
6.1
7.6
6.1
4.6
6.1
9.1
7.6
6.1
-40
4.6
3.0
1.5
4.6
4.6
3.0
1.5
6.1
4.6
4.6
3.0
6.1
6.1
4.6
3.0
Winter
Design
Temp
°C
Unit Size
80,000 BTUH
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Pipe Dia.
mm
38
51
64
76
102
38
51
64
76
102
38
51
64
76
102
-7
4.6
12.2
12.2
10.7
9.1
4.6
15.2
27.4
22.9
19.8
4.6
15.2
21.3
21.3
21.3
-18
4.6
6.1
4.6
3.0
1.5
4.6
15.2
13.7
10.7
9.1
4.6
15.2
15.2
12.2
10.7
-29
4.6
3.0
1.5
4.6
10.7
9.1
6.1
4.6
4.6
12.2
9.1
7.6
4.6
-40
3.0
1.5
4.6
7.6
6.1
4.6
1.5
4.6
9.1
7.6
6.1
3.0
Winter
Design
Temp
°C
Unit Size
100,000 BTUH
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Pipe Dia.
mm
51
64
76
102
51
64
76
102
51
64
76
102
-7
6.1
15.2
12.2
10.7
6.1
24.4
28.9
24.4
6.1
24.4
32.0
27.4
-18
6.1
6.1
4.6
3.0
6.1
16.8
13.7
10.7
6.1
19.8
16.7
13.7
-29
4.6
3.0
1.5
6.1
10.7
9.1
6.1
6.1
13.7
10.7
7.6
-40
3.0
1.5
6.1
7.6
6.1
3.0
6.1
9.1
7.6
4.6
Winter
Design
Temp
°C
Unit Size
120,000 BTUH
140,000 BTUH
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Pipe Dia.
mm
64
76
102
64
76
102
64
76
102
64
76
102
64
76
102
64
76
102
-7
3.0
15.2
12.2
3.0
22.9
28.9
3.0
22.9
32.0
1.5
16.7
15.2
1.5
19.8
32.0
1.5
19.8
38.1
-18
3.0
6.1
4.6
3.0
16.8
13.7
3.0
19.8
15.2
1.5
7.6
4.6
1.5
19.8
15.2
1.5
19.8
18.3
-29
3.0
3.0
3.0
10.7
7.6
3.0
13.7
9.1
1.5
3.0
1.5
1.5
13.7
9.1
1.5
15.2
12.2
-40
3.0
1.5
3.0
7.6
4.6
3.0
9.1
6.1
1.5
1.5
1.5
9.1
6.1
1.5
35
7.6
