Operation Manual
Document nr. : 021171
Version : V1.0
MC 785D 0/+100
O
C
Client : General
Page : 5 of 20
3
Control of the thermostat.
Normally the displays show the measured temperature and the selected setpoint.
Switching the thermostat on and off.
With the ON/OFF key the MC 785D can be switched on and off. Is the thermostat switched off,
all displays are off. No control function is active.
Select and change temperature setpoint.
With the UP and DOWN keys the desired setpoint can be selected. The LED's next to the
setpoint display indicate which setpoint is shown.
By pushing the SETPOINT key, the setpoint starts flashing. With the UP and DOWN keys the
setpoint can be changed. By pressing the SETPOINT key again, the new setpoint is accepted.
Read-out and switching sensors on and off.
By pressing the SENS key the temperature of the first sensor is shown in the upper display.
The lower display shows the number of the sensor and of the sensor is switched on or off.
'S1on' means that the temperature of sensor 1 is shown and that the sensor is switched on.
Sensors that are switched on are used for the control, switched off sensors not. If more sensors
for a thermostat are switched on, the control is based on the average of those sensors.
If during the read-out of a sensor is pressed on the SETP key, a sensor can be switched on or
switched off.
By pressing the SENS key once again, the next sensor is shown. After all sensors are shown,
the average measured temperature and the setpoint are shown in the display.
Reset the alarm.
As soon as an alarm situation occurs and an error message appears on the display can, by
pressing the RESET ALARM key, the alarm be reset.
The error message remains in the display, until the cause of the error is solved.
Day/night input.
If the NIGHT input is closed, the MC 785D turns to the night mode. The NIGHT LED will light.
The setpoints are increased with the night offset.
External alarm input.
If the external alarm input is closed, an alarm message “FE” appears in the display. The alarm
relay is activated. By pressing the RESET ALARM key, the alarm be reset. The error message
remains in the display, until the cause of the error is solved.
