"Kevsy1" wrote in message
oups.com...
The 'unusual' fixing I mentioned above is a compression gate valve
(BS5154) but dows not have the red turning dial on it! Just the loose
nut at the end. Turning this just makes the nut go up and down the
thread. (http://www.gofixit.co.uk/en-gb/dept_1289.html)


I'm no plumber or even real DIYer but it sounds to me like the valve has got
stuck on hot water only? There is a 2 or 3 way valve which is operated by a
motorised switch and this switch turns the valve depending on whats
required - so, ie if its just hot water the motorised valve will turn the
valve to allow only hot water to run to the taps and when heating is
required it moves again to allow the flow of water just to the radiators. I
think tere is also a mid posistion to allow both if needed. In my mind I
think either the motorised switch has packed up or the valve that it turns
has got stuck.
Just my thoughts.

Good luck