Ii-Placement And Installation; Iii-Charging - Lennox LGM Series Manual

II-PLACEMENT AND INSTALLATION

Make sure the unit is installed in accordance with the instal­
lation instructions and all applicable codes. See acces­
sories section for conditions requiring use of the optional
roof mounting frame (C1CURB10).

III-CHARGING

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.
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:
REFRIGERANT STAGES
TRADITIONAL FIN/TUBE COIL
CONDENSER COIL
STAGES 1 & 2
EVAPORATOR
COIL STAGE 2
2
1
FIGURE 27
1-
Attach gauge manifolds to discharge and suction lines. With
the economizer disabled, operate the unit in cooling mode
at high speed using the following mobile service app menu
path:
SERVICE > COMPONENT TEST > COOLING > COOL 4
2- Use a thermometer to accurately measure the outdoor
ambient temperature.
3- Apply the outdoor temperature to tables 11 through 18
to determine normal operating pressures. Pressures
(BOTH FANS ARE ENERGIZED
WITH A Y1 DEMAND)
B4
B5
EVAPORATOR
COIL STAGE 1
are listed for sea level applications at 80
5
67 F wet bulb return air.
4- 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.
5- If discharge pressure is high, remove refrigerant from
the system. If discharge pressure is low, add refriger­
ant to the system.
S Add or remove charge in increments.
S Allow the system to stabilize each time refrigerant
is added or removed.
6- Use the following subcooling method along with the
normal operating pressures to confirm readings.
TABLE 11 581027-01
LGM/LCM092U No Reheat
CIRCUIT 1
Outdoor
Dis­
Coil
charge
Entering
+10 psig
Air Temp
655 F 252
755 F 293
855 F 335
955 F 382
1055 F 434
1155 F 490
TABLE 12 581028-01
LGM/LCM092U Reheat
Outdoor
Coil Dis­
Entering
charge
Air Temp
+10 psig
655 F 258
755 F 301
855 F 344
955 F 392
1055 F 445
1155 F 504
TABLE 13 581029-01
LGM/LCM102U No Reheat
Outdoor
Coil Dis­
Entering
charge
Air Temp
+10 psig
655 F 256
755 F 294
855 F 333
955 F 381
1055 F 433
1155 F 487
Page 36
5
F dry bulb and
CIRCUIT 2
Dis­
Suction
charge
+5 psig
+10 psig
140 269
143 311
146 354
148 403
150 454
153 508
Circuit 1 Circuit 2
Dis­
Suction
charge
+5 psig
+10 psig
140 269
139 308
141 349
143 398
145 447
148 501
Circuit 1 Circuit 2
Dis­
Suction
charge
+5 psig
+10 psig
140 259
143 300
147 341
149 388
151 438
155 491
Suction
+5 psig
137
139
142
144
147
150
Suction
+5 psig
136
137
139
142
144
147
Suction
+5 psig
139
141
143
146
149
153