Vailiant 837 ecotec plus combi

[scrapmandave]

Hi we have just had this boiler fitted, when using the cold water or using the toilet flush the boiler fired up, so we had a one way valve fitted and had the dead legs capped off on the pipe work and it cured it. But now the boiler ocasionally lights up when no water or heating is been used and the thermostat is off. Any ideas anyone thanks

 

[JPC]

dont know this boiler but does it have a preheat function? look at instructions

 

[Biggles..]

If there is a letter C on the display then preheat(comfort) is on.

To disable turn dhw temp knob all the way down and back to the reqd temp,turning up to full reenables comfort

 

[Boilerman2]

deffo the preheat functionallity

 

[scrapmandave]

Thanks alot everyone for your help