Lennox LCH092H Unit Information page 55

go below the target liquid temperature when adjusting
charge. Note that suction pressure can change as
charge is adjusted.
7 Example LCH150 Circuit 1: At 95°F outdoor ambient
and a measured suction pressure of 130psig, the target
65 °F
Suct
(psig)
108
114
Circuit 1
119
125
108
115
Circuit 2
124
131
E-Refrigerant Charge and Check - Fin/Tube Coil & TXV
LCH094U, 122U, 152U
WARNING-Do not exceed nameplate charge under any
condition.
This unit is factory charged and should require no further
adjustment. If the system requires additional refrigerant, re­
claim the charge, evacuate the system, and add required
nameplate charge.
This unit is equipped with solenoid valves
which do not allow refrigerant flow between the high side and
the low side when the unit is de-energized. When reclaiming/
evacuating the system, make sure refrigerant/vacuum is
pulled from both the suction and discharge lines. When adding
nameplate charge, add 1/3 to the suction line and 2/3 to the
discharge line.
NOTE - System charging is not recommended below 60°F
(15°C). In temperatures below 60°F (15°C) , the charge
must be weighed into the system.
If weighing facilities are not available, or to check the
charge, use the following procedure:
IMPORTANT - Charge unit in standard cooling mode.
1 Attach gauge manifolds and operate unit in cooling
mode with economizer disabled until system stabilizes
(approximately five minutes). Make sure outdoor air
dampers are closed.
2 Make sure both compressors are operating.
3 Use a thermometer to accurately measure the outdoor
ambient temperature.
4 Apply the outdoor temperature to tables 20 through 22
to determine normal operating pressures. Pressures
are listed for sea level applications at 80
5
and 67 F wet bulb return air.
5 Compare the normal operating pressures to the pres­
sures obtained from the gauges. Minor variations in
LCH150S Normal Operating Pressures - Fin/Tube - RFC
75 °F
Disc Suct Disc
(psig) (psig) (psig)
253 112 295
255 119 296
257 129 303
264 136 308
273 111 314
277 119 318
284 131 327
289 140 334
5
F dry bulb
liquid temperature is 96°F. For a measured liquid tem­
perature of 106°F, add charge in increments until mea­
sured liquid temperature agrees with the target liquid
temperature.
TABLE 19
Outdoor Coil Entering Air Temperature
85 °F 95 °F
Suct Disc Suct
(psig) (psig) (psig)
114 338 117
122 342 125
136 348 141
146 358 155
114 356 117
122 362 125
137 372 141
148 382 155
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 refrigerant
to the system.
S Add or remove charge in increments.
S Allow the system to stabilize each time refrigerant
is added or removed.
7 Use the following approach method along with the nor­
mal operating pressures to confirm readings.
Outdoor Coil
Entering Air
Temp
655 F
755 F
855 F
955 F
1055 F
1155 F
Outdoor Coil
Entering Air
Temp
655 F
755 F
855 F
955 F
1055 F
1155 F
Page 55
105 °F
Disc Suct Disc
(psig) (psig) (psig)
384 119 438
390 127 444
403 145 460
413 161 470
400 119 451
409 128 460
422 145 474
434 160 486
TABLE 20
LCH094U
Discharge +10
psig
238
273
313
361
396
448
TABLE 21
LCH122U
Discharge +10
psig
250
288
331
378
412
463
115 °F
Suct Disc
(psig) (psig)
122 501
129 501
149 522
167 530
121 508
129 512
147 532
163 541
Suction +5 psig
136
141
143
146
149
152
Suction +5 psig
134
138
141
143
144
147