507582-04
Page 19 of 54
Issue 2220
Maximum Allowable Exhaust Vent Lengths Using Ventilated Attic or Crawl Space for Intake Air in Feet
Standard Termination at Elevation 0 - 10,000 ft
Number
of 90°
Elbows
Used
1-1/2” Pipe
2” Pipe
2-1/2” Pipe
3” Pipe
Model
Model
Model
Model
45
70
90
110
45
70
90
110
45
70
90
110
45
70
90
110
1
15
10
n/a
n/a
56
41
24
n/a
85
85
63
28
103
102
83
83
2
10
n/a
51
36
19
80
80
58
23
98
97
78
78
3
n/a
46
31
14
75
75
53
18
93
92
73
73
4
41
26
9
70
70
48
13
88
87
68
68
5
36
21
4
65
65
43
8
83
82
63
63
6
31
16
n/a
60
60
38
3
78
77
58
58
7
26
11
55
55
33
n/a
73
72
53
53
8
21
6
50
50
28
68
67
48
48
9
16
1
45
45
23
63
62
43
43
10
11
n/a
40
40
18
58
57
38
38
NOTE
:
Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length
calculation.
Table 7C.
Figure 23. Typical Exhaust Pipe Connections
Pipe size determined in table 7.
2”
TOP VIEW
EXHAUST
INTAKE
2”
2”
2”
2”
or
TRANSITION
3”
*2”
*2”
1-1/2”
or
TRANSITION
NOTE
: 1-1/2” Vent Pipe
Diameter Allowed Only
on 045/070 Units
DO NOT transition
from larger to smaller
pipe in horizontal runs
of
exhaust pipe
.
DO NOT transition
from smaller to larger
pipe in horizontal runs
of
exhaust pipe
.
* When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible.
NOTE
: Exhaust pipe and intake pipe must be the same diameter.
