WH Expansion tank rust-through?

I have a newish - 2-3 year old max - water heater expansion tank
that has developed 3 rust holes, one of which has started leaking.

Why the rust spots (and the hole)?

The expansion tank is a State Industries Inc 2 gallon tank. I got
from a local plumbing supply place. The Model is ETC2X.

I'm figuring it will be a warranty replacement. How can I tell how
old it is?

The actual leak just started today, but the spots have developed
over time no doubt (I can try to upload some pictures tomorrow night
after work).

What would cause such an issue? Terribly corrosive water eh? Nothing
out of the ordinary in the was "tested" with a DIY kit from the
local Home Depot. We'll have to have this checked by a seasoned
professional (vs water filter sales type - suggestions would be
helpful for a reputable testing outfit, in Northern VA), but nothing
else has been an issue in 4.5 years at this house.

The tank is a horizontal mount above a Ruud PH50 50 gallon gas
fueled water heater that is a 1002... serial, which I think
translates into October 2002 manufacture. So it is 5.5 years old,
thusly replaced a year before we moved in.

In-house water pressure is 39 - lowish, but it serves the house
well. I do have a new Pressure Reduction Valve on the main. The
old was stuck at 50psi & in close range to a poorly done whole house
filter (with no filter in it), that had cutoffs that were not full
flow valves - lack of flow was an issue. This change was about 4
weeks ago - I don't think lower pressure would cause sudden expansion
tank rust (?). You'd think I would have noticed the rust streaks
across the tank when I did the PRV?

Why is this expansion tank just a few years old? The blue (I don't
have details on it other than I recall it was blue) tank that was
installed got a pinhole - no visible sign of rust. It was just a
tiny itty bitty hole in the inlet end that was squirting a tiny
stream of water at the wall (lotta good a pan does for that sort
of issue). This tank looked good - probably installed with
the Ruud - so it failed even sooner than it's replacement,
but with no visible rust (I should have kept it and cut it apart,
depending on warranty value of current one, I'll plan to cut
it apart).

So - tomorrow off to supply for some exchange (?) or big box to
find another ... or, to diligently research tankless water heater.

If I have multiple choices of brand, what would be recommended?

Any other recommendations - besides a water test pronto?

change it asap

39 psi is pretty low, but if you are happy... whatever.....

you really ought to change that expansion tank asap...


most state brands are really not that good and I have known
of a couple of catastrophic floods due to them and other brands
blowing a penny sized hole out the side of it....
in a totally flooding a finished basement....

you dont want that to happen.

the only good thing was I was not the fellow that
did the original install....so it was not on me to do the clean up...


I do install them ......but the customer never sees the need to
maintain them after the fact..... and on averrage they will outlast the heater anyway..

but you got a nasty one that can deal you some nasty greif
it you dont move quickly


try a amtrol.....



here is some info on tankless

http://www.weilhammerplumbing.com/houseofhorrors/

changed tank ...

One local supply had the Watergaurd - not that again, the
other had a Watts (PLT-5). Neither had the Amtrol as
recommended.

I'll keep an eye out for one & buy it as a spare Later today
might be cut-it-open time for the old one.

And as a reminder, I wrote on the new one when I put it
in.

Thanks for the reply!

Also - on tankless - Thanks for the link. That would be way future
when the current WH dies, them tankless things
are expensive, and I'd have to experience one for myself.

Just make sure the expansion tank you got is for potable water and not designed for a boiler.

What is the water pressure on the city main? It sound to me like either your PRV is set too low or perhaps you don't even need one. If the city main pressure is less than 80 psi, I'd pull the PRV and expansion tank out...you don't need them. If you do need to reduce the pressure with a PRV, make sure it is working OK and crank the pressure up to 50 or 60 psi and get an new expansion tank. If you have a PRV, you must have an expansion tank also. If you don't have your own pressure gauge, you should get one at any hardware store for $12-$15.