Cause of this corrosion to expansion tank?

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TipsMcStagger

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I noticed this corrosion on an electric water heater at a friends apartment.

What would cause this and is there any repair that should be made to prevent potential failure?

Thanks.


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Dj2

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The one under the Expansion Tank could be a result of a galvanized short nipple between the tank and the copper female fitting.

The one on the shut off valve... scratch off some of it, and what do you see?
 

TipsMcStagger

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The one under the Expansion Tank could be a result of a galvanized short nipple between the tank and the copper female fitting.

The one on the shut off valve... scratch off some of it, and what do you see?

The expansion tank appears to be threaded directly into a copper fitting.

I scraped the white build-up from the valve. It was surprisingly "crusty." It actually appears that some of the brass has been corroded away. There's a small depression in that spot.

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Reach4

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My buddy is going to have the valve and the expansion tank replaced.
I am not a plumber. I would not do so. I would clean up the valve with a Scotchbrite pad. I think there may be a tiny leak where the thermal expansion tank connects, but there is nothing to indicate this could fail catastrophically. For the tank, maybe brush the crud with a brass brush.

When you said apartment, I presumed your friend was a renter, and was figuring to have the landlord do stuff because it was "free". But maybe one of you tends to be obsessive, so do what makes you comfortable.
 

TipsMcStagger

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I am not a plumber. I would not do so...

...When you said apartment, I presumed your friend was a renter, and was figuring to have the landlord do stuff because it was "free". But maybe one of you tends to be obsessive, so do what makes you comfortable.
It's a condo and it's often unattended for long stretches; so a little conservative preventive maintenance could help avert a major catastrophe while the apartment is unoccupied.
 

Terry

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From my job yesterday. The previous plumber installed a new water heater and left this old relic in. There was water all over the garage and it got all the boxes of clothing wet. What a mess.
 

Reach4

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From my job yesterday.
Are you thinking TipsMcStagger should replace that expansion tank soon?

TipsMcStagger, you could turn off the main water valve at the condo when away for months. Put the WH on vacation if you have such as setting; otherwise off.
 

LLigetfa

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My guess is that they are minor leaks and that some of the encrustations are from minerals in the water. On a former HWT I had replaced, the TPR had a very small leak and it completely filled up the discharge port with minerals to the point it couldn't be manually opened. I would expect a TPR to not have dissimilar metals causing electrolytic corrosion but then maybe they were not designed to have moisture constantly present on that part of the TPR.

Probably there is some dissimilar metals at play and possibly there is a small leak that provides the water to set off the electrolytic corrosion. The ball valve probably has an impurity in the metal and a resultant pinhole. I suspect the leak will increase over time but don't expect a catastrophic failure.

The tank is likely leaking a little at the threads. I would unscrew it, clean up the threads, and reassemble it with Teflon tape.
 

Terry

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The tank is likely leaking a little at the threads. I would unscrew it, clean up the threads, and reassemble it with Teflon tape.

If you remove the tank, replace the tank. The bladder is only good for so many years and then they rust out.
The tank is cheap, the leak isn't.
 

TipsMcStagger

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If you remove the tank, replace the tank. The bladder is only good for so many years and then they rust out.
The tank is cheap, the leak isn't.
Agreed. The installation is 12 years old.

The peace of mind is well worth the cost of a valve, expansion tank and some labor.
 

Reach4

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While I would keep the pressure tank and WH both, others would not. I would think a serious leak in either is unlikely, but I would think it would be more probable in the WH than the expansion tank.

I would turn off the water when away for months. That is effective and free.
 
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