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.