8
MAXIMUM ALLOWABLE EXPOSED VENT LENGTHS INSULATION TABLE -- FT. (M)
Maximum Length of Uninsulated and Insulated Vent Pipe-Ft (M)
Two
Stage
Furnace
High Heat
Input
Winter
Design
Tem p °F
(°C)
Pipe
Length in
Ft. & M
No Insulation 3/8-in. (9.5 mm) 1/2-in. (12.7 mm)
Pipe Diameter-in. (mm) Pipe Diameter-in. (mm) Pipe Diameter-in. (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)
40000*
20 (-10)
Ft. 40.0 35.0 35.0 N/A N/A 50.0 104.0 94.0 N/A N/ A 50.0 122.0 110.0 N/A N/A
M 12.2 10.7 10.7 N/A N/A 15.2 31.7 28.7 N/A N/A 15.2 37.2 33.5 N/A N/A
0 (-20)
Ft. 19.0 14.0 12.0 N/A N/A 50.0 61.0 54.0 N/A N/A 50.0 74.0 65.0 N/A N/A
M 5.8 4.3 3.7 N/A N/A 15.2 18.6 16.5 N/A N/A 15.2 22.6 19.8 N/A N/A
-20 (-30)
Ft. 9.0 3.0 1.0 N/A N/A 50.0 41.0 35.0 N/A N/ A 50.0 51.0 43.0 N/A N/A
M 2.7 0.9 0.3 N/A N/A 15.2 12.5 10.7 N/A N/A 15.2 15.5 13.1 N/A N/A
-40 (-40)
Ft. 3.0 0.0 0.0 N/A N/A 39.0 29.0 23.0 N/A N/ A 48.0 37.0 30.0 N/A N/A
M 0.9 0.0 0.0 N/A N/A 11.9 8.8 7.0 N/A N/A 14.6 11.3 9.1 N/A N/A
60000
20 (-10)
Ft. 30.0 51.0 51.0 45.0 N/A 30.0 135.0 138.0 120.0 N/A 30.0 135.0 162.0 141.0 N/A
M 9.1 15.5 15.5 13.7 N/A 9.1 41.1 42.1 36.6 N/A 9.1 41.1 49.4 43.0 N/A
0 (-20)
Ft. 30.0 24.0 23.0 16.0 N/A 30.0 93.0 82.0 69.0 N/A 30.0 111.0 98.0 83.0 N/A
M 9.1 7.3 7.0 4.9 N/A 9.1 28.3 25.0 21.0 N/A 9.1 33.8 29.9 25.3 N/A
-20 (-30)
Ft. 18.0 11.0 9.0 1.0 N/A 30.0 65.0 56.0 44.0 N/A 30.0 79.0 68.0 55.0 N/A
M 5.5 3.4 2.7 0.3 N/A 9.1 19.8 17.1 13.4 N/A 9.1 24.1 20.7 16.8 N/A
-40 (-40)
Ft. 10.0 3.0 0.0 0.0 N/A 30.0 48.0 40.0 29.0 N/A 30.0 59.0 50.0 38.0 N/A
M 3.0 0.9 0.0 0.0 N/A 9.1 14.6 12.2 8.8 N/A 9.1 18.0 15.2 11.6 N/A
80000
20 (-10)
Ft. 20.0 64.0 64.0 56.0 47.0 20.0 70.0 173.0 150.0 125.0 20.0 70.0 175.0 177.0 147.0
M 6.1 19.5 19.5 17.1 14.3 6.1 21.3 52.7 45.7 38.1 6.1 21.3 53.3 53.9 44.8
0 (-20)
Ft. 20.0 32.0 30.0 22.0 11.0 20.0 70.0 104.0 87.0 67.0 20.0 70.0 124.0 104.0 82.0
M 6.1 9.8 9.1 6.7 3.4 6.1 21.3 31.7 26.5 20.4 6.1 21.3 37.8 31.7 25.0
-20 (-30)
Ft. 20.0 17.0 14.0 6.0 0.0 20.0 70.0 71.0 57.0 40.0 20.0 70.0 86.0 71.0 52.0
M 6.1 5.2 4.3 1.8 0.0 6.1 21.3 21.6 17.4 12.2 6.1 21.3 26.2 21.6 15.8
-40 (-40)
Ft. 15.0 7.0 5.0 0.0 0.0 20.0 61.0 52.0 40.0 24.0 20.0 70.0 64.0 50.0 33.0
M 4.6 2.1 1.5 0.0 0.0 6.1 18.6 15.8 12.2 7.3 6.1 21.3 19.5 15.2 10.1
100000
20 (-10)
Ft. N/A 25.0 79.0 70.0 59.0 N/A 25.0 110.0 186.0 155.0 N/A 25.0 110.0 219.0 182.0
M N/A 7.6 24.1 21.3 18.0 N/A 7.6 33.5 56.7 47.2 N/ A 7.6 33.5 66.8 55.5
0 (-20)
Ft. N/A 25.0 40.0 31.0 19.0 N/A 25.0 110.0 109.0 86.0 N/A 25.0 110.0 131.0 104.0
M N/A 7.6 12.2 9.4 5.8 N/A 7.6 33.5 33.2 26.2 N/ A 7.6 33.5 39.9 31.7
-20 (-30)
Ft. N/A 23.0 21.0 13.0 0.0 N/A 25.0 91.0 74.0 54.0 N/A 25.0 110.0 90.0 68.0
M N/A 7.0 6.4 4.0 0.0 N/A 7.6 27.7 22.6 16.5 N/ A 7.6 33.5 27.4 20.7
-40 (-40)
Ft. N/A 13.0 10.0 1.0 0.0 N/A 25.0 68.0 53.0 35.0 N/A 25.0 83.0 66.0 46.0
M N/A 4.0 3.0 0.3 0.0 N/A 7.6 20.7 16.2 10.7 N/ A 7.6 25.3 20.1 14.0
120000
20 (-10)
Ft. N/A N/A 15.0 85.0 73.0 N/A N/A 15.0 100.0 190.0 N/A N/A 15.0 100.0 224.0
M N/A N/A 4.6 25.9 22.3 N/A N/A 4.6 30.5 57.9 N/A N/A 4.6 30.5 68.3
0 (-20)
Ft. N/A N/A 15.0 41.0 29.0 N/A N/A 15.0 100.0 109.0 N/A N/A 15.0 100.0 131.0
M N/A N/A 4.6 12.5 8.8 N/A N/A 4.6 30.5 33.2 N/A N/A 4.6 30.5 39.9
-20 (-30)
Ft. N/A N/A 15.0 20.0 7.0 N/A N/A 15.0 94.0 71.0 N/A N/A 15.0 114.0 88.0
M N/A N/A 4.6 6.1 2.1 N/A N/A 4.6 28.7 21.6 N/A N/A 4.6 34.7 26.8
-40 (-40)
Ft. N/A N/A 15.0 7.0 0.0 N/A N/A 15.0 69.0 48.0 N/A N/A 15.0 85.0 62.0
M N/A N/A 4.6 2.1 0.0 N/A N/A 4.6 21.0 14.6 N/A N/A 4.6 25.9 18.9
* Not all f amilies have these models.
† Insulation thickness based on R value of 3.5 per in.
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