Instruction manual

45
NOTE: Maximum Equivalent Vent Length (MEVL) does NOT include elbows or terminations. Use Table 14 - Deductions from
Maximum Equivalent Vent Length to determine allowable vent length for each application.
Table 15 – Maximum Equivalent Vent Length -- Ft. (M)
4501 to 10,000 Ft. (0 to 1370 M) Altitude
Altitude
FT (M)
Unit Size
DIRECT VENT (2-PIPE) AND VENTILATED COMBUSTION AIR ONLY
Vent Pipe Diameter
1-1/2 2 2-1/2 3 4
4501 to 5000
(1370 to
1524)
60,000 35 (10.7) 111 (33.8) 198 (60.4) 221 (67.4) NA
80,000 23 (7.0) 85 (25.9) 146 (44.5) 195 (59.4) 216 (65.8)
100,000 NA 40 (12.2) 91 (27.7) 200 (61.0) 222 (67.7)
120,000 NA NA NA 80 (24.4) 211 (64.3)
5001 to 6000
(1524 to
1829)
60,000 37 (11.3) 103 (31.4) 186 (56.7) 207 (63.1) NA
80,000 22 (6.7) 76 (23.2) 137 (41.8) 183 (55.8) 200 (61.0)
100,000 NA 33 (10.1) 85 (25.9) 188 (57.3) 208 (63.4)
120,000 NA NA NA 74 (22.6) 199 (60.7)
6001 to 7000
(1829 to
2134)
60,000 35 (10.7) 96 (29.3) 174 (53.0) 194 (59.1) NA
80,000 20 (6.1) 71 (21.6) 120 (36.6) 171 (52.1) 185 (56.4)
100,000 NA 31 (9.4) 79 (24.1) 178 (54.3) 195 (59.4)
120,000 NA NA NA 68 (20.7) 187 (57.0)
7001 to 8000
(2134 to
2438)
60,000 32 (9.8) 89 (27.1) 163 (49.7) 181 (55.2) NA
80,000 18 (5.5) 66 (20.1) 120 (36.6) 159 (48.5) 170 (51.8)
100,000 NA 29 (8.8) 73 (22.3) 167 (50.9) 182 (55.5)
120,000 NA NA NA 62 (18.9) 175 (53.3)
8001 to 9000
(2438 to
2743)
60,000 30 (9.1) 82 (25.0) 152 (46.3) 168 (51.2) NA
80,000 17 (5.2) 62 (18.9) 111 (33.8) 148 (45.1) 156 (47.5)
100,000 NA 27 (8.2) 67 (20.4) 157 (47.9) 170 (51.8)
120,000 NA NA NA 56 (17.1) 164 (50.0)
9001 to
10,000
(2743 to
3048)
60,000 27 (8.2) 76 (23.2) 142 (43.3) 156 (47.5) NA
80,000 15 (4.6) 57 (17.4) 103 (31.4) 137 (41.8) 142 (43.3)
100,000 NA 24 (7.3) 62 (18.9) 147 (44.8) 157 (47.9)
120,000 NA NA NA 51 (15.5) 153 (46.6)
Notes:
1. 3 --- and 4 ---in. Vent pipe systems require long radius elbows.
2. Vent sizing for Cana dian install a tions over 4500 ft. (1370 M) above sea level a re subject to acceptance by the local authorities having jurisdiction.
3. NA --- Not allowed; pressure switch will not close, or flame disturbance may result.
4. Do not use pipe size greater than those specified in table or incomplete combustion, flame disturbance, or flame sense lockout may occur.
5. Size both the combustion ---air and vent pipe independently, then use the larger diameter for both pipes.
6. Assume the two 45_ elbows equal one 90_ elbow. Wide radius elbows are desirable and may be required in some cases.
7. Elbows and pipe sections within the furnace casing and at the vent termination should not be included in vent length or elbow count.
8. The minimum pipe length is 5 ft. (1.5 M) for all applications.
9. Use 3 ---in. (76 mm) diameter vent termination kit for installations requiring 4 ---in. (102 mm) diameter pipe.
987MA