Page 20
LGH/LCH156, 180, 210, 240, 300S
Cooling Start-Up
IMPORTANT-The crankcase heater must be energized
for 24 hours before attempting to start compressor. Set
thermostat so there is no demand to prevent
compressors from cycling. Apply power to unit.
NOTE - These units must not be used as a “construction
heater” at any time during any phase of construction. Very
low return air temperatures, harmful vapors and
misplacement of the filters will damage the unit and its
efficiency. Additionally, a unit which will be subject to cold
temperatures when not in operation must have a vapor
barrier installed to seal the duct connections. Failure to
protect the unit from moisture laden air or harmful vapors
(generated from the construction process and temporary
combustion heating equipment) will cause corrosive
condensation within the unit. Failure to properly protect the
unit in this situation will cause electrical and electronic
component failure and could affect the unit warranty status.
A-Preliminary Checks
1- Make sure that 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.
3- Check to ensure that refrigerant lines do not rub against
the cabinet or against other refrigerant lines.
4- Check voltage at disconnect switch. Voltage must be
within range listed on nameplate. If not, consult
power company and have voltage condition
corrected before starting unit.
5- Make sure filters are in place before start‐up.
B-Start-Up
Supply Air Inverter Units - Refer to the Supply Air
Inverter Start-Up section.
1- Initiate first and second stage cooling demands
according to instructions provided with thermostat.
2-
156, 180H, 210, 240H, 300S -
First-stage thermostat demand will energize
compressors 1 and 2. Second-stage thermostat
demand will energize compressors 3 and 4 (fourth
compressor on 20 and 25 ton units only). On units
with an economizer, when outdoor air is
acceptable, a first-stage demand will energize the
economizer; a second-stage demand will energize
compressors 1 and 2.
180U & 240U -
First-stage thermostat demand will energize one of
the following compressor combinations:
Compressor 1 (circuit 1) and Compressor 3 (circuit 2)
Compressor 1 (circuit 1) and Compressor 4 (circuit 2)
Compressor 2 (circuit 1) and Compressor 3 (circuit 2)
Compressor 2 (circuit 1) and Compressor 4 (circuit 2)
Second-stage thermostat demand will energize
the remaining two compressors. On units with an
economizer, when outdoor air is acceptable, a
first-stage demand will energize the economizer;
a second-stage demand will energize
compressors in the same manner as a first-stage
demand (no econo).
IMPORTANT
Run units equipped with tandem compressors in full
load (all compressors running) for a minimum of thir
ty (30) minutes or until compressor sump superheat
is above 20°F for each compressor. Check the oil
level of each tandem compressor assembly using
the sight glass installed in the oil equalization line
near the base of the compressors. The oil level
should be visible in the sight glass, preferably in the
middle. If the oil level is not visible in the sight glass,
refer to the section in the Unit Service Manual titled
“Tandem Compressor Oil Level Test Procedure” to
add oil to the system.
3-
156, 180H, & 210 -
Units contain three refrigerant circuits or systems.
Evaporator and condenser coil refrigerant circuits 1
and 2 make up stage 1 cooling. Evaporator and
condenser coil refrigerant circuit 3 makes up stage 2
cooling. See figure 19.
240H, 300S -
Units contain four refrigerant circuits or systems.
Evaporator and condenser coil refrigerant circuits 1
and 2 make up stage 1 cooling. Evaporator and
condenser refrigerant circuits 3 and 4 make up stage
2 cooling. See figure 20.
180U, 240U -
Units contain two refrigerant circuits or systems.
Evaporator and condenser coil refrigerant circuits 1
makes up stage 1 cooling. Evaporator and condenser
refrigerant circuit 2 makes up stage 2 cooling. See
figure 21.
4- Each refrigerant circuit is separately charged with
R410A refrigerant. See unit rating plate for correct
amount of charge.
5- Refer to Cooling Operation and Adjustment section
for proper method to check refrigerant charge.
