Table 11—Maximum Allowable Pipe Length (Ft)
ALTITUDE
UNIT SIZE
(BTUH)
DIRECT VENT (2-PIPE) ONLY
NON-DIRECT VENT
(1-PIPE) ONLY
NUMBER OF 90° ELBOWS
Termination
Type
Pipe Dia
(IN.)*
Pipe Dia
(IN.)*
1
2
3
4
5
6
0 to 2000
40,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
50
45
40
35
30
25
2
2
70
70
70
70
70
70
60,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
50
45
40
35
30
25
2
2
70
70
70
70
70
70
80,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
30
25
20
15
10
5
2
2
70
70
70
70
70
70
100,000
2 Pipe or 2-In.
Concentric
2
2
45
40
35
30
25
20
2-1/2
2-1/2
70
70
70
70
70
70
120,000
2 Pipe or 3-In.
Concentric
2-1/2
2-1/2
10
NA
NA
NA
NA
NA
3
3
35
30
15
NA
NA
NA
3†
3
70
70
70
70
70
70
ALTITUDE
UNIT SIZE
(BTUH)
DIRECT VENT (2-PIPE) ONLY
NON-DIRECT VENT
(1-PIPE) ONLY
NUMBER OF 90° ELBOWS
Termination
Type
Pipe Dia
(IN.)*
Pipe Dia
(IN.)*
1
2
3
4
5
6
2001 to 3000
40,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
45
40
35
30
25
20
2
2
70
70
70
70
70
70
60,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
45
40
35
30
25
20
2
2
70
70
70
70
70
70
80,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
26
21
16
11
6
NA
2
2
70
70
70
70
70
70
100,000
2 Pipe or 2-In.
Concentric
2
2
40
35
30
25
20
15
2-1/2
2-1/2
70
70
70
70
70
70
120,000
2 Pipe or 3-In.
Concentric
3
3
31
26
12
NA
NA
NA
3†
3
63
62
62
61
61
61
ALTITUDE
UNIT SIZE
(BTUH)
DIRECT VENT (2-PIPE) ONLY
NON-DIRECT VENT
(1-PIPE) ONLY
NUMBER OF 90° ELBOWS
Termination
Type
Pipe Dia
(IN.)*
Pipe Dia
(IN.)*
1
2
3
4
5
6
3001 to 4000
40,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
42
37
32
27
22
17
2
70
70
70
70
70
70
60,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
42
37
32
27
22
17
2
2
70
70
70
70
70
70
80,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
25
20
15
10
5
NA
2
2
70
70
70
70
70
70
100,000
2 Pipe or 2-In.
Concentric
2
2
38
33
28
23
18
13
2-1/2
2-1/2
70
70
70
70
70
70
120,000
2 Pipe or 3-In.
Concentric
3
3
29
24
10
NA
NA
NA
3†
3
59
59
58
57
57
56
ALTITUDE
UNIT SIZE
(BTUH)
DIRECT VENT (2-PIPE) ONLY
NON-DIRECT VENT
(1-PIPE) ONLY
NUMBER OF 90° ELBOWS
Termination
Type
Pipe Dia
(IN.)*
Pipe Dia
(IN.)*
1
2
3
4
5
6
4001 to 5000‡
40,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
40
35
30
25
20
15
2
2
70
70
70
70
70
70
60,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
40
35
30
25
20
15
2
2
70
70
70
70
70
70
80,000
2 Pipe or 2-In.
Concentric
1-1/2
1-1/2
23
18
13
8
NA
NA
2
2
70
70
70
70
70
68
100,000
2 Pipe or 2-In.
Concentric
2
2
36
31
26
21
16
11
2-1/2
2-1/2
70
70
70
70
70
70
120,000
2 Pipe or 3-In.
Concentric
3†
3
56
55
54
53
52
52
See notes on next page.
35