Water Tank Theory ?

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Statjunk

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Can someone explain to me why the water tank installation calles for a galvanized nipple to be used to enter the tank? Why can't I just use copper up to the union?

Every galvanized nipple I've ever removed was corroded!

Thanks

Tom
 

Gary Swart

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I'm no pro, but I think the recommended nipples are what they call "dielectric". My spelling of that may be off, but they are not galvanized steel. That's what I have used in tanks that I have installed, in fact, they have been included with the tank. From them I go to a flexible copper pipes and a ball valve that is connected to the water supply or hot water outlet pipe. You very well may get some different answers, but this has worked for me. I avoid galvanized pipe like the plague!
 

Shacko

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statjunk said:
Can someone explain to me why the water tank installation calles for a galvanized nipple to be used to enter the tank? Why can't I just use copper up to the union?

Every galvanized nipple I've ever removed was corroded!

Thanks

Tom

I know this will be a PITA, but call the manufactor and they will tell why they want galve., sorry.

.................................................................
"If all else fails, read the directions"
 

Statjunk

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Sorry not galvanized. Why do they call for "dielectric" nipples?

Tom
 

Jadnashua

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Dissimilar metals can create a crude battery in a water system. This can cause the metal ions to migrate and quickly weaken or disolve one of the 'less noble' metals. The idea is to basically isolate the two metals with an insulator and prevent that. How quickly, or if at all, this happens depends a lot on the content of your water; its pH, and dissolved minerals, and the metals involved.

Now, do they work? Sort of...depends on the quality, and how they are installed, and as mentioned, the water.

Heat makes it worse (speeds up the reaction), so on a WH, it can make a difference.

I'll leave it to the pros who see this all of the time. Comments seem to say they may not be worth the trouble.
 

Jimbo

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According to Rheem's technical literature, the dielectric is to protect the nipple. The water heater itself is adequately protected by the anode rod, but a plain galvanized nipple will corrode.
 

Dubldare

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Actually there is something a bit funny about galvanic corrosion. Whichever is larger, the anodic (think steel) or the cathodic (think copper) material in a system will dictate how severe corrosion will be. The more steel, less corrosion over time; the more copper...bad news for steel

A house plumbed with all galvanized pipe will be much easier on a water heater than a house plumbed in copper. In a copper house, without adequate dielectrics that heater will get the brunt of it.
 
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GrumpyPlumber

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dubldare said:
Actually there is something a bit funny about galvanic corrosion. Whichever is larger, the anodic (think steel) or the cathodic (think copper) material in a system will dictate how severe corrosion will be. The more steel, less corrosion over time; the more copper...bad news for steel

A house plumbed with all galvanized pipe will be much easier on a water heater than a house plumbed in copper. In a copper house, without adequate dielectrics that heater will get the brunt of it.

Having read more than a few of your posts, there is no question your a plumber.
An experienced one.
 

Dubldare

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GrumpyPlumber said:
Having read more than a few of your posts, there is no question your a plumber.
An experienced one.



Thank you Sir, you are too.(even if you do look a lot like Walter Mathau)
 

Statjunk

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dubldare said:
Actually there is something a bit funny about galvanic corrosion. Whichever is larger, the anodic (think steel) or the cathodic (think copper) material in a system will dictate how severe corrosion will be. The more steel, less corrosion over time; the more copper...bad news for steel

A house plumbed with all galvanized pipe will be much easier on a water heater than a house plumbed in copper. In a copper house, without adequate dielectrics that heater will get the brunt of it.


Is it possible for you to explain this in a way that I would understand?

My bottom line interpertation of what you wrote is that in a copper piped house the "dielectric" nipples are necessary to save the water heater. Is that correct? If so why?

Thanks
Tom
 

GrumpyPlumber

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Put two different types of conductive metal with water and trace amounts of mineral or salinity between...you have a battery.
In basic elementary school they teach is this with a potato/lemon with a piece of zinc and a piece of copper protruding.
The electric currents eat away the metal over time.

I thought Dubldare's explanation was perfect...any more complicated though...I'd have asked for a full refund.
 

Dunbar Plumbing

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I asked the director of the division of plumbing in my state why it is allowable to use a copper female adaptor onto a galvanized dielectric nipple. I told him I always used 3/4 DUF's onto the nipples to ensure that copper never comes in contact with the galvanized and there is a less probability of galvanic reaction.

The response given back that copper and galvanized is legal for that connection is the fact that water is not in the equation. ?????

Mentioning that the dielectric nipple has a plastic inner sleeve that protects.


