And was surprised that a few radiators (admittedly the taller ones for bathroom, and cloakroom) had quite a bit of air in - so much that the boiler pressure (which has held steady at 1.5 bar over summer) dropped to below 0.5 and I had to top up the filling loop.
But the heating fired up fine, and no cold spots.
Just wonder where the air came from - the system was flushed and filled with inhibitor last year (10/10/15 to be exact :) )
Most will have been likely been air coming out of suspension in the water. You may also have some corrosion by product gas (depending on the concentration and effectiveness of the inhibitor). Its also possible there is a very small leak somewhere - it may be so slow that you never see liquid water escape, but a tiny amount of air can diffuse in.
Normally IIRC its hydrogen from mild corrosion by the CH water.
Fe + 2H2O => FeO2 + 4H...
Don't smoke while bleeding, then?
Mmm. I looked at that and thought 'I think that's wrong'
See here for MUCH better explanation
See later post. Its more complex than that but yes I have seen a flame from a bleeding rad...
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