FRICK QUANTUM EVAPORATOR CONTROL PANEL S90-600 O
OPERATION Page 21
CONTROL SETUP -
“DEFROST SETPOINTS” SCREEN
Defrost is used to remove the build up of ice that reduces
cooling efficiency. The defrosting of a zone can consist of
five steps: Pump out, Soft Hot Gas, Hot Gas, Bleed, and
Fan Delay. Each step has an operator adjustable time
setpoint.
· During “Pump Out” the liquid output is closed
(de-energized) while the suction valve and the
fan output remain opened (energized) to remove
and evaporate as much as possible of the
remaining liquid refrigerant.
· During “Soft Hot Gas” the soft hot gas valve is
opened, the other valves are closed, and the fans
are stopped. The soft hot gas valve is used to
slowly turn on hot gas and lower the pressure
differential that occurs when going from cooling
to defrosting. – (enhanced unit only)
· During “Hot Gas” the hot gas valve is opened,
the other valves are closed, and the fans are
stopped. The hot gas solenoid is energized for
the set amount of time. This step allows high
pressure/high temperature gas to enter the
evaporator coil and melt the frost build up from
the evaporator coils clearing the coil for good
airflow.
· During “Bleed” the hot gas solenoid output is de-
energized, and the bleed solenoid output is
energized for the set amount of time. This bleed
step is usually energized for a few minutes to
allow the hot gas trapped in the evaporator coil to
slowly release from the tubing. This prevents
quick over pressurization of the suction piping
line and vessel.
· During “Fan Delay” the bleed solenoid is de-
energized and the liquid and suction solenoid
outputs are energized again allowing the liquid
refrigerant to cycle through the evaporator coil
thus cooling the evaporator to an operating
temperature. This step usually lasts for just a few
minutes and is used mainly to frost the small
amount of water left on the unit so as to not blow
water over product when the fan is restarted.
· After “Fan Delay”, the fan output is energized
again to provide air movement across the
evaporator coil to re-initiate the cooling process.
Note: If a zone does not have a Bleed solenoid, the
bleed step of the defrost cycle can be used to close
the Hot Gas solenoid valve and use the bleed time for
cooling of the hot gas trapped in the evaporator.
· Pump Out - The time in minutes to pump out the
liquid in the coils. During this step, the liquid and
hot gas valves are closed, the suction valve is
opened, and the fans are running. The fan runs
according to the fan settings that were entered
on the “Defrost Setpoints” screen. If it is a two-
speed fan, the selected fan speed is energized. If
it is a modulating fan, the fan is turned on the
amount of the variable percent.
· Soft Hot Gas - The time in minutes to provide
soft hot gas defrost of the coils. During this step
the soft hot gas valve is opened, the other valves
are closed, and the fans are stopped. -
(enhanced unit only)
· Hot Gas - The time in minutes to provide hot gas
defrost of the coils. During this step the soft hot
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