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New Spin on an Old Problem – Vacuuming up Fireplace Ashes

January 4, 2013

Vacuum HoseI’ve got a fire investigation report on my desk from a fire our troops examined recently.  The homeowner built a fire in the fireplace and cleaned the hearth afterward.  He used the vacuum to remove dirt, wood chips and ash from the hearth while the newly built fire was burning.  The fireplace had glass doors and investigators surmise the vacuum may have sucked some live embers out under the glass.  Upon cleaning up the hearth, the homeowner emptied the vacuum out into a plastic garbage can in the garage (this was a pretty neat and tidy guy).  A couple of hours later the wife came home and opened the automatic garage door to find the garage charged with smoke and the garbage can almost consumed by fire.  Fire had burned into the common wall between the garage and house causing about $30,000 in damage.

A vacuum cleaner bag or canister is filled with combustible dust.  Dust represents the finest particle size and provides the best surface-area-to-mass ratio a fuel can have.  Circulate a bunch of air through that (by vacuuming), add hot embers, and you’ve got a pretty good formula for ignition.  Give it some more air by dumping it into a garbage can and you’re mixing it up even more.  It’s not surprising that the garbage can was on fire a couple of hours later.

We’ve not seen this happen before, but the mechanism is easy for us fire investigators to understand.  Consequently we’re trying to get the word out so we don’t see this fire happen again.

If you use a vacuum to clean your hearth (and I do that at my house), ensure you don’t get ANY live embers in the vacuum.  If you think that may have happened, remove the bag or canister and set it outside away from the house.  Remember any filter in your vacuum may have embers hung up there too.  If you suspect you picked up live embers, you might want to move the entire vacuum outdoors and away from the house.  You could also dump the dust into a metal container and douse it with water to ensure any embers are extinguished.  Either way, embers that have been given plenty of air in a vacuum and stored with combustible dust are just waiting to ignite.

If you’ve got questions about fire safety you can call us at 509-466-4602, or e-mail me at, or you can post your question here.


From → Fire Prevention

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