Vaillant VCW 20/1 T3W Central heating & hot water not working

[Louis Garner]

Hello, first post on here.

I have an old vaillant combi boiler which has been working fine (or as well as it can for its age!) for the last year or so, bar a few diverter valve problems causing the radiators to sometimes heat up when running hot water.

Last week we turned the heating on, was running fine for an hour and then without warning the burners stopped firing up and slowly the radiators went cold, which is when we noticed something had happened. I then turned the heating off.

However now the burners won't light up at all, not even for hot water. The pilot still lights. The pump still seems to work, when I run the hot water tap I can hear it wurring away. I hear all the normal noises when the tap is turned on, as if it is going to work, but nothing happens. For both hot water and heating.

I've been in contact with our boiler man who does know this boiler and has serviced it before. We have tried fault finding but nothing has worked yet. We tried the overheat switch, removing the pump proving switch and pressing the valve pin to see if it was that not working, unplugging the NTC.

The system pressure seems normal.

Is there anyone that has any ideas of what to try or knows what's happened?

Thanks,
Louis

 

[terryplumb]

What's the model number ,and what do you mean when you say the pilot lights ?

 

[Louis Garner]

It's a VCW 20/1 T3W H. That's all I can see written anywhere on the boiler.

When I say the pilot lights I mean the pilot flame is still lit. And I have turned if off and back on again when checking various things to see if the problem is solved.

 

[Louis Garner]

.

 

[terryplumb]

Sorry overlooked that you gave the model in the post title !!

 

[terryplumb]

.

 

[Louis Garner]

No worries!