Hi, I just moved into a new house with an F&E setup. The central heating pump only comes on when the hot water is on and the cylinder thermostat is set higher than current temp. As soon as the cylinder reaches temp or the hot water is turned off the pump shuts down and stops circulating water to the rads. I've replaced the room thermostat. And I've prelaced the power head on the 3-port valve. The spindle turns fine, so I am assumed the mechanical but if the valve is ok. Any ideas from there? Is it maybe the wiring now either from the boiler or from the control unit? Any help much appreciated. In already cranking the hot water up to 80 just to keep the heating on! I'll need to run all the hot taps to drain the cylinder next!