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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
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
LCH150S Normal Operating Pressures - Fin/Tube - RFC
Outdoor Coil Entering Air Temperature
65 °F 75 °F 85 °F 95 °F 105 °F 115 °F
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Circuit 1
108 253 112 295 114 338 117 384 119 438 122 501
114 255 119 296 122 342 125 390 127 444 129 501
119 257 129 303 136 348 141 403 145 460 149 522
125 264 136 308 146 358 155 413 161 470 167 530
Circuit 2
108 273 111 314 114 356 117 400 119 451 121 508
115 277 119 318 122 362 125 409 128 460 129 512
124 284 131 327 137 372 141 422 145 474 147 532
131 289 140 334 148 382 155 434 160 486 163 541
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
5F dry bulb
and 67
5F 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 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.
TABLE 20
LCH094U
Outdoor Coil
Entering Air
Temp
Discharge +10
psig
Suction +5 psig
655 F 238 136
755 F 273 141
855 F 313 143
955 F 361 146
1055 F 396 149
1155 F 448 152
TABLE 21
LCH122U
Outdoor Coil
Entering Air
Temp
Discharge +10
psig
Suction +5 psig
655 F 250 134
755 F 288 138
855 F 331 141
955 F 378 143
1055 F 412 144
1155 F 463 147
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