ARGH! Hot water heater ruptured!?!

WTF? I am walking down the stairs to my basement, when I hear <splash>! I get to the bottom, and there is a puddle on the floor. Looks like a gallon of water has been spilled (some old carpet underlay has managed to soak up the rest).
Confused, I search for the source of the water....only to discover that the side of my hot water heater has buckled out on the vertical seam, approx. 2 feet off the floor. It's 7 years old.
Ummm...I don't understand...isn't the pressure relief valve supposed to prevent this sort of thing from happening? Does anyone have any ideas on why this might happen?
Anyway, I shut off the cold water intake, turned off electricity, and flipped the T&P valve to release any remaining pressure (seemed to work ok, as I got some nice dirty water to exit the tank, which turned to clear after a couple of seconds). No more leaks (yet); I hope it holds overnight.
Any advice would be appreciated, as I have never experienced anything like this before!
Cheers, Dave
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Are you sure it's the tank itself? It could be a leak around the inlet or outlet tube that ran down between the outer "skin" and the tank and found a weak area along the seam to get out. It doesn't sound like you have enough water to be a ruptured tank, and if it were, you probably wouldn't have had any presure to release with the release valve.
Check the fittings around the top of the tank to be sure. If the installer used steel pipe coupled to copper, it would eventually corrode enought to spring a leak. You may only need to replace the fitting - using brass rather than steel - rather than the entire tank. Of course the damaged skin, and water logged insulation underneath are a problem that might result in a new tank anyway.

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did you cycle the relief valve once or twice a year? if not it may not work properly. after a few years closed, mineral deposits may prevent it from working.
the valve comes with a warning attached to it but it may have been torn off. its also in the water heater manual. yet people often neglect this.
randy
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xrongor wrote:

FWIW I keep hearing "expert" plumbers advising against manually test cycling the T&P relief valve, claiming that the valves are likely to not not reseat properly and then dribble slightly.
Course, those are the guys who get the replacement job if the heater does fail through overpressure. <G>
IMHO a properly designed water heater installation won't experience overpresure unless the city water supply pressure goes out of limits, which rarely happens. The use of properly maintained expansion tanks in instances where supply backflow check valves are mandated will prevent thermal expansion from creating overpressure, and the heater's thermal overlimit controls should prevent overtemperature and boiling water explosions.
Course there's always that once in a blue moon time when all the other safey measures fail, and the T&P relief valve is there to take care of those occurances.
BTW you can save four keystrokes by just calling it a "water heater", like their manufacturers do. Why would anyone bother heating "hot" water?
Jeff
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Jeff Wisnia (W1BSV + Brass Rat '57 EE)

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ya they sometimes do drible for a day or two. particularly if you cycle an older valve that has never been cycled. i have yet to see one that wont reseat eventually.
randy
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