Vent: Tried using a shop vac to clean a chimney and almost blew myself up

So last week I figured I'd speed things up on a job in Portland by hooking my shop vac up to the bottom of the flue to suck out the soot while I brushed from the top. Sounded smart in my head, right? Well, I got about three minutes in and the vacuum motor started making this weird high pitched whine, then POP and a cloud of black dust shot out the exhaust. Turns out fine ash and a hot motor create a nice little dust bomb situation. My whole truck looked like I set off a smoke grenade inside it, and the homeowner came out asking if I was okay. Learned my lesson the hard way: stick to the drop cloth and hand sweeping, no shortcuts. Has anyone else tried a vacuum setup and ended up with a mess like this?

2 comments

2 Comments

walker.hayden25d ago

Hold on, careful with the wording there. It wasn't "fine ash and a hot motor" that did it, it was more like fine ash floating around in the air inside that vacuum. That dust cloud is actually flammable. Once the motor sparks, which they all do, it ignites that suspended dust. That's the real reason it blew up on you, not just because the motor got hot. A lot of folks don't realize shop vacs aren't rated for combustible dust like that. You got lucky it was just a pop and not a full on fireball.

shah.ben25d ago

Wait, so I can't just blame the motor for being 'too hot' like my toaster? Thanks @walker.hayden for making me realize my shop vac could've turned into a firework show.