New Steam Installation-Problem with Flooring

DStoney828

I need to know if anyone has run into this problem and if they have an answer or advice.

I completed an installation of a Weil McLain PEG gas fired steam boiler, which was set up on 4" cap blocks. Flooring below boiler was cement which was solid and in good condition.

After initial start-up, boiler ran for approx. 30 minutes before I heard a loud boom and had some black smoke and a burning odor. I shut the boiler down and found that the flooring under the burners had basically blown apart into pieces about a 1/2" thick, the width and depth of the burners.

Burner I replaced was a gas fired Utica boiler which had a metal tray under the burners. So I feel that this floor did not get as hot with the previous boiler. Prior to this, the house had an oil burner approx. 12 years ago. I did notice an odor of oil in the basement.


This is the 2nd time I have had this happen to me. The first was installed on a cement floor that had old tile with an adhesive at one time. The tile was gone, but the adhesive layer you could see lightly. This boiler sat directly on the floor. That evening the floor blew apart and actually blew the burners up and out of place. Actually bending a few.


What caused the floor to literally blow into pieces and what can be done to prevent this in the future? Has this happened to anyone else?

Thank you,

Dean

Mark Hunt

W/M PEG series


These boilers do not have a deflector shield on the bottom as you know. The amount of downward radiant transfer is very high. They ARE NOT approved for installation on flammable flooring.

While I have never had a floor explode, I would have to say that it is do to moisture in the flooring. Heat it up and it expands. Heat it enough and the floor explodes.

I would suggest a heavy gauge metal shield under future installations and you will have to put the boilers on blocks.

Good luck.


Mark H

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Robert O'Connor_7

WM?

Check draft/chimney, may be a good place to start. Its never happened to me, and I can't even guess how many PEG's we have installed. You got me scrathing my head..Robert O'Connor/NJ

Mark Hunt

I once saw


a W/M LGB set fire to a block of wood that was under it. Draft was fine, but the downward radiant heat was enough to set the wood on fire!

The EG series is not approved for installation on combustable flooring beacause it does not have a heat shield.

It doesn't suprise me that this happened.

Mark H

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Constantin

What surprises me...

... is that this is the second time this happened to you. I would have inquired with WM, the Wall, or other resources to get ot the bottom of the first explosion before installing another WM unit. Maybe I'm just a safety nut.

I second the notion that there was something afoul with the floor below, though I am surprised that simple water-logging could lead to such a violent reaction. Presumably, the homeowners are not pleased.

My response to this type of situation would be to fix the floor, then reinstall the boiler on a thermal shield of some sort. Consider some of the high-temp insulation options from McMaster Carr like Mineral Wool sheets that are good for temps up to 1200°F and not too expensive ($15 for a 2"x24"x48" sheet). They should cut down heat transmission significantly.

Howevever, the main lesson I see here is to avoid using this WM boiler. Presumably there are other choices out there that don't spend their time frying the floor beneath them instead of putting all that heat into the HX. If I want basement heat, I'll install a radiator, badly insulated boilers need not apply.

DStoney828

A concrete floor is presumably a non combustable material and this boiler is safe to install on concrete floors(correct me if I am wrong). I have installed Weil McLain Peg boilers on an average of 2-3 a week during the heating season for 3 years and I only bring this up because of the reoccurance.

The first time this happened I did not put the boiler up on block because of height restrictions. I credited this floor breaking up to the adhesive that was applied over the cement in the past. I thought the cement may have been poorous and the adhesive was absorbed into the floor causing the vapors in the floor to combust.

I am following up with a WM rep on Monday to see what has to be done in the future to prevent this. Yesterdays occurance, the boiler was up on 4" block on a solid cement floor. No wood or combustable material was involved.

I agree with the previous post (thanks Mark) about possible moisture in the floor causing the pressure build up under the cement. Sounds logical. Damper and flue/chimney were not an issue. System was up and running properly as I was finishing up and running unit for 30 minutes when this happened.

Thanks for everyones input...hard to believe that I am the only one to see this happen to.

Dean

Mark Eatherton1

Concrete floors do not necessarily mean fire protection...

It sounds as though you are the victim of downward radiant energy into a wet cement environment, and seeing explosive spalling of the cement. Ever seen what happens to cement if you hold an oxy-acetylene torch against it? EXPLOSIVE!!

Not being a W/M man, I can't speak for the manufacturer, but wonder why they would allow a product with such a MAJOR downward radiant energy loss onto the market without some means of protection. No one ever reads the instructions anymore...

I've been witness to boilers that were not rated for use on a combustible surface that were infact installed on 1-1/2" thick cement, placed on top of a conventionally framed plywood floor. The continuous downward radiation caused the concrete to get hot enough to the point that the wood on the OTHER side of the cement, pyrolized and flashed over (caught on fire). You will note that most boiler manufacturers require some means of allowing this compounded radiation to be released, I.E. cinder blocks with the holes such that the pad can "breath". They do that for a reason. They understand that compounded radiation CAN and WILL saturate a cementitious compound such that any combustible materials on the other side WILL eventually combust.

Don't be deceived by the outward appearance of a given surface. Just because it won't "burn" openly doesn't mean that it can't conduct enough thermal energy to allow something else to burn. Been there, seen that, don't care toi see it again...

Proceed with caution.

ME

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DStoney828

Great information Mark. I agree that the appearance of a cement foundation can be deceptive. It is whats under the surface that can cause a problem(ie. moisture wood or any other combustable vapor or material). I will be following up with the manufacture rep. on Monday to remedy this and all future installations. Thank you!

Mark Hunt

Sorry


My point was that the EG series is not approved for installation on combustables BECAUSE it does not have a heat shield.

Your installs were perfectly fine.

As I said, it doesn't suprise me that this happened. There is a TON of radiant energy being lost downward in boilers designed this way.

Mark H

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Unknown

Could it have been oil

from the original boiler that seeped into the cement ? I know by the old ones we rip out that many of them had the chamber brick that sat right on the cement . With the new boiler creating that downward heat it might ignite any oil residue in the floor . 12 years is a long time to still smell oil , is the oil tank removed ?

I've installed quite a few Peerless gas boilers ( oil to gas conversions ) with open space below the burners , right on the concrete floor where an oil boiler sat for decades and never seen the floor ignite like you say . Sounds like a scary experience .