Charging - Lennox LGA Series Unit Information

R410A Refrigerant
Units charged with R410A refrigerant operate at much
higher pressures than R22. The expansion valve and liquid
line drier provided with the unit are approved for use with
R410A. Do not replace them with components designed for
use with R22.
R410A refrigerant is stored in a pink cylinder.
IMPORTANT
Mineral oils are not compatible with R410A. If oil
must be added, it must be a polyol ester oil.
Manifold gauge sets used with systems charged with
R410A refrigerant must be capable of handling the higher
system operating pressures. The gauges should be rated
for use with pressures of 0−800 on the high side and a low
side of 30" vacuum to 250 psi with dampened speed to 500
psi. Gauge hoses must be rated for use at up to 800 psi of
pressure with a 4000 psi burst rating.
Turn off power to the unit.
C−Refrigerant Charge and Check
WARNING−Do not exceed nameplate charge under any
condition.
This unit is factory charged and should require no further
adjustment. If the system requires charge, 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− Attach gauge manifolds and operate unit in cooling mode
until system stabilizes (approximately five minutes).
Make sure all outdoor air dampers are closed.
2− Check each system separately with all stages operat-
ing.
3− Use a thermometer to accurately measure the outdoor
ambient temperature.
4− Apply the outdoor temperature to tables 6 through 19
to determine normal operating pressures.
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 refriger-
ant to the system.
D Add or remove charge in increments.
D Allow the system to stabilize each time refriger-
ant is added or removed.
7− Use the following approach method along with the nor-
mal operating pressures to confirm readings.
LGA/LCA Series 248 − R22 − CAV
CIRCUIT 1
Outdoor
Coil En-
DIs Suc
tering Air +10 +5
psig psig
Temp
65_F* 158 68
75_F 181 69
85_F 207 70
95_F 235 71
105_F 269 74
115_F 304 76
*Outdoor fans may cycle on and off at this temperature.
LGA/LCA Series 248 − R22 − VAV
CIRCUIT 1
Outdoor
Coil En-
Dis. Suc.
tering Air +10 +5
psig psig
Temp
65_F* 150 71
75_F 181 73
85_F 212 75
95_F 242 78
105_F 274 80
115_F 306 82
*Outdoor fans may cycle on and off at this temperature.
LGA/LCA Series 248 − R410A − CAV
CIRCUIT 1
Outdoor
Coil En-
Dis. Suc.
tering Air +10 +5
psig psig
Temp
65_F* 248 120
75_F 284 122
85_F 324 125
95_F 367 127
105_F 415 131
115_F 468 139
*Outdoor fans may cycle on and off at this temperature.
Page 53
TABLE 6
CIRCUIT 2 CIRCUIT 3 CIRCUIT 4
Dis Suc DIs Suc DIs
+10 +5 +10 +5 +10
psig psig psig psig psig
156 72 157 75 156
183 77 190 82 190
211 77 218 83 217
241 78 248 84 248
273 80 282 86 284
310 82 320 87 322
TABLE 7
CIRCUIT 2 CIRCUIT 3 CIRCUIT 4
Dis. Suc. Dis. Suc. Dis.
+10 +5 +10 +5 +10
psig psig psig psig psig
150 75 158 79 156
180 77 190 81 190
210 79 220 82 220
241 80 252 83 254
272 82 285 84 288
302 84 315 85 320
TABLE 8
CIRCUIT 2 CIRCUIT 3 CIRCUIT 4
Dis. Suc. Dis. Suc. Dis.
+10 +5 +10 +5 +10
psig psig psig psig psig
250 134 250 139 251
287 137 288 143 290
329 139 329 145 332
374 141 375 147 379
425 144 425 150 430
478 146 475 152 485
Suc
+5
psig
72
80
80
82
86
85
Suc.
+5
psig
81
82
83
84
86
87
Suc.
+5
psig
136
139
142
145
147
150