
Page 45
TABLE 21 CONT.
Maximum Allowable Intake or Exhaust Vent Length
Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Intake and Exhaust must be same size.
NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation.
Concentric Termination at Elevation 0 - 4500 ft
Number
Of 90°
Elbows
Used
1-1/2” Pipe
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
63
48
32
12
95
95
79
44
111
111
104
104
2
10
n/a
58
43
27
7
90
90
74
39
106
106
99
99
3
n/a
53
38
22
2
85
85
69
34
101
101
94
94
4
48
33
17
n/a
80
80
64
29
96
96
89
89
5
43
28
12
75
75
59
24
91
91
84
84
6
38
23
7
70
70
54
19
86
86
79
79
7
33
18
2
65
65
49
14
81
81
74
74
8
28
13
n/a
60
60
44
9
76
76
69
69
9
23
8
55
55
39
4
71
71
64
64
10
18
3
50
50
34
n/a
66
66
59
59
Concentric Termination Elevation 4501 - 10,000 ft
Number
Of 90°
Elbows
Used
1-1/2” Pipe
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
63
48
32
n/a
95
95
79
44
111
111
104
94
2
10
n/a
58
43
27
90
90
74
39
106
106
99
99
3
n/a
53
38
22
85
85
69
34
101
101
94
94
4
48
33
17
80
80
64
29
96
96
89
89
5
43
28
12
75
75
59
24
91
91
84
84
6
38
23
7
70
70
54
19
86
86
79
79
7
33
18
2
65
65
49
14
81
81
74
74
8
28
13
n/a
60
60
44
9
76
76
69
69
9
23
8
55
55
39
4
71
71
64
64
10
18
3
50
50
34
n/a
66
66
59
59