9
MAXIMUM ALLOWABLE PIPE LENGTH (FT / M)
Direct Vent (2---Pipe Only)
NUMBER OF 90
_
ELBOWS
UNIT SIZE
(BTUH)
ALTITUDE
Termination
Type
Pipe Dia
(IN.)*
1
2
3
4
5
6
60,000
0 to 2000
2 Pipe or 2---In.
Concentric
1---1/2
50 / 15.2
45 / 13.7
40 / 12.9
35 / 10.7
30 / 9.1
25 / 7.6
2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
80,000
2 Pipe or 2---In.
Concentric
1---1/2
30 / 9.14
25 / 7.6
20 / 6.1
15 / 4.6
10 / 3.0
5 / 1.5
2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
100,000
2 Pipe or 2---In.
Concentric
2
45 / 13.7
40 / 12.9
35 / 10.7
30 / 9.1
25 / 7.6
20 / 6.1
2---1/2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
120,000
2 Pipe or 3---In.
Concentric
2---1/2 one
disk
10 / 3.0
NA
NA
NA
NA
NA
3 one disk
35 / 10.7
30 / 9.1
15 / 4.8
NA
NA
NA
3 one disk†
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
UNIT SIZE
(BTUH)
ALTITUDE
Termination
Type
Pipe Dia
(IN.)*
NUMBER OF 90
_
ELBOWS
1
2
3
4
5
6
60,000
2001 to
3000
2 Pipe or 2---In.
Concentric
1---1/2
45 / 13.7
40 / 12.9
35 / 10.7
30 / 9.14
25 / 7.6
20 / 6.1
2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
80,000
2 Pipe or 2---In.
Concentric
1---1/2
26 / 7.9
21 / 6.4
16 / 4.9
11 / 3.4
6 / 1.8
NA
2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
100,000
2 Pipe or 2---In.
Concentric
2
40 / 12.2
35 / 10.7
30 / 9.1
25 / 7.6
20 / 6.1
15 / 4.6
2---1/2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
120,000
2 Pipe or 3---In.
Concentric
3 one disk
31 / 9.4
26 / 7.9
12 / 3.7
NA
NA
NA
3 one disk†
63 / 19.2
62 / 18.9
62 / 18.9
61 / 18.6
61 / 18.6
61 / 18.6
UNIT SIZE
(BTUH)
ALTITUDE
Termination
Type
Pipe Dia
(IN.)*
NUMBER OF 90
_
ELBOWS
1
2
3
4
5
6
60,000
3001 to
4000
2 Pipe or 2---In.
Concentric
1---1/2
42 / 12.8
37 / 11.2
32 / 9.8
27 / 8.2
22 / 6.7
17 / 5.2
2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
80,000
2 Pipe or 2---In.
Concentric
1---1/2
25 / 7.6
20 / 6.1
15 / 4.6
10 / 3.0
5 / 1.5
NA
2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
100,000
2 Pipe or 2---In.
Concentric
2
38 / 11.6
33 / 10.1
28 / 8.5
23 / 7.0
18 / 5.5
13 / 4.0
2---1/2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
120,000
2 Pipe or 3---In.
Concentric
3 one disk
29 / 8.8
24 / 7.3
10 / 3.0
NA
NA
NA
3 one disk†
59 / 18.0
59 / 18.0
58 / 17.8
57 / 17.4
57 / 17.4
56 / 17.0
UNIT SIZE
(BTUH)
ALTITUDE
Termination
Type
Pipe Dia
(IN.)*
NUMBER OF 90
_
ELBOWS
1
2
3
4
5
6
60,000
4001 to
5000‡
2 Pipe or 2---In.
Concentric
1---1/2
40 / 12.2
35 / 10.7
30 / 9.1
25 / 7.6
20 / 6.1
15 / 9.6
2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
80,000
2 Pipe or 2---In.
Concentric
1---1/2
23 / 7.0
18 / 5.5
13 / 4.0
8 / 2.4
NA
NA
2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
68 / 20.7
100,000
2 Pipe or 2---In.
Concentric
2
36 / 11.0
31 / 9.4
26 / 7.9
21 / 6.4
16 / 4.8
11 / 3.4
2---1/2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
120,000
2 Pipe or 3---In.
Concentric
3 one disk†
56 / 17.1
55 / 16.8
54 / 16.5
53 / 6.2
52 / 15.8
52 / 15.8
UNIT SIZE
(BTUH)
ALTITUDE
Termination
Type
Pipe Dia
(IN.)*
NUMBER OF 90
_
ELBOWS
1
2
3
4
5
6
60,000
5001 to
6000‡
2 Pipe or 2---In.
Concentric
1---1/2
37 / 11.3
32 / 9.8
27 / 8.2
22 / 6.7
17 / 5.2
12 / 3.7
2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
80,000
2 Pipe or 2---In.
Concentric
1---1/2
22 / 6.7
17 / 5.2
12 / 3.7
7 / 2.1
NA
NA
2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
68 / 20.7
63 / 19.2
100,000
2 Pipe or 2---In.
Concentric
2
33 / 10
28 / 8.5
23 / 7.0
18 / 5.5
13 / 4.0
8 / 2.4
2---1/2
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
120,000
2 Pipe or 3---In.
Concentric
3 one disk†
53 / 16.2
52 / 15.8
50 / 15.2
49 / 14.9
48 / 14.6
47 / 14.3
*See notes on next page.
355B
A
V
