What should I do if the thermostat indicates ER, …?

This means that there is an error with the probe. Verify that the probe is correctly connected to thermostat connectors 3 and 4. (There is no polarity.)

Verify the probe resistance. It must be between 8 and 12 KOhms at an ambient temperature between 20 oC and 30oC. Replace the probe if there is no resistance.

Contact the Customer Service Department ( Link on page 3.0) for assistance.