I'll try and make this simple. The shareflow valve is not behaving as it should, it keeps on heating the central heating water even when the room thermostat says it's warm enough. I'm going on holiday on Sunday and slightly worried about it, it's difficult to describe but here goes, when the CH & HW comes on it directs water to the CH. When the room thermostat clicks off what should happen is that the shareflow directs water to the HW cylinder only until that reaches temp then the pump/boiler cuts out, well it doesn't it just keeps getting hotter and because the HW temp never gets up to temp (hot but not enough) the boiler keeps fired up and pumping red hot water through the radiators, here's the thing; when the room thermostat is right down (5c) and I turn the thermostat down on the cylinder the valve suddenly centers and the pump stops then I click it back and it stays there but the pump starts therefore circing HW to the tank so the problem is to do with the valve not centering after room temp has been achieved when HW & CH is on. Surely an electrical problem?
Any help appreciated