Air in rad

[LUCIALIA]

I have a rad that requires bleeding every few days, combi boiler, constant pressure, no obvious leaks. The only thing I can think is that the rad is located on a floor above the boiler, any ideas?

 

[Chrisgy]

It's a sealed system so air usually gets in through a tiny leak on radiator valves. Another way it could get air in is if the system is sludged up, which then eats away at the metal in the system which turns to hydrogen

 

[villa_tom]

Had this on a job once and put leak sealer in the system - it worked a treat