FAULT WITH VAILLANT COMBI BOILER

[chrissy86]

I have a Vaillant combination boiler (VUW 282/1E). It's approx. 10 years old and still working with the exception of the following problem:

First thing in the morning when you switch on the hot water everything works perfectly but when you switch it off and switch it on again, it doesn't work (it stalls). You need to let the boiler stand for 10-15 mins before it restarts again. It needs an interval before it starts as normal. However on the radiator mode it works OK.

Can you tell me what variable of components would be responsible for this intermittent fault? Thanks.

[RusClarke10]

When you say it "Stalls" - does it do anything...Fan run ?.......

If no then this may be due to the micro switch on the diverter valve

If yes then it could be due to scale on the plate heat exchanger.