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Bleed Radiators

Anyone know how to bleed a radiator that looks like this? (hot water)

I have several of these - couple have valves that are easy to turn on/off.
But then there's many of these...no valve I can see.
I know they CAN be bled - plumbers in past have - I didnt check how.


  • delta T
    delta T Member Posts: 884
    That thing on left sticking up from the top is an automatic air vent. check to see if the little cap on top is open. IF the vent is working correctly and there is air in it, opening the cap (you do not need to remove it completely) should vent out any air caught in the rad, and not let water past. Don't be surprised if it leaks, I would have one on hand just in case. Caleffi makes some very good ones.
  • excalibur
    excalibur Member Posts: 5
    Thanks for the reply.
    So there was a little cap on top - I thought that would do it, and removed it (and accidentally dropped the cap in the fins btw - cant get it out).
    Anyway, removing that cap, didn't cause any air to come out.
    Another issue is, some radiators don't have that cylinder thing at all.
  • SWEI
    SWEI Member Posts: 7,356
    edited September 2016
    Try slowly unscrewing the air vent -- just be prepared to screw it back in if you get water.

    Convectors like that were frequently equipped with remote coin vents -- look for a small diameter soft copper tube and you should find a fitting with a screw slot at the end of it, quite likely reachable from outside the enclosure with a long bladed screwdriver.

    While you're at it, be sure to brush and vacuum those fins...
    delta T
  • Danny Scully
    Danny Scully Member Posts: 1,424
    @excalibur, do whatever you can to get that cap back. Once you have it, you'll notice there is a pin in the top of that vent. Depress the pin (with a pen tip or something of the sort) and expel air until water comes out. Then, screw the cap back on.