Now that may be true, but the reality of this situation is that the edge of that nipple is exposed to water and copper, sometimes those connections are not water tight AND

every time I pull one of those apart years later, the galvanized nipple threads are severely deteriorated and almost fully restricted/crustated on the copper fitting, even on the DUF's I use even though a minimal amount of galvanized is used.

This problem could be solved with an all brass dielectric union made similar to the galvanized and brass nipples. Were talking about ferrous to non-ferrous metals.....brass nipples used to come factory installed on the older models.
 
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GrumpyPlumber

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RUGGED said:
Now that may be true, but the reality of this situation is that the edge of that nipple is exposed to water and copper, sometimes those connections are not water tight AND

every time I pull one of those apart years later, the galvanized nipple threads are severely deteriorated and almost fully restricted/crustated on the copper fitting,

YUP...YUP...YUP
 

Molo

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will one of you pros thouroughly explain what connections are appropriate for coming off of a water heater... any rules to follow? please!

TIA,
Molo
 

Cass

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Here is what I have found and what I do.

Galv. dielectric unions:
almost always severely corroded when water heater is replace sometimes severely restricting/stopping water flow B 4 unit needs replacing. 1/2" copper pipe pounded through the union with a hammer will open up the union and restore flow in these cases.

Galv. nipples with copper Fem. adapter:
same problem as above but sometimes leaking at connection due to severe dielectric action. 1/2" copper my not make it through the nipple depending on nipple length.

Insulated Galv. nipples with copper Fem adapter:
This is my choice for use on water heater installs. The copper Fem. Adp. must be soldered to the copper pipe B 4 being threaded on to the nipple.
This prevents the insulation in the nipple from being burned, melting and becoming ineffective.
Any water heater replacements with the insulated nipples that I have done. The nipples were the same the day I replace them as they were the day it was installed so long as the adapter was was not soldered on the tank.

Brass nipples:
Would be best with max flow but in most cases, not all, the extra flow is negligible.
 

Terry

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I live in earthquake country, so for most water heaters I use a flexible connector going into brass nipples at the water heater.

I don't bother with galvanized, they are a waste of time.

When I've gone back to replace perfectly good water heaters 10 years later, I'm able to reuse the brass nipples for the new water heater.
Ten years later and it still looked like a new install.
 

Master Plumber Mark

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Dialectric nipples are sweet

Terry, you live in probably the most pristene
area of the country.....

The same with Colorado..... a Delta faucet installed on
a kitchen sink back in 1975 still looks new today....

but its not that way in the rest of the country...
----------------------------------------------------------------------

almost all water heaters are comming out with dialectric nipples on top of them these days.....with the little check balls in them for heat loss....

I usually just install two copper female adapters to it and everyone is happy...I dont see a problem with it....

even back when they did not come with the nipples, I usually just installed them with two copper male adapters over useing galvanized nipples....

With every one we have ever taken out that were installed with copper male adapters, , their might be some
corrosioin inside the copper nipples where they have scaled up about half way shut....

.but it nothing like you see with galvanized nipples or

dialectric unions....the unions are the very worst in this area... we have to go back out and clean out the debris that builds up in them


nothing irritates me more than spending about 10 bucks for those unions only to see them corrode shut in Indiana


I agree with your idea that
the new flexible supply lines that go on top of the heater to the plumbing system
seems to be about the best way to isolate the water heater from
grounding problems, galvanic reactions, and other troubles

they just cost too much at about 9 bucks each
 
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Molo

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Also, So far, some guys just use copper out of the tank, some use brass, some use the insulated dielectric nipples. What are the nipples that come on the tanks? They don't look like brass or copper. The one that I recently installed had a blue plastic flapper in the cold nipple. Is this good or bad? Will the flapper break off? Are they dielectric nipples that the heaters come with, how can you tell if they're insulated?

Thanks,
Molo
 
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hj

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electrolysis

Unfortunately, the previous expanation of electrolysis, while seemingly brilliant was incorrect. The reason for electrolysis is that all metals have a location on the nobility scale. The farther apart they are the greater the electolytic effect, and the most noble will erode the least noble. Copper is distant from steel and above it, so if the two are in close proximity, in the presence of water which becomes the electrolyte, the steel will deteriorate. Brass in intemediate to either of them so the action between brass and steel is minimal, as is the action between copper and brass. This is why brass valves and fittings can be used with either material, or between them as an isolator. A 6" brass nipple on the top of the tank will give adequate protection from electrolytic action.
 
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