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Discuss 3/4 Brass coupling with nylon thread, why? in the Fittings & Pipes area at

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  1. Plumb Duff

    Plumb Duff New Member

    Hi all, I recently got with a pressurised water heater connections consisting of 3/4 brass nipples and brass couplings, the coupling has rubber seals and nylon internal thread, why would this be the case and can I not just directly couple to the water heater without the coupling supplied using 3/4 elbows to the water heater with the nipples fitted? What is the purpose of the supplied coupling? (attached photo)

    Attached Files:

  2. SimonG

    SimonG Trusted Plumber Top Contributor!!

    So you dont damage the heater by riving on the fittings.
  3. JCplumb

    JCplumb Plumber

    They're dielectric couplings, they help prevent corrosion in the heater.
    If you don't fit them your warranty will be worthless.
  4. Plumb Duff

    Plumb Duff New Member

    I should perhaps clarify it is the nipple that is designed to first connect to the water heater then the coupling into that, if I can connect direct to the nipple with an elbow (and this would be the preferred way due to space constraints) then I don’t need the brass/nylon coupling?

    In reply to SimonG (thank you) surely the heater protected from damage by the nipple? Correct me if I'm wrong.
  5. stani

    stani Plumber GSR

    Jcplumb is absolutely correct and the warranty is worthless without them.
  6. Plumb Duff

    Plumb Duff New Member

    JC yes that sort of makes sense to me as it looked like it was designed for electrical isolation (albeit water is a conductor) having said that I'm using PVC covered aluminium pipe and it would suite a lot better if I could use the supplied coupling a couple of metres from the tank as opposed to directly onto it, would it make any difference... in your opinion?
  7. stani

    stani Plumber GSR

    It's not for electrical insulation it's to stop corrosion caused by dissimilar metals.
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  8. stani

    stani Plumber GSR

  9. Plumb Duff

    Plumb Duff New Member

    Advise duly taken they will be fitted, many thanks to all that replied
  10. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    To be fair them ones look decent ones, normally there a bit of formed plastic just normally bin them as the tails out the heaters are plastic any way :s so no need and they always break/ snap as they can't take the heat and cooling

    Ariston water heaters

    also are you G3 registered as any pressurised water heater needs to be installed by a G3 qualified person
    Last edited: Sep 14, 2016
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