Pumping over or venting

[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

 

[gassafe]

Looks like pipework fault... Get a plumber to change it to a different style of cold feed & vent

 

[JCSPLUMBING]

Could be pipework but it looks correct as in the vent, cold feed and pump in right order. Mental way to pipe it up to be honest with the primary flow going up then down to the pump meeting the vent and cold feed on the way.

 

[gassafe]

Did you fit the pump the correct way round

 

[0304Driver]

Probably restricted in the section of pipe between open vent and cold feed

 

[JCSPLUMBING]

I agree with gas safe. Pump looks upside down

 

[Unregistered]

Pump is upside down, downward flow. From the boiler up past vent then cold feed then down through pump and round system. If it were the other way round surely I would be pumping back to the boiler?

 

[gassafe]

Pump should be facing the correct way unless the head was rotated on the body... Pumping towards the 3 port is correct.

I still think the feed & vent Could be changed, sounds like it's making a loop up the vent & down the cold feed... Will be bringing a lot of air into the system too