Lennox SCA Series User Manual

Page 37
2− Check each system separately with all stages operat-
ing.
3− Use a thermometer to accurately measure the outdoor
ambient temperature.
4− Apply the outdoor temperature to tables 5 through 10
to determine normal operating pressures. Pressures
are listed for sea level applications at 80°F dry bulb and
67°F wet bulb return air.
5− Compare the normal operating pressures to the pres-
sures obtained from the gauges. Minor variations in
these pressures may be expected due to differences in
installations. Significant differences could mean that
the system is not properly charged or that a problem
exists with some component in the system. Correct
any system problems before proceeding.
6− If discharge pressure is high, remove refrigerant from
the system. If discharge pressure is low, add refriger-
ant to the system.
S Add or remove charge in increments.
S Allow the system to stabilize each time refriger-
ant is added or removed.
7− Use the following approach method along with the nor-
mal operating pressures to confirm readings.
TABLE 5
SCA120 CAV NORMAL OPERATING PRESSURES
Outdoor
Coil
Entering
Air Temp
CIRCUIT 1 CIRCUIT 2
Dis. +10
psig
Suct. +5
psig
Dis. +10
psig
Suc. +5
psig
65_F 250 139 248 137
75_F 288 144 285 145
85_F 326 146 321 147
95_F 370 148 366 149
105_F 417 150 414 151
115_F 469 152 463 153
TABLE 6
SCA120MSAVt NORMAL OPERATING PRESSURES
Outdoor
Coil
Entering
Air Temp
CIRCUIT 1 CIRCUIT 2
Dis. +10
psig
Suct. +5
psig
Dis. +10
psig
Suc. +5
psig
65_F 251 137 251 139
75_F 288 138 288 140
85_F 326 140 326 143
95_F 369 143 270 145
105_F 416 146 417 148
115_F 467 149 467 150
TABLE 7
SCA240 CAV NORMAL OPERATING PRESSURES
Outdoor
Coil En-
tering Air
Temp
CIRCUIT 1 CIRCUIT 2 CIRCUIT 3 CIRCUIT 4
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
65_F 247 128 240 130 247 136 242 130
75_F 294 131 286 133 294 138 288 132
85_F 340 134 333 136 341 140 334 135
95_F 387 137 380 139 387 142 381 138
105_F 433 140 427 142 434 145 427 141
115_F 480 143 474 144 480 147 473 144
TABLE 8
SCA240 MSAV NORMAL OPERATING PRESSURES
Outdoor
Coil En-
tering Air
Temp
CIRCUIT 1 CIRCUIT 2 CIRCUIT 3 CIRCUIT 4
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
65_F 234 120 235 131 243 133 243 138
75_F 280 123 282 134 292 136 290 140
85_F 327 127 329 137 340 139 337 143
95_F 373 131 376 140 389 141 384 145
105_F 420 134 424 144 437 144 431 148
115_F 466 138 471 147 485 147 478 150
TABLE 9
SCB288 CAV Normal Operating Pressures
Outdoor
Coil En-
tering Air
Temp
CIRCUIT 1 CIRCUIT 2 CIRCUIT 3 CIRCUIT 4
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
65_F 246 118 231 119 253 127 246 123
75_F 297 121 284 124 304 131 295 126
85_F 348 125 336 128 354 135 344 129
95_F 399 129 388 133 405 138 394 133
105_F 450 132 440 137 456 142 443 136
115_F 501 136 493 141 506 146 492 139
TABLE 10
SCB288 MSAVt Normal Operating Pressures
Outdoor
Coil En-
tering Air
Temp
CIRCUIT 1 CIRCUIT 2 CIRCUIT 3 CIRCUIT 4
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
Dis
+10
psig
Suc
+5
psig
65_F 254 109 240 118 263 121 244 123
75_F 301 113 286 122 310 124 291 127
85_F 347 117 332 126 357 127 338 130
95_F 394 121 378 130 404 130 385 133
105_F 441 124 424 135 451 132 432 137
115_F 488 128 470 139 498 135 479 140

Lennox SCA Series Specifications

General

Brand	Lennox
Model	SCA Series
Category	Air Conditioner
Language	English