IM 778 / 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-pressure
alarms available in software. While either alarm is active,
compressor operation is suspended. In a refrigerant 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 automatically resets when the attained
temperature is within setpoints. The controller also mon-
itors leaving water temperature. If the leaving water tem-
perature is outside software-configurable setpoints, com-
pressor 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 initi-
ation of the test, compressor operation is suspended for
a minimum of five minutes, cooling attained temperatures
are cleared, and attained temperature alarms are
cleared. The unit then switches to full heat for four min-
utes and then records the attained supply air tempera-
ture. 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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