when i turn a hot tap on the burner lights as if it is heating the water but there is no hot water at the tap. the boiler is serviced regularly but is nevertheless 12 years old.

Richard Jackson, December 2006

Do the radiators get hot when you turn on a hot tap?.
You may need to fit service kit t0019. This is for the diverter valve that directs hot water round the radiators or through the domestic hot water heat exchanger. Perhaps fulcrum arm movement is too small due to a failed DHW demand diaphragm (common problem), or perhaps diverter valve bobbin&washer &'o'ring need replacing (included in the t0019 kit). Not a huge job, if you are reasonably practical, have the user manual and time. When you turn on the hot tap you should see the fulcrum arm move, and see the microswitch operate that tells the boiler you need hot water.

Ian, January 2007

It sounds like the primary water divert valve is not working properly, you really need a specialist vokera repairer to look at it.

moris, December 2006