Lennox LCH036 Installation Instructions Manual page 29

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
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
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
LGH/LCH036S NORMAL OPERATING PRESSURES - ALL-ALUMINUM COIL
65 F
Suct Disc Suct
(psig) (psig) (psig)
113 235 117
121 239 122
138 248 141
157 264 160
LGH/LCH036H NORMAL OPERATING PRESSURES - ALL-ALUMINUM COIL
65 F
Suct Disc Suct
(psig) (psig) (psig)
115 242 116
121 245 124
138 255 143
155 267 160
LGH/LCH036, 048, 060, 072
Outdoor Coil Entering Air Temperature
75 F 85 F
Disc Suct
(psig) (psig) (psig)
274 116
284 125
288 144
297 163
Outdoor Coil Entering Air Temperature
75 F 85 F
Disc Suct
(psig) (psig) (psig)
283 119
284 126
294 146
305 165
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).
D If measured liquid temperature is higher than
the target liquid temperature, add refrigerant to
the system.
D 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
temperature
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
95 F
Disc Suct Disc
(psig) (psig)
329 118 379
327 127 378
329 147 375
339 167 387
TABLE 8
95 F
Disc Suct Disc
(psig) (psig)
328 120 382
329 128 379
340 148 389
349 168 399
Page 29
the process until measured
agrees with the
105 F
Suct Disc Suct
(psig) (psig) (psig)
121 438 124
129 437 132
151 427 151
172 437 175
105 F
Suct Disc Suct
(psig) (psig) (psig)
122 444 124
129 447 131
151 441 152
171 454 175
liquid
target liquid
115 F
Disc
(psig)
497
506
497
492
115 F
Disc
(psig)
535
528
515
514