Vaillant 937 Ecotec Plus problem

[Alansmithers]

Hi all,

Hoping someone can help...
We have a 937plus about 8 years old.
Some weeks ago we noticed radiators were hot but no hot water when demanded. Quick fix was to switch boiler off the back on.
Our regular heating guy has diagnosed faulty diverter valve which seems logical to my very uneducated mind!
However, today we've had radiators on permanently even though: thermostat is set way below ambient temp, controller is in the OFF setting and the storage tanks have been turned off (temp dial on boiler all the way to left so the 'C' symbol is off - we did that a few weeks back so as to prevent any demand for storage tank heating). The diverter valve is due to be replaced in a couple of weeks.
Can anyone tell me what could cause the boiler to fire when there is no demand from hot water, room thermostat or pre- charge tanks?
I'm now worried it might be more than a duff valve!
Thanks in advance
Alan


Hmmm..... Seems that someone had turned the pre-charge back on so hopefully that's mystery solved and a new diverter will sort it!

 

[Riley]

Alan although you decided to claim that I was scared to tell you last time, I will say it again for avoidance of doubt. We will NOT give information relating to the repair of boilers. You may claim that you aren’t carrying out the work but a. How do we know that? and b. You may not but the next person might. Your thread was closed last time for this reason. As is this one. Please just trust your engineer to sort it