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Table 7 -- Maximum Allowable Pipe Length
- Ft (M) (Continued)
UNIT
SIZE
ALTITUDE
(BTUH)
80,000
80,000
6001 to 7000
(1829 to 2134)$
100,000
120,000
UNIT
SIZE
ALTITUDE
(BTUH)
80,000
80,000
7001 to 8000
(2134 to 2438):[:
100,000
120,000
UNIT
SIZE
ALTITUDE
(BTUH)
60,000
80,000
800! to 9000
(2438 to 2743)$
100,000
120,000
UNIT
SiZE
ALTITUDE
(BTUH)
60,000
80,000
9001 to 10000
(2743 to 3048)$
100,000
120,000
Disk usage-Unless
otherwise
stated
Wide radius elbow.
Direct Vent (2-Pipe
Only)
Termination
Type
2 Pipe or 2-In. (51)
Concentric
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 3-In.
(78)
Concentric
Termination
Type
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 3-In.
(78)
Concentric
Termination
Type
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 3-In.
(78)
Concentric
Termination
Type
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 2-In.
(51)
Concentric
2 Pipe or 3-In.
(78)
Concentric
use perforated
disk as!
Pipe
Dia
In. (ram)*
1-1/2
(38)
2 (51)
1-1/2
(38)
2 (51)
2 (51)
2 - 1/2 (64)
3 (76) one disk1-
Pipe
Dia
In. (ram)*
1-1/2
(38)
2 (51)
1-1/2
(38)
2 (51)
2 (51)
2 - 1/2 (64)
3 (76) one disk1-
Pipe
Dia
In. (ram)*
1-1/2
(38)
2 (51)
1-1/2
(38)
2 (51)
2 (51)
2 - 1/2 (64)
3 (76) one disk1-
Pipe
Dia
In. (ram)*
1-1/2
(38)
2 (51)
1-1/2
(38)
2 (51)
2 (51)
2 - 1/2 (64)
3 (76) one diskl-
embly (factory-sup
NUMBER OF 90 ° ELBOWS
1
2
3
4
5
6
35 (10.7)
30 (9.1)
25 (7.8)
20 (6.1)
15 (4.8)
10 (3.0)
70 (21.3)
70 (21.3)
68 (20.7)
87 (20.4)
86 (20.1)
84 (19.5)
20 (6.1)
15 (4.8)
10 (3.0)
5 (1.5)
NA
NA
62
70 (21.3)
70 (21.3)
88 (20.7)
87 (20.4)
(18.9)
57 (17.4)
31 (9.4)
26 (7.9)
21 (8.4)
18 (4.9)
11 (3.4)
6 (1.8)
70 (21.3)
70 (21.3)
88 (20.7)
87 (20.4)
68 (20.1)
84 (19.5)
49 (14.9)
48 (14.6)
47 (14.3)
45 (13.7)
44 (13.4)
43 (13.1)
NUMBER
OF 90 ° ELBOWS
1
2
3
4
5
6
32 (9.8)
27 (8.2)
22 (8.7)
17 (5.2)
12 (3.7)
7 (2.1)
68 (20.1)
85 (19.8)
83 (19.2)
82 (18.9)
60 (18.3)
59 (18.0)
18 (5.5)
13 (4.0)
8 (2.4)
NA
NA
NA
68 (20.1)
85 (19.8)
83 (19.2)
82 (18.9)
57 (17.4)
52 (15.8)
29 (8.8)
24 (7.3)
19 (5.8)
14 (4.3)
9 (2.7)
NA
86 (20.1)
85 (19.8)
83 (19.2)
82 (18.9)
60 (18.3)
59 (18.0)
48 (14.0)
44 (13.4)
43 (13.1)
41 (12.5)
40 (12.2)
38 (11.6)
NUMBER
OF 90 ° ELBOWS
1
2
3
4
5
6
30 (9.1)
25 (7.6)
20 (8.1)
15 (4.6)
10 (3.0)
5 (1.5)
82 (18.9)
80 (17.8)
58 (17.7)
56 (17.1)
55 (18.8)
53 (18.2)
17 (5.2)
12 (3.1)
7 (2.1)
NA
NA
NA
82 (18.9)
80 (18.3)
58 (17.7)
56 (17.1)
51 (15.5)
48 (14.0)
27 (8.2)
22 (6.7)
17 (5.2)
12 (3.7)
7 (2.1)
NA
82 (18.9)
80 (18.3)
58 (17.7)
56 (17.1)
55 (18.8)
53 (18.2)
43 (13.1)
41 (12.5)
39/11.9)
37 (11.3)
35 (10.7)
34 (10.4)
NUMBER
OF 90 ° ELBOWS
1
2
3
4
5
6
27 (8.2)
22 (8.7)
17 (5.2)
12 (3.7)
7 (2.1)
NA
57 (17.4)
55 (18.8)
53 (18.2)
51 (15.5)
49 (14.9)
47 (14.3)
15 (4.6)
10 (3.0)
5 (1.5)
NA
NA
NA
57 (17.4)
55 (18.8)
53 (18.2)
51 (15.5)
48 (14.0)
41 (12.5)
24 (7.3)
19 (5.8)
14 (4.3)
9 (2.7)
NA
NA
57 (17.4
55 (18.8)
53 (18.2)
51 (15.5)
49 (14.9)
47 (14.3)
39 (11.9)
37 (11.3)
35 (10.7)
33 (10.1)
31 (9.5)
29 (8.8)
parts bag).
Vent sizing for Canadian
installations
over 4500 ft. (1370M) above sea level are subject to acceptance
by the local authorities
having jurisdiction.
NA-Not
Allowed;
pressure switch will not make.
NOTES:
1. Do not use pipe size greater than those specified
in table or incomplete
combustion,
flame disturbance,
or flame sense lockout may occur.
2. Size both the combustion
-air and vent pipe independently,
determine
the smallest diameter allowed by the table for each pipe, then use the larger diameter for both pipes.
3. Assume two 45 ° elbows equal one 90 ° elbow. Long radius elbows are desirable and may be required in some cases.
4. Elbows and pipe sections within the furnace casing and at the vent termination
should not be included
in vent length or elbow count.
5. The minimum
pipe length is 5 ft. (1.5M) for all applications.
42
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