Ever since we had the boiler installed about 2 years ago the central heating has worked fine but the running hot water has only been luke warm unless we run the hot water tap at a trickle.
Now the hot water tap runs cold all the time unless the central heating is turned on

Fred Greasby, October 2008

yor boiler needs a new water flow sensing valve (changeover valve) one of the worst in the world to change.

mark, March 2009