Mythbusters takes on water heaters as rockets….

The other night I watched Mythbusters with my partner, Michael, a show which I have to admit I only see occasionally and only when he’s watching it. It’s okay, but I usually prefer reading. Anyhow, one of the myths that they were attempting to bust is the idea that a water heater can become like a rocket and shoot through a home’s roof when it has failed.

Ok, I’ve been an agent, and a homeowner, for many years and I am fully aware of this “truth” mostly from having spoken with many knowledgeable contractors and inspectors over the years – not to mention feedback from my dad who is an all around great fix-it guy.

Well, for anyone who has heard about this “myth” before but didn’t believe it… here is the clip from the Mythbusters folks. It’s quite eye-opening….

I wonder, if this happened to a homeowner and the insurance company determined it was the homeowner’s fault due to negligence because of lack of maintenance – does this mean they wouldn’t pay? I’m all about maintenance on a home’s water heater and replacing them BEFORE failure of any kind so I hope I never find out personally.

20 thoughts on “Mythbusters takes on water heaters as rockets….

  1. I did talk to an insurance agent I work with frequently (Gerald Grinter and here was his reply:
    “Isn’t Mythbusters a cool show! I’ve heard of this myth before but have never seen it done. Believe it or not most of the damage done would be covered by your insurance. Everything except the water heater is covered as the heater was damaged to due either normal wear and tear or neglegence. Either way it is an inconvenience and the water and structural damage that is done can be more of a headache than replacing a water heater when it has reached the end of its useful life. In any case don’t try this at home!”

  2. My post seems to have disappeared. Anyway, I’d asked:

    How many things have to happen for this to occur? I can think of at least two:

    1. The temperature/pressure relief valve has to fail.


    2. The thermostat has to fail.

    I’d think you’d also need a backflow prevention device in there somewhere, and I’m not certain hot water tanks have those. If they don’t, and the house doesn’t have one, I don’t see this happening at all.

    When water tanks fail one of two things are far more likely:

    1. A leak (typically slow at first).

    2. Inadequate hot water.

  3. It does require safety measures that are built into water heaters today to fail – and they covered that in the original show. However, if a homeowner didn’t realize what some of these things were and somehow disabled them it is possible it could happen. Also, consider if a water heater were left for many years beyond its original useful life – and there are some of those out there as I know I’ve seen them – those would be the ones I’d be most concerned with blowing.

  4. The inadequate hot water is if one of the heating elements burns out. In that case an explosion would probably be just about impossible no matter what you did. You can replace them, but typically by the time they burn out the tank is fairly old and probably should be replaced anyway.

    Anyway, given the safety features on tanks my reason to replace a tank would be to prevent a floor from being ruined, etc.

  5. There was a small business along Aurora Avenue at which the tank became a rocket a few years ago — it was a small (5 gal?) water heater installed above the bathroom in the back of the building–it shot through the roof and landed in a parking lot a block away. Fortunately nobody was seriously hurt.

    If I remember correctly from the news reports, the pressure relief valve failed (or wasn’t installed) and steam built up inside the tank (which does not normally happen due to the tank being completely filled with water at the system supply pressure, so somehow the tank became partially empty of water). It’s the pressurized steam that causes it to act like a rocket. So yes, multiple failures have to happen in order for this to occur, and it’s not something I would lose any sleep over.

    As for reporting any kind of water damage to your insurance company, I have three words for you: DON’T DO IT! All of the insurance companies share a ‘secret’ database of homeowner claims, and previous water damage claims on a property can lead to exhorbitant rates and/or denial of coverage for future owners. The insurance companies are deathly afraid of having to pay for expensive toxic mold abatement charges which may occur as a result of prior water damage to the structure. This is yet another thing to check on before buying a house–go to your insurance agent and ask him/her to run a quote on homeowner’s insurance on any properties that you are seriously considering buying, as the quote will reflect the information contained in their database (which of course they don’t share with the public).

  6. The database isn’t really “secret” – it’s called the CLUE report. It stands for Comprehensive Loss Underwriting Exchange and there is a large database of ALL claims made on properties through it. How do you get access? Well, if you’re buying a place you might try and ask the seller to get a copy of the report from his/her insurance company because only the owner of a property can request it. Another option is to make sure and ASK your insurance company when you are getting a binder for a new home purchase if they’ll be pulling the report or getting access to it as part of the binder process. Even if they can’t give you a copy they should be able to see if a claim has been made.

    Insurers may not want to have to deal with mold abatement BUT they would rather KNOW about a prior water issue than not when deciding if they’ll take on a property to insure. You put yourself into some dangerous liability positions by not handling it properly. When making a claim for water damage the good news about working with an insurance company is that they are VERY motivated to make sure it is handled correctly and not the way some homeowner’s will do it which is to patch the old problem area, use KILZ to hide the stain, and hope no one notices the new paint is a cover up.

    A lot of the public doesn’t realize that while you can buy a home in 30 days with finance underwriting being completed in that period of time, insurance companies can take up to 90 days to complete their underwriting and it’s possible a policy can be cancelled after a homeowner moves in. Impossible you say? Hardly. My mom, also an agent (in KS) has had this happen to clients a couple of times over her almost 20 years in the business. I have yet to run into it, but it does happen.

  7. I own a Boiler company in Seattle Wash. and have seen a few problems with pressure vessals. I also was shown a truck tire that blew and killed three men standing next to it. I have alot of respect for anything with pressure in it. A hot water tank can be a very dangerous if not inspected when dealing with Industrial equipment. Inspectors also look at aircompressor tanks yearly as well. I have been told that Large Industrial propane tanks, are not inspected. That could be a Myth but was told to me by a state inspector. A big church was taken down to the ground a few years ago by a large hot water tank, the only thing left was the cement foundation. Check out those tanks. The saftys on home owner tanks are cheap and work on temp. as well as pressure.

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