How to shut down a dry fired boiler?

Unknown

1. Shut off the gas as far away from boiler as possible even at gas meter if you have to.

2. Shut off any possible feed of water to the boiler.

3. Shut off the power to boiler at the breaker or pull the fuse. In some cases if that boiler is glowing pull the electric meter off the house. Do not endanger yourself in any way.

4. Get the people out of the house for next 24 hours.

5. After 24 hours have a professional contractor who knows and understands boilers come in and check it.

6. Do not attempt to cool the boiler in any way let time (24 hours) cool it down.

This is a potentially dangrous condition. I have experienced 13 boiler explosions in my career. One in particular buried a piece of cast iron into the concrete foundation 1/2" . In another instance the boiler blew and ruptured the gas line there was then a second explosion which was the gas. Out of the 13 explosions 7 were the result of the gas valve sticking open. Four others were caused by someone placing one of the old gas controls with a manual operator on it on manual and walking away they did not know what it was for and it brought the gas on to give them heat so they left it run. No limit, pop safety or relief valve let go boiler keeps running finally blows. The other two were the result of low water cut off failure and a plugged pigtail on the pressuretrol.

Nothing worse than superheating water and then pressure with it is not a good combination, super heated water turns into steam and steam occupys 1700 times as much space as water. It becomes a bomb or in the case of water heaters a rocket.

I have been training fire departments on this and other hazards for years. Over reaction is better than no actions.

steve_6

Does anyone have a procedure to shut down a dry fired boiler. I'm a fireman and our department gets called to a number of homes, apartments, and commercial buildings every heating season for this problem. Most all of them are gas fired and the conditions can range from just overheated to cherry red hot. My greatest concern is the automatic feed on some of these boilers. I've seen some of these units start flowing water again simply by accidentally bumping into them . Thanks for your input!

ed wallace

dry fire

i would shut off the gas supply and if unit has auto water feed i would shut off water supply also if you can locate the fuse or circuit breaker turn that off also with oil the same things apply its no fun dealing with a dry fire situation

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sootmonkey

hey

here in maine it is code to install low water cut outs. talk to your local code guy and see if he can get the ball rolling on getting this into your code. just a thought.

DanHolohan

I think

he's dealing with boilers where the low-water cutoff didn't.

Eric Taylor

silly question

Wouldn't the boiler's high limit still operate in a dry fire situation? I bet it would be a bit delayed, but shouldn't it protect against heating to "cherry red"? I've read stories of dry firing boilers and have been wondering...

ET

Unknown

High limit

On a steam boiler, the limit works on pressure. If there is no water, there is no pressure.

A dry fired steam boiler is NOT a pretty thing. I've seen one where all of the metal was gray, or blue. All of the wires were bare. The gas control was open, permanently. It had set ablaze a chair in the same room, which lit the ceiling and caused the call to the fire dept. THEY shut the gas and power and water off.


6 hours later, I put water in it. It held it. I wouldn't have believed it. I saw it glowing red and it never cracked. I still shake my head when I think about it.

The low water cut off was not being flushed at all.

Noel

Eric Taylor

Hmmm.

Thanks Noel

Just a thought though-- I understand that new boilers are, or should be equipped with a LWCO to prevent dry firing, but in some cases the LWCO has been known to fail. Could a temperature based high limit still be used on a steam boiler in addition to the LWCO? Set it to say 260*F or so-- higher than the steam temp should ever get and it would kill the fire before the furniture.

I'm not in the trade, but I'm curious.

ET

Unknown

That would do what you expect it would.

> Thanks Noel

>

> Just a thought though-- I

> understand that new boilers are, or should be

> equipped with a LWCO to prevent dry firing, but

> in some cases the LWCO has been known to fail.

> Could a temperature based high limit still be

> used on a steam boiler in addition to the LWCO?

> Set it to say 260*F or so-- higher than the steam

> temp should ever get and it would kill the fire

> before the furniture.

>

> I'm not in the trade,

> but I'm curious.

>

> ET

Unknown

That would do what you expect it would.

It would need to be a manual reset so that it wouldn't repeat the dryfire situation. In no way would this REPLACE any of the code required controls, but it could be added to them.

Nothing beats weekly maintenance on a steam boiler. That's the REAL key to long life for a boiler. Notice and fix leaks as they occur and the boiler will last a long, long time.

Noel