Lennox LHT180 Installation Instructions Manual page 20

TABLE 6
240 Compressor 1 Frequency 68Hz - 581169-01
Outdoor
Circuit 1
Coil En­
Dis +10 Suc +5
tering Air
psig
Temp
65 °F 260
75 °F 297
85 °F 338
95 °F 384
105 °F 434
115 °F 485
E-Charge Verification - Approach Method - AHRI Testing
(Fin/Tube Coil)
1- Using the same thermometer, compare liquid
temperature to outdoor ambient temperature.
Approach Temperature = Liquid temperature (at
outdoor coil outlet) minus ambient temperature.
2- Approach temperature should match values in table
7. An approach temperature greater than value
shown indicates an undercharge. An approach
temperature less than value shown indicates an
overcharge.
3- The approach method is not valid for grossly over or
undercharged systems.
guide for typical operating pressures.
TABLE 7
APPROACH TEMPERATURES - FIN/TUBE COIL
Liquid Temp. Minus Ambient Temp.
Unit
1st Stage
2°F + 1
180
(1.1°C +0.5)
6°F + 1
240
(3.3°C +0.5)
LHT/LDT180, 240
Circuit 2
Dis. +10 Suc +5
psig psig psig
135 264 135
136 304 136
138 346 138
140 394 140
142 443 142
144 494 144
5 through 6
Use tables
2nd Stage
5.0°F + 1
(2.8°C +0.5)
6°F + 1
(3.3°C +0.5)
F-Compressor Controls
See unit wiring diagram to determine which controls are
used on each unit.
1- High Pressure Switch (S4, S7)
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, S88)
The compressor circuit is protected by a low
pressure switch. Switch opens at 40 psig + 5 psig
(276 + 34 kPa) and automatically resets at 90 psig
+ 5 psig (621 kPa + 34 kPa).
3- Crankcase Heater (HR1, HR2)
Units have compressors which contain a belly band
compressor oil heater which must be on 24 hours before
running compressors. Energize by setting thermostat so
that there is no cooling demand, to prevent compressor
from cycling, and apply power to unit.
4- Outdoor Fan Operation
Outdoor fans 1, 2, and 3 are energized when
compressor 1 is energized. As cooling demand
increases, all six outdoor fans are energized. See
figure 16.
as a
Outdoor fans 2, 3, 5, and 6 are de-energized when
outdoor temperature drops below 62°F (17°C).
COMPRESSORS
1 2
Page 20
OUTDOOR FANS
COND.
COND.
FAN 6
FAN 3
COND. COND.
FAN 5 FAN 2
COND. COND.
FAN 4 FAN 1
FIGURE 16