6 User Guide RS8GR602 © Danfoss 2016-10 AK-CT 450A
Hot gas application
Defrost
Depending on the application you may choose between the
following defrost methods:
Electric: The heating element is activated
Hotgas: Here the solenoid valves are controlled so that the
hotgas can ow through the evaporator
Brine: Here, the solenoid/motor valve is opened on the supply
pipe, so that hot brine can be fed through.
Natural: Here the fans are kept operating during the defrost
Defrost sequence
1) Pump down
2) Defrost
3) Waiting position after defrost
4) Draining (drain delay. Hotgas only)
5) Drip o
6) Delay of fan
Hot gas defrost (application 7 only)
This type of connection can be used on systems with hotgas
defrost, but only in small systems in, say, supermarkets – the
functional content has not been adapted to systems with large
charges.
Must not be used together with PMLX and GPLX valves, unless
a time delay relay is installed, which ensures that the PMLX/GPLX
valve is closed completely before the hotgas is turned on.
Drip tray heating element
It is possible to control a heating element in the drip tray for
hot gas defrosting. When defrosting is commenced, the heating
element is activated. The heating element remains activated until
a set time after defrosting has ended by time or temperature.
Start of defrost
A defrost can be started in dierent ways
Interval: Defrost is started at xed time intervals, say, every
eighth hour. An interval must ALWAYS be set to
a "higher" value than the period set between two
defrostings when a schedule or network signal is used.
Refrigeration time: Defrost is started at xed refrigeration time
intervals, in other words, a low need for refrigeration will
”postpone” the defrost
Schedule: Here defrost can be started at xed times of the
day and night. However, max. 6 times
Contact: Defrost is started with a contact signal on a digital input
Network: The signal for defrost is received from a system unit
via the data communication
Manual: An extra defrost can be activated from the controller’s
lower-most button
All the mentioned methods can be used at random – if just of
them is activated a defrost will be started.
Stop of defrost
Defrosting can be stopped by either:
• Time
• Temperature (with time as safety).
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