I just learned water heaters have an "anode" and its important

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I just got a used water heater (consumer electric) and I replaced the bottom element that burned out because the sediment had collected enough to cover it. Well, since it was outside, I flushed it all out. Then I read about the most important factor of a water heaters life in the anode. I shined a light inside and saw a long rod that looked like in was suck in the ocean for years, with so much buildup that it looked bumpy. I took it out and it is a aluminum version, How do I clean it? lime away and some scraping? My labor is cheaper that buying new parts or heaters.
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davidlaska wrote:

Labor can't replace material. Its called a "sacrificial" anode for a good reason. See here: <http://www.waterheaterrescue.com/pages/WHRpages/English/Longevity/water-heater-anodes.html
--
Grandpa

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<http://www.waterheaterrescue.com/pages/WHRpages/English/Longevity/water-heater-anodes.html
Why do they call it an anode?
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On Sat, 09 Jun 2007 12:16:35 -0700, Ook wrote:

http://en.wikipedia.org/wiki/Anodes
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I know what an anode is. I also know what a cathode is. But that doesn't answer my question....I stick this rod in the middle of my water heater - what makes it an anode, and not a cathode?
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Ook wrote:

just skip it? It says: "Sacrificial anode
In cathodic protection, a metal anode that is more reactive to the corrosive environment of the system to be protected is electrically linked to the protected system, and partially corrodes or dissolves, which protects the metal of the system it is connected to. As an example, an iron or steel ship's hull may be protected by a zinc sacrificial anode, which will dissolve into the seawater and prevent the hull from being corroded. Sacrificial anodes are particularly needed for systems where a static charge is generated by the action of flowing liquids, such as pipelines and watercraft."
--
Grandpa

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I read it. It still doesn't explain why it's not a "sacrificial cathode".
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"Galvanic anodes are designed and selected to have a more "active" voltage (technically a more negative electrochemical potential) than the metal of the structure (typically steel). For effective CP, the potential of the steel surface is polarized (pushed) more negative until the surface has a uniform potential. At that stage, the driving force for the corrosion reaction is halted. The galvanic anode continues to corrode, consuming the anode material until eventually it must be replaced. The polarization is caused by the current flow from the anode to the cathode. The driving force for the CP current flow is the difference in electrochemical potential between the anode and the cathode." (http://en.wikipedia.org/wiki/Cathodic_protection)
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The water that was going into the tank had enough rust to make it a light tea colored. The tank cleaned out very well, I dropped a light inside at night and saw that the inside was very shinny. The only corrosion was at the base lip of the steel container. I put everything back together and added an additional anode. Not of this is worth it for your average homeowner, but I am retired so my time is free.
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Ook wrote:

Then you don't really "know" what an anode (or cathode) is... :)
It's an anode if it attracts anions, and a cathode of it attracts cations...I'm pretty sure that's the definition you know. (DOH! :) )
Which, of course is sort of a circular definition. What actually makes it one or the other is the relative position on the scale of electrical potential of the material from which it is made with respect to the other material.
--
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Ook wrote:

anode isn't a cathode.
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<...snipped...>

Obvious to you and me perhaps. If the rod was made of copper or gold, what would it be?
--
Better to be stuck up in a tree than tied to one.

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar.org
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wrote:

protection, and I don't even think copper is either in this particular situation. But what does that have to do with cathodic protection? Cathodic protection involves the application of electricity to the object, whereas the current supplies the electrons that normally would be obtained from the iron in converting iron to iron oxide. In anodic protection the electrons that normally would be taken from the iron to form iron oxide are instead taken from the anode - hence the use of something easy to oxidize like aluminum or zinc.
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Larry W wrote:

--
Grandpa

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On Jun 9, 2:10 pm, "Ook" <Ook Don't send me any freakin' spam at zootal dot com delete the Don't send me any freakin' spam> wrote:

Thank you very much for the perfect link, now I know what a worn out anode looks like, the key to my problem. There was an old water heater I pulled an anode from, the water heater was old, but never used.
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If you can pull out your anode you're lucky. For some reason, my water heater was installed such that the incoming pipes block access to the anode.
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On Sat, 9 Jun 2007 12:16:35 -0700, "Ook" <Ook Don't send me any freakin' spam at zootal dot com delete the Don't send me any freakin' spam> wrote:

They were invented back in the days they used vacuum tubes, and these tubes also had an anode. If they added a cathode, that would be one hell of a tube. If it's an electric water heater, you already have the filament (the heating elements). Maybe in the future they will develop a transistorized water heater that also serves as the cpu for your 100,000 mhz computer. (which is needed to run MS Vista).
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Thanks for the link. My water heater looks new and hasn't given me any problems although its almost 30 years old.. The last time I checked was more than 10 years ago and other than vacuuming up a few rust scales next to the burners I haven't had to do anything since. The anode must have been exhausted by now. I'll change it. Maybe it will do something about the hardwater problem I do have.
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Replace it.
Bob
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Here's a silly followup question.
Do gas water heaters have an anode too, or just electric?

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