3iE Energy-Monitoring Thermostat

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What does it mean if my thermostat reads error message “ER2” on the display?

The ER2 message will occur if the floor sensor has a short circuit or has a loose connection. Your electrician can make sure all connections are secure and test the probe using a multimeter set to the lowest possible ohms scale. The resistance reading should be between 7 and 17 ohms.  If a short is found and a backup sensor probe was not installed, you can bypass the error message by setting the thermostat to read the air temperature instead.

Menu > Settings > Set Heating Target > Target Air Temperature