Just to keep you all posted, Plumber came today and from a cold start checked the heating and water system out....The conclusion was as a lot of you have already said.....IT WAS..... the Boiler Thermostat this has been replaced at a very reasonable cost £30.00 for the part and an hours labour...
I have turned down the pump to Speed 2 and I have checked the cylinder thermostat and I have given the adjuster a bit of a wiggle...By that i mean...I have a thermostatic valve like the one you have on a radiator which is by the Hot Water cylinder?....this is what i have moved (Just in case it...
My central heating/Hot water is getting very hot and is purging back through the header tank (As I believe it should if the pressure due to exspantion)
My question is that one of the thermostats can't be working properly?????.....but how can I check to see what one it is?...Ie hot water...