Boilers heat the water and a valve directs the heated water to the radiators or to the taps - storage tank on some boilers and directly to the taps on a combi boiler.
If the diverter valve is stuck in one position this may be the cause - a heating engineer will fix it for you - as soon as you can find one.
In the mean time, if you have a storage tank for hot water it may well have an immersion heater - a luxury that combination boilers lack.
Good luck...
Peccavi
January 2010
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix plumbing.