VDH ALFA 75 RTDF Manual

1 Function

The ALFA(NET) 75 RTDF is a panel mount real-time defrost thermostat with various defrost- and
fan-control settings. The thermostat has three relays outputs for function cooling, fan and defrost.
The room- and defrost-temperature are being measured by two SM811 2-wire temperature
sensors.
The ALFANET 75 RTDF is provided with an RS-485 network connection and can be readout or set by
an PC with the ALFANET program connected thru an ALFANET PC-Interface.

2 Installation

On the connection diagram of the ALFA(NET) 75 RTDF is shown how the sensors, power supply,
relays and optional network are to be connected. After connecting the ALFA(NET) 75 RTDF to the
power supply, a self-test function is started. As this test is finished, the measured room
temperature of the temperature sensor (control) appears in the display.

3 Control

The ALFA(NET) 75 RTDF thermostat can be controlled by four pushbutton on the front.
These keys are;
SET
∏ UP
π DOWN
°C

4 Viewing/changing setpoint

By pushing the SET key the setpoint appears in the display. The decimal point of the last display starts
blinking, to indicate this readout. A few seconds after releasing the SET key the setpoint disappears and the
measured temperature is shown again in the display.
To change the setpoint push the SET key, release the SET key. Now push the SET key again together with the
UP or DOWN keys to change the setpoint. A few seconds after releasing the keys the measured temperature
(control) shows again in the display.
Description: Alfa(net) 75 RTDF -50/+50°C
Type: Manual
File: Do150014 ALFANET 75 RTDF -50+50°C
V10 EN.docx
VDH Products BV
Manual
-50/+50°C
- view / change set value and reset alarm.
- increase set value.
- decrease set value.
- hidden push button above SET key and behind °C symbol.
ALFA(NET) 75 RTDF
Pages: 8
By: BVDB
Signed:
Doc.no: 150014
Version: 1.0
Date: 19-01-2015