Dielectric Union Needed?

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jesse shapiro

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I just had a Rheem Power Vent unit installed. The technician installed the copper pipe from the house directly to the two heat trap nipples. The nipples are silver in color so I assume made of steel. I contacted Rheem to confirm if those nipples acted as dielectric unions and their response was:

"The nipples do have a plastic lining on the inside, but they are not considered dielectric nipples. "

Do I need to worry about corrosion? I had this exact set up with my last GE Power Vent and I noticed corrosion around the nipples. It was 8 years old when replaced. Should I add dielectric unions?
 

jesse shapiro

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Thank you SHEPLMBR. Rheem is saying that they are not considered dielectric nipples, but you are saying that they function in the same capacity? Connecting directly to copper is no problem?
 

Jeff Handy

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Looks like there would still be a direct metal to metal connection from the copper supplies, to the nipples threads, to the top of your tank, with nipples like those.
 

Jeff Handy

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Teflon tape cuts down that connection a little, but the nipple threads will usually at least partially cut through it while being cranked in.
 

Jeff Handy

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I can see the internal plastic lining of the nipples being slippery and great for not choking up the nipples with mineral formation.

But I still see that he will have the copper supplies connected directly to the steel threads of the nipples, with only pipe dope or teflon tape giving some possible amount of relief from full contact of both metals to each other.

Unless maybe the copper supplies have a threaded brass female connector, which would help as a transition metal.
 

voletl

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Galvanic action only occurs when two dissimilar Metals touch each other in the presence of water because the nipple is lined with plastic the water never touches the steel which means you can connect the copper adapter to the steel nipple without any problems dielectric unions are not needed it does not matter whether or not you have enough pipe dope or Teflon tape

And if you ever do see any corrosion on the connections at the nipples it's because you have a leak
 
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