Replace Radiator valve

Discussion in 'Plumbers' Talk' started by Antonyswans, Oct 28, 2022.

  1. Antonyswans

    Antonyswans New Member

    Hello,
    I need to change my radiator valve but am unsure what size I need. The original valve was installed in the 1960’s and the pipework size is 40mm circumference. The valve has 15 DIN stamped on it and was made by Honeywell. I can provide a photo of the old valve
    Please can you advise me if a replacement could be fitted?
    Thanks
     

    Attached Files:

  2. Built2last

    Built2last Active Member

    12mm pipework I think so change with a 12mm radiator valve.
     
  3. Antonyswans

    Antonyswans New Member

    Thanks for your advice
     
  4. Antonyswans

    Antonyswans New Member

    Does this mean that I cab buy a 10/15mm valve as a replacement, as it will fit any size between 10 & 15mm?
     
  5. andy48

    andy48 Screwfix Select

  6. Antonyswans

    Antonyswans New Member

    Thanks very much
    Wish me luck with the leaks
     
  7. Built2last

    Built2last Active Member

    Drain down the system before you start.
     
  8. Mike83

    Mike83 Screwfix Select

    Pipe work doesn’t look 12mm but could be wrong.
    Best trying to measure the diameter to be sure.
     
  9. longboat

    longboat Screwfix Select

    As Mike has said, the pipework doesn't look to be 12mm.
    I'd say 8mm.
    How did you measure the circumference?
     
  10. Antonyswans

    Antonyswans New Member

    Hi,
    I wrapped a flexible tape around the pipe and it measured 40mm; so I divided by Pi and it was 12.7388... so allowing for slight errors, I assumed that it was near enough 12 mm. Although this pipework is dated from 1968
     
  11. longboat

    longboat Screwfix Select

    A flexible tape (unless incredibly thin) will give a massively inaccurate reading when placed around such a small diameter due to the thickness of the tape itself.
    For best results use a vernier calliper or if not available use a tape measure held close to the pipe to gauge the closest increment.
    That pipe is definitely not 12mm.
    I'd say 8, but could be 10 at a push.
     
  12. Antonyswans

    Antonyswans New Member

    Thanks again,
    I just re-measured with some brown tape and its now 30mm so it comes out at 9.55.. so I now assume that it is 10mm as you said. I also used a tape accross the pipe and I''m reasonably sure that it is 10mm.
    I'll try a 10mm valve first.
    Thanks again to everyone for thier help and advice (This D.I.Y. is not as easy as it looks!!)
     
    longboat likes this.
  13. McSport

    McSport Screwfix Select

    Have a mix of 15 and 10mm in my house and changed all the valves last year

    You can get standard 15mm valve and use a reducer
    My Drayton RT212 came with these. Tighten up and they snap. You would need to remove the old olive.
    https://www.screwfix.com/p/flomasta-compression-reducing-internal-coupler-15-x-10mm/70435

    I think the pros prefer the multipart version. I had no problems with the ones I used though.
    https://www.toolstation.com/made4trade-compression-reducer/p43650

    Get yourself a digital vernier caliper
    Often in Lidl or Aldi for less than £10. So useful for measuring this sort of thing.
     
  14. Mike83

    Mike83 Screwfix Select

    The bend in the pipework below the valve makes it look like 8mm pipe.
    8mm pipe will have a circumference of 26mm I think.
    Some valves will have both 8 and 10mm reducers included.
    Some snap reducers don’t actually fit inside some valves if bought separately.
     
    McSport likes this.
  15. Antonyswans

    Antonyswans New Member

    Thanks for all the help that you have given.

    With all the work involved, it’s a shame that I couldn’t just get a replacement head and just replace that, as the original just snapped, and won’t turn the valve. The problem is that nothing will fit, as it is so old, so I have to replace the whole valve body and head.

    Thanks again
     
  16. Antonyswans

    Antonyswans New Member

    Does anybody know if I can get a suitable replacement for this type of TRV Honeywell Head.

    I believe that it dates from the 1960’s. It will save me from having to replace the whole valve

    Thanks
     

    Attached Files:

  17. Mike83

    Mike83 Screwfix Select

    Not sure about the head.
    If there’s another radiator that you always have on maximum then you could just use that head for the radiator in question.
    This would give a temporary solution.
     
  18. Mike83

    Mike83 Screwfix Select

    You could try emailing Honeywell about a replacement head.
    There may be a head that fits but I’m not sure.
     
  19. McSport

    McSport Screwfix Select

  20. Antonyswans

    Antonyswans New Member

    Thanks for all your help and support.
    I'll see if I can get a replacement head; if not, I'll just buy a new complete valve. I have a set of calipers on order, as suggested, so I'm all set to go.
    Thanks again, your advice had been invaluable
     
    longboat and McSport like this.

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