sounds like the diaphram on the divertor valve has gone. not really a DIY job as usually means taking a few parts out of the boiler, and can be tricky sometimes.
what is happening is the divertor vavle is stuck in the central heating position and when you open a tap it fires the boiler but it send the water round the heating side rather than the hot water heat exchanger.
hudds gas
February 2010
howtomendit.com for free repair help, information and advice.
