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LGH/LCH036, 048, 060, 072
C-Refrigerant Charge and Check - All-Aluminum Coil
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,
reclaim the charge,
evacuate the system, and add
required nameplate charge.
NOTE - System charging is not recommended below
60F (15C). In temperatures below 60F (15C), 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
high stage only
.
1- Make sure outdoor coil is clean. Attach gauge
manifolds and operate unit at full CFM in cooling mode
with economizer disabled until system stabilizes
(approximately five minutes). Make sure all outdoor air
dampers are closed.
2- Compare the normal operating pressures (see tables
7 - 13) to the pressures obtained from the gauges.
Check unit components if there are significant
differences.
3- Measure the outdoor ambient temperature and the
suction pressure. Refer to the appropriate circuit
charging curve to determine a target liquid
temperature.
Note - Pressures are listed for sea level applications.
4- Use the same thermometer to accurately measure the
liquid temperature (in the outdoor section).
If measured liquid temperature is higher than
the target liquid temperature, add refrigerant to
the system.
If measured liquid temperature is lower than
the target liquid temperature, recover some
refrigerant from the system.
5- Add or remove charge in increments. Allow the
system to stabilize each time refrigerant is added or
removed.
6- Continue the process until measured liquid
temperature agrees with the target liquid
temperature. Do not go below the target liquid
temperature when adjusting charge. Note that
suction pressure can change as charge is adjusted.
7- Example LGH/LCH036H: At 95°F outdoor ambient
and a measured suction pressure of 130psig, the
target liquid temperature is 98°F. For a measured
liquid temperature of 106°F, add charge in
increments until measured liquid temperature agrees
with the target liquid temperature.
TABLE 7
LGH/LCH036S NORMAL OPERATING PRESSURES - ALL-ALUMINUM COIL
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)
113 235 117 274 116 329 118 379 121 438 124 497
121 239 122 284 125 327 127 378 129 437 132 506
138 248 141 288 144 329 147 375 151 427 151 497
157 264 160 297 163 339 167 387 172 437 175 492
TABLE 8
LGH/LCH036H NORMAL OPERATING PRESSURES - ALL-ALUMINUM COIL
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)
115 242 116 283 119 328 120 382 122 444 124 535
121 245 124 284 126 329 128 379 129 447 131 528
138 255 143 294 146 340 148 389 151 441 152 515
155 267 160 305 165 349 168 399 171 454 175 514
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