F
Fidd01
Problem with pumping over on a domestic vented central heating system.... I am a fairly capable diy'er and have started to tackle the CH in our home, the system had started pumping over into the F&E tank. I had initially put it down to a failing pump (getting noisy) pump changed bit of gunk evident so put some system cleaner in. 1 week passed still pumping over... Thought maybe a problem with actuator or 3 port valve, actuator functioning correctly, changed 3 port valve body incase of blockage. Still pumping over.... BUT only on hot water?!? Attached is a picture of a fairly standard installation, the only thing I can think of is the reducer to 15mm on the HW side of the 3 port valve being a bottle neck (this has been removed and inspected for sludge none present) should this be 22mm??? Or do I have another problem?!? Many thanks in advance