VRT 350f vaillant thermostat problem

[Lauren Roberts]

Our thermostat has a desired temperature of 20 degrees Celsius but it is turning on the heating, not matter what the temperature is. It is currently reading 26 degrees Celsius. We have tried turning the heating mode off but the thermostat turns back to auto immediately and resets the date as well.
Is this just a problem with the thermostat and do we need to order a new one?

 

[CBW]

Have you tried new batteries?

 

[Lauren Roberts]

Yes. Brand new from the packet. Not sure what else it could be. Connection seems to be fine- 9 or 10 for the RF. But regardless the heating stays on continuously.