Daryton TRV 4 Problem

Discussion in 'Plumbers' Talk' started by Mosaix, Nov 13, 2017.

  1. Mosaix

    Mosaix Member

    Hi I have a radiator that had an original Drayton TRV fitted many, many year ago. The valve itself seized up and wouldn't open any more so I bought a new TRV 4 complete with valve. Fitted no problem.

    Problem is the old TRV had the room comfortable set to 3. The TRV 4 seems to need setting to 5 before it achieves the same level, leaving only MAX left. Anything below 5 and there's no flow at all even when the room is chilly. There is flow below 5 first thing in the morning when the room is quite cold but it soon shuts down.

    I have checked the valve itself and there seems to be full movement up and down of the 'spindle'. There is unrestricted air flow around the TRV.

    Is there an adjustment that I can make or is it faulty?

    Thanks in anticipation.
  2. The Teach

    The Teach Well-Known Member

    Have you tried for a few days with the sensor head removed ?
    Mosaix likes this.
  3. Mosaix

    Mosaix Member

    Thanks for the reply, Teach. Would that help? I only fitted it yesterday.
  4. The Teach

    The Teach Well-Known Member

    it could have a faulty sensor or valve body or it could be ok,its a process of elimination.

    Whats the setting on this radiator lockshield valve.
    Fully open,half open or just open a little ?
    Mosaix likes this.
  5. Mosaix

    Mosaix Member

    Sorry, should have said, Teach, lockshield full open.

    Removed the sensor a few minutes ago - radiator now red hot.
  6. The Teach

    The Teach Well-Known Member

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  7. Mosaix

    Mosaix Member

    Got it from Screwfix, funnily enough, but some months back now. Just got round to fixing it.

    Will follow and read the link, thanks.
  8. Mosaix

    Mosaix Member

    Sometimes I can be SO stupid.

    I bought two TRV 4s, fitted them both. The other is in a cold, unused bedroom and I haven't tested that one yet. I've swapped that sensor onto this valve at setting 3 and will now wait for it to adjust. The room is very hot having had the sensor head off for the last hour.

    Will keep you informed.
  9. KIAB

    KIAB Well-Known Member

    You need a Drayton Presetting key, if you remove the head, you'll the black body, this has numbers on it 1-6, 1 being the least flow, 6 maximum flow.
    Set it to the same number as valve you replaced, with the TRV4 it is the lockshield, which balances the radiator..

    Pre setting key: https://www.screwfix.com/p/drayton-pre-setting-key-0735132-2-pack/1351r

    And this linky: https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&ved=0ahUKEwiLgoHug7zXAhVLCMAKHcGKCfkQFgjaATAH&url=https://www.partscenter.co.uk/wcsstore7.00.805.890/ExtendedSitesCatalogAssetStore/images/products/AssetPush/DTP_AssetPushHighRes/std.lang.all/ti/on/Drayton_TRV4_Installation.pdf&usg=AOvVaw3lbTYh51pwdYjEz5aWyZ-B

    See this video.

    Last edited: Nov 13, 2017
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  10. Mosaix

    Mosaix Member

    Thanks, KIAB. I don't have a pre-setting key but on the black body I can see a number 5. If I set it to 3 that would seem to indicate that I would get a reduced flow over what I have now. Wouldn't that make the problem worse i.e. make it shut down even sooner? Sorry if I'm being dim.
  11. KIAB

    KIAB Well-Known Member

    My second link earlier reply explains better than I ever can.

    You have to balance the radiator by setting the number, so you get a 11 degree difference in the flow & return temperature.
    The number 5 need to aline with the notch on the body you need to set new valve to the same figure as on the old valve.
    The lockshield other end needs to be fully open.
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  12. Mosaix

    Mosaix Member

    Thanks, Kiab. Old valve very, very old. No such thing as a number on the old valve. When I said '3' in my post above I was referring to the sensor head temperature setting. Sorry for the confusion.

    I'm waiting for the room to cool down to see if the replacement valve opens at setting 3. If it does then the original sensor is faulty.

    Once I'm sure the sensor head is OK I'll investigate the balancing.

    Thanks again.

    Edit: Closer examination of the valve body shows that the notch is aligned with '2'. Is that nearly fully open or nearly fully closed?
    Last edited: Nov 13, 2017
  13. dobbie

    dobbie Well-Known Member

  14. KIAB

    KIAB Well-Known Member

    No 2 nearly fully close, if you had Drayton setting key, you could try setting it to 3 or maybe 4 to increase the flow.
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  15. Mosaix

    Mosaix Member

    Thanks, dobbie.

    If room temperature is deficient:
    1. Open valve fully by turning setting to ‘MAX’ and allow time for radiator
    to fully heat the room. If heat is still not sufficient, slacken the ring nut
    and remove the head completely. This allows the valve to open fully. If
    the room still fails to warm sufficiently, the deficiency is not due to the
    thermostatic radiator valve and further investigation of the system is

    So, I turned to 'MAX' and the heat was sufficient as it was at 5. But below that there seems no flow even when the room is chilly. Anyway, I'm waiting for the room to cool down to see if the replacement head does the trick.
  16. The Teach

    The Teach Well-Known Member

    Some trv's have a delay in opening,something to do with saving energy.
    Always fitted trv's on the return pipe,horizontally as per the makers instructions (danfoss).Reaction time is instant.
    Not a fan of Drayton trv4.
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  17. KIAB

    KIAB Well-Known Member

    Got the trv4's here, & one is being a right swine,losing patience with balancing radiators,come the spring going to replace the lot.
    Mosaix likes this.
  18. Mosaix

    Mosaix Member

    I've read, in one of the links that have been posted, that the TRV should be fitted finger tight only. Doesn't say that in the instructions that came with it. Looks like I need to slacken it off. That could be the problem all along.
  19. KIAB

    KIAB Well-Known Member

    Only need to hand tight the trv head, but I've seen them where you have needed to use a slip joint to loosen them.
    Mosaix likes this.
  20. Dr Bodgit

    Dr Bodgit Well-Known Member

    I've had the heads come loose so have nipped them up just a smidge, just be careful not to crack anything.
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