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Radiator Valve Sizes

Discussion in 'Plumbing Forum' started by AWJD, Jan 9, 2017.

Discuss Radiator Valve Sizes in the Plumbing Forum area at

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  1. AWJD

    AWJD New Member

    I tried to adjust the lockshield valve on my 15 year kitchen radiator and it started leaking. I therefore decided to replace it and thought this would be a straightforward job. Unfortunately, the thread on the old valve appeared to be about 1" in diameter as was the nut on the radiator outlet.

    I went round to our local Graham Plumbing merchant and nobody there seemed to have ever come across a radiator with this size valve before. If I can't find a suitable valve or converter then this radiator will need to be replaced which seems a little bit drastic.

    Is the world going mad or is there a plumber out there who can offer me a solution?
  2. rocketmanbkk

    rocketmanbkk Plumber

    Post a pic of the valve. You might need. Valve & rad tail

    A pic will tell a thousand words
  3. Chalked

    Chalked Plumber GSR

    Most new radiator valves are 1/2 inch, thread/ 15mm copper. You have a union type radiator valve. These are 1". The trouble is that there are lots of different types of these, so you are better off removing the tail ( the bit in the rad) and use the tail that comes with a new valve.
    • Like Like x 1
  4. COHIBA1207

    COHIBA1207 New Member

    Hi 3/4" on domestic is normally the biggest on a rad this age
    Commercial valves can be bigger for black iron fitting
    try using brass bushes or reducers to get to the correct size if there is enough room on the pipework
    use a good seal prob PTFE as bushes and reducers are often not tapered
  5. turnpin

    turnpin Trusted Plumber

    Welcome AWJD to the forum's....any chance of a picture of the valve as it could be helpful with your enquiry...regards Turnpin :welcome:
  6. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    It's a lockshield Union mate
  7. rpm

    rpm Trusted Plumber

    Welcome to the forum.

    Bit of an over kill isn`t? Bushes and fittings can be parallel or tapered threads and easy for an amateur to get wrong.
  8. AWJD

    AWJD New Member

    I attempted to load a picture of the valve via the 'Image' icon but, after selecting the file, the update file(s) link didn't work. Could someone please explain what is going wrong?
  9. AWJD

    AWJD New Member

    Not sure the upload of the picture worked but if it did it shows the Lockshield valve with 1" thread. .

  10. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Stnd drain off lockshield, if it's leaking where the ptfe tape is wants some compound on it
    • Like Like x 1
  11. king of pipes

    king of pipes Trusted Plumber GSR

    Take the picture on your phone to screwfix with you they sell them fitted one today it's a standard valve bud
  12. rpm

    rpm Trusted Plumber

    Isn`t it an O-ring to make the seal?
  13. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    No mating surface like big gate valves
    • Like Like x 1
  14. AWJD

    AWJD New Member

    This valve has reached the end of its life and was leaking underneath where it's now covered in black RTV silicon. As said, the problem in replacing it is that it appears to have a 1" thread on the radiator outlet which must have been common when I fitted it 15 years ago. This size fitting no longer seems to be available unless someone knows better?
  15. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    We have told you it's a stnd lock shield drain off
    • Like Like x 2
    Last edited: Jan 9, 2017
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