I am having the same problem now. The symptoms I have is that The heating is working fine, but I am getting no hot water out of the taps.
I started to have the problem, and when i put the hot water on, it would take ages for the water to come through hot, i think that the thermostat was faulty, but eventually it was working ok, then after about 2 days it took approx 30 mins of constant flowing water for warm water to come through. now, I cant get any hot water out what so ever.
Has any one got any ideas why this is happeneing?
Many Thanks
Chris, January 2009