32
Table 8 – Maximum Allowable Pipe Length -- Ft. (M)
VARIABLE SPEED VENT SIZING TABLE
ALTITUDE
FT. (M)
UNIT SIZE
(BTUH)
Termination
Type
Direct & Non---
Direct Pipe
Dia.
In. (mm)*
NUMBER OF 90
_
ELBOWS
1
2
3
4
5
6
0 to 2000
(0 to 610)
60,000
2 Pipe or 2---In.
(51) Concentric
1---1/2 (38)
50 (15)
45 (14)
40 (13)
35 (11)
30 (9)
25 (8)
2 (51)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
80,000
2 Pipe or 2---In.
(51) Concentric
1---1/2 (38)
30 (9)
25 (8)
20 (6)
15 (5)
10 (3)
5 (2)
2 (51)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
100,000
2 Pipe or 2---In.
(51) Concentric
2 (51)
45 (14)
40 (13)
35 (11)
30 (9)
25 (8)
20 (6)
2---1/2 (64)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
120,000
2 Pipe or 3---In.
(76) Concentric
2---1/2 (64)
10 (3)
NA
NA
NA
NA
NA
3 (76)
35 (11)
30 (9)
15 (5)
NA
NA
NA
3 (76)†
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
ALTITUDE
UNIT SIZE
(BTUH)
Termination
Type
Direct & Non---
Direct Pipe
Dia. In. (mm)*
NUMBER OF 90
_
ELBOWS
1
2
3
4
5
6
2001 to 3000
(610 to 914)
60,000
2 Pipe or 2---In.
(51) Concentric
1---1/2 (38)
45 (14)
40 (13)
35 (11)
30 (9)
25 (8)
20 (6)
2 (51)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
80,000
2 Pipe or 2---In.
(51) Concentric
1---1/2 (38)
26 (8)
21 (6)
16 (5)
11 (3)
6 (2)
NA
2 (51)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
100,000
2 Pipe or 2---In.
(51) Concentric
2 (51)
40 (12)
35 (11)
30 (9)
25 (8)
20 (6)
15 (5)
2---1/2 (64)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
120,000
2 Pipe or 3---In.
(76) Concentric
3 (76)
31 (9)
26 (8)
12 (4)
NA
NA
NA
3 (76)†
63 (19)
62 (19)
62 (19)
61 (19)
61 (19)
61 (19)
ALTITUDE
UNIT SIZE
(BTUH)
Termination
Type
Direct & Non---
Direct Pipe
Dia. In. (mm)*
NUMBER OF 90
_
ELBOWS
1
2
3
4
5
6
3001 to 4000
(914 to 1219)
60,000
2 Pipe or 2---In.
(51) Concentric
1---1/2 (38)
42 (13)
37 (11)
32 (10)
27 (8)
22 (7)
17 (5)
2 (51)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
80,000
2 Pipe or 2---In.
(51) Concentric
1---1/2 (38)
25 (8)
20 (6)
15 (5)
10 (3)
5 (2)
NA
2 (51)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
100,000
2 Pipe or 2---In.
(51) Concentric
2 (51)
38 (12)
33 (10)
28 (9)
23 (7)
18 (6)
13 (4)
2---1/2 (64)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
120,000
2 Pipe or 3---In.
(76) Concentric
3 (76)
29 (9)
24 (7)
10 (3)
NA
NA
NA
3 (76)†
59 (18)
59 (18)
58 (18)
57 (17)
57 (17)
56 (17)
ALTITUDE
UNIT SIZE
(BTUH)
Termination
Type
Direct & Non---
Direct Pipe
Dia. In. (mm)*
NUMBER OF 90
_
ELBOWS
1
2
3
4
5
6
4001 to 5000‡
(1219 to 1524)
60,000
2 Pipe or 2---In.
(51) Concentric
1---1/2 (38)
40 (12)
35 (11)
30 (9)
25 (8)
20 (6)
15 (10)
2 (51)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
80,000
2 Pipe or 2---In.
(51) Concentric
1---1/2 (38)
23 (7)
18 (6)
13 (4)
8 (2)
NA
NA
2 (51)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
68 (21)
100,000
2 Pipe or 2---In.
(51) Concentric
2 (51)
36 (11)
31 (9)
26 (8)
21 (6)
16 (5)
11 (3)
2---1/2 (64)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
120,000
2 Pipe or 3---In.
(76) Concentric
3 (76)†
56 (17)
55 (17)
54 (17)
53 (16)
52 (16)
52 (16)
ALTITUDE
UNIT SIZE
(BTUH)
Termination
Type
Direct & Non---
Direct Pipe
Dia. In. (mm)*
NUMBER OF 90
_
ELBOWS
1
2
3
4
5
6
5001 to 6000‡
(1524 to 1829)
60,000
2 Pipe or 2---In.
(51) Concentric
1---1/2 (38)
37 (11)
32 (10)
27 (8)
22 (7)
17 (5)
12 (4)
2 (51)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
80,000
2 Pipe or 2---In.
(51) Concentric
1---1/2 (38)
22 (7)
17 (5)
12 (4)
7 (2)
NA
NA
2 (51)
70 (21)
70 (21)
70 (21)
70 (21)
68 (21)
63 (19)
100,000
2 Pipe or 2---In.
(51) Concentric
2 (51)
33 (10)
28 (9)
23 (7)
18 (6)
13 (4)
8 (2)
2---1/2 (64)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
70 (21)
120,000
2 Pipe or 3---In.
(76) Concentric
3 (76)†
53 (16)
52 (16)
50 (15)
49 (15)
48 (15)
47 (14)
*See notes on next page.
355B
A
V
