And I guess that's the real question. How much longer will one get from a tank if they do check and replace the anode when it's needed? It would seem to make sense to me too. I started doing it on my current water heater which is about 6-7 years old now. The original anode is about 1/2 gone now. While it seems to make sense and I've seen lots of opinions, I haven't actually seen any tests or studies done. Has anyone else?
snipped-for-privacy@optonline.net wrote: ...
Far too many variables to be able to do any meaningful tests -- differences in tanks, anode design, water, usage, etc., etc., etc., ...
Best one could do would be a test under a given set of controlled conditions for a given tank design, but that would have virtually no value outside that test environment...
If that were the case, then no one would be able to test and evaluate much of anything. Yet tests are routinely done on a wide variety of products, aren't they? Consumer Reports, for example, tests everything from dish washers to paint. And all those depend on a multitude of factors that can vary widely.
If some simple tests showed that anode monitoring and replacement made a substantial difference in longevity in a few different tanks and environments, that would be a lot more substantial that it does work, as opposed to peoples opinions.
I wonder if the anode rod really becomes important once the glass lining has already failed somewhere?
most tank leaks I have had occur around fittings, at seams etc. never saw one in the middle of a tank.
so my theory is the anode erodes, its erosion driven by everything in the plumbing system, everywhere theres water.
then the glass lining fails, the anode already partially gone fails, noted as thin wire laying loose in bottom of tank duiring disection...
then finally the tank leaks.
tanks are so cheap, new ones more efficent, most humans will only buy one every 10 years or so while owning a home. so at most 5 or 6 tanks max.......
for me stretching tanks life and perhaps creating leak at anode connection just isnt worth the risk.
Today I tend to replace tank every 19 years or so before it fails.
that way I pick the time place and cost.
no christmas even blizzard thank you.
the small added cost is worth the bucks, for peace of mind and convenience
That's a different question than the one you asked which at least I interpreted as for a given tank, and more importantly, a given application (namely your own specific installation).
I think there's little doubt that sacrificial anodes have benefits in general.
As for the wide-range applicability of CR tests and CR testing protocols, don't get me started on them (again)... :(
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.
Obvious to you and me perhaps. If the rod was made of copper or gold, what would it be?
I don't understand the relevance of your post. Gold isn't useful as anodic 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.
In a water heater, they would be called a "rod" offering no protection.
I think you have cause and effect reversed here. It seems more likely that the anode prevents corrosion at the fittings where the glass doesn't coat. The anode wears out, the rust starts at the fittings, and continues at the edge of the glass, causing it to flake off. Replacing the anode prevents the rust, preventing the glass damage.
$10 anode vs $200 heater? Hmmm. Let me think.
Every wateh heater leak I've ever seen started as a small drip, leaving plenty of time to replace at your convenience - if you keep an eye out for the drips.
Bob
Haven't bought an anode for a while have you? $10???
the last one that failed sprayed water oiut the flue vent, it was a sudden failure and highly inconvenient on a hoilday weekend, blizzard weather.
the day I bought it 4 degrees, it was horrible
Again, the major cause of failure is corrosion. The anode largely prevents corrosion as the anode corrodes instead. I'm sure that almost noone replaces anodes, so a few years after it dissappears, the water heater fails.
There's a reason they put them in in the first place.
Bob
>
The interesting question is whether checking and replacing the anode beyond what the manufacturer put there really extends the life of the tank and is worth it. One possibility is that making sure the anode still has material left does significantly prolong the life. The other possibility is that the anode size that is put there is sufficient to prevent premature corrosion failure in most cases. By that I mean it gets the tank to the service life where other failure mechanisms become prevalent, so that even if you do replace it, it may not buy you much more time, because the tank is likely to now fail from another failure mode that the anode doesn't prevent.
But like I said in my previous post, I've seen lots of opinions on this, but nothing really backed up with any test data or scientific analysis.
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).
By the way, it's probably not aluminum, it's magnesuim. I once took an old magnesium anode and filed off some dust. Then I put a torch to the dust (outdoors in a safe place) and watched the fireworks. It looked sort of like a sparkler.
First: Thanks for the helpful information and links.
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.
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.
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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