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Old 01-28-2010, 10:45 PM   #1
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Default Dielectric nipples or not??

Dielectric fittings is the seperation of two dissimiliar metals right? I see how dielectric unions seperate the alloys with a plastic sleeve and rubber gasket. Could someone help me out with how the "dielectric nipples" that come with water heaters work? They are a galv. nipple with a plastic sleeve in the inner walls. How can it break the circuit if you screw a copper female adpt. on one end of the nipple and screw the other end in the water htr.? All the metals are still contacting. How can they be called Dielectric nipples? Some help?
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Old 01-28-2010, 10:49 PM   #2
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They can call them anything they want. It's debatable whether dielectric unions work so I'm sure the nipples don't.






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Old 01-28-2010, 10:51 PM   #3
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they dont do diddly..unless there a bradford white heater yank em and put brass or stainless

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Old 01-28-2010, 10:53 PM   #4
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I never use dielectric unions, they suck. I have yet to see one that isnt almost corroded or rusted shut after 5-10 years.

I use 7/8" X 3/4" FIP brass compression adapters.
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Old 01-28-2010, 11:07 PM   #5
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used to have to use dielct coups, not unions, to connect ridgid lp lines from house to tank preventing lightning strike on house making the propane tank explode. that's it! i'm calling the mythbusters
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Old 01-28-2010, 11:38 PM   #6
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They are not Die-electric in any way. They just have a plastic liner which is supposed to hold the water way open. It does nothing by way of stopping galvanic corrosion.

They work ok if you use a brass female on the top and bottom it out so that the brass seals up against the plastic liner. While not truly die-electric, that method will at least hold the waterways open. The best method is to insert pex dip tubes inside the nipples and cut the one on the hot side so that it only protrudes about 1" into the tank. The flang at the top of the dip tube provides an even better seal against the brass female. When done this way there is zero flow loss from galvanic corrosion. It may also improve tank life but I have no evidence to support that yet. Only theory.
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Old 01-28-2010, 11:43 PM   #7
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They do keep the waterway open. That's alone is worth something.

I've replaced water heaters that were under warranty that were installed with galvanized and only four years old that were less than 1/2 open due to rust buildup.
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Old 01-28-2010, 11:48 PM   #8
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Those nipples to keep people from putting copper adapters directly into the heater making the heater fail at the inlets. The nipples keeps that copper to steel connection above the tank....so people wont call and say their water heater is leaking and get it covered under a warranty. Copper to steel eats steel, more so in some water. i guess you also have the option of installing dielectric unions but I dont do either and I take the steel mipples out all together and and other crap i can find in there but the diptube.
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Old 01-29-2010, 08:14 AM   #9
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Somebody explain the difference in these dielectric waterways and the nipples in the w/h's. We used ones similar to these when running Vict. galv. mains and transitioning to copper in commercial projects.

http://www.victaulic.com/Docs/lit/09.07.pdf

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Old 01-29-2010, 05:52 PM   #10
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Would it be better to have a 2" brass nipple in the steel tank, then a c x f adaptor, to copper tube?

Why wouldn't the manufactures just put brass nipples in, instead of steel?
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