How to bleed un-coprative central heating pump

[Timgear]

OK that is a 3 port mid position valve , for future referance you have an open vent Y plan system, turn the heating and HW both off then move the lever on that valve across to manual and latch it then try bleeding again

I've just turned everything off, waited for the pump to turn off, I moved the MPV to manual and bled the pump, a little water tricked out. When I turned it back on its sounded great but after around 30 seconds it came back with the trapped air sound.

I'm guessing there might be off-gassing in the pipes or a more trapped air? (The boiler is set to 65 degrees due to the current temperature.) Would that temp potentially cause off gassing?

 

[ianmcd]

does the pump circulate but just noisy ?

 

[Timgear]

does the pump circulate but just noisy ?

Yes, all the radiators are hot, it just sounds like there is constantly air trapped in the pump, I'm just worried it could cause damage to the pump as it didn't sound like that prior to the flush.

 

[ianmcd]

Just run it for a while and see if it moves the air on its own, you wont damage it running it for a few hours, if it goes dry it will squeal loudly

 

[Timgear]

Just run it for a while and see if it moves the air on its own, you wont damage it running it for a few hours, if it goes dry it will squeal loudly

Awesome, will leave it for tonight and check back in the morning! Thank you for all your help and advice!

 

[HERTS P&D]

With the heating on, jockey the pump speed up and down, this normally moves any stuck air.

Andy