Iv-Startup - Operation - Lennox LGM Series Manual

TABLE 18
300 Reheat Compressor 1 Frequency 68Hz - 581023-01
Outdoor Circuit 1 Circuit 2
Coil
Dis. Suc. Dis.
Entering
+10 +5 +10
Air
psig psig psig
Temp
65°F 274 121 295
75°F 316 124 339
85°F 363 126 387
95°F 415 129 442
105°F 469 132 497
115°F 525 136 558
E-Charge Verification - Approach Method - AHRI Test-
ing (Fin/Tube Coil)
1 - Using the same thermometer, compare liquid
temperature to outdoor ambient temperature.
Approach Temperature = Liquid temperature (at con-
denser outlet) minus ambient temperature.
2 - Approach temperature should match values in table
19. 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. Use tables 9 through 18 as
a guide for typical operating pressures.
TABLE 19
APPROACH TEMPERATURES - FIN/TUBE COIL
Liquid Temp. Minus Ambient Temp.
Unit
1st Stage 2nd Stage
156 3.0°F + 1 6.0°F + 1
Std. (1.7°C +0.5) (3.3°C +0.5)
156 1.7°F+1 1.7°F+1
Reheat (0.9°C+0.5) (0.9°C+0.5)
180 2.5°F + 1 5.0°F + 1
Std. (1.4°C +0.5) (2.8°C +0.5)
180 1.0°F + 1 2.8°F + 1
Reheat (0.6°C +0.5) (1.6°C +0.5)
210 1.0°F + 1 5.5°F + 1
Std. (0.6°C +0.5) (3.1°C +0.5)
210 2.5°F + 1 3.7°F + 1
Reheat (1.4°C +0.5) (2.1°C +0.5)
240 3.5°F + 1 8.3°F + 1
Std. (1.9°C +0.5) (4.6°C +0.5)
240 1.9°F + 1 3.8°F + 1
Reheat (1.1°C +0.5) (2.1°C +0.5)
300 1.5°F+1 5.5°F+1
Std. (0.8°C+0.5) (3.1°C+0.5)
300
2.8°F+1 4.2°F+1
Reheat (1.5°C+0.5) (2.3°C+0.5)
Circuit 3 Circuit 4
Suc. Dis. Suc. Dis. Suc.
+5 +10 +5 +10
psig psig psig psig psig
120 259 114 275
122 301 123 317
124 346 131 362
127 395 137 414
130 447 142 464
133 502 145 519
3rd Stage 4th Stage
6.5°F + 1
NA
(3.6°C +0.5)
2.7°F+1
NA
(1.5°C+0.5)
5.5°F + 1
NA
(3.1°C +0.5)
4.8°F + 1
NA
(2.7°C +0.5)
3.0°F + 1 6.0°F + 1
(1.7°C +0.5) (3.3°C +0.5)
6.0°F + 1 4.3°F + 1
(3.3°C +0.5) (2.4°C +0.5)
4.7°F + 1 7.5°F + 1
(2.6°C +0.5) (4.2°C +0.5)
2.2°F + 1 5.4°F + 1
(1.2°C +0.5) (3.0°C +0.5)
4.0°F+1 6.5°F+1
(2.2°C+0.5) (3.6°C+0.5)
3.8°F+1 5.4°F+1
(2.1°C+0.5) (3.0°C+0.5)

IV-STARTUP - OPERATION

Refer to startup directions and to the unit wiring diagram
when servicing. See unit nameplate for minimum circuit
ampacity and maximum fuse size.
A-Preliminary and Seasonal Checks
+5
1 - Make sure the unit is installed in accordance with
120 the installation instructions and applicable codes.
128
2 - Inspect all electrical wiring, both field and factory
installed for loose connections. Tighten as required.
135
Refer to unit diagram located on inside of unit
141
control box cover.
144
3 - Check to ensure that refrigerant lines are in good
147
condition and do not rub against the cabinet or
other refrigerant lines.
4 - Check voltage. Voltage must be within the range
listed on the nameplate. If not, consult power
company and have the voltage corrected before
starting the unit.
5 - Recheck voltage and amp draw with unit running. If
voltage is not within range listed on unit nameplate,
stop unit and consult power company. Refer to unit
nameplate for maximum rated load amps.
6 - Inspect and adjust blower belt (see section on
Blower Compartment - Blower Belt Adjustment).
B-Cooling Startup See figure 7 for unit refrigerant
circuits
NOTE-Crankcase heaters must be energized 24 hours
before attempting to start compressor. Set thermostat so
that there is no demand to prevent compressor from cy-
cling.
Apply power to unit.
1 - Initiate first and second stage cooling demands
according to instructions provided with thermostat.
2 - First-stage
indoor blower in Low Cooling CFM. Second-stage
thermostat demand will energize indoor blower
in High Cooling CFM. Both demands energize
compressor
The remaining compressors will be energized to
modulate the discharge air temperature.
3 - 156, 180-
Units contain three refrigerant circuits or systems.
210, 240, 300 -
Units contain four refrigerant circuits or systems.
4 - Each refrigerant circuit is separately charged with
R410A refrigerant. See unit rating plate for correct
amount of charge.
5 - Refer to the Refrigerant Check and Charge section
to check refrigerant charge.
Page 35
thermostat demand will
1 (variable speed
energize
compressor).