54
NOTE: Maximum Equivalent Vent Length (MEVL) includes standard and concentric vent termination and does NOT include elbows.
Use Table 15 - Deductions from Maximum Equivalent Vent Length to determine allowable vent length for each application.
Table 14 – Maximum Equivalent Vent Length -- Ft.
Ft.
Unit Size
60,000
80,000
100,000
120,000
Altitude
(feet)
Pipe Dia. (in)
1 ½
2
2 ½
3
1 ½
2
2 ½
3
4
2
2 ½
3
4
2 ½
3
4
0---2000
50
100
175
200
30
95
130
175
200
45
80
175
200
10
75
185
2001---3000
45
95
165
185
70
125
165
185
40
75
165
185
70
175
3001---4000
40
90
155
175
25
115
155
175
38
155
175
5
65
165
4001---4500
35
85
150
170
23
110
150
165
36
70
170
N/A
60
160
4501---5000
80
165
22
145
160
150
165
5001---6000
37
75
140
155
100
135
150
33
140
155
155
6001---7000
35
70
130
145
20
90
125
140
31
135
145
50
140
7001---8000
32
66
120
135
18
66
120
125
29
66
125
135
46
130
8001---9000
30
62
115
125
17
62
80
110
115
27
62
115
125
43
120
9001---10000
27
57
105
115
15
57
75
100
105
24
57
100
115
39
115
Meters
Unit Size
60,000
80,000
100,000
120,000
Altitude
(meters)
Pipe Dia. (mm)
38
51
64
76
38
51
64
76
102
51
64
76
102
64
76
102
0---610
15.2 30.4 53.3 60.9
9.1
28.9 39.6 53.3 60.9 13.7 24.3 53.3 60.9
3.0
22.8 56.3
611---914
13.7 28.9 50.2 56.3
21.3
38.1 50.2 56.3 12.1
22.8
50.2 56.3
21.3 53.3
915---1219
12.1 27.4 47.2 53.3
7.6
35.0 47.2 53.3 11.5
47.2
53.3
1.5
19.8 50.2
1220---1370
10.6
25.9
45.7
51.8
7.0
33.5
45.7 50.2
10.9
21.3
51.8
NA
18.2 48.7
1371---1524
24.3
50.2
6.7
44.1 48.7
45.7 50.2
1525---1829
11.2 22.8 42.6 47.2
30.4 41.1 45.7 10.0
42.6 47.2
47.2
1830---2134
10.6 21.3 39.6 44.1
6.0
27.4
38.1 42.6
9.4
41.1 44.1
15.2 42.6
2135---2438
9.7
20.1 36.5 41.1
5.4
20.1
36.5 38.1
8.8
20.1 38.1 41.1
14.0 39.6
2439---2743
9.1
18.8 35.0 38.1
5.1
18.8 24.3 33.5 35.0
8.2
18.8 35.0 38.1
13.1 36.5
2744---3048
8.2
17.3 32.0 35.0
4.5
17.3 22.8 30.4 32.0
7.3
17.3 30.4 35.0
11.8 35.0
Long
Medium
Mitered
Concentric
Standard 2-in., 3-in., or
optional 4-in. termination.
ELBOW CONFIGURATIONS
VENT TERMINAL CONFIGURATIONS
A13110
Table 15 – Deductions from Maximum Equivalent Vent Length -- Ft. (M)
Pipe Diameter (in):
1-1/2
2
2-1/2
3
4
Mitered 90º Elbow
8
(2.4)
8
(2.4)
8
(2.4)
8
(2.4)
8
(2.4)
Medium Radius 90º Elbow
5
(1.5)
5
(1.5)
5
(1.5)
5
(1.5)
5
(1.5)
Long Radius 90º 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)
4
(1.2)
4
(1.2)
Medium Radius 45º Elbow
2.5
(0.8)
2.5
(0.8)
2.5
(0.8)
2.5
(0.8)
2.5
(0.8)
Long Radius 45º 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)
Concentric Vent Termination
NA
0
(0.0)
NA
0
(0.0)
NA
Standard Vent Termination
0
(0.0)
0
(0.0)
0
(0.0)
0
(0.0)
0
(0.0)
NOTES
:
1. Use only the smallest diameter pipe possible for venting. Over---sizing may cause flame disturbance or excessive vent terminal icing or freeze---up.
2. NA --- Not allowed. Pressure switch will not close, or flame disturbance may result.
3. Vent sizing for Canadian installations over 4500 ft. (1370 M) above sea level are subject to acceptance by the local authorities having jurisdiction.
4. Size both the combustion air and vent pipe independently, then use the larger size for both pipes.
5. Assume the two 45
_
elbows equal one 90
_
elbow. Wide radius elbows are desirable and may be required in some cases.
6. Elbow and pipe sections within the furnace casing and at the vent termination should not be included in vent length or elbow count.
7. The minimum pipe length is 5 ft. (2 M) linear feet (meters) for all applications.
8. Use 3---in. (76 mm) diameter vent termination kit for installations requiring 4---in. (102 mm) diameter pipe.
