Page 24
TABLE 13
Maximum Allowable Exhaust Vent Lengths With Furnace Installed in a Closet or Basement 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” 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 10 10
N/A N/A
71 56 34
N/A
115 100 78 33 118 117 98 88
2
N/A N/A
66 51 29 110 95 73 28 113 112 93 83
3 61 46 24 105 90 68 23 108 107 88 78
4 56 41 19 100 85 63 18 103 102 83 73
5 51 36 14 95 80 58 13 98 97 78 68
6 46 41 9 90 75 53 8 93 92 73 63
7 41 26 4 85 70 48
N/A
88 87 68 58
8 36 21 n/a 80 65 43 83 82 63 53
9 31 16 n/a 75 60 38 78 77 58 48
10 26 11 n/a 70 55 33 73 72 53 43