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Page 51
TABLE 23
Maximum Allowable Exhaust Vent Length Using Ventilated Attic or Crawl Space For Intake Air in Feet
NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation.
Standard Termination at Elevation 0 - 10,000 ft
Number
Of 90°
Elbows
Used
1-1/2
2” Pipe
2-1/2” Pipe
3” Pipe
Model
Model
Model
Model
045 070 090 110 045
070
090
110 045
070
090
110
045
070
090 110
1
15
10
n/a n/a
61
46
24
n/a
90
90
68
33
108
107
88
88
2
10
n/a
56
41
19
85
85
63
28
103
102
83
83
3
n/a
51
36
14
80
80
58
23
98
97
78
78
4
46
31
9
75
75
53
18
93
92
73
73
5
41
26
4
70
70
48
13
88
87
68
68
6
36
21
n/a
65
65
43
8
81
82
63
63
7
31
16
60
60
38
3
78
77
58
58
8
26
11
55
55
33
n/a
73
72
53
53
9
21
6
50
50
28
68
67
48
48
10
16
1
45
45
23
63
62
43
43