Radiator Valve Sizes

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

  1. Hi, welcome to the new look UKPlumbersForums.co.uk - Login with your usual login details, or sign up if you don't already have an account. If you post just once, all the advertisements get automatically removed. We have some competitions coming soon, and lots of new feaures. 

Dismiss Notice

Couple of important things to note. 1. We use Cookies, deal with it. Every website does. 2. Nobody but a currently-registered Gas Engineer should be touching gas or gas appliances. Don't mess with gas at all. 

Discuss Radiator Valve Sizes in the Plumbing Forum area at UKPlumbersForums.co.uk.

  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 Trusted Plumber GSR Top Contributor!!

    It's a lockshield Union mate
     
  7. rpm

    rpm Trusted Plumber Top Contributor!!

    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. .

    Rad_Valve.jpg
     
  10. ShaunCorbs

    ShaunCorbs 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 Plumber GSR Top Contributor!!

    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 Top Contributor!!

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

    ShaunCorbs 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 Trusted Plumber GSR Top Contributor!!

    We have told you it's a stnd lock shield drain off

    http://www.screwfix.com/p/chrome-an...ff/36552#product_additional_details_container
     
    • Like Like x 2
    Last edited: Jan 9, 2017
  16. snowhead

    snowhead Well-Known Member

  17. johnf

    johnf Active Member

    Its a common valve. We do know better and we are trying to tell you this :dizzy2:
     
  18. rpm

    rpm Trusted Plumber Top Contributor!!

    When doing 6"- 18" gate valves there was a gasket, how do these seal then?
     
  19. ShaunCorbs

    ShaunCorbs Trusted Plumber GSR Top Contributor!!

    Just brass on brass mating surfaces
     
  20. rpm

    rpm Trusted Plumber Top Contributor!!

  21. rpm

    rpm Trusted Plumber Top Contributor!!

    Ok, got it. Little cross posting going on there.
     
  22. PlumbBobBob

    PlumbBobBob Guest

  23. ShaunCorbs

    ShaunCorbs Trusted Plumber GSR Top Contributor!!

    • Like Like x 1
  24. AWJD

    AWJD New Member

    I have now been to both the main plumbing merchants in Abingdon (Grahams and Plumb Centre) and nobody in either had ever seen a Lockshield valve with drain with a 1" thread to the radiator. The guy in the Plumb Centre said he'd worked there for 25 years and never seen one even though my radiator is only 15 years old.

    How come I can then walk into Screwfix of all places and buy one over the counter as recommended by you guys on the forum? It seems to be a standard size for Screwfix but to nobody else in the industry?
     
  25. ShaunCorbs

    ShaunCorbs Trusted Plumber GSR Top Contributor!!

    Because it's not a 1" lockshield with drain off :banghead:
     
    • Like Like x 1
  26. AWJD

    AWJD New Member

    It doesn't matter what the technical description for the valve is, I took the original one into the plumbing merchants and they said they had never seen one before with that sized thread on the radiator outlet!!
     
  27. rpm

    rpm Trusted Plumber Top Contributor!!

    You have a screwfix and a b&q in Abingdon suggest you try either of them, b&q will have them out on display.
     
    • Like Like x 1
  28. AWJD

    AWJD New Member

    I didn't say it was a '1" lockshield with drain off '. In fact it is a 10mm radiator valve with drain off which can be configured either as a lockshield or a manual valve as described on the packaging but it has a 1" thread on the radiator connection.
     
  29. ShaunCorbs

    ShaunCorbs Trusted Plumber GSR Top Contributor!!

    But that's not the rad connection, it's the connection on the Union
     
  30. rpm

    rpm Trusted Plumber Top Contributor!!

    AWJD, it is made up of 2 parts, the 1st part screws into the radiator on a tapered thread then your valve connects from this part via the large nut to your 10mm pipe.
     
    • Like Like x 1
  31. AWJD

    AWJD New Member

    My radiator came with the tail/unions already in place and that is what I was trying to connect a new valve to. What I was trying to understand is what are considered standard union thread sizes for these types of valve and why Screwfix do a 1" threaded connection to the union but proper plumbing merchants don't?

    Fortunately, I've now got a replacement valve from Screwfix and so the problem is solved!
     
  32. rpm

    rpm Trusted Plumber Top Contributor!!

    Hurrah! :hurray: :party:
    I think the merchant was messing with you tbh.
     
    • Like Like x 1
    Last edited: Jan 10, 2017
  33. PlumbBobBob

    PlumbBobBob Guest

    it is called 3/4" not 1" that's why
     
  34. rpm

    rpm Trusted Plumber Top Contributor!!

    Which makes BSP so confusing to the unexperienced.
     
    • Like Like x 1
  35. Stoney Ground

    Stoney Ground GSR

    What was the screwfix part number in case one of us guys come up against the same problem.
     
    • Like Like x 1
  36. AWJD

    AWJD New Member

    I bought part 36552 from Screwfix. As said, I took the original valve into the 2 x plumbing merchants and neither had a size that matched. I'm going back to Screwfix tomorrow to get another valve for the other end of the radiator without the drain.
     
  37. AWJD

    AWJD New Member

    I was referring to the diameter of the tread which was 1". And yes, this is also referred to as a 3/4" BSP thread- and the plumbing merchants still didn't stock it!
     
  38. rpm

    rpm Trusted Plumber Top Contributor!!

    Glad you got it sorted in the end however left wondering exactly what words you used ie did you say 1" for the radiator in which case I can understand the response you got.
     
  39. AWJD

    AWJD New Member

    I needed to sort out the issues with my radiator valves because this summer I will need to get all the valves changed (TRVs included this time) and didn't want any nasty surprises in terms unavailable parts. My final understanding is the following:

    1. All my old radiators and modern radiators use tails which all have a 1/2 BSP male tapered threads going into the radiator.

    2. Therefore, since replacement valves come with a tail, it should be possible, worst case, simply to replace the old tails (and valves) with the new tails (and valves).

    3. The old standard for valves was to use a 3/4 BSP union connection ('O' ring or fibre washer seal) to the radiator tail.

    4. The new standard for valves is to use a 15mm compression connector to the radiator tail.

    5. Many plumber merchants don't appear to stock radiator valves with union connections any more - fortunately, other outlets, such as Screwfix do stock them still.

    This has been a bit of a steep learning curve for me, not helped by not knowing what correct terminology to use at times! However, I got there in the end!
     
Loading...