Worcester Bosch 28i boiler?

Probably not at this time of year.
All combi boilers quote a 35c rise at a given flow (depending on output), you'll probably find you are getting a 35c rise, but given the colder input water, the output water will be relatively colder too!
You're probably guilty (as most are) of trying to run a tap too fast for the boiler to be able to cope.
Only possible solution I can give, is slow the tap down, allow the boiler more time to heat the water coming through the boiler, generally, the bath tap is the main cause for complaint in this instance.

20c input = 55c output (0-10c input = 35-45c output), hope it makes sense

Carefree
December 2010