Unit Start−Up And Operation - Lennox 15CHAX−24 Installation Instructions Manual

Unit Start−Up and Operation
Each 15CHAX packaged cooling unit is factory−charged
with R−410A refrigerant. The compressor is hermetically
sealed, internally sprung and base−mounted with
rubber−insulated hold−down bolts.
Pre−Start Check List:
1 − Make sure refrigerant lines do not rub against the cabi-
net or each other.
2 − Inspect all electrical wiring, both factory− and field−
installed, for loose connections.
3 − Check voltage at the disconnect switch. Voltage must
be within the range listed on the unit nameplate. If not,
consult power company and have voltage condition
corrected before starting unit.
4 − Recheck voltage with unit running. If power is not with-
in the range listed on the unit nameplate, stop the unit
and consult the power company. Check unit amper-
age. Refer to unit nameplate for correct running amps.
5 − Make sure filter is in place before unit start−up.
6 − Before placing the unit into full operation, energize the
unit for three false starts. Energize the compressor
just long enough for it to make a few revolutions, wait
five to seven minutes before repeating a second and
third time.
Cooling Sequence of Operation
When the thermostat calls for cooling, the R" to Y" circuit
is closed to energize the compressor contactor. The
contactor brings on both the compressor and outdoor fan.
The thermostat also closes the R" to G" circuit to energize
the circulating air blower. When the cooling demand is
satisfied, the thermostat opens the circuits, as well as the
compressor contactor. The compressor and outdoor fan
80°F db / 67°F wb RETURN AIR
UNIT PRESSURE
15CHAX−24
15CHAX−30
15CHAX−36
Suction Suction
15CHAX−42
15CHAX−48
15CHAX−60
15CHAX−24
15CHAX−30
15CHAX−36
Liquid Liquid
15CHAX−42
15CHAX−48
15CHAX−60
Table 7
Normal Operating Pressures
Air Temperature Entering Outdoor Coil (°F)
65 70 75 80
142 143 144 146
134 136 138 140
143 144 146 147
140 140 140 141
140 141 142 144
143 144 145 146
219 242 264 287
232 255 277 300
244 268 292 316
225 247 269 291
243 264 285 307
257 280 303 326
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immediately stop. The circulating air blower continues
operating through a 90−second delay.
Unit compressors have internal protection. If there is an
abnormal rise in the compressor temperature, the
protector will open and the compressor will stop.
System Performance
For maximum performance of this cooling system, the
operating temperatures and pressure should be checked
and subcooling determined at Standard ARI test conditions
of 82_ F outdoor temperature / 80_ F indoor dry bulb / 67_ F
indoor wet bulb. If subcooling measured deviates from
values in table 6, refrigerant charge should be adjusted
accordingly for maximum performance.
Table 6
Suction Superheat Values
Unit Model No.
15CHAX−24
15CHAX−30
15CHAX−36
15CHAX−42
15CHAX−48
15CHAX−60
Verify system performance using table 7 as a general
guide. Table 7 should not be used for charging unit. Minor
variations in these pressures may be expected due to dif-
ferences in installations. Significant differences could
mean that the system is not properly charged or that a prob-
lem exists with some component in the system.
Used carefully, this table could serve as a useful service
guide. Data is based on 80°F dry bulb / 67°F wet bulb return
air. Allow unit operation to stabilize before taking pressure
readings.
82 85 90 95
146 147 148 149
141 142 144 146
148 149 151 152
141 141 142 142
144 145 146 147
146 147 147 148
296 310 333 355
309 323 345 368
326 340 363 369
300 314 337 357
315 328 349 370
335 349 372 395
Suction Superheat
82_F OD / 80_F IDDB
/ 67_F IDWB
12_
15_
10_
100 105 110 115
150 151 152 153
148 149 151 152
155 155 157 157
143 144 145 147
148 149 150 151
149 150 151 152
379 398 430 457
390 408 440 470
410 429 461 493
383 402 434 457
391 408 440 470
418 436 468 497