11
MAXIMUM EQUIVALENT VENT LENGTH -- FT. (M) (CONTINUED)
NOTE: Maximum Equivalent Vent Length (MEVL) includes standard and concentric vent termination and does NOT include elbows.
Use Table 2 - Deductions from Maximum Equivalent Vent Length to determine allowable vent length for each application.
Table 3 – Maximum Equivalent Vent Length -- Ft. (M)
4501 to 10,000 Ft. (1371 to 3048 M) Altitude
Altitude
FT (M)
5
Unit Size
DIRECT VENT (2-PIPE) AND SINGLE-PIPE
Vent Pipe Diameter (in.)
1
1-1/2 2 2-1/2 3 4
4501 to 5000
(1370 to 1524)
40,000 33 (10.1) 171 (52.1) 196 (59.7)
NA
2
NA
60,000 20 (6.1) 111 (33.8) 198 (60.4) 221 (67.4) NA
80,000 13 (4.0) 54 (16.5) 146 (44.5) 195 (59.4) 216 (65.8)
100,000 NA 16 (4.9) 91 (27.7) 200 (61.0) 222 (67.7)
120,000 NA NA NA 80 (24.4) 211 (64.3)
140,000
4
NA NA NA 60 (18.3) 134 (40.8)
5001 to 6000
(1524 to 1829)
40,000 27 (8.2) 158 (48.2) 179 (54.6) NA NA
60,000 16 (4.9) 103 (31.4) 186 (56.7) 207 (63.1) NA
80,000 11 (3.4) 49 (14.9) 137 (41.8) 183 (55.8) 200 (61.0)
100,000 NA 12 (3.7) 85 (25.9) 188 (57.3) 208 (63.4)
120,000 NA NA NA 74 (22.6) 199 (60.7)
140,000
4
NA NA NA 50 (15.2) 109 (33.2)
6001 to 7000
(1829 to 2134)
40,000 21 (6.4) 145 (44.2) 162 (49.4) NA NA
60,000 13 (4.0) 96 (29.3) 174 (53.0) 194 (59.1) NA
80,000 NA 44 (13.4) 120 (36.6) 171 (52.1) 185 (56.4)
100,000 NA 10 (3.0) 79 (24.1) 178 (54.3) 195 (59.4)
120,000 NA NA NA 68 (20.7) 187 (57.0)
140,000
4
NA NA NA 41 (12.5) 87 (26.5)
7001 to 8000
(2134 to 2438)
40,000 15 (4.6) 133 (40.5) 146 (44.5) NA NA
60,000 10 (3.0) 89 (27.1) 163 (49.7) 181 (55.2) NA
80,000 NA 40 (12.2) 120 (36.6) 159 (48.5) 170 (51.8)
100,000 NA NA 73 (22.3) 167 (50.9) 182 (55.5)
120,000 NA NA NA 62 (18.9) 175 (53.3)
140,000
4
NA NA NA 32 (9.8) 63 (19.2)
8001 to 9000
(2438 to 2743)
40,000 10 (3.0) 121 (36.9) 130 (39.6) NA NA
60,000 7 (2.1) 82 (25.0) 152 (46.3) 168 (51.2) NA
80,000 NA 35 (10.7) 111 (33.8) 148 (45.1) 156 (47.5)
100,000 NA NA 67 (20.4) 157 (47.9) 170 (51.8)
120,000 NA NA NA 56 (17.1) 164 (50.0)
140,000
4
NA NA NA 23 (7.0) 42 (12.8)
9001 to 10,000
(2743 to 3048)
40,000 5 (1.5) 110 (33.5) 115 (35.1) NA NA
60,000 NA 76 (23.2) 142 (43.3) 156 (47.5) NA
80,000 NA 31 (9.4) 103 (31.4) 137 (41.8) 142 (43.3)
100,000 NA NA 62 (18.9) 147 (44.8) 157 (47.9)
120,000 NA NA NA 51 (15.5) 153 (46.6)
140,000
4
NA NA NA 16 (4.9) 20 (6.1)
NOTES:
1. Use only the vent pipe sizes shown for each furnace. It is NOT necessary to choose the smallest diameter pipe possible for venting.
2. NA --- Not allowed. Pressure switch will not close, or flame disturbance may result.
3. Total equivalent vent lengths under 10’ for 40,000 BT UH furnaces from 0 to 2000 f t. (0 to 610 M) above sea level r equ ire use of an outlet choke plate .
Failure to use an outlet choke when required may result in flame disturbance or flame sense lockout.
4. Not all furnace families include 140,000 BTUH input models.
5. Vent sizing for C a nadian installations over 4500 ft (1370 M) above sea level are subject to acceptance by local autho rities having jurisdiction.
6. Size both the combustion air and vent pipe independently, then use the larger size for both pipes.
7. Assume the two 45_ elbows equal one 90_ elbow. Wide radius elbows are desirable and may be required in some cases.
8. Elbow and pipe sections within the furnace casing and at the vent termination should not be included in vent length or elbow count.
9. The minimum pipe length is 5 ft. (2 M) linear feet (meters) for all applications.
10. Use 3 ---in. (76 mm) diameter vent termination kit for installations requiring 4---in. (102 mm) diameter pipe.
59TP6A
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