FRICK QUANTUM EVAPORATOR CONTROL PANEL S90-600 O
OPERATION Page 23
CONTROL SETUP -
“HEATING SETPOINTS” SCREEN
Heating is sometimes used to raise the temperature within
an area of a plant such as a loading dock. If the control
temperature is less than or equal to the “Heat On”
setpoint, control switches to using the heating setpoints.
The process of heating initiates with the “Pre-heat” stage.
“Pre-heat” is used to properly prepare for heating. “Pre-
heat” can consist of three steps: Pump Out, Soft Hot Gas,
and Fan Delay. If the control temperature does not equal
or exceed the “Heat Off” setpoint, then heating will occur
after “Pre-heat” completes. During the heating stage, the
hot gas valve is open and fans are running. If the control
temperature equals or exceeds the “Heat Off” setpoint
after “Pre-Heat” has completed, then control stops the
heating and proceeds to the “Post-heat” stage. The “Post-
heat” stage is used to properly exit from heating. “Post-
heat” can consist of two steps: Bleed, and Fan Delay.
Each step has an operator adjustable time setpoint.
Pre-Heat:
· 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 heating. – (enhanced unit only)
• During “Fan Delay” the hot gas valve is opened,
the other valves are closed, and the fans are
stopped. The fan remains off 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. The hot gas
valve remains opened until the temperature rises
to or above the hot gas off temperature setpoint
Post-Heat:
· 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 so as not to too
quickly over pressurize 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 heating 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.
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