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Posted by on June 11, 2007, 7:55 pm
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> >> > I wonder if the anode rod really becomes important once the glass
> >> > lining has already failed somewhere?
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> >> > most tank leaks I have had occur around fittings, at seams etc.
> >> > never
> >> > saw one in the middle of a tank.
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> >> > so my theory is the anode erodes, its erosion driven by
> >> > everything
> >> > in
> >> > the plumbing system, everywhere theres water.
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> >> > then the glass lining fails, the anode already partially gone
> >> > fails,
> >> > noted as thin wire laying loose in bottom of tank duiring
> >> > disection...
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> >> 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.
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> >> > then finally the tank leaks.
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> >> > 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.......
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> >> > for me stretching tanks life and perhaps creating leak at anode
> >> > connection just isnt worth the risk.
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> >> $10 anode vs $200 heater? Hmmm. Let me think.
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> >> > Today I tend to replace tank every 19 years or so before it
> >> > fails.
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> >> > that way I pick the time place and cost.
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> >> 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.
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> >> Bob
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> > 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.
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> > the day I bought it 4 degrees, it was horrible
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> 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.
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> There's a reason they put them in in the first place.
>
> Bob
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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.
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