Sound of air pulsing through central heating pump

[mangroa]

I have just drained by heating system, replaced some radiators and refilled.

Now when the heating is running I hear a periodic sound of air rushing around the pipes.

I've been around bleeding everything a few times but no more air is coming out but the noise persists.

Can anyone shed any light on whats wrong?
Alan

 

[HERTS P&D]

Leave it for 24hrs then bleed again, also is there a bleed nipple next to the cylinder?

Andy

 

[mangroa]

Leave it for 24hrs then bleed again, also is there a bleed nipple next to the cylinder?

Andy

Thanks for the reply, I'll bleed everything tomorrow. And yes, there is a nipple next to they cylinder. I'll bleed that as well.
Alan