Hi all, I have a two port valve s plan system and my hot water only works when the central heating is on but not when hot water only is selected. I swopped the valve actuator's over and the boiler fires up when hot water only is selected, great! I left the ch actuator valve head of so I could get a like for like replacement and now find the the central heating is getting warm. Does the valve stay open when the actuator is removed or could it be that it was open when I removed the actuator? Any help much appreciated.