Another water heater explodes - InspectionNews

fritzkelly · #1 (**permalink**) 08-15-2008, 07:02 AM

Amazing that no one seems to have a clue how this happens.
Good Morning Yahoo!

Jerry McCarthy · #2 (**permalink**) 08-15-2008, 08:09 AM

You would think the local firemen would be familiar with a water heater's PTRV and what "may" happen should it not release when pressure builds up?

Jerry Peck · #3 (**permalink**) 08-15-2008, 09:39 AM

Quote:

Originally Posted by Jerry McCarthy

You would think the local firemen would be familiar with a water heater's PTRV and what "may" happen should it not release when pressure builds up?

One would think so.

Golly, Ah sur don no why dat ting sploded like dat, Ah mean thar thwartnt no gas ta it.

Jim Luttrall · #4 (**permalink**) 08-15-2008, 12:15 PM

When I saw a report on the news this morning, they were saying it was a suspected gas leak when they zoomed in on the tank. I could see it was no gas leak, the tank exploded and became a missile. I guess since we so rarely see this we can be thankful that the TPR requirements are working, not 100%, but working.
How much you want to bet that was a DIY job and they find a plug in the line?

Jerry Peck · #5 (**permalink**) 08-15-2008, 12:40 PM

You guys did notice, I presume, that that was not an "old" tank. Many of the tanks which blow are "old" tanks.

That one is since the 1990s when they started using foam insulation outside the tank instead of fiberglass insulation. There is foam still attached to the tank.

Just had a thought ... maybe that was the problem ... foam chunks fell off during lift off and ...

Jerry McCarthy · #6 (**permalink**) 08-15-2008, 01:26 PM

What that WH looked like before it became a missle, you think?

Bruce Ramsey · #7 (**permalink**) 08-15-2008, 05:01 PM

I was a firefighter for a while. There is plenty of book learning to become a firefighter. There is pleny of field training. How to carry, set, and climb ladders. Hydrodyamics of water through various size hoses, inflow of water from a 5 inch hydrant to muliple 3 inch hoses and the approxmiate water flow to the fire. Levels of oxygen vs flamable vapors, flash points. Of course all firefighters have to also be EMT so ongoing medical training. Hazardous Materials are every looming and all the various protocols to keep the firefigher safe, contain the hazmat problem and keep the public from interfering. There are three levels of Firefighter, with associated classroom and field training. Firefighers are sorted into engine companies and ladder companies with different duties and training. Lets not forget officer leadership training.

There are lists of additional cerfiications in all kinds of hazards. Swiftwater, Confined Space, Trench, Farm Machinery, Rope, Building Collapse, Vehicle extrication, SAR, etc. Each of those displines has at least a 40 hour classroom requirement. And each of those requires constant refresher courses to keep the certication active.

If TPRs are functioning, firefighters never hear about them. When they fail, they only see the results. Don't care how it happened, just clean up the mess.

We see everyday that even plumbers don't know about TPR and the proper installation. Failing safety valves are very low on the list of things firefighters learn about.

imported_John Smith · #8 (**permalink**) 08-15-2008, 05:32 PM

Im glad it wasnt a house I inspected. Electric or gas, it doesnt matter - pressure beyond the maximum allowable working pressure of the tank will result in failure. Usually they leak (by design) before they launch like a missle.

Jerry McCarthy · #9 (**permalink**) 08-15-2008, 07:15 PM

Ah, er, John, are you saying that an operable PTRV is not significant in preventing what we are all seeing in the main thrust of this thread? I agree, anything in water, holds water, keeps water out, or repels water eventually leaks. Not a comforting thought if I where a submariner. However, that's the nature of how things work, sort of like home inspectors who say they have never been sued.............................................. ......... for which I say that’s a “yet.”

Brian Thomas · #10 (**permalink**) 08-15-2008, 07:43 PM

Im not surprised that most people automatically suspect a gas leak when something explodes like that. I dont think that many people outside of plumbers and HI and people in this type of field even know what a TPR valve is, much less what its designed to prevent!

BY the way, nice pic WC Jerry! I wonder if he would have trouble collecting insurance on that if it was known that the TPR valve was purposely plugged like that

Rick Cantrell · #11 (**permalink**) 08-15-2008, 07:56 PM

I don't know this for a fact, but I've heard, that if a heating element corrodes into, it will break down the water into hydrogen and oxygen gases, that are released into the water tank. Then it can be ignited by the broken element. If that is so, then no PTRV in the world would help.

Billy Stephens · #12 (**permalink**) 08-15-2008, 08:28 PM

Quote:

Originally Posted by Rick Cantrell

I don't know this for a fact, but I've heard, that if a heating element corrodes into, it will break down the water into hydrogen and oxygen gases, that are released into the water tank. Then it can be ignited by the broken element. If that is so, then no PTRV in the world would help.

.
That would require the tank to very low to allow a large volume of gas to be present for the type of damage that was reported.

Tank would also be ripped into multiple pieces instead of launched through the structure and landing more than a block away.

fritzkelly · #13 (**permalink**) 08-15-2008, 09:50 PM

The real myth is that this is "caused" by a faulty TPR valve, its not, its caused by a faulty thermostat and a faulty TPR valve. So, why aren't we testing thermostats?
Jerry, those "new" tanks are old now, I hate to tell you, 1990 was 18 years ago, pretty old in water heater years.

(I think 1 human year is 5 water heater years)

Bruce King · #14 (**permalink**) 08-15-2008, 10:29 PM

Since the electric water heaters also have a thermal cut out switch, a bad thermostat and bad TPRV does not always cause a tank launch.

Seems like you would need 3 failures or 2 failures and one plugged TPRV port.

I had a tank with a bad thermostat once that got very hot, the TPRV did not discharge at all, the overtemp cutout tripped and shut it off. A new thermostat and a push in on the red button and all was well.

Here is some related info on bulging water heaters from AO Smith

http://www.hotwater.com/bulletin/bulletin41.pdf

allen elliott · #15 (**permalink**) 08-16-2008, 05:17 PM

Jerry M. can you clarify the reason for fireman comment?

Randy Aldering · #16 (**permalink**) 08-16-2008, 05:33 PM

That fire captain needs to follow one of us around on a few home inspections.

Michael Thomas · #17 (**permalink**) 08-16-2008, 07:09 PM

Ya' can't make this stuff up: posted yesterday at doityourself.com

"I wouldn't necessarily call it a "leak", but I noticed a small amount of water (not puddling and about 4 inches x 8 inches) directly next to my hot water tank yesterday, and it is still there today. I am pretty sure the water is from the tank, as there is nothing else that could have caused the water to be there.

I live in Phoenix and the hot water tank is in my garage. It is about 110 outside and 120-130 in the garage.

Should I have the tank serviced?"

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