Constantly having to bleed radiators

[Djnikon]

Hi all,
I have an oil fired CH system with 10 radiators. In the past two months I have found myself having to continuously bleed the system as a small panel in the hall and a large panel in the bedroom are only warm to half way up and full of air.
Once I bleed the system it's fine for a week and then I have to do it again as the same two panels are only warm.

What could be causing this? Where can the air be getting in?

 

[Burnerman]

The dirt found in a heating system is called magnetite, and it has the curious property of producing its own hydrogen gas.
Next time you bleed, try and light the gas that comes out (unless the bleed valves are plastic, of course....) sure impresses people, too!
Its a sure sign of a dirty system.
Of course, air could be drawn in somewhere, but water leaks could be obvious too.
John

 

[bhm1712]

i wouldnt recommend trying to ignite it

 

[45yearsagasman]

It is perfectly safe to light hydrogen from a ch system. Collect the gas by inverting a tin over the bleed screw and allowing the lighter than air gas to fill the tin. Remove the tin to a safe area and apply ignition source. There you go.