Iv-Startup - Operation - Lennox LGH Series Unit Information

C-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
37. 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 24 through 35
as a guide for typical operating pressures.
TABLE 37
APPROACH TEMPERATURES - FIN/TUBE COIL
Liquid Temp. Minus Ambient Temp.
L Series
Unit
1st Stage 2nd Stage
9°F + 1
156H Std.
(5.0°C +0.5) (5.0°C +0.5)
156H
6°F+1
Reheat (3.3°C+0.5) (3.3°C+0.5)
6°F + 1
180H Std.
(3.3°C +0.5) (3.3°C +0.5)
180H
4°F + 1
Reheat (2.2°C +0.5) (2.2°C +0.5)
5°F + 1
180U
(2.8°C +0.5) (3.6°C +0.5)
6°F + 1
210H Std.
(3.3°C +0.5) (3.3°C +0.5)
210H 4°F + 1
Reheat (2.2°C +0.5) (2.2°C +0.5)
6°F + 1
240H Std.
(3.3°C +0.5) (3.3°C +0.5)
240H 4°F + 1
Reheat (2.2°C +0.5) (2.2°C+0.5)
4°F + 1
240U
(2.2°C +0.5) (3.6°C +0.5)
5°F+1
300S Std.
(2.8°C+0.5) (2.8°C+0.5)
300S 3°F+1
Reheat (1.7°C+0.5) (1.7°C+0.5)
4°F + 1
300U
(2.2°C +0.5) (5.5°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.
3rd Stage 4th Stage
9°F + 1 11°F + 1
(6.1°C +0.5)
6°F+1 11°F+1
(6.1°C+0.5)
6°F + 1 6°F + 1
(3.3°C +0.5)
4°F + 1 6°F + 1
(3.3°C +0.5)
6.5°F + 1
NA
6°F + 1 7°F + 1
(3.9°C +0.5)
4°F + 1 7°F + 1
(3.9°C +0.5)
6°F + 1 7°F + 1 7°F + 1
(3.9°C +0.5) (3.9°C +0.5)
4°F + 1 8°F + 1 8°F + 1
(4.4°C +0.5) (4.4°C +0.5)
6.5°F + 1
NA
5°F+1 8°F+1 8°F+1
(4.4°C+0.5) (4.4°C+0.5)
3°F+1 8°F+1 8°F+1
(4.4°C+0.5) (4.4°C+0.5)
10°F + 1
NA
A-Preliminary and Seasonal Checks
1 - Make sure the unit is installed in accordance with
the installation instructions and applicable codes.
2 - Inspect all electrical wiring, both field and factory
installed for loose connections. Tighten as required.
Refer to unit diagram located on inside of unit
control box cover.
3 - Check to ensure that refrigerant lines are in good
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 26 and 27
NA
NOTE-Crankcase heaters must be energized 24 hours
NA
before attempting to start compressor. Set thermostat so
that there is no demand to prevent compressor from cy-
NA
cling. Apply power to unit.
NA
1 - Initiate first and second stage cooling demands
according to instructions provided with thermostat.
NA
2 - First-stage
NA
compressors 1 and 2 on all standard and high
efficient units. Second-stage thermostat demand
NA
will energize compressor on all standard and high
efficiency units and compressor 4 on LGH240H/300.
First-stage
one compressor from each circuit on ultra high
efficiency units. Second-stage thermostat demand
NA
will energize the remaining two compressors, one in
each circuit, on ultra high efficiency units.
3 - Units contain three or four refrigerant circuits or
stages.
4 - Each refrigerant circuit is separately charged with
NA
refrigerant. See unit rating plate for correct amount
of charge.
NOTE - Refer to III-CHARGING for proper method
to check refrigerant charge.
Page 79
thermostat demand will
thermostat demand will
energize
energize