52
Operation
Unit operations must be controlled with
thermostat or unit controller, never at the
main power supply, except for emergency or
complete shutdown of the unit.
Refrigerant Detection System
Unit is equipped with a Refrigerant Detection
System (RDS) to detect leaked refrigerant
within the conditioned airstream. The RDS
system consists of a mitigation board and one
or more refrigerant sensors in the conditioned
airstream. In the event of a refrigerant leak
that could leak into the occupied space, the
RDS sensors will send an alarm to the
mitigation board. In the event of an alarm, the
compressor operation is disabled and the
indoor blower is enabled to provide
circulation airflow in accordance with UL
60335-2-40. The board will remain in alarm
state for five minutes after RDS sensor has
cleared the alarm below the concentration
setpoint.
The mitigation board is equipped with an
alarm output. For VAV applications and
applications utilizing zone dampers, the
VAV boxes and zone dampers must be wired
to the mitigation board output to open all
VAV boxes and zone dampers to allow for
the required circulation airflow to prevent
stagnation of leaked refrigerant.
Verify functionality of RDS by removing
sensor connection at the mitigation board and
ensuring that all sequences above take place,
including the opening of VAV boxes and
zone dampers if applicable.
Packaged DX Cooling Operation and
Control
When a call for cooling is made the supply
fan motors and compressors will energize.
Electric Heating Operation
When a call for heating (G and W1, W2, etc.)
is made the supply fan motors and electric
resistance heaters will energize. Heating is
accomplished by passing electrical current
through a specified amount of resistance
heaters which will produce the required heat.
On a fault condition the main limit located in
the supply air or the auxiliary limit located
downstream the supply blower will remove
power from all contactors.
Steam or Hot Water Preheating
Operation
Valve control for steam and hot water heating
coils are by others. Heating is accomplished
by passing steam or hot water through the
steam or hot water coil assembly.
Maintenance
(See back of the manual for maintenance
log.)
At least once each year, a qualified service
technician must check out the unit. Supply
COMPRESSOR CYCLING
3 MINUTE MINIMUM OFF TIME
To prevent motor overheating
compressors must cycle off for a
minimum of 3 minutes.
5 MINUTE MINIMUM ON TIME
To maintain the proper oil level
compressors must cycle on for a
minimum of 5 minutes.
The cycle rate must not exceed 7
starts per hour.
Refrigerant sensors may only be
replaced with manufacturer approved
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