VDH ALFA 21 User manual

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User Manual
ALFA 21 and
ALFANET 21
Cool/Heat
Thermostat
0-100OC
VDH doc: 070706 Version: v1.0 Date: 04-07-2007
Software: 053273_ALFA 11/21/31 0-100 File: Do070706.wpd Range: 0/+100C per 1C
*Function.
The ALFA(NET) 21 is a digital thermostat for panel mounting. The function from
the thermostat can be programmed for cooling or heating.
The ALFANET 21 has a RS 485 network connection so it can be read out and
adjusted on the Alfanet.
*Installation.
On the topside of the ALFA(NET) 21 is shown how the sensor, power supply and
relay have to be connected.
After connecting the ALFA(NET) 21 to the power supply, a self-test function is
started. As this test is finished, the measured temperature appears in the display.
When the relay is activated, the led 'on' will light-up in the display.
*Control.
The ALFA(NET) 21 Thermostat can be controlled by three push buttons on the
front.
These keys are:
SET - view / change the setpoint.
UP - increase the setpoint.
DOWN - decrease the setpoint.

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*Viewing setpoint.
By pushing the SET key the setpoint appears in the display. The led 'set' starts
blinking. A few seconds after releasing the SET key the setpoint disappears and the
measured temperature is shown in the display.
*Changing setpoint.
Push the SET key and the setpoint appears in the display. Release the at SET key.
Now push the SET key again and together with the UP or DOWN keys the setpoint
can be changed. A few seconds after releasing the keys the measured temperature
shows again in the display.
*Setting internal parameters.
Next to the adjustment of the setpoint, some internal settings are possible like
differential, sensor-offset, setpoint range and the function cooling or heating.
By pushing the DOWN key more than 10 seconds, you enter the 'internal
programming menu'. In the left display the upper and lower segment are blinking.
Over the UP and DOWN keys the required parameter can be selected (see table for
the parameters).
If the required parameter is selected, the value can be read-out by pushing the SET
key. Pushing the UP or DOWN keys together with the SET key allows you to change
the value of this parameter.
If after 20 seconds no key is pushed, the ALFA(NET) 21 changes to it's normal
operation mode.
*Parameters ALFA(NET) 21.
Para-
meter
Description Parameter Range Standard
Value
01
02
03
04
Switching differential
Minimum setpoint
Maximum setpoint
Offset temperature sensor
1..30C
0..+100C
0..+100C
-15..+15C
3
0
+100
0
10
11
Startup delay after power failure
Relays on at sensor failure
0..99 Minutes
0 = No, 1 = Yes
0
0
15
16
17
18
19
20
Function cooling or heating
Switch on delay relays 1)
Switch off delay relays 1)
Parameter 16/17 in sec. or min.
Minimum on-time relays
Minimum off-time relays
0 = Cool
1 = Heat
0..99
0..99
0 = Seconds
1 = Minutes
0..99 Minutes
0..99 Minutes
0
0
0
0
0
0
90
95
96
97
98
99
Network number
Software version
Production year
Production week
Serial number (x1000)
Serial number (units)
1..250
0..255
00..99
1..52
0..255
0..999
1
-
-
-
-
-
1) During delay time the LED ‘on’ is flashing.

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*Adjustment sensor.
The sensor can be adjusted by using the Sensor Offset (parameter 04). Indicates
the ALFA(NET) 21 e.g. 2C too much, the Sensor Offset has to de decreased with
2C.
*Error messages.
In the display of the ALFA(NET) 21 the following error messages can appear:
Er - Sensor broken. Solution:
- Check if the sensor is connected correctly.
- Check the sensor (1000at 25C).
- Replace the sensor.
EE - Settings are lost. Solution:
- Reprogram the settings.
*Technical details.
Model : ALFA 21 Cool/Heat Thermostat
ALFANET 21 Cool/Heat thermostat with Network
Range : 0/+100C, readout per 1C
Supply : 230 Vac 50/60Hz
Relay : SPDT 250V/16A(C-NO), 8A(C-NC) (cos phi=1)
Control : by push buttons on the front.
Communication : RS485-Network (2x twisted pair shielded, min. 0,75mm2)
Front : Polycarbonate
Sensor : SM 811/2m (1000at 25C)
Demensions : 144 x 72 x 50mm (hbd)
Panel hole : 139 x 67mm (hb) bij doorvoer in front
- Provided with memory protection during power failure.
- Connection with screw terminals on the back side.
- Equipped with self test function and sensor failure detection.
- Special version on request available.
*Function Diagram.

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*Dimensions. *Connections.
*Adresse.
VDH Products BV Tel: +31 (0)50 - 30 28 900
Produktieweg 1 Fax: +31 (0)50 - 30 28 980
9301 ZS Roden Email: [e-mail]
Nederland Internet: www.vdhproducts.nl