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User manual
ALFA 75 RTDF

Cool/Defr. Thermostat
with fan-control and
realtime defrost.

VDH do c.020993

Version: v 1.1

Date: 15-02-2005

Software: ALFA(NET) 75 RTDF

File: Do020993.WP8

Range: -50,0/+50,0

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* Description.

The 

ALFA 75 RTDF

 is a co ol/def rost therm osta t with various defrost- a nd fa n-contro l settings . 

* Installation.

On the top side of the 

ALFA 75 RTDF

 is shown how the sensor, power supply and relays has to be

con nec ted. 
After connecting the 

ALFA 75 RTDF

 to the power supply, a self test function is started. As this test

is fin ish ed  the  m ea su red te m pe rature of the te m perature-se ns or (con trol) ap pe ars in the  display.

* Control.

The 

ALFA 75

 thermostat can be controlled by four push buttons on the front. These keys are:

SET

- view / cha nge  the s etpo int.

UP

- increase value.

D OW N

- decrease value.

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- hidden push button above 

SET

 key and behind 

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 sym bo l.

* View setpoint.

By pushing the 

SET

 key the setpoint appears in the display. The decimal point of the last display

starts blinking to indicate this. After a few seconds after releasing the 

SET

 key the setpoint

disappears  and the measured temperature is shown again.

* Changing setpoint.

Push the 

SET

 key and the setpoint appears in the display. Release the 

SET

 key. Now push the

SET

 key again together with the 

UP

 or 

D OW N

 keys to change the setpoint. After a few seconds

after releasing the 

SET

 key the setpoint disappears  and the measured temperature is shown again.

* Status of the Relays.

By pushing the hidden 

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 key the display shows the status of the relays. Each display segment

shows the status of the relay output, showing 0= off and 1=on. The code 110 means relay
1(com pr.) en relay 2(fan) are on and relay 3(defr.) is off.

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