Hi... I'd really appreciate some advice on the below... sorry for the length of the post 
I have an open-vented system, with a condensing boiler on ground floor, Grundfos pump on first floor and HW cylinder, CW storage and expansion tank with combined vent and feed in the loft. I have a problem with air noise (banging) when my HW heating system is running - it sounds like a 'lump' of air is circulating, as the noise is intermittent. I don't believe it is temperature-related, as the noise starts as soon as the HW heating comes on. When my CH and HW systems are running together, there is absolutely no noise, it's just when HW runs alone there is a problem. The noise seems to come from pipework around the pump - it's certainly not from near the boiler.
On Corgi advice, I've had the system powerflushed, the expansion tank lifted higher above the level of the cyclinder, and an AAV put on the flow into the HW cylinder, but none of this has helped. When the system was drained, a lot of air was coming out - the water was spluttering out. One other thing which is probably related, is that one of my radiators upstairs needs regular bleeding - every few weeks I can take air out of it.
I've had a few Corgis scratching their heads over it - anyone have any ideas of things I can try? I'm at the point of switching to a timed immersion heater for HW, as the noise is so bad (echos around the radiators...).
Thanks in advance
I have an open-vented system, with a condensing boiler on ground floor, Grundfos pump on first floor and HW cylinder, CW storage and expansion tank with combined vent and feed in the loft. I have a problem with air noise (banging) when my HW heating system is running - it sounds like a 'lump' of air is circulating, as the noise is intermittent. I don't believe it is temperature-related, as the noise starts as soon as the HW heating comes on. When my CH and HW systems are running together, there is absolutely no noise, it's just when HW runs alone there is a problem. The noise seems to come from pipework around the pump - it's certainly not from near the boiler.
On Corgi advice, I've had the system powerflushed, the expansion tank lifted higher above the level of the cyclinder, and an AAV put on the flow into the HW cylinder, but none of this has helped. When the system was drained, a lot of air was coming out - the water was spluttering out. One other thing which is probably related, is that one of my radiators upstairs needs regular bleeding - every few weeks I can take air out of it.
I've had a few Corgis scratching their heads over it - anyone have any ideas of things I can try? I'm at the point of switching to a timed immersion heater for HW, as the noise is so bad (echos around the radiators...).
Thanks in advance
