Temperature out of range

If the room temperature exceeds or drops below the measuring range, i.e. above 50 °C or below 0 °C, the limiting temperatures blink, e.g., 0 °C or 50 °C.

In addition, the heating output is activated if the current setpoint is not set to Off, the thermostat is in heating mode and the temperature is below 0 °C.

For all other cases, no output is activated.

The thermostat resumes normal operation as soon as the temperature is within the measuring range.

Fault on display

A fault message "Erx" appears on the display in the event of hardware component failure or incorrect configuration:



Fault description


Internal sensor error


Built-in sensor is broken.

  • If possible, use external temperature sensor to measure room temperature
  • Otherwise, replace thermostat

External / remote sensor error (RDF4..BN)


External sensor is broken or connection to terminal malfunctions.

  • Check input X1 configuration
  • Check wiring between sensors and terminals
  • Replace with another external sensor

For fault status messages on BACnet, see Fault and alarm functions on BACnet.

For fault status messages on Modbus, see Fault and alarms function on Modbus.