Imploding water heater?

[frenchie]

I always use this video:

http://www.waterheaterblast.com/

it's a lot shorter, so even impatient DIYers will actually watch it.

[Redwood]

Yea it's short but it lacks the true effects...
Digging a hole, dropping one in the hole and lighting the fuse isn't real world!
When one of these cook off the house is toast!
Take a look at these links to see how the house makes out when a water heater blows!

TV News Coverage of a Water Heater Explosion

Slideshow showing the damage to the house from above link

Thats real world baby!

[Ladiesman271]

What I'm asking is if there was anytime when the water heater was in effect a closed container while it was cooling. If you were to take a 1 gallon tin and heat it in a pan of boiling water then screw on the cover and take it off the heat it would collapse....

It would not collapse if you use a vacuum relief valve on the cover. That water heater has one installed on it, but is it any good?

I wonder how old that heater is anyhow? Even to my DIYers eyes that water heater is now toast!

[Redwood]

It really is a moot point whether it was vacuum or, pressure...
The water heater is scrap!

[tankman 2]

For what it is worth, the expansion tank pictured looks to be one designed for a hydronic system. Not sure if it is connected to the water heater or not. If it is a hudronic tank it will not last long on a potable water system like this one.
btw
I agree. Change the water heater and have a professional do it!

[nhmaster]

The expansion tank in the picture is connected to the boiler, not the water heater.

[hj]

Definitely. The glass liner is not flexible so any movement of the metal would crack it. But since even a new heater might not have a perfect glass lining, that is why heaters have anode rods. One thing not mentioned in all the posting, unless I missed it while scanning them, is that it is almost impossible to create a destructive negative presssure with the heater in the basement, and even if it were possible, you have a vacuum relief valve to prevent it.

[jimbo]

This doesn't end the debate, but is interesting. It shows that the bottom of a water heater is concave ( dished inward ) but the top is convex ( domed upward ):

http://uk.youtube.com/watch?v=1ofSyXUW0TY

[Scuba_Dave]

I wasn't aware an expansion tank was needed on a WH?
My last house had gas WH & it didn't have one. But that doesn't really mean anything as I found a lot of problems with my old house. I have seen them on boilers, but never one on a WH connection. New house was an oil fired WH & was replaced with an electric model when the oil fired started leaking & the bottom let loose. I know a new pressure relief valve was installed, as the old one was leaking

I saw the exploding Wh video on another site maybe 2 months ago
I was unaware that something like that could happen