Can a water heater build up enough pressure and blow through the roof?

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MythMod

My wife and I are avid viewers since you guys started doing this.

As we're watching tonight's show, I couldn't believe the timing.

Two weeks ago a neighbor's home exploded. It sounded like a bomb going off from in our house two blocks away.
Here is a picture
Here is the local article

It didn't go through the roof, but it did blow the window glass into the porches and yards of the homes across the street. By the time I got home from work, I'd say 5-10 feet of the house had begun sinking into the hole left by the explosion.

My neighbor and her cat were rescued by another neighbor - he pulled her out through one of those front windows.

A day after seeing the previews for this week's show, I could not believe what I heard on the news . There was an explosion of a hot water heater that ripped part of a house apart.

Here is the local story

It's funny, but when I was younger, we had a problem with the water heater boiling all the water in it. It was a 50 gallon water heater and someone had welded the relief valve shut (I guess it dripped too much). Anyway, the water heater did not blow up. It was the toilet that did. As preasure built up in the water heater, it pushed back against the incoming water and eventually made it to the cold water side. Then, it just had to find a weak point, which was the downstairs toilet. So at about 2am in the morning, there was a big bang (my bed was against the same wall), and then a whole high preasure steam bath.

This is a strange question, but I was hoping someone might be able to answer it.

Does anyone recognize the t-shirt that Tory was wearing during the last jean myth? It was black and had a white icon of what appeared to be a gas mask.

I believe I have seen it before, but can't seem to find it with some Google'ing.

Any clues?

Thanks and great episode!

I time the flight of the hot water heater at just over 11 seconds (the outdoor house flight). From the quick calculations, neglecting air resistance, it would seem that it cleared 500 feet . Impressive flight

Thank you Mythbusters. I am univate01. I posted this as a sugested myth about six months ago. I do not know if this is the right place to post this because I cannot understand the system .It is too complicated and extensive. Thank You!

The only problem I saw with the myth (which is a big one) is that they used a small building. It looked like the steam tore the building apart. It may not have been part of the myth but I think it is worth looking at.

The only thing that would have made this a little more accurate would have been to test the different water heater brands and also different water heater plumbing connectors(hard-piped, Braided stainless lines, and copper flex lines, also pvc, cpvc) to see if the plumbing lines would give way first. Granted if the home had galvanized pipe like adam and jamie used the end result would be similar in that it would exlpode. But most modern homes since the 70's are plumbed with galvanized pipe. And most new construction homes here in FL have Pvc, cpvc or copper flex. Soft -soldered copper line burst at the joint rather easily thats why in HVAC we use much more expensive silver-solder. What do you guys think???

I see a problem with this myth. The tank they used was completely sealed off. Thus allowing the pressure within the tank to reach an astounding 350 PSI. The issue I see is that even with the Pressure Relief Valve gone, a water heater will never be compeletly sealed off. It will be connected to... get this, Plumbing!! Although there have been some documented cases, I believe that the plumbing pipe or fixtures ie, faucets, toilets etc... would fail long before the tank was allowed to reach a PSI of 350, thus relieving the tank of its bomb like qualities. The conditions that the tank was tested under made it seem like everyone has a potential bomb lurking in their basement, and may have everyone a bit freaked out. I would like to see the test run again connected to some plumbing fixtures using several different types of pipe, to see if houshold plumbing would even hold up to that kind of pressure. Love the show...keep it up!

Eric in Tallahssee

More exploding water heaters!
More flying steam rockets!
(If it flew high enough, would it be a space heater?)
More!More!More!

That episode was great!!! I'm just curious why the 6 gallon water heater just fsssshhhhhh instead of KABLOOIE! Like it's 30 gallon and 52 gallon cousins. Was it something in the bunker...does it have to be a certain size to be able to go NASA on you and bust through the roof...or was it just a one time fluke? What do you guys think?

Not that it means much in the grand scheme of things but does the state of California not require ceiling joists in there homes. I just figure that 2x6 ceiling joists might secure the building better.

Since it HAS happened to people with it hooked up to regular plumbing, yes it can happen.
The sealing off of the tank was explained. Re-watch it. I've had a neighbor who DID cap the T&P valve. I had to go over to remove the cap myself.
And there were joists. The roof was even secured. Check out building codes and see what's required.
Absolutely astounding how destructive the steam release was!

I know it can happen, i did awknowledge it in my first post, it used to happen a lot more in the old days. I just wanted to see if by being hooked up to plumbing, would the result be as spectacular, and as likely. It could even result in an exploding faucet or toilet.

On a side note; it's a "water heater", NOT a "hot water heater" as so many people (including Adam) keep calling it. Not only is "hot water heater" incorrect, but it doesn't even make sense. If the water was already hot, it wouldn't need to be heated.

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hello all, i am a former plumber and i think this myth was great! If you ever revisit this i think there are 2 things you can do to enhance it. 1. Alot of time peole will put the water heater right on the floor and the water heater will rust on the bottom and weaken the intregrity of the water heater, which might give you more of a rocket effect. 2. the is a theory almost like when you first released the pressure relief valve, the theory i heard was that the ouside temperature vs. the inside temp of the water heater will cause a flash of steam and will cause an explosion. i am wondering if different temp. on the outside of the tank would cause the explosion to be more fierce. I am in the north east and some basements are not heated and i can see how a tank at 212 or + with an introduction to 20 degree weather can cause an issue. Thank you for your time....

This really happened in Burien, Washington, on Saturday, July 28, 2001. News article at http://seattlepi.nwsource.com/local/33094_boom28.shtml descibes it with a map. The water heater landed 439 feet away, landing just past an 8-lane roadway. Four people were injured from the explosion.

This article also cites another incident in 1993 in a home in South St. Paul, Minnesota.

There were some people who also "tried this at home" and made a video and website about it.

http://www.waterheaterblast.com/