Ii−Placement And Installation; Start Up; Preliminary Checks; Cooling Start Up - Lennox LGA Series Unit Information

II−PLACEMENT AND INSTALLATION
Make sure the unit is installed in accordance with the
installation instructions and all applicable codes. See
accessories section for conditions requiring use of the
optional roof mounting frame (LARMF18/36 or
LARMFH30/36).
III−STARTUP − OPERATION − CHARGING
IMPORTANT−The crankcase heater must be energized for
24 hours before attempting to start compressor. Set thermo-
stat so there is no demand to prevent compressors from cycl-
ing.
IMPORTANT
Units contain either R22 or R410A refrigerant. Check
the nameplate to determine the type of refrigerant
before installation or servicing.
NOTE − These units must not be used as a construction heat-
er" at any time during any phase of construction. Very low re-
turn 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 op-
eration must have a vapor barrier installed to seal the duct con-
nections. Failure to protect the unit from moisture laden air or
harmful vapors (generated from the construction process and
temporary combustion heating equipment) will cause corro-
sive condensation within the unit. Failure to properly protect
the unit in this situation will cause electrical and electronic com-
ponent 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−Cooling Start−Up
1− Initiate first and second stage cooling demands ac-
cording to instructions provided with thermostat.
2− First−stage thermostat demand will energize com-
pressors 1 and 2. Second−stage thermostat demand
will energize compressors 3 and 4 (fourth compres-
sor on 21 and 25 ton units). On units with an econo-
mizer, when outdoor air is acceptable, a first−stage
demand will energize the economizer; a second−
stage demand will energize compressors 1 and 2.
3− Units contain four refrigerant circuits or systems. Evap-
orator 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 figures 8 and 9.
360H with 3 compressors −
Units contain three refrigerant circuits or systems.
Evaporator and condenser coil refrigerant circuits 1
and 2 make up stage 1 cooling. Evaporator and con-
denser coil refrigerant circuit 3 makes up stage 2 cool-
ing.
4− Each refrigerant circuit is separately charged with R22
or 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.
Three Phase Scroll Compressor Voltage Phasing
Three phase scroll compressors must be phased se-
quentially to ensure correct compressor and blower rota-
tion and operation. Compressor and blower are wired in
phase at the factory. Power wires are color−coded as fol-
lows: line 1−red, line 2−yellow, line 3−blue.
1− Observe suction and discharge pressures and blower
rotation on unit start−up.
2− Suction pressure must drop, discharge pressure must
rise, and blower rotation must match rotation marking.
If pressure differential is not observed or blower rotation is
not correct:
3− Disconnect all remote electrical power supplies.
4− Reverse any two field−installed wires connected to the
line side of S48 disconnect or TB13 terminal strip. Do
not reverse wires at blower contactor.
5− Make sure the connections are tight.
Discharge and suction pressures should operate at their
normal start-up ranges.
Page 52