Vaillant EcoTecplus831 turning on when Thermostat set to off

[jeh45]

My boiler is randomly turning on, to heat the rads, when the wireless controller is set to OFF. I had the 'stat set to auto and it was behaving and coming on in the evening and morning but today it randomly came on in the day when the 'stat was set to OFF and the room temp was well above the night set back temp. We had an engineer come to look at the boiler a few months ago because it had a fault and when he left he said he had turned it on in a way I wouldn't be able to (?!) but that it would turn off later. It did turn off but then turned on, to heat the rads, out of the blue much like today. As we didn't need the heating then I just turned the rad temp down on the boiler - to stop it turning on at all. Now it's getting cooler and I need the rads to heat up, the problem is recurring. Could this be something the engineer did? Any ideas? All help welcome! Vaillant tech support are closed on the weekend so I'm a bit stuck until Monday - I'd like a blast of heat in the evening for when the little ones are having baths, and I'd like one in the morning so they don't wake up cold, but apart from that I don't need it but, I don't want to get up at 5.30 to turn the heating on...Thanks in advance!

 

[picasso]

It might be the diverter valve is letting by and you have preheat switched on, try turning the hot water knob all the way to off and then back but not all the way on or you will turn the preheat back on, you will need to get the diverter valve looked at but at least the rads wont heat up randomly.

 

[jeh45]

Thank you picasso, I shall try that and see how I get on. I hope this boiler doesn't have yet another fault!!!

 

[Bunnyman]

One of the most reliable boilers in the market mate.... When heat comes on when it shouldn't just press the I button an post back with the code... He sounds as if he put it in sweep mode to do the boiler checks, this will not impact on anything for you at all