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.
just skip it? It says:
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."
"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."
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
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
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.
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
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'
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).
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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