15
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.)*
12 3 456
0to2000
40,000
2 Pipe or 2-In.
Concentric
1-1/2 1-1/2 50 45 40 35 3025
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 3025
2 2 70 70 70 70 70 70
80,000
2 Pipe or 2-In.
Concentric
1-1/2 1-1/2 3025201510 5
2 2 70 70 70 70 70 70
100,000
2 Pipe or 2-In.
Concentric
22454035 302520
2-1/2 2-1/2 707070707070
120,000
2 Pipe or 3-In.
Concentric
2-1/2 2-1/2 10 NA NA NA NA NA
3335 30 15 NANANA
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.)*
12 3 456
2001 to 3000
40,000
2 Pipe or 2-In.
Concentric
1-1/2 1-1/2 45 40 35 302520
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 302520
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
224035 30252015
2-1/2 2-1/2 707070707070
120,000
2Pipeor3-In.
Concentric
333126 12NANANA
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.)*
12 3 456
3001 to 4000
40,000
2 Pipe or 2-In.
Concentric
1-1/2 1-1/2 42 37 32272217
2 70 7070707070
60,000
2 Pipe or 2-In.
Concentric
1-1/2 1-1/2 42 37 32272217
2 2 70 70 70 70 70 70
80,000
2 Pipe or 2-In.
Concentric
1-1/2 1-1/2 25201510 5 NA
2 2 70 70 70 70 70 70
100,000
2 Pipe or 2-In.
Concentric
2238 33 28 23 18 13
2-1/2 2-1/2 707070707070
120,000
2Pipeor3-In.
Concentric
3329 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.)*
12 3 456
4001 to 5000‡
40,000
2 Pipe or 2-In.
Concentric
1-1/2 1-1/2 40 35 30252015
2 2 70 70 70 70 70 70
60,000
2 Pipe or 2-In.
Concentric
1-1/2 1-1/2 40 35 30252015
2 2 70 70 70 70 70 70
80,000
2 Pipe or 2-In.
Concentric
1-1/2 1-1/2 23 18 138NA NA
2 2 70 70 70 70 70 68
100,000
2 Pipe or 2-In.
Concentric
2236 3126211611
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 page 17.
Combustion-air and vent piping for Direct Vent/2-Pipe
(All Sizes) and Non-Direct Vent/1-Pipe (Sizes 040
through 120 Only) Applications