Radiator Pipe that Superheated

Donna Day

Two days ago a beam in our basement caught fire. This beam was directly above a steam radiator pipe that was carrying water from the boiler to the rest of the house. This pipe was insulated and the paper surrounding the insulation also burned. The firemen who investigated said that a steam pipe should not get hot enough to burn wood. The firemen shut off the boiler while they were putting out the fire. There was no damage to the boiler. After they left, my husband tired to restart the boiler. It would not come on. We called a local heating company.

When the repairman came out, he said that the boiler would not restart because there was a problem with the water feeder. However, he said that this was not the cause of the beam catching fire. He said that the pipe could not get that hot. He said that if the boiler had overheated, that it would have glowed cherry red and would have been obvious to the fireman. He checked the boiler and said that there was water in the boiler.

I e-mailed Dan Holohan to see if he had any ideas. He said he had only known of pipes to superheat when they "dry-fired". According to our heating contractor, this didn't happen. My husband followed Dan's suggestion to check for water in the boiler. He drained 10-15 gallons from it and the automatic water feeder did kick in and refill.

FYI. Our boiler has never not started before this, so I am still concerned that the water feeder might have caused this problem.

The boiler is directly below our bedroom, so I am now afraid to sleep at night and we are turning the furnace off during the night.

I am searching for answers, hopefully one other than replacing our system. We heat approximately 3800 sq. ft. and we would have to have two units if we went to another heating system.

Has anyone ever heard of a boiler superheating maybe a day before, causing a beam to smolder for hours, and somehow refilling and cooling down before the fire was discovered? There must be a reason why this occurred. Although everyone agrees the fire was caused by the pipe superheating, they can find no reason why it would have done this.

The only other problem we have had with this system was a couple of months ago when the thermostadt started resetting itself to a higher temperature. The heating contractor just reprogrammed it. He couldn't find any problems with it and it has not reset itself since.

We would truly appreciate any ideas anyone has on this.

Thanks.

Ken_8

Holy Guacamole!

But rest assured, all the comments about the hot steam pipe(s) are correct. A steel steam pipe at a maximum of 220 degrees (which is as hot as the pipes can get under normal operation) cannot start any fire.

This does not however go to the question of what DID actually start the fire!

Wiring would be my first logical suspect. A light bulb can occassionally also get hot enough to start paper going - especially if in a sealed fixture. If the boiler is oil- fired, sootier than typical, it is remotely possible that a "rough start," or mini-puff-back may have allowed a soot "scab" to become be ejected from the firebox area or clean out door/inspection plate and throw a spark?

Extremely unlikely, but as we all know, weird things can happen. (Murphy's Law).

Let us know what your detective work uncovers.

We can all benefit from your story. Please post again. You might save another's life by soing so.

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Bill Nye

I will

have to agree with Ken. My first impression is that it is an electrical thing.

Steamhead

\"Paper surrounding insulation also burned\"

could be the key here. I have known of a steam pipe that was actually touching a beam, causing the wood to deteriorate and lower its ignition temperature. Since paper is made from wood, the same thing could have happened here.

Was the paper actually touching the pipe? What kind of insulation material (fiberglass, old asbestos etc) was used with the paper?

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Donna Day

The insulation was fiberglass. It was a type of insulation made for round pipes and the outside of the insulation (the part that touched the wood) was some type of paper over foil. We insulated 3 years ago. We believe the paper part actually touched the wood. The firemen cut away part of the beam, so I am not sure if it was just extremely close or actually touching. Our house was built in 1910. It is certainly possible that the wood has become damaged over time. One other thing. The firemen did mention that there was a nail protruding from the wood into the insulation. Could the nail have heated to the point of starting the fire? But again, could the pipe get hot enough to heat up the nail to start a fire?

Donna Day

Ken, Thanks for your reply.

There were no wires running near the beam. Our house was built in 1910. The furnace was orginally a coal furnace. When a boiler was installed about 15-20 years ago, it was oil. At some point the oil furnace was converted to gas.

There is still a lot of coal dust in the walls and wood of the boiler room. However, we don't know of anything that could cause a spark. This is what is driving us crazy; we thought about other problems like a spark or wiring, but there was no wiring in that area. Could old coal dust have a lower flash point?

Bill Nye

Electrical

I was once in a house that had a bad neutral wire from the street. There was no driven ground rod, the panel was grounded to the galvanized water service with an aluminum clamp. It had oxidized and was actually glowing red because of the heat.

The owners had been getting shocks so someone grounded all of the receptacles . It was an older home. My partner had to service the boiler on a Sunday and I stopped to help him. He had removed the fuses to the boiler yet he still got shocked. We read 58 volts with a meter at any metal point on the boiler.

It was the largest metal thing and was connected to the water pipe so it became the ground. It was an old coal conversion boiler and had contact with the dirt floor.

Steamhead

That nail

could have conducted enough heat to ignite wood that had deteriorated as mentioned above. This is even more likely if the pipes had been uninsulated for a long time.

Also, how thick was that fiberglass? We normally use 1-inch thickness on steam pipes, which leaves the outer foil paper no more than warm to the touch.

I hope no one was hurt.

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Donna Day

The pipes were uninsulated for a long time. The fiberglass insulation is 2 1/2"-3" thick. Would this cause heat to build up more? We thought this would keep the heat close to the pipe and the outside cover of the insulation would stay cool. Is this the wrong?

Donna Day

Thanks. We will definately investigate that more.

Uni R

Fahrenheit 451

Isn't 451°F the ignition temperaure for paper? There must have been something else with a really low flash point if that fire was triggered by a steam pipe. Any vinegar (acetic acid) in the area or something different like that?

Donna Day

No. There is just a glue that seals the paper. But this insulation is supposed to be designed for pipes.

Ken_8

Uni's got a point.

The steam pipes are no where near the ingition point of anything - that is commonly in any part of a house - including coal dust! An open flame is required and there is no open flame in a steam pipe. However, it is interesting to note the nail appeared to be in the immediate vicinity of the fire start-point? There is an aluminum strip on some of the FG insulation of which you speak, steel is a conducter...

So we need to find a bad ground - and an electrical "leak" somewhere in the area of the boiler and all that's attached, like the water meter jumper? Water heater jumper, feed circuit to the boiler? Nearby wire? Nail went thru a wire in the past and now has a nail acting as an electrode? Somebody put a nail thru a wire (sta, power, etc.) and "energized" the entire boiler?

Just for the heck of it, try a meter between any part of the boiler system metal and an absolutely known-to-be-good ground. We may have a high resistance circuit hiding out somewhere.

Any chance the nail in the floor [passes into an appliance? range? fridge? sink with disposer? with a dishwasher?

I am 99.9% sure this is not a warm steam pipe ignition fault.

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