# Dielectric Unions, Dielectric Nipples, Expansion Tanks



## DUNBAR PLUMBING (Sep 11, 2008)

Tell me how a copper FIP to a dielectric nipple is a reliable connection in the plumbing industry when every single one I've removed always has buildup that is flow restricting and severe deterioration of the beginning threads of the dielectric nipple.

I've noticed they've changed the material choice that serves as the threaded connection to all thermal expansion tanks...what's the major malfunction of these dielectric nipples? 


And don't think it's always homeowners and hacks that burn up/destroy dielectric nipples during installation; I've seen countless times in new construction where they didn't even jig the uprights, just threaded the FIP's and rolled with it. 

Those dielectric nipples with the heat traps, small floating ball? DESTROYED when heat warps the function of that moving component. 

I've been around long enough where tanks came without factory installed nipples, we just used MIP's and that was it. Always though, clogged right where the two connected to the steel tank.

I can honestly say I do not think every connection that has leaked, or is leaking at a copper to dielectric nipple is the result of installer error. I see this a lot, and installer error MOST of the time will reflect a leak right away on that application.

You can wrap teflon/dope it all you want; once you start threading those two pieces together you will lose any chance that you are covering the exposed top thread pattern to the nipple, and water becomes the #1 reason in conjunction with those 2 metals to start becoming defective.

I just reworked a water line last night, looked over at a 5 year water heater that's completely destroyed due to those connections. Never leaked for years...but apparently they did in the past 18 months which now the water heater is in need of replacement due to ongoing leaks that new connections to the tank will not resolve.


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## SewerRatz (Apr 25, 2009)

I have always put brass IPS unions on the dielectric nipples, then a mail adapter into it for the hot side cold side a brass nipple then a brass IPS tee for the expansion tank port. Never had any issues with my installs this way.


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## Don The Plumber (Feb 14, 2010)

SewerRatz said:


> I have always put brass IPS unions on the dielectric nipples, then a mail adapter into it for the hot side cold side a brass nipple then a brass IPS tee for the expansion tank port. Never had any issues with my installs this way.


 I like it, but what do you do if they require dielectric unions? Half the houses I go in, have leaky, rusty dielectrics, on top of the heater. The other ones that don't leak, are all corroded inside.

Then the heaters I replace that were bought from box stores, that have galv. nipples (cuz they don't come with heater nipples for some reason) are really nasty looking, & as Dunbar said, shorten the life of the tank substantially.


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## SewerRatz (Apr 25, 2009)

Don The Plumber said:


> I like it, but what do you do if they require dielectric unions? Half the houses I go in, have leaky, rusty dielectrics, on top of the heater. The other ones that don't leak, are all corroded inside.
> 
> Then the heaters I replace that were bought from box stores, that have galv. nipples (cuz they don't come with heater nipples for some reason) are really nasty looking, & as Dunbar said, shorten the life of the tank substantially.


Our code allows for brass fittings to be used in place of dielectric unions.

"Unions between copper pipe/tubing and dissimilar metals shall either be made with a brass converter fitting or be a dielectric type union. "


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## Protech (Sep 22, 2008)

Same here



SewerRatz said:


> Our code allows for brass fittings to be used in place of dielectric unions.
> 
> "Unions between copper pipe/tubing and dissimilar metals shall either be made with a brass converter fitting or be a dielectric type union. "


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## PLUMB TIME (Feb 2, 2009)

"Unions between copper pipe/tubing and dissimilar metals shall either be made with a brass converter fitting or be a dielectric type union. "

Not anymore.

Or maybe I need to keep reading the new code that they can't afford to print.:whistling2:


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## Pipe Rat (Apr 5, 2009)

I'm with seweratz Brass IMO is the best choice.:yes:


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## SewerRatz (Apr 25, 2009)

PLUMB TIME said:


> "Unions between copper pipe/tubing and dissimilar metals shall either be made with a brass converter fitting or be a dielectric type union. "
> 
> Not anymore.
> 
> Or maybe I need to keep reading the new code that they can't afford to print.:whistling2:


That was cut and pasted from the code they can not afford to print. Here let me do you a favor I will post the whole page of the code and give you the link. http://www.ilga.gov/commission/jcar/admincode/077/077008900C03500R.html

TITLE 77: PUBLIC HEALTH 
CHAPTER I: DEPARTMENT OF PUBLIC HEALTH 
SUBCHAPTER r: WATER AND SEWAGE 
PART 890 ILLINOIS PLUMBING CODE 
SECTION 890.350 UNIONS​ 


*Section 890.350 Unions* 

Unions may be used in the drainage and venting system when accessibly located above ground. Unions shall be installed in a water supply system within 5 feet of regulating equipment, water heaters, water conditioning tanks, water conditioning equipment, pumps, and similar equipment which may require service by removal or replacement. Where small equipment may be unscrewed, only one union shall be required. 
a) Drainage System. Unions may be used in the trap seal and on the inlet and outlet side of the trap. Unions shall have metal to metal seats except that plastic unions may have plastic to plastic seats. 

b) Water Supply System. Unions in the water supply system shall be metal to metal with ground seats, except that plastic to metal unions may utilize durable, non-toxic, impervious gaskets. Unions between copper pipe/tubing and dissimilar metals shall either be made with a brass converter fitting or be a dielectric type union. 


