Help! - radiator valve ( 3 photos attached)

Discussion in 'Plumbers' Talk' started by martyc, Dec 30, 2010.

  1. martyc

    martyc New Member

    Hi all

    I have a radiator in the kitchen that has a TRV on one side ( I have taken the wheel head off and the pin is moving up and down freely) and on the other side (see attached photos) there is a strange looking screw head cap that looks like there is a hexagonal head for a spanner to undo it.

    The problem is that the radiator isn't letting in hot water unless I open the bleed valve which obviously isn't going to be the solution!

    Could anyone tell me if they know what this valve is and if I take the cap off will water go spray everywhere? Not sure if it is just an isolation valve and once taken off it will expose a pin?

    Any help is greatly appreciated as don't want any water accidents :'(


    Attached Files:

  2. midlands heating

    midlands heating New Member

    its just a balancing (lockshield) valve take the top of and underneath will be either a screw or allen key type valve to open or close. But beware if you do not know what your doing as the system may be balanced and opening this rad may effect others !!
  3. martyc

    martyc New Member

    Thanks mate

    So its possible that this was closed off when someone before I moved in decorated, took the rad off etc?

    So potentially if I opened it slightly no water would spray out but could just unbalance the system?

    Many thanks
  4. midlands heating

    midlands heating New Member

    basically yes yes and no
    could be shut
  5. martyc

    martyc New Member

    Thanks very much shall take the cap off and hope it works
  6. martyc

    martyc New Member

    Hi mate

    I took the cap off and there was an allen key slot as you mentioned. I opened it up slightly and water sprayed everywhere so closed it off again - any ideas why it done that as I thought from what you said it wouldn't?

    Would you normally have to drain down the whole system (Rad is in the Kitchen so obviously all water above) to take the allen key screw out? I don't think taking the screw out, recharging the system and replacing the cap would make it water tight would it?

    Any help greatly appreciated

  7. RobSmart

    RobSmart New Member

    I'm not sure but if the pin in the TRV is moving freely then it sounds like this has seized up or something. Normally when the you take the head of a TRV, you can't move the pin with the pressure from your finger as its too stiff.

    The TRV goes on the outlet side of the rad too, so if the other valve was closed, then no hot water would enter the rad when you open the bleed valve.

    You could try giving it a few taps with a hammer to try and free if off a bit (not too hard though!)

    If you want to change the TRV for a new one, you could try a can of pipe freezing spray which can be used to create a temporary block in the system to allow you a 10 minutes to swap out a TRV (its pretty easy and take a few minutes as long as the pipe work all lines up nice). I think you can get a pipe freezing spray kit in B and Q for about 10 quid.
  8. tom.plum

    tom.plum Screwfix Select

    you'd have a hard time getting a freeze kit on that valve, there's not room between the floor and valve, i would connect a hose to that drain off and let it drain off and work on it dry, its much easier to do it that way if you're not sure about how to go about it, you'll fell pressured if you freeze it cos you never know exactly how long you have before the tidal wave hits you, :)

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