Cooling Start-Up - Lennox LGH480 Installation Instructions Manual

Cooling Start-Up

IMPORTANT-The crankcase heater must be energized for
24 hours before attempting to start compressor. Set control
so there is no cooling demand to prevent compressors from
operating. 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.
IMPORTANT
Three Phase Scroll Compressor Voltage Phasing
Three phase scroll compressors must be phased sequen­
tially to ensure correct compressor and blower* rotation
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.
*Supply air VFD motors should rotate in the correct di­
rection; verify scroll compressor rotation separately.
Contact technical support if the VFD blower is rotating
incorrectly.
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
1- Initiate first and second stage cooling demands
according to instructions provided with thermostat.
2- 2 Heat / 2 Cool Thermostat -
First-stage
compressors 1 and 2. Second-stage thermostat
demand will energize compressors 3 and 4. 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. Refer to the Unit Controller manual provided with
each unit for other staging options.
3- Each refrigerant circuit is separately charged with
R410A refrigerant. See unit rating plate for correct
amount of charge. See figure 31 for refrigerant routing
on units equipped with a variable air volume supply air
blower. See figure 49 for refrigerant routing on units
equipped with a hot gas reheat coil.
4- Refer to Refrigerant Check and Charge section for proper
method to check refrigerant charge.
Manifold gauge sets used with systems charged with
R410A refrigerant must be capable of handling the higher
system operating pressures. The gauges should be rated
for use with pressures of 0-800 on the high side and a low
side of 30" vacuum to 250 psi with dampened speed to 500
psi. Gauge hoses must be rated for use at up to 800 psi of
pressure with a 4000 psi burst rating.
C-R410A Refrigerant
Units charged with R410A refrigerant operate at much
higher pressures than R22. The expansion valve and liquid
line drier provided with the unit are approved for use with
R410A. Do not replace them with components designed for
use with R22.
R410A refrigerant is stored in a pink cylinder.
Mineral oils are not compatible with R410A. If oil must
be added, it must be a polyol ester oil.
Page 32
thermostat demand will
IMPORTANT
LGH/LCH420, 480, 540, 600
energize