​Now if there is more changes to the code I do hope the state will at lease update the version they have published in the website. http://www.ilga.gov/commission/jcar/admincode/077/07700890sections.html


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## LEAD INGOT (Jul 15, 2009)

Have any of you guys tried stainless steel unions? They are legal by my code for potable. And I have taken a couple apart that have been in place for 2 years, no build up, no corrosion. I can't remember where SS is on the dielectric reactivity scale w/ brass, copper, etc. But in real world app, they work great. We all have had dielectrics, with ports that are almost closed within a year.


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## Protech (Sep 22, 2008)

Depends which alloy you’re talking about. They vary greatly in electro negativity.



LEAD INGOT said:


> Have any of you guys tried stainless steel unions? They are legal by my code for potable. And I have taken a couple apart that have been in place for 2 years, no build up, no corrosion. I can't remember where SS is on the dielectric reactivity scale w/ brass, copper, etc. But in real world app, they work great. We all have had dielectrics, with ports that are almost closed within a year.


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## LEAD INGOT (Jul 15, 2009)

Protech said:


> Depends which alloy you’re talking about. They vary greatly in electro negativity.


 The ones I have installed are on standard dielectric nipples, installed from the factory. After 2 years, they look great, inside and out. It was something I tried in a personal application as a long term test.


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## Master Mark (Aug 14, 2009)

*why not flexible connectors????*

Where l have you been lately DUNBAR???

We are having very good luck with
BLACK Brass Craft *flex connectors... @ 9 bucks each...*

They are 10 times better than dialectric unions.
and they certainly break the electralysis and galvanic corrosion to the heater...

they save me tons of time and they dont leak 
and I save a whole bunch of solder joints and fittings.......

I install them on all my heaters directly
 to the dialectric nipples... ...
we have run across a few black flex 
connectors installed on units about 12-years old. showing no signs of corrosion...

as far as *expansion tanks,* I feel they are worthless, I tore one out 
yesterday that must have weighed 35 lbs , it was waterlogged and just 
hanging in mid air with only the copper arm off a 3/4 tee for support.... 




flex connectors vs dialectric unions..... 

flex connectors wins hands down..:thumbup::thumbup:


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## Pipe Rat (Apr 5, 2009)

I have to disagree with expansion tanks being worthless. When they fail they need to be replaced just as any other fixture. :thumbsup:


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## Protech (Sep 22, 2008)

I firmly believe that a thermal expansion valve should always be installed with a tank. When the tank goes bad the valve will start to drip and that is when the plumber is called out. No valve, no service call when the rank bladder goes. Thermal expansion is left unchecked and destroys something.



Piperat said:


> I have to disagree with expansion tanks being worthless. When they fail they need to be replaced just as any other fixture. :thumbsup:


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## Master Mark (Aug 14, 2009)

*damages from water logged thermal tanks...*



Protech said:


> I firmly believe that a thermal expansion valve should always be installed with a tank. When the tank goes bad the valve will start to drip and that is when the plumber is called out. No valve, no service call when the rank bladder goes. Thermal expansion is left unchecked and destroys something.


I used to be gung-ho about thermal tanks back in 2001
I have seen a lot of them go un-checked for a decade 
and literally rust out a hole through the side and flood a 
home worse than any heater could have done....

Unless you have a *maintaince contract* with the home owner,
you have little chance of getting back in the home 
every 2 years to check the damn thing to see if it is working correctly
and most homeowners are too lazy or clueless on how to check them ...

the one yesterday was water logged and the weight was hanging in mid air when I 
got there, so I offered the HO another one for $89 bucks..
This heater had failed in 4 years with the thermal tank on it....
of course he told me no thanks....and I was in no mood to get 
into a "code pissing contest" with the fellow ..
the new power vent unit was installed in a pan on bricks,
and piped to the sump pit , the t+p over flow pipe was also put in to the pit...

we always put our heaters in a PAN, and pipe everything
to the nearest drain.... 

If their is no drain for the t+p , then I
will usually insist on a thermal expansion tank..
Or they are gonnna sign off on it......


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## TheMaster (Jun 12, 2009)

One 40 gas Ruud water heater......30 years old.








Make it two with consecutive serial numbers......30 years old









Now look how they are piped........keep in mind that they are OLDER than some of you are:whistling2:








Thanks for looking:thumbsup:


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## RealLivePlumber (Jun 22, 2008)

Master Mark said:


> Where l have you been lately DUNBAR???
> 
> We are having very good luck with
> BLACK Brass Craft *flex connectors... @ 9 bucks each...*
> ...


 :no:


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## Protech (Sep 22, 2008)

Ya but we already know you have pretty decent water there and also you can't beat those old rheem/ruuds (even though the new ones are garbage).



TheMaster said:


> One 40 gas Ruud water heater......30 years old.
> 
> 
> 
> ...


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