8
MAXIMUM ALLOWABLE EXPOSED VENT LENGTHS INSULATION TABLE -- FT. / M
Maximum Length of Uninsulated and Insulated Vent Pipe-Ft (M)
Modulating
Furnace High
Heat Input
Winter Design
Te m p ° F ( ° C )
Pipe
Length in
Ft. & M
No Insulation 3/8-in. (9.5 mm) 1/2-in. (12.7 mm)
Pipe Diameter-inches (mm) Pipe Diameter-inches (mm) Pipe Diameter-inches (mm)
1.5 2.0 2.5 3.0 4.0 1.5 2.0 2.5 3.0 4.0 1.5 2.0 2.5 3.0 4.0
(38) (51) (64) (76) (102) (38) (51) (64) (76) (102) (38) (51) (64) (76) (102)
60000
20 (-10)
Ft. 34.0 29.0 28.0 23.0 N/A 55.0 88.0 79.0 69.0 N/A 55.0 104.0 93.0 81.0 N/A
M 10.4 8.8 8.5 7.0 N/A 16.8 26.8 24.1 21.0 N/A 16.8 31.7 28.3 24.7 N/A
0 (-20)
Ft. 14.0 9.0 7.0 0.0 N/A 55.0 49.0 43.0 34.0 N/A 55.0 60.0 52.0 42.0 N/A
M 4.3 2.7 2.1 0.0 N/A 16.8 14.9 13.1 10.4 N/A 16.8 18.3 15.8 12.8 N/A
-20 (-30)
Ft. 5.0 0.0 0.0 0.0 N/A 41.0 32.0 26.0 18.0 N/A 50.0 40.0 33.0 24.0 N/A
M 1.5 0.0 0.0 0.0 N/A 12.5 9.8 7.9 5.5 N/A 15.2 12.2 10.1 7.3 N/A
-40 (-40)
Ft. 0.0 0.0 0.0 0.0 N/A 30.0 21.0 16.0 8.0 N/A 37.0 28.0 22.0 13.0 N/A
M 0.0 0.0 0.0 0.0 N/A 9.1 6.4 4.9 2.4 N/A 11.3 8.5 6.7 4.0 N/A
60600
20 (-10)
Ft. 34.0 29.0 28.0 23.0 N/A 55.0 88.0 79.0 69.0 N/A 55.0 104.0 93.0 81.0 N/A
M 10.4 8.8 8.5 7.0 N/A 16.8 26.8 24.1 21.0 N/A 16.8 31.7 28.3 24.7 N/A
0 (-20)
Ft. 14.0 9.0 7.0 0.0 N/A 55.0 49.0 43.0 34.0 N/A 55.0 60.0 52.0 42.0 N/A
M 4.3 2.7 2.1 0.0 N/A 16.8 14.9 13.1 10.4 N/A 16.8 18.3 15.8 12.8 N/ A
-20 (-30)
Ft. 5.0 0.0 0.0 0.0 N/A 41.0 32.0 26.0 18.0 N/A 50.0 40.0 33.0 24.0 N/ A
M 1.5 0.0 0.0 0.0 N/A 12.5 9.8 7.9 5.5 N/ A 15.2 12.2 10.1 7.3 N/A
-40 (-40)
Ft. 0.0 0.0 0.0 0.0 N/A 30.0 21.0 16.0 8.0 N/A 37.0 28.0 22.0 13.0 N/A
M 0.0 0.0 0.0 0.0 N/A 9.1 6.4 4.9 2.4 N/A 11.3 8.5 6.7 4.0 N/A
80000
20 (-10)
Ft. 35.0 39.0 39.0 33.0 25.0 35.0 118.0 107.0 92.0 76.0 35.0 130.0 125.0 109.0 90.0
M 10.7 11.9 11.9 10.1 7.6 10.7 36.0 32.6 28.0 23.2 10.7 39.6 38.1 33.2 27.4
0 (-20)
Ft. 22.0 16.0 14.0 7.0 0.0 35.0 69.0 60.0 49.0 35.0 35.0 83.0 72.0 60.0 45.0
