Thermostatic radiator valve stuck on full

Discussion in 'Plumbing and Central Heating' started by d000hg, 9 May 2016.

  1. d000hg

    d000hg

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    I noticed a month or so ago that the radiator in my study only comes on full whack whenever the heating is on. I tried turning the thermostatic valve all the way down to OFF but it makes no difference and means on the odd time we have the heating on my study is intolerable!

    I don't know how these things work so...

    1. If I remove it, will the radiator be left on or off? Without the control unit, can I manually adjust the valve?
    2. What is the likelihood that it IS the thermostatic unit that has failed, not the fitting plumbed in to the radiator?
    3. Are these things all interchangeable, I can just buy a new one secure that it will fit? Or do I need to make sure I get one that's the same brand (Myson I think)?
    Cheers for any advice
     
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  3. 45yearsagasman

    45yearsagasman

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    The sensor head may have failed, or it may be the pin in the valve body is siezed in the open position. Remove the head, they usually unscrew with the knurled ring, and try depressing the pin to free it up. Removing the head, will with any TRV allow the valve to stay open no matter what. Depends on how old the valve is as to whether replacement parts are available. Far better to fit a complete new valve imo.
     
  4. d000hg

    d000hg

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    Ah, so the head and the plumbed in valve are really one unit. Can you clarify, this pin of which you speak - does the pin depress to open or to close the valve? e.g. when I remove the head should the pin spring up and I should be able to push it down with my finger? If the pin seems stuck is this a job for WD-40?
     
  5. ianmcd

    ianmcd

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    with the sensor head removed , no tools normally needed, the pin only moves a few millimeters it doesnt spring as you called it, if you can depress it that is it closed and it should then come back out and that is it fully open but as I say it is only a very small movement if it wont go in WD 40 wouldnt do and harm, it could also be that the sensor head is not tightened properly that would also cause the symptom you have
     
  6. d000hg

    d000hg

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    I'll take a look then, thanks. Right now the main issue is getting the radiator turned off!
     
  7. ianmcd

    ianmcd

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    Then close the Lockshield valve at the other end of the radiator and the radiator wont heat at all, if you cant work out how to close it post a pic of it and someone will advise you how to , there are a few types but all only take a few mins to do
     
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  9. d000hg

    d000hg

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    Good point. The one at the other end is a standard one pretty identical to this I found online. There's no knob on it; do I use pliers to grasp the top bit and turn clockwise, or is there more to it?

    I really should know more about this from helping dad as a kid but while the plumbing parts I can remember, I never dealt with valves before!

    [​IMG]
     
  10. ianmcd

    ianmcd

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    yes thats all you do just turn the spindle clockwise till it closes, might be a good idea to count how many turns it takes to close it and when you need to open it again use the same amount of turns, as if your system has been properly balanced we use this valve to do so, but to be honest not many systems are, it wont do any harm though and doesnt take any effort to count as you do it.
     
  11. Agile

    Agile

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    Pliars chew up the spindle.

    The correct tool to use is an adjustable spanner.

    Tony
     
  12. d000hg

    d000hg

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    148715659065859570050.jpg
    So I thought I had fixed this... Then today I found it snapped clean off like this in the floor...! How on earth?
     
  13. ianmcd

    ianmcd

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    well no wonder it wouldnt shut off
     
  14. d000hg

    d000hg

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    I attacked the pin with WD40 and a small hammer when this thread was first live and got it moving again - as someone suggested it had indeed seized up.

    I actually had the thermo-valve working OK then it seemed to stop again. Now this...
     
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