Last winter, our radiators regularly lost their heat and consequently needed bleeding frequently. I couldn't see any obvious leak. What could be causing this and what should I check for?

  • btw, checking for a leak is easy. Just add a little pressure to the system and see if stays for a few days. If it drops back to the level where the system opens the incoming valve you probably have a leak.
    – Vitalik
    Jul 30, 2010 at 3:06
  • @Vitalik, you can't add presure to a system that is not sealed, header tanks are sill in common use in the UK on older systems.
    – Walker
    Dec 8, 2011 at 10:50

1 Answer 1


I had this issue too. Bled the system once myself, twice with professional plumbers who kept telling me that i didn't do it correctly. Cost me an arm and a leg. The worst part was when i asked a "plumber with 25 years of experience" where the air is coming from he couldn't explain it. Some people were saying it's because i have an old type of expansion tank with the air, others were saying that the water from the city comes with some air.

What solved it is installing "Spirovent Air Eliminator". Not a sound this winter and i could finally sleep without hearing a waterfall.

P.S. Got a few more opinions on this forum

  • That isn't the only brand which makes this widget... But, yes, it sounds like an air eliminator isn't in the system and probably should be. BUT the question I'd have is where the air is coming from -- are you losing water somewhere and having to draw in water to replace it, or is there a pinhole leak somewhere on the intake of a pump that's letting it pull some air along with the water?
    – keshlam
    Jan 11 at 10:08

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