I've just had fitted a Worcester combi boiler to replace an existing combi and is a sealed system.
The problem I've had is that the upstairs radiators constantly fill with air that I purge only to reappear after a few days. This is causing the pressure to increase in the system each time.
Can't find any leaks and I don't need to top up the water. Is there any type of valve in the boiler that may let air in but not let water out?
Mezza