ALFA(NET) 75 RTDF -50/+50°C
Doc.no.: 150014 version 1.0
Page 2 of 8
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Status of the relays
By pushing the hidden °C key the display shows the status of the relays. Each display segment
shows the status of the relay output, showing =off, =on and on last segment=natural defrost
active. The code
means relay 1(compr.) and 2(fan) are on and relay 3(defr.) is off.
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View defrost sensor (if present)
By pushing the UP key the defrost temperature appears in the display. A few seconds after
releasing the UP key the defrost temperature disappears and the measured temperature (control)
is shown again.
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Manual starting/stopping of defrost
The defrost cycle is automatic started and stopped. These defrost settings thru internal
parameters.
Stop defrost: If there is a defrost cycle active, the defrost can be manually stopped by pushing
the UP and the DOWN keys simultaneously.
Start deforst: If there is no defrost cycle active, the defrost can be manually startet by pushing
the UP and the DOWN keys simultaneously.
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Fan control
The ALFANET 75 RTDF has several parameters for fan-control. Normally the fan is always active.
Accept for one of the following parameters to be set to 1, the fan can be stopped;
Parameter 20 = 1:
Fan switch differential active
The fan is only active when the defrost temperature is “parameter 21” lower than the
measured control temperature. Fan on: Tdefr. < (Tcontrol-Tfandiff.(P21)) As there are no
other conditions to switch the fan off.
Parameter 25,26:
Fan on-delay after defrost
The fan is switched off during defrost and to prevent blowing in hot-air in the room after
defrost and the dripping-off time (P27), there are two conditions which can be set;
a: The fan is blocked until the defrost sensor measures a temperature lower than the
temperature setting of parameter 25.
b: The fan is blocked until the defrost-delay-time of parameter 26 has stopped. Unless the
defrost sensor has reached the temperature setting of parameter 25.
Parameter 22 = 1:
Compressor off than fan off
The fan deactivates as the compressor deactivates, with a delay of “parameter 23” minutes.
Provided that there is no other conditions to deactivates the fan.