Hi folks...when I turn my boiler on for hot water...with our oil boiler..after a few moments it fires up and pump also runs but within a few mins in shuts down, the pump is still permanently running but the boiler never fires again...I have put my hand on the valve near the storage tank and it's cold on the pipework...I have also tried to operate the manual lever on the valve but there is no resistance and it feels like it's doing nothing!! Can anyone help? Thank-you. Just one thing I should mention is I have the central heating side drained down at the moment whilst I replace some rads...it's a sealed system which is obviously meaning there is no pressure in the rad system but I'm assuming this shouldn't effect the hot water side of my system...any advice or help much appreciated...