A story from a boler inspector

Carl PE

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George_10

I got this story today from a state boiler inspector

A home owner had a copper coil running thru his fireplace.
He wanted to gain hot water while heating his living room.
After he had started a roaring fire in his fireplace, he heard a noise. He relized instantly that he had forgotten to turn on the circulating pump for the coil. As he rushed to hit the switch, there was a tremendous explosion in his living room.

Needless to say the water in the coil, boiled, turned to steam and with no place to go blew up and blew out the whole side of his living room. The mantel on the fireplace flew thru the home and destroyed the island/bar in the kitchen. Bricks from the fireplace were sent flying and were later found yards and yards from the home. The living room was left with one whole side blown out with an unintended exit to the outside. Fortunately no one was killed. The home owner was lucky, just a few cuts and scratches from flying debris.

Just a moment of forgetfullness, lack of safety/engineering precautions and inattention to detail; was almost deadly. Obviously this could have been prevented, but who would have thought such a minor thing could have such devastating results. I do not know who installed this system, but it sure should have been planned bettter so this was impossible to happen.

I think this highlights the reasons to use a true pro in your home. What if one of his children or his wife had been in front of one of these flying missles from the explosion. The what ifs and the why are still running thru my mind as I write this story.

Constantin

Yup,

Couldn't have said it better myself.

Dale

Picture of a thermal switch?

Manual switchs depend on Manual to turn them on, often with not good results. A auto thermal switch turning on the pump shure would have helped along with the temp relief. Not sure some folks know how hot a wood burning fireplace can get, I had my railroad rail an irons a dull red one evening, about 1200 F if I remember my forging chart.

Boiler Guy

Wood Stove

Similar situation happened in an ice fishing shack on a river 20 miles north 2 winters ago. Guy built a beautiful shack on retractable wheels and decided to install 1/2" copper piping brazed to the outside of the wood stove. By using a 12V RV pump to pump fresh water from a fresh water jug instant hot water was born. Good idea until the tap was turned off. 6 men taken to hospital when water overheated and tubing exploded, blowing out the wall and scalding all of them. He let the shack float down river on the ice in the spring --- never to be seen again.

Darin Cook_3

Physics in action

High pressure goes to low pressure ALWAYS






Darin

Jay_17

Hmmmm

Ok, What exactly was trapping the water/steam in these pipes? I can see one side having a valve, in both cases, but what was preventing the water pushing back through the pump (I assume an impeller pump, not positive displacement) into the heating system or water jug? Of course we don't know much about the actual setup of either system
I understand the danger of steam and pressure and all that, but I have to question how these systems ended up being sealed.
I guess I am a sceptic at heart, especially of stories on the web.
Jay

Dave Yates (PAH)

If you're gonna play with bombs

you gotta know how to defuse the darn things. I USED to install fireplace boilers and wood or coal boilers, but the math behind the Btu content and need to provide more than adequate relief capacity is a must for any installer.

The hydronic delivery side of a sealed vessel can't be a stop & go thermostatic control for delivering even comfort. Once heat is being generated, the water has to be kept on the go to heat emitters capable of unloading the hottest fire that particular boiler can generate. Air-tight combustion air inlet dampers is a must to snuff out the fire if needed and relief valve capacity was always designed to handle more than the contents of the boiler and system.

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jerry scharf_2

I'll bet some did go backwards through the pump

Jay,

It's a question of how much you can force.

Using the oft quoted 1700 to 1 expansion for steam, a cup of water wants to produce over 10 cubic feet of steam. If this happens in 1/10th of a second for a flash, the pressure will increase to many hundreds of atmospheres in that time.

The water in the pump will flow backwards, but you have an entire water system that the water would have to push through, pump, pipes, valves, well pump or city meter... There's no way that water can get out of the way fast enough to keep the pressure below burst point.

jerry

George_10

The inspector told me he had pictures of the accident

I have no reason to believe it did not happen pretty much as I descibed it. All of you are right, how was this preventable situation allowed to develope.

Who did the installation and why were there no automatic safety devices present to prevent just such an occurance.

The inspector told me their dept. was invited in by the fire dept. since the explosion was due to steam.

Boiler Guy

The pump

had a plastic check in the discharge side of the head. Relief at the weakest point.

Alan Bright

RV pressure pumps...

All of the RV domestic water pumps I have used in 30 years of RVing have integral check valves with pressure operated
12 v. switches. Do it your self disaster from first consideration, a person sure didn't want the hot water running back into the jug, it might melt!

Big AL