Can anyone throw some light on this problem? I have a deck mounted bath shower mixer tap & has always worked well & is very powerful as water comes off mains. For the last few days the water temperature has been getting cooler & today it was only running cold despite the cold tap not being on. Then I realised there was heat in the bathroom radiator (and all others in house) but the central heating thermostat wasn't on. I have a glowworm combi boiler. I haven't noticed (yet) if the radiators are getting hot when I run the basin taps or downstairs taps.
It sounds very much as though the diverter valve in the boiler is stuck.
This valve diverts hot water to either the rads or the hot water system depending on which is selected.
I think that's the first thing I would have checked.
Thanks Builder. Yes, I've now had a plumber come in & it is indeed the diverter valve causing the problem. He's coming back Thurs afternoon to fix the problem & in the meantime, I have no hot water. Thanks for your reply
You can sometimes move the diverter valve yourself - there is a lever on the side which you just slide from one end to the other. It's worth giving it a try. Be warned, it needs a firm push.