Anodes & odor???

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Cliffyk

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Hello All,

"Newbie" here, so please be gentle...

A couple months ago, our now 3 year-old A.O. Smith 40 gallon electric heater developed the "rotten egg" smell. We have a shallow well, with a chlorine injection iron/manganese filter and a softener/tannin filter after that-both regularly maintained and functioning properly. After some research I found through this site and others that the 3 year-old magnesium anode rod might be eroded and promoting the growth of sulfur-reducing bacteria creating the stench.

Well sure enough, on 6/24 I replaced the OEM anode with a Camco 42" aluminum/zinc rod and the stink vanished, literally damned close to "immediately". It was a real bear getting the OEM rod out, ended up using a cordless 1/2" impact wrench (rated for 600 lb·ft "break-away" torque), and it took 4 - 5 seconds of pounding to break it loose.

Used Teflon paste on the new one, I plan on pulling it for inspection in 6 mos. (Christmas Eve).

FWIW, judging by the core wire, the OEM rod was only 24" or so.


20220624_134733.jpg


I have a couple remaining questions though:

Why is it that it was nearly 3 years before the stink began (same water, same treatment)?
What happened so quickly to the bacteria, did they suddenly die off, or just stop farting?


Thank you for any info...
 

Reach4

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Why did it wait? Not sure. Maybe the bacteria did not get established right away. Maybe you kept the WH hotter before.

But anyway, sulfate-reducing bacteria SRB use metal ions to do the sulfate reducing, and finds zinc+aluminum to not be as taste as magnesium.

There are people who remove anodes and put in brass plugs to avoid the smell, even tho that will probably reduce the life of the WH. I use a powered anode. The one I use seems to be no longer available.
 

Cliffyk

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Reach4,

Thank you for your comments. Water temp had not been altered since the heater's installation, but further research indicates the stink is a common sign of a badly corroded magnesium electrode. I thought the aluminum+zinc might be less appealing to their appetites and/or less upsetting to their digestive process.

Cruising the web I found a whole bunch of confusion, misunderstanding, misinformation and just plain flat-out wrong information on the subject. I am not a chemist or physicist--MSME here, however I know just enough about both to be dangerous--I know some and will ask them.

A controlled tank life comparison 'twixt anode v. no anode in contemporary "glass-lined" tanks would be interesting. Modern ceramic coatings are pretty damned impressve--I'd bet on there being little significant difference in tank life. Nearby copper/brass/bronze fittings and plumbing might be a different story--IDK?
 

Reach4

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I think an exhausted magnesium element will generate a lot less H2S than a new one.

My theory on the glass lining is that there would be cracks.

There is an electric WH, Rheem Marathon, with a plastic body that needs no anode. There are stainless steel tank gas WHs that don't use/need an anode.
 

Cliffyk

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Thank you again for your thoughtful response--I no longer get to "talk" much with people who know what they are talking about.

Modern ceramic coatings are far removed from the plain ol' "powdered glass" (porcelain) coatings used years ago--much less prone to chipping and cracking.

Re: "stainless' steel. the term is largely a misnomer, if they contain iron (wouldn't be "steel" without it) even the higher end ferritic and Austenitic alloys are stain resistant at best--if a magnet sticks to it, it will rust (perhaps just localized or only at stress points, but it will corrode); however as the metals alloyed to enhance corrosion resistance do tend to be cathodic a sacrificial anode is likely unnecessary.

I have also found that in this age of Asian outsourcing of nearly everything claims of "stainless steel' have to be accompanied by a quite large "pinch of salt".

Were I in the market for a heater--and not 74 with Parkinson's and otherwise in less than perfect health--I'd look into that Rheem with the polymer lined tank.

For now my 3 y-o A.O. Smith with a new anode will likely outlast me.
 
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