K
Kerry d
Hello, I have tried that and it still does not work. There is no green light on the boiler, so it will not connect.I phoned Vaillant's helpline with this issue and they told me to turn the boiler off and remove the batteries from thermostat at the same time, then put them back in and turn boiler on at the same time, and it was all OK after that, and continued to be until we moved house in June of 2020.