SEQUENCES OF OPERATION CONTINUED
Hot Gas Bypass
Hot gas bypass is a means of capacity control during
lower ambient temperature conditions.
The Hot Gas Bypass valve is an adjustable valve and
should be set to open when the refrigerant suction
pressure drops to 107 – 112 psig. It varies unit capacity by
introducing discharge refrigerant into the evaporator
circuit where it creates a false evaporator load. The hot
gas is cooled prior to its return to the compressor as it
passes through the evaporator.
The Hot Gas Bypass Solenoid Valve is energized
through the thermostat and routs discharge gas to the
hot gas bypass valve. It is deenergized during the pump
down cycle.
Optional Motorized Outside Air Damper
Motorized dampers are energized to open when the
compressor or compressors are operating.
Optional Clogged Filter Indicator
Dirty or clogged filters are red flagged by an indicator
when the preset pressure differential across the filters is
reached. The indicator is factory installed and manual-
reset. It includes contacts for remote annunciation.
SureTrip™ Phase Monitor
Provides line voltage monitoring and momentary power
failure (brown out) protection. At power interruption,
thermostat control voltage is interrupted. This device is
auto-reset with 5 minute time delay when line power is
restored. This devise also provides phase reversal
protection; therefore if it is replaced, motor rotation
should be verified.
START-UP PROCEDURES
Electrical shock, fire and/or explosion hazard.
Use extreme care during all of the following
checks and procedures.
Make sure Electric Power is turned OFF as
instructed in appropriate steps.
Failure to follow this warning can result in
property damage, personal injury, and/or death.
Check the unit’s operation as outlined in the following
instructions.
Blower and Phasing Check
1. Shut electric power OFF at unit disconnect.
2. Check to see that clean, properly sized air filters are
installed.
3. Check to see that everything inside the unit is clear
and ready to operate safely. Ensure that there are no
objects in, on or around the motor, belt or blower
wheel.
4. Set thermostat Heat-Cool selector (or time clock/
interlock switch) to OFF.
5. Set thermostat fan switch to AUTO.
6. Turn electric power ON. Nothing should start running.
If any unusual arcing, odors or noises are
encountered, shut electric power OFF immediately
and check for wiring errors.
NOTE: The circulation blower motor and compressor(s)
are three phase and are factory synchronized for proper
rotation. Even if the circulation blower motor comes on
and air seems to be circulating, it is possible that the
blower motor rotation is incorrect due to improper
phasing. The scroll compressor(s) (if equipped) will run
backwards under this condition and be damaged. It is
therefore necessary to check for proper rotation.
CAUTION
Do NOT operate the unit with the compressor(s) running
until proper blower rotation has been confirmed by
running the following test.
7. Set system ON. The circulating air blower should
come ON.
8. Shut electric power OFF at unit disconnect and
visually observe the direction of the blower rotation as
it slows down. Do NOT put hands or any other object
in, on or around the belt, motor or blower wheel. If
blower wheel rotation is the same as the directional
arrow on the blower housing, proceed to the next
step.
Moving parts hazard.
Do NOT put hands or any other object in, on or
around the motor, belt or blower wheel. Ensure
that there are no objects in, on or around the
motor, belt or blower wheel before turning
electric power on.
Failure to follow this warning can result in
property damage, personal injury, and/or death.
WARNING
WARNING
!
!
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