Refrigerant Circuits - Lennox KGA Series Service Literature

5- Make sure the connections are tight.
Discharge and suction pressures should operate at their
normal start‐up ranges.

REFRIGERANT CIRCUITS

092/150
EVAPORATOR
COIL STAGE 2
2
1
FIGURE 19
D-Safety or Emergency Shutdown
Turn off power to unit. Close manual and main ga valves.
IV-CHARGING
WARNING
Refrigerant can be harmful if it is inhaled. Refrigerant
must be used and recovered responsibly.
Failure to follow this warning may result in person­
al injury or death.
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:
1- Attach gauge manifolds and operate unit in cooling
mode with economizer disabled until system stabilizes
(approximately five minutes). Make sure outdoor air
dampers are closed.
2- Check each system separately with all stages operating.
3- Use a thermometer to accurately measure the outdoor
ambient temperature.
4- Apply the outdoor temperature to tables 7 through 10
to determine normal operating pressures.
(BOTH FANS ARE ENERGIZED
WITH A Y1 DEMAND)
EVAPORATOR
COIL STAGE 1
Pressures are
listed for sea level applications at 80°F dry bulb and 67°F wet
bulb return air.
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 refrigerant
to the system.
S Add or remove charge in increments.
S Allow the system to stabilize each time refrigerant
is added or removed.
7- Use the following approach method along with the nor­
mal operating pressures to confirm readings.
KGA092 NORMAL OPERATING PRESSURES
CIRCUIT 1
Outdoor
Dis­
Coil
charge
Entering
+10 psig
Air Temp
655 F 260
755 F 301
855 F 343
955 F 388
1055 F 435
1155 F 481
KGA102 NORMAL OPERATING PRESSURES
CIRCUIT 1
Outdoor
Dis­
Coil
charge
Entering
+10 psig
Air Temp
655 F 262
755 F 299
855 F 342
955 F 386
1055 F 434
1155 F 487
KGA120 NORMAL OPERATING PRESSURES
CIRCUIT 1
Outdoor
Dis­
Coil
charge
Entering
+10 psig
Air Temp
655 F 275
755 F 313
855 F 355
955 F 400
1055 F 447
1155 F 499
Page 26
TABLE 7
CIRCUIT 2
Dis­
Suction charge Suction
+5 psig +5 psig
+10 psig
130 269
133 311
135 354
138 401
140 449
142 497
TABLE 8
CIRCUIT 2
Dis­
Suction Suction
charge
+5 psig +10 psig +5 psig
128 270
131 310
134 353
137 399
140 448
143 501
TABLE 9
CIRCUIT 2
Dis­
Suction Suction
charge
+5 psig +5 psig
+10 psig
135 282
137 323
140 366
142 414
145 464
148 517
132
133
136
139
141
144
129
131
134
136
139
142
136
138
141
143
145
148