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How best to make threaded fittings on radiator valves weep-proof

Discussion in 'Plumbing and Central Heating' started by John_Ha, 6 Feb 2017.

  1. John_Ha

    John_Ha

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    I apologise if these sound silly questions, but I would love some advice on making threaded fittings weep-proof.

    I have 1/2" Danfoss Randall RA-G Single Pipe TRV Body which comes with a fitting which screws onto the 1" OD outlet of the TRV and screws into the radiator. (see https://www.heatingcontrolsonline.co.uk/danfoss-randall-rag-single-pipe-trv-body-p-1195.html)

    Q1. The fitting has a rounded conical end which mates with the chamfered outlet port of the TRV. Do I just screw it up tight? Or should I put in something like Boss White? Or can I buy a "funnel-shaped gasket" which goes between fitting and valve?

    Q2. The other ended of the fitting has a tapered thread so I know what to do - use PTFE tape. I was surprised to see the thread has many small nicks in it which presumably make it work like a saw.

    TRV.jpg

    Q3. I am using these radiator extender tails where the thread which screws into the radiator is not tapered. Should I use a rubber or similar gasket or seal between the extender shoulder and the radiator? Or wrap the threads in PTFE, and twist the PTFE into a cord so I create something a bit like an O-ring by the shoulder? Or ...?

    extender.jpg

    It is probably needless to say that Q1 and Q3 are weeping - probably at the thought of my poor workmanship.

    Any assistance will be gratefully received.
     
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  3. Nige F

    Nige F

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    Q 1. If you have Boss White use a thin smear of that . Q3. Get some Loctite 55 for the threads.
     
  4. oldbuffer

    oldbuffer

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    Q1. Use a bit of Jet Lube type paste, although it everything lines up square you can usually get away without it.
    Q2. I'd use Loctite 55, it generally seals better than PTFE. The small notches in the thread are advised when using 55.
    Q3. I'd carefully nick the threads with a file and use Loctite 55. Usually the radiators are not sufficiently smooth at the outside of the femal thread to allow a gasket / O ring to be used.

    Nige F can type quicker than I can
     
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  5. John_Ha

    John_Ha

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    Thank you both.

    I suspected that. I remade the joint today with PTFE and sure enough it is still weeping. Loctite 55 here I come ...
     
  6. Madrab

    Madrab

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    I use gas PTFE, it's thicker than standard PTFE and ideal for these types of jobs. TBH it's an experience thing too, you know by how tight it feels going in whether it's been wound enough and if it's going to weep or not ;)
     
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  8. Happyplumber

    Happyplumber

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    Loctite 55 on all threads,can't remember the last time I used PTFE
     
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  9. John_Ha

    John_Ha

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    Loctite 55 has now been elevated to the status of magic whereas PTFE has been downgraded to "trump trash" :)
     
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  10. easyflow

    easyflow

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    Who by ?
     
  11. dilalio

    dilalio

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    Make them watertight and you won't weep! :LOL:
     
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