Diaelectric unions??

Matt_29

I would like to use a diaelectric union to join some copper to steel piping for a 180 degree residential closed hot water boiler system... are they suitable for and/or do they even make them for this type of application

tls_9

In My Opinion

You would be better off using a dielectic nipple or a brass nipple. Victaulic and groovelok both make threaded dielectric nipples. The need to use a dielectric connection in a closed loop system is debatable. Dielectric unions ,as a rule, pardon the slang, suck.

tom

Alan(CaliforniaRadiant)Forbes

Dielectric unions

should not be used on closed loop hydronic systems, especially high temperature ones. That rubber washer will fail in short order.

If your nervous about electrolysis, use a brass nipple between the copper and galvanized pipe. We use a male adaptor and tie the two together directly.

Dielectric devices need only be used for domestic water systems.

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ScottMP

I have been

Installing boilers for twenty plus years with Black Steel headers and copper runs. I have never used a dielectric fitting.

Not needed.

Scott

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Robert O'Connor_7

Transition..

Dielectric unions (as Allen mentioned) do not stand up well in especially high temperature hydronic applications. We use a simple all brass ball valve which in a way kills two birds with one stone.

Robert O'Connor/NJ

Ken_8

Scott's right

The entire concept of dielectric unions and fittings is mis-understood and completely over-blown with regard to our particular discipline. We mix aluminum, steel, iron, non-ferrous metals of all kinds and platstics with little to no "dielectric issues."

Issues of way off neutral pH and anode/cathode interactions of "active" metals is more for the labs than general heating. Electrolysis per se is not an issue in what we do.

Of course as soon as I dismiss the issue - someone will remind me of the time they had vinegar heated in a galvanized brine tank and mixed it with aluminum tubing pumped with a zinc and lead circ. pump into a tin vessel filled with enriched uranium and I'll be made the fool once again...

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hr

Dielectric flanges!

I used to build these when I had a brass flange business years ago "Smart parts for Neat Heat"

I used a 3/8" bolt and some high temperature and strength washers. Then I sleeved the bolt with either plastic tube or two layers of heat shrink tubing. Then a flat EPDM gasket in between.

All simple off the shelf components, these days, if you need a mechanical joint and dielectric to please an inspector or something.

hot rod

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