Noisy heating / One radiator problem

[MarkH]

Hi, first post - just discovered forum and enjoying reading ALL the threads.

After some advice. My central heating is making noises when it 'clicks off' via the thermostat, sounds like air in the system.
When checking/bleeding rads for air they are all ok except one. This one has air in it and is cold in parts. I drain the air until water is coming out. Day or so later go back to same rad and again full of air. Thsi has been ongoing for a while basically this one rad keeps getting air in it - all others are clear. Can also get to the point where the bleed valve is removed and there is nothing (no air or water) coming out.

Blocked/knackered rad ??

Any advice much appreciated. Thanks.

 

[Sam Gangee]

I'm no expert but AFAIK there are only three ways that air can get in:

1. Empty header tank (in loft?) caused by ball float valve sticking closed.

2. Porous radiator or other leak in system allowing air to be sucked in.

3. Severe corrosion in the system resulting in electrolytic action producing hydrogen gas. I'm tempted to say light a match next time you bleed the system but you might think I'm serious!

Radiator systems should have a corrosion inhibitor added. I think it's around £15 a gallon and a gallon is enough for an "average" house.

 

[breezer]

I am not a plumber or heating engineer.

as you say the radiator is cold in parts and it is always the same one it points to either its inlet valve is not fully open when you bleed it or it is full of sludge.

because of this you can never properly bleed it. you could always take it off and as some one on this forum did put a pressure washer on it to thoroughly clean it.

 

[MarkH]

Thanks for the replies.

The inlet valve was fully open. I have just closed and opened it and once again bled the radiator. Lots of air came out (as it always seems to). I have left it now with the rad having NO cold parts. All ok, but my guess is when I check it again tomorrow there will be more air and it'll be cold in parts.