Lennox LGT036 Installation Instructions Manual page 29

072 NORMAL OPERATING PRESSURES - REHEAT - ALL-ALUMINUM COIL - 581111-01
65 F
Suct Disc Suct
(psig) (psig) (psig)
108 276 109
116 281 118
135 294 137
156 310 158
072 CHARGING CURVE - REHEAT - ALL-ALUMINUM COIL - 581111-01
130
120
110
100
90
80
70
60
105 115
C-Compressor Controls
See unit wiring diagram to determine which controls are
used on each unit. Optional controls are identified on
wiring diagrams by arrows at junction points.
1- High Pressure Switch (S4)
The compressor circuit is protected by a high
pressure switch which opens at 640 psig + 10 psig
(4413 kPa + 70 kPa) and automatically resets at 475
psig + 20 psig (3275kPa + 138 kPa).
2- Low Pressure Switch (S87)
The compressor circuit is protected by a loss of
charge switch. Switch opens at 40 psig + 5 psig (276
+ 34 kPa) and automatically resets at 90 psig + 5
psig (621 kPa + 34 kPa).
LGT/LCT036, 048, 060, 072
Outdoor Coil Entering Air Temperature
75 F 85 F
Disc Suct
(psig) (psig) (psig)
316 111
320 120
332 140
348 161
125
TABLE 12
95 F
Disc Suct Disc
(psig) (psig)
363 113 418
367 123 422
379 143 432
394 165 447
135 145
Suction Pressure (psig)
3- Diagnostics Sensors (RT46, RT48)
Two thermistors are located on specific points in the
refrigeration circuit. The thermistors provide constant
temperature feedback to the Unit Controller to protect
the compressor. Thermistors take the place of the
freezestat and low ambient pressure switch.
4- Compressor Crankcase Heater (HR1)
Crankcase heater must be energized at all times to
prevent compressor damage due to refrigerant
migration. Energize crankcase heater 24 hours before
unit start-up by setting thermostat so that there is no
cooling demand (to prevent compressor from cycling)
and apply power to unit.
Page 29
105 F 115 F
Suct Disc Suct
(psig) (psig) (psig)
116 480 118
125 484 128
146 494 149
168 508 172
Outdoor Temperature (°F)
95°
85°
75°
65°
155 165
Disc
(psig)
550
554
563
576
115°
105°
175