no its not continually, just occasionally when the boiler/pump is running
had the experience before and it disapperead, now its reared its ugly head again
will have to monitor it more at the header tank to see whats going on
having trouble with air in the central heating system, its a vented system and i have a couple of rads that require bleeding frequently
in conjunction with this, the overflow from the header tank is throwing out water
could there be a problem where water is being displaced by air in the...