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NOTE: Maximum Equivalent Vent Length (MEVL) does NOT include elbows or terminations. Use Table
Maximum Equivalent Vent Length to determine allowable vent length for each application.
Altitude
Unit Size
FT (M)
BTU/Hr
40,000*
60,000
0 to 2000
80,000
(0 to 610)
100,000
120,000
40,000*
60,000
2001 to 3000
80,000
(610 to 914)
100,000
120,000
40,000*
60,000
3001 to 4000
80,000
(914 to 1219)
100,000
120,000
40,000*
60,000
4001 to 4500
80,000
(1219 to
1370)
100,000
120,000
* Not all families have these models.
Note: See notes at end of venting tables.
Note: Table 3 for altitudes over 4500 ft. (1370 M)
Pipe Diameter (in):
Mitered 90º Elbow
Medium Radius 90º Elbow
Long Radius 90º Elbow
Mitered 45º Elbow
Medium Radius 45º Elbow
Long Radius 45º Elbow
Tee
* Note: 3 --- and 4 ---in. 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 1 or Table 3
minus the number of elbows multiplied by the deduction for each elbow in Table 2.
Standard vent terminations and concentric vent terminations count for zero deductions.
Example
A direct- -vent 60,000 Btuh furnace installed at 2100 ft. (640 M ) with 2- -in. (51 mm) vent piping. Venting system includes, FOR EACH
PIPE, (3) 90_ long radius elbows, (2) 45_ long radius elbows and a concentric vent kit.
Maximum Equivalent Vent Length
Deduct (3) 90 long radius
Deduct (2) 45 long radius
Maximum Vent Length
MAXIMUM EQUIVALENT VENT LENGTH - - FT. (M)
Table 1 – Maximum Equivalent Vent Length - - Ft. (M)
0 to 4500 Ft. (0 to 1370 M) Altitude
DIRECT VENT (2-PIPE) AND NON---DIRECT VENT (1---PIPE)
1-1/2
50
(15.2)
210
30
(9.1)
135
20
(6.1)
70
NA
25
NA
45
(13.7)
198
27
(8.2)
127
17
(5.2)
64
NA
22
NA
39
(11.9)
184
23
(7.0)
119
15
(4.6)
59
NA
19
NA
36
(11.0)
177
21
(6.4)
115
14
(4.3)
56
NA
17
NA
Table 2 – Deductions from Maximum Equivalent Vent Length - - Ft. (M)
1-1/2
8
(2.4)
8
5
(1.5)
5
3
(0.9)
3
4
(1.2)
4
2.5
(0.8)
2.5
1.5
(0.5)
1.5
16
(4.9)
16
3
x
2
x
Vent Pipe Diameter (in.)
2
2-1/2
(64.0)
250
(76.2)
(41.1)
235
(71.6)
(21.3)
175
(53.3)
(7.6)
110
(33.5)
NA
15
(4.6)
(60.4)
232
(70.7)
(38.7)
222
(67.7)
(19.5)
165
(50.3)
(6.7)
104
(31.7)
NA
11
(3.4)
(56.1)
214
(65.2)
(36.3)
210
(64.0)
(18.0)
155
(47.2)
(5.8)
98
(29.9)
NA
8
(2.4)
(53.9)
205
(62.5)
(35.1)
204
(62.2)
(17.1)
150
(45.7)
(5.2)
94
(28.7)
NA
NA
2
2-1/2
(2.4)
8
(2.4)
(1.5)
5
(1.5)
(0.9)
3
(0.9)
(1.2)
4
(1.2)
(0.8)
2.5
(0.8)
(0.5)
1.5
(0.5)
(4.9)
16
(4.9)
=
127 ft.
3 ft.
=
- 9 ft.
1.5 ft.
=
- 3 ft.
=
115 ft.
7
2
- Deductions from
3
4
NA
NA
265
(80.8)
NA
235
(71.6)
265
(80.8)
235
(71.6)
265
(80.8)
100
(30.5)
250
(76.2)
NA
NA
250
(76.2)
NA
222
(67.7)
249
(75.9)
223
(68.0)
250
(76.2)
93
(28.3)
237
(72.2)
NA
NA
235
(71.6)
NA
210
(64.0)
232
(70.7)
211
(64.3)
236
(71.9)
86
(26.2)
224
(68.3)
NA
NA
228
(69.5)
NA
202
(61.6)
224
(68.3)
205
(62.5)
229
(69.8)
83
(25.3)
217
(66.1)
3*
4*
NA
NA
NA
NA
NA
NA
NA
NA
3
(0.9)
3
(0.9)
NA
NA
NA
NA
NA
NA
NA
NA
1.5
(0.5)
1.5
(0.5)
16
(4.9)
16
(4.9)
(From Table 1)
(From Table 2)
(From Table 2)
For EACH vent or inlet pipe
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