Monday, January 11, 2016

Stopping The Decay From Within - 5 Years In

Five years ago more or less, I wrote a post about installing an anode in our water heater.  In that post I talked about why our aluminum water heater tank would need an anode, and why the anode was magnesium instead of zinc.

Well, I recently began to get a nagging feeling, more subconscious than anything, that maybe, maybe I should take a look at that anode.  After all, as expensive as these specialty water heaters are and with an aluminum tank, I really did not want it to go without protection.

December, 2010

Above is the anode as it looked just before it was installed.  And below is its current state...  pretty good in fact.

January, 2016
It is only about half consumed, which means that the tank probably could have gone longer on that anode.  But I am a little concerned about the way the anode was consumed.   I would have expected it to have been eaten away pretty much uniformly along its length.  Instead, the outboard half was nearly gone and the inboard half was only lightly touched.  Strange.  Perhaps it has to do with the water flow paths inside the heater.

But in any case, the water heater should now be good for another five years at least.  I'll pull this anode in 2021.

Do you change the zinc in your household water heater?  You should...




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8 comments:

Drew Frye said...

Is it possible there is sludge in the heater? Or is it possible that the first potion is in a sleeve, not in the main flow of the tank?

Otherwise, I agree.

Robert Salnick said...

Hi Drew -

I hope there is not that much sludge in there - the anode sits about 75% of the way up from the bottom of the heater! I don't think there is a sleeve, but the heater does have aluminum coils inside it for the engine hot water to provide heat - I don't know where they are in there, but it seems likely that the coils are partially shielding the anode from the bulk flow...

bob

Verena Kellner said...

I found one of those on our new boat and have been wondering what it is for! Thanks so much for clearing up another new boat mystery!
Verena
http://pacificsailors.com/

Robert Salnick said...

Glad I could help Verena!

Anonymous said...

Sometimes when I've purchased these from places that mark the price with adhesive stickers, the adhesive inhibits uniform corrosion of the anode. Maybe that or some other substance prevented uniform corrosion?

Robert Salnick said...

Good observation, Anon. But that is something I regularly check when installing zincs... and by extension this anode too.

Jeani said...

Am I correct in assuming that this does not apply to a tankless hot water heater?

Robert Salnick said...

Boy, I'm not sure Jeani. Does your owners manual show an anode?

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