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3/4 Brass coupling with nylon thread, why?

Discuss 3/4 Brass coupling with nylon thread, why? at UK Plumbers Forums; 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 ...
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    Question 3/4 Brass coupling with nylon thread, why?

    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)
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    Default Re: 3/4 Brass coupling with nylon thread, why?

    So you dont damage the heater by riving on the fittings.
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    Default Re: 3/4 Brass coupling with nylon thread, why?

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

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    Default Re: 3/4 Brass coupling with nylon thread, why?

    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.

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    Default Re: 3/4 Brass coupling with nylon thread, why?

    Jcplumb is absolutely correct and the warranty is worthless without them.

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    Default Re: 3/4 Brass coupling with nylon thread, why?

    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?

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    Default Re: 3/4 Brass coupling with nylon thread, why?

    It's not for electrical insulation it's to stop corrosion caused by dissimilar metals.
    quality likes this.

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    Default Re: 3/4 Brass coupling with nylon thread, why?


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    Default Re: 3/4 Brass coupling with nylon thread, why?

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

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    Default Re: 3/4 Brass coupling with nylon thread, why?

    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
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