12 - VENTING GUIDELINES
TABLE 6 - DIRECT AND NON-DIRECT VENT LENGTHS
MAXIMUM ALLOWABLE LENGTH OF EXHAUST OR INTAKE
MODEL
PIPE
SIZE
NUMBER OF 90° ELBOWS
NOTES
0
1
2
3
4
5
6
60
1½”
25
20
15
10
5
-
-
1. Count concentric vent
fi
tting as
straight pipe.
2. Use medium or long sweep
elbows where possible.
3. One 90° elbow is equivalent to
two 45° elbows.
4. For direct vent, the listed lengths
are allowed for each vent (intake
and exhaust).
5. For non-direct vent, the listed
lengths are allowed for exhaust.
The intake should have a 1½”
or 2” snorkel intake
fi
tting.
(
Figure 9
)
6. Include the 2 vestibule elbows
when calculating total vent length
for all models.
2”
75
70
65
60
55
50
45
3”
100
95
90
85
80
75
70
80
2”
50
45
40
35
30
25
20
3”
100
95
90
85
80
75
70
100
2”
50
45
40
35
30
25
20
3”
100
95
90
85
80
75
70
120
3”
100
95
90
85
80
75
70
When 1½” or 3” pipe is used, exit the cabinet with 2” pipe. Reduce or increase immediately after exiting the
cabinet making provisions to secure the vent bracket between cabinet and
fi
tting.
Use of a concentric termination reduces the allowable length by 5 feet from lengths shown in this table.
Figure 11 - Vertical Venting
Roof Termination
Exhaust
18” MIN.
Figure 10 - Periscoped Vent Detail
19
