507281-06
Page 21 of 58
Issue 1724
Table 5C.
Maximum Allowable Exhaust Vent Lengths with Furnace Installed in a Closet or Basement Using Ventilated Attic or Crawl
Space for Intake Air in Feet
Standard Termination at Elevation 0 - 4,500 ft
Number of
90° Elbows
Used
2” Pipe
2-1/2” Pipe
3” Pipe
Modal
Model
Model
45
70
90
110
135
45
70
90
110
135
45
70
90
110
135
1
61
51
29
9
n/a
95
95
73
38
n/a
113
112
93
93
89
2
56
46
24
4
90
90
68
33
108
107
88
88
84
3
51
41
19
n/a
85
85
63
28
103
102
83
83
79
4
46
36
14
80
80
58
23
98
97
78
78
74
5
41
31
9
75
75
53
18
93
92
73
73
69
6
36
26
4
70
70
48
13
88
87
68
68
64
7
31
21
n/a
65
65
43
8
83
82
63
63
59
8
26
16
60
60
38
3
78
77
58
58
54
9
21
11
55
55
33
n/a
73
72
53
53
49
10
16
6
50
50
28
68
67
48
48
44
Standard Termination at Elevation 4,501 - 10,000 ft
Number of
90° Elbows
Used
2” Pipe
2-1/2” Pipe
3” Pipe
Model
Model
Model
45
70
90
110
135
45
70
90
110
135
45
70
90
110
135
1
61
51
37
n/a
n/a
95
95
73
38
n/a
113
112
93
93
89
2
56
46
32
90
90
68
33
108
107
88
88
84
3
51
41
27
85
85
63
28
103
102
83
83
79
4
46
36
22
80
80
58
23
98
97
78
78
74
5
41
31
17
75
75
53
18
93
92
73
73
69
6
36
26
n/a
70
70
48
13
88
87
68
68
64
7
31
21
65
65
43
8
83
82
63
63
59
8
26
16
60
60
38
3
78
77
58
58
54
9
21
11
55
55
33
n/a
73
72
53
53
49
10
16
6
50
50
28
68
67
48
48
44
*Size intake and exhaust pipe length separately. Values in table are for intake or exhaust, not combined total. Both intake and exhaust
must be same pipe size.
Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length
calculation.