Lennox LCH156H, Installation Instructions Manual

Page: 23 / 59

Page 23
507124-04 3/2016
D-Refrigerant Charge and Check - All-Aluminum Coils
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
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- 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- Check each system separately with all stages
operating. Compare the normal operating pressures
(see tables 4 - 8) 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 on Page 26 through Page 35 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/LCH180H Circuit 1: At 95°F outdoor
ambient and a measured suction pressure of
130psig, the target liquid temperature is 96.5°F. For
a measured liquid temperature of 106°F, add charge
in increments until measured liquid temperature
agrees with the target liquid temperature.
TABLE 4
LGH/LCH156H NORMAL OPERATING PRESSURES - ALUMINUM COIL
Normal Operating Pressures
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
110 241 112 279 115 321 117 367 119 419 122 472
118 245 121 282 124 324 127 370 129 420 131 474
137 255 140 292 142 333 145 378 148 431 152 484
154 266 160 304 163 346 163 392 171 441 174 496
Circuit 2
111 249 112 287 113 328 116 374 118 423 121 474
119 253 120 291 122 332 124 378 127 428 129 481
137 263 139 301 142 342 145 387 146 438 149 490
153 276 158 313 162 356 164 402 167 451 171 505
Circuit 3
115 256 116 294 118 335 120 381 122 429 124 480
123 261 125 299 128 340 130 386 132 436 133 488
140 273 143 311 146 353 149 398 152 449 154 502
157 284 162 324 166 367 169 413 171 462 174 515