MK/MV – Medium Profile Series Unit Coolers (E206993_M)
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9.2
DEFROST OPERATION
KE2 Evap OEM defrost uses a two-tier approach:
a.
Monitors the coil performance to extend the time between defrosts.
b.
Monitors the coil’s efficiency (comparing the temperature of the coil to the space temperature)
and only calls for defrost when efficiency is less than 90% (incoming data is compared to the
evaporator profile data stored in the controller’s memory).
The following figure illustrates how the KE2 Evap OEM controller monitors the temperature difference
between the coil and space, to determine the optimum time to initiate defrost.
Figure 21 RECOGNITION OF NECESSITY TO DEFROST
Defrost process involves pumping down the refrigerant, defrosting, draining the water and
delaying fan operation upon initiation of the refrigeration cycle.
9.2.1 PUMP DOWN SETTINGS
“Defrost Pump Down Time” is the minimum specified duration for pump down. When “Defrost Pump
Down Time” is not defined, the controller monitors coil temperature and determines the pump down
is finished when coil temperature is close to the room temperature.
