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COMBUSTION--AIR AND VENT PIPING FOR DIRECT VENT/2--PIPE (ALL SIZES) AND
NON--DIRECT VENT/1--PIPE (SIZES 040 THROUGH 120 ONLY) APPLICATIONS (CON’T.)
ALTITUDE
FT (M)
UNIT SIZE
(BTUH)
DIRECT VENT (2-PIPE) ONLY
NON-DIRECT
VENT (1-PIPE)
ONLY
NUMBER OF 90° ELBOWS
TERMINATION
TYPE
PIPE DIA
IN. (mm)*
PIPE DIA
IN. (mm)*
1 2 3 4 5 6
9001 to 10,000‡
(2743 to 3048)
40,000
2Pipeor2-in 1-1/2 (38) 1-1/2 (38)
42
(12.8)
37
(11.3)
32
(9.8)
27
(8.2)
25
(7.6)
20
(6.1)
Concentric 2 (51) 2 (51)
57
(17.4)
55
(16.8)
53
(16.2)
51
(15.5)
49
(14.9)
47
(14.3)
60,000
2Pipeor2-in
Concentric
2 (51) 2 (51)
45
(13.7)
40
(12.2)
38
(11.6)
33
(10.1)
31
(9.4)
29
(8.8)
80,000
2Pipeor2-in
Concentric
2 (51) 2 (51)
30
(9.1)
25
(7.6)
14
(4.3)
9
(2.7)
7
(2.1)
NA
2-1/2 (64) 2-1/2 (64)
57
(17.4)
55
(16.8)
53
(16.2)
51
(15.5)
49
(14.9)
47
(14.3)
100,000
2Pipeor3-in
Concentric
2-1/2 (64) 2-1/2 (64)
21
(6.4)
13
(4.0)
5
(1.5)
NA NA NA
3 (76) 3 (76)
54
(16.5)
49
(14.9)
44
(13.4)
39
(11.9)
34
(10.4)
29
(8.8)
120,000
2Pipeor3-in.
Concentric
NA 3 (76)†
39
(11.9)
37
(11.3)
35
(10.7)
33
(10.1)
31
(9.4)
29
(8.8)
4 (102)† no
disk
4 (102)† no disk
10
(3.0)
5
(1.5)
NA NA NA NA
* Disk usage-Unless otherwise specified, use perforated disk assembly (factory-supplied in loose parts bag).
# If one disk is stated, separate 2 halves of perforated disk assembly and use shouldered disk half. When using shouldered disk half, install screen sidetowardinletbox.
† W ide radius elbow.
‡ Vent sizing for Canadian installations over 4500 ft (1370 M) 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, then use the larger diameter for both pipes.
3. Assume two 45° elbows equal one 90° elbow. Wide radius elbows are desirableandmayberequiredinsomecases.
4. Elbows and pipe sections within the furnace casing and at the vent t ermination should not be included in vent length or elbow count.
5. The minimum pipe length is 5 ft (1.5 M) for all applications.
6. Use 3-in. (76 mm) diameter vent termination kit for installations requiring 4-in (102 mm) diameter pipe.
353AAV