IM 742 / Page 15
● Condensate Overflow Protection – A liquid sensor at
the top of the drain pan senses a high water level. Upon
sensing water, cooling operation is suspended, while
heating operation is allowed. The controller creates an
alarm available in software. The alarm automatically
resets when the water level returns to normal.
● Safety Control – The unit monitors refrigerant pressure
and generates separate high-pressure and low-pres-
sure alarms available in software. While either alarm is
active, compressor operation is suspended. In a refriger
-
ant low-temperature condition, an alarm occurs and the
unit operates in cooling mode for 60 seconds to defrost
the heat exchanger, after which compressor operation is
suspended. These alarms can be reset in software or by
cycling power to the controller.
● Attained Temperature and Water Temperature Alarms
– Attained temperature, water temperature alarms with
software-adjustable setpoints are available in software.
The controller samples supply air and records attained
temperatures for heating and cooling. If after two hours
of operation, the attained temperature does not meet the
software-configurable setpoint for heating or cooling as
appropriate, a software alarm occurs. The alarm auto
-
matically resets when the attained temperature is within
temperature is within setpoints. The controller also
monitors leaving water temperature. If the leaving water
temperature is outside software-configurable setpoints,
compressor operation is suspended and high or low
water temperature alarms occur. The alarm automatically
resets when the water temperature returns to within 6
deg. F of the setpoint.
● Unit Self-test Mode – While the unit is in occupied
mode, a self-test can be initiated via software. Upon
initiation of the test, compressor operation is suspended
for a minimum of five minutes, cooling attained tem-
peratures are cleared, and attained temperature alarms
are cleared. The unit then switches to full heat for four
minutes and then records the attained supply air tem-
perature. Compressor operation is then suspended for
five minutes. The unit then switches to full cooling for
four minutes and the attained supply air temperature
is recorded. Attained temperature alarms are set if the
attained temperatures failed to reach alarm setpoints
during heating or cooling.
BACnet
®
WSHP Unit Controller
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