Strange problem with my boiler.

[wisiu]

Hi, a have very strange problem with my boiler so I will try to describe this as good as I can I have Vaillant boiler I think is Ecotec but I can't find any details about which model it is.
First problem is, when open a hot tap, water is getting warmer and after a few second is cold and then lukewarm. Boiler is still running and the temperature on the display shows 65 degrees and the strange thing is that the radiators are warming up even if I switch of the heating on the boiler. This problem appears only when I set up the heating temperature on the boiler to over half on the knob, also same problem when I increase the pressure in the heating system over 0.5 bar ( green field is over 1 bar ).

Another problem is that sometimes the water in the heating system does not run to the radiators, boiler warms up very quickly and turn off and after a few minutes again turn on and off but radiators are cold. I have to switch of mains and on again and then I can hear the water runs OK and heating works fine.

I know is a bit complicated but I have tried to describe this as it is and I would appreciate any help or advice what is wrong with the boiler and how to fix it.
Thank You
Slawek

 

[petit_pablo]

Diverter valve fault

 

[wisiu]

Thanks for the answer , I think I shouldn't do it myself but how much it should cost me for the labour and the valve? and where to find an engineer?

 

[Agile]

It is one of the few repairs that a competent DIYer can usually mnanage.

We charge in our local area in London about £84 fee plus about £94 for the new valve and that to include a service.

Tony

 

[wisiu]

It does not looks difficult to replace that valve but I thought I can't touch my boiler if I am not a licensed engineer

 

[John506]

Diverter valve is within the boiler yes but it;s on the water side, you don't need to be a RGI to carry out this job.

 

[wisiu]

That's s true so first I need to find out which model of Vaillant it is, is there any plate with serial numbers etc. inside?

 

[petit_pablo]

Either on the back of the control panel or underneath the boiler will be a dataplate.

The valve is the same through most of the range so you shouldnt end up with the wrong one.

 

[wisiu]

Vaillant Diverter Valve 252457 I think is's this one.

 

[wisiu]

My boiler is Turbomax Plus 828 E, do I need to drain out whole system or can I only do it draining out the boiler?

 

[petit_pablo]

Just drain the boiler. The isolation valves are usually pretty good on vaillants too.