M 6.7 4.9 4.3 2.1 0.0 10.7 21.0 18.3 14.9 10.7 10.7 25.3 21.9 18.3 13.7
-20 (-30)
Ft. 11.0 5.0 2.0 0.0 0.0 35.0 46.0 39.0 29.0 16.0 35.0 57.0 48.0 37.0 23.0
M 3.4 1.5 0.6 0.0 0.0 10.7 14.0 11.9 8.8 4.9 10.7 17.4 14.6 11.3 7.0
-40 (-40)
Ft. 4.0 0.0 0.0 0.0 0.0 35.0 33.0 26.0 17.0 4.0 35.0 41.0 34.0 24.0 11.0
M 1.2 0.0 0.0 0.0 0.0 10.7 10.1 7.9 5.2 1.2 10.7 12.5 10.4 7.3 3.4
100000
20 (-10)
Ft. N/A 47.0 47.0 41.0 32.0 N/ A 50.0 110.0 112.0 93.0 N/A 50.0 110.0 132.0 110.0
M N/ A 14.3 14.3 12.5 9.8 N/A 15.2 33.5 34.1 28.3 N/A 15.2 33.5 40.2 33.5
0 (-20)
Ft. N/A 21.0 19.0 12.0 1.0 N/A 50.0 74.0 61.0 45.0 N/A 50.0 89.0 74.0 57.0
M N/ A 6.4 5.8 3.7 0.3 N/A 15.2 22.6 18.6 13.7 N/A 15.2 27.1 22.6 17.4
-20 (-30) Ft. N/A 8.0 6.0 0.0 0.0 N/A 50.0 49.0 38.0 23.0 N/A 50.0 60.0 48.0 32.0
M N/ A 2.4 1.8 0.0 0.0 N/A 15.2 14.9 11.6 7.0 N/A 15.2 18.3 14.6 9.8
-40 (-40) Ft. N/A 1.0 0.0 0.0 0.0 N/A 42.0 34.0 24.0 10.0 N/A 50.0 43.0 32.0 18.0
M N/ A 0.3 0.0 0.0 0.0 N/A 12.8 10.4 7.3 3.0 N/A 15.2 13.1 9.8 5.5
120000
20 (-10)
Ft. N/A N/A 15.0 49.0 40.0 N/A N/ A 15.0 100.0 111.0 N/ A N/A 15.0 100.0 131.0
M N/ A N/A 4.6 14.9 12.2 N/A N/A 4.6 30.5 33.8 N/A N/A 4.6 30.5 39.9
0 (-20)
Ft. N/A N/A 15.0 17.0 6.0 N/A N/A 15.0 75.0 57.0 N/A N/A 15.0 90.0 70.0
M N/ A N/A 4.6 5.2 1.8 N/ A N/A 4.6 22.9 17.4 N/A N/A 4.6 27.4 21.3
-20 (-30)
Ft. N/A N/A 10.0 2.0 0.0 N/A N/A 15.0 48.0 32.0 N/A N/A 15.0 59.0 42.0
M N/ A N/A 3.0 0.6 0.0 N/ A N/A 4.6 14.6 9.8 N/A N/A 4.6 18.0 12.8
-40 (-40)
Ft. N/A N/A 1.0 0.0 0.0 N/A N/A 15.0 32.0 17.0 N/A N/A 15.0 41.0 25.0
M N/ A N/A 0.3 0.0 0.0 N/ A N/A 4.6 9.8 5.2 N/A N/A 4.6 12.5 7.6
* Pipe len gth (f t) specified for maximum pipe lengths located in unconditioned spaces. Pipes located in u nconditioned space cannot exceed total allowable pi pe
length calculated from Table 1 or 3.
† Insulation thickness based on R value of 3.5 per in.
59MN7A
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