The cylinder stat controls the temp of the hot water and when the stat makes demanding hot water it supplies the pump and the boiler.Plus if u have a three port mid pos diverter valve it could be stuck in the heating only position.
George Bowden
November 2008
Could be if it is an older boiler that the header tank is dry in the loft.On water only the boiler will only stay lit for a very short time but when the rads are on the pump will pump the existing water around the system leaving the boiler on long enough to get some hot water.t
Tony S
November 2008
YOU NEED CENTRAL HEATING IF YOU ONLEY HAVE A COLD WATHER FEED 'BECAUSE THE CENTRAL HEATING HOTS UP YOUR WATER 'BUT YOU DONT HAVE TO HAVE THE HEATING ON JUST THE HOT WATER BUTTON ON IF THAT MAKES SENS..
MARY
November 2008
system type? boiler type? any igloo's? :-)
iain
November 2008
I can answer this question...
why do I have to have central heating on to have hot water?