Air in radiator (keeps returning)

[jimjordan]

I'm having to bleed air out of one of my downstairs radiators every couple of weeks as the radiator is only getting hot up to about half way.

I then have to refill the system to top up the water in the central heading system.

It's only this one radiator that needs bleeding, the rest are fine.

It suggests I have a leak somewhere, but I'm not seeing any water leaking anywhere.

The pipes downstairs are all set into the screed (no floorboards).

Any idea how to diagnose this further?

 

[ALEC1]

could be advanced corrosion in the radiator.....

 

[plumbplumb]

Possibly hydrogen gassing up. can be eliminated when you bleed radiator hold a lighter against it if it lights is hydrogen if not then next options.

Pump,vent cold feed issue either configuration or blocked/restricted cold feed.

Leak on the system. likely if the pipes are in screed and are copper and not wrapped they can quite easily rot through. you wouldn't notice a leak necessarily

 

[Armo74]

Whip rad off take it outside and give it a good flushing out with a hose. Give it a few good taps with a rubber mallet to dislodge any stubborn bits of iron oxide.