I've been having a problem with air in a sealed system, not huge amounts but enough to make the system noisy. It only seems to be noticable when the hot water is on by itself, and i'm not getting much air in the rads.
- Definately air not hydrogen, and there is plenty of inhibitor in system.
- Quite a large system, 30KW condensing boiler, 6m head Grundfos Alpha pump set to max. Pressure vessel is between boiler & pump intake.
- Zone valves are on returns, not feeds.
- Boiler, pump, zone valves etc all downstairs, and there is quite a long run to HW cylinder (17m of pipework approx).
- System pressure seems to remain constant, and does not drop over time.
I've pressurised system to 3bar and checked for leaking compression joints, rad valves etc, everything seems fine.
How long roughly does it normally take for air in the system to clear after a refill on a sealed system? (note there is no air separator)
I'm pretty sure air is being drawn in, any suggestions to what the most likely causes could be?