INSTALLATION INSTRUCTIONS Gas Furnace: (F/G)MAC
440 01 4201 01 47
Specifications subject to change without notice.
Table 14 DEDUCTIONS FROM MAXIMUM EQUIVALENT VENT LENGTH - Feet (Meters)
Pipe Diameter (in): 1-1/2 2 2-1/2 3* 4*
Mitered 90° Elbow 8 (2.4) 8 (2.4) 8 (2.4)
Medium Radius 90° Elbow 5 (1.5) 5 (1.5) 5 (1.5)
Long Radius 90° Elbow 3 (0.9) 3 (0.9) 3 (0.9) 3 (0.9) 3 (0.9)
Mitered 45º Elbow 4 (1.2) 4 (1.2) 4 (1.2)
Medium Radius 45° Elbow 2.5 (0.8) 2.5 (0.8) 2.5 (0.8)
Long Radius 45° Elbow 1.5 (0.5) 1.5 (0.5) 1.5 (0.5) 1.5 (0.5) 1.5 (0.5)
Tee 16 (4.9) 16 (4.9) 16 (4.9) 16 (4.9) 16 (4.9)
* Note: 3- and 4-inch vent pipe systems require long radius elbows.
Venting System Length Calculations
The maximum length for each vent pipe (inlet or exhaust) equals the Maximum Equivalent Vent Length (MEVL) from Table 12 and
Table 13 minus the number of elbows multiplied by the deduction for each elbow in Table 14.
Standard vent terminations and concentric vent terminations count for zero deduction.
Example
A Direct-Vent 60,000 BTU/Hr furnace installed at 2100 ft altitude with 2-inch vent piping.
Venting system includes, FOR EACH PIPE, (3) 90º long radius elbows, (2) 45º long radius elbows and a concentric vent kit.
Maximum Equivalent Vent Length = 127 ft Table 12
Deduct (3) 90° long radius elbows 3 x 3 ft = - 9 ft Table 14
Deduct (2) 45° long radius elbows 2 x 1.5 ft = - 3 ft Table 14
Maximum vent length
115 ft (For EACH vent or inlet pipe)
Table 15
Maximum Allowable Exposed Vent Lengths in Unconditioned Space
Maximum Length of Uninsulated and Insulated Vent Pipe-Ft (M)
(F/G)9MAC
Max. Heat
Input
Winter
Design
Temp °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
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
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