Wood catching fire?

[SCSmoker]

Hi Guys,

Loving my smoker so far, but have one issue repeatedly rear it's head.  About 45 minutes in, I will hear a pop/whooshing sound and see a bunch of smoke shoot out from around the door. When I open the smoker to investigate, I see the wood is on fire (whenever I open the box the flames are going strong). Any idea what causes this? It happens almost every time and is really annoying.

I use 3-4oz of wood, and have tried two types...

Thanks

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[benjammn]

that is commonly seen with the first runs of the unit, it is a backdraft type situation but it quells over time. for some reason the first moments that the smoker gets up to temp will burn the wood causing a situation where the wood will get to the point of combustion but will not, it gets starved for air and then suddenly gets a burst of air from the vacuum inside, causing a "poof". normally this doesn't happen at all after a few runs and making sure you aren't using dried wood from the Home Depot or other big box stores, since they are really dry. Mine did it twice that I know of but hasn't since but I also no longer buy wood from the local stores. if the wood is kiln dried it will want to combust not smoke, there is the problem. Don't be afraid just let it do its thing and it will move on. but try some different woods and/or soak first to keep it from doing that.

[benjammn]

Also, don't open the door on these units unless you really need to. 3-4oz is pretty lean overall and should do just fine. first smokes will need to take some time to seal up the door with the creosote, it will act as a sealant eventually and make the smoke not escape from the door.

So just let the first few firings go along and then if it continues you need to let us know.

The situation about "backdraft" is this: there is chamber that has a heat source and fuel source, the fuel source (wood chunks) gets super heated by the heat source (element) and therefore fills the chamber (smoker) with smoke that is super saturated with fuel but is lacking in oxygen to burn, once the chamber gets to a certain temp it allows surfaces to expand and create gaps that wouldn't normally be there (such as the door expanding slightly), thus allowing in extra oxygen, this creates a spontaneous combustion (the poof) that ignites the fuel, worse thing you can do is open the door, this will allow a large amount of oxygen in and will cause the fuel to fire up instantly. Leaving it be will allow the system to adjust appropriately and just smoke.

[Three Sons BBQ]

Ben:

Thanks for the lesson! I never thought about the sequence of events.  Good to know should we all run into the "poof" to just ride it out. Suspect it would scare the day lights out of me.

Couple of items....

Since I'm rarely around the smoker, say for an 18 hour pork butt I guess I open the my kitchen door say 15 times to just look at the bright Auber display, is there any visual evidence or signature left inside the box after this occurs? I suspect no.

Lastly I use a lot of apple and cherry that I cut down. I has been drying in my shed for a couple years. It is not kiln dried and will have moisture due to what is in the air only. I.e. It's not green or fresh cut, so it's dry but not void of any water. This okay???

[swthorpe]

Dry wood is the likely culprit.    I experienced the huge belch ("poof") on the first couple of smokes.   It is scary; I remember the first time thinking the door was going to blow off (of course it didn't).   I started soaking my wood chunks for a few hours before each smoke, and the belch disappeared.   I am now almost a year in to smoking and a couple of weeks ago I tried my same wood without soaking...the belch returned!  So, now I soak for a couple of hours each time.   I doubt I am adding a lot of moisture to the wood, but it seems to help.

My primary wood is cherry that was cut off from a tree in my front yard two years ago and has been stacked in a wood pile ever since. 

[DivotMaker]

Ben's explanation is dead-on.  I've never experienced this in my #1, but encountered it during the first test run on the electronic #2!  Scared the crap out of me.  I was standing near the unit, looking at the temp display, and smoke started shooting out from everywhere!  All around the door, and both holes, for 3-4 seconds!  I was using the SI hickory dowels (new ones, so they were fresh).

Since then, it's been much less, and I've been "stepping" the heat up.  I initially set it to 130, let it get to temp and cycle into maintenance mode.  After about a 5 minute rest, I step it to 170, repeat the process, then up to 225.  A more gradual warm up has stopped the combustion problem.  I use Fruitawood cherry and SI or Fruitawood hickory mostly.

I believe this phenomena only happens in the 2s and 3s, due to the much larger elements.  When it's at full power, it increases the chance of igniting the wood.  Sounds like there are several ways to solve this, as we see here!

[Walt]

My #2 belched early in a cook the 1st couple of times I used it.  I ignored it & the food was great once done.  I havn't seen it belch since & the food is still great.  It really seems to be irrelevant to the outcome, although disturbing to witness.

[old sarge]

I too have experienced the belching around my smoker.  Beer!

Back on the topic, I have read about this on other sites, and it seems rather typical.  Some users experience  it and some do not.  The fire issue is prevalent on a particular 'big box' smoker and is related to too much air.  Which is one reason to not open the smoker during the early stages of cooking.  I suspect combustion gasses are present in sufficient quantity that the glowing ember of the smoldering wood is the source of temporary ignition, and that plus the oxygen in the smoker initially combine and you get a belch or two.

If it was a severe problem, the belching would be consistent throughout the smoke.  I have not read here or elsewhere that this phenomenon is constant.  Also, some of the rumbling noises might be nothing more than the metal of the wood box heating and expanding or contracting. Eventually system equilibrium is reached and the unit settles down and all is well.

Now, on the subject of beer...........

[benjammn]

Yes....beer belches are more commonly found around my smoker. I have yet to find the culprit but I will let you all know when I find it.

Cheers!

[DivotMaker]

I believe the culprit, Ben, are those tiny bubbles...those beautiful, plentiful, little tiny taste bubbles!

[benjammn]

This is going to take some research. Lots of research.

[old sarge]

A twelve pack should be sufficient.

[DivotMaker]

I've began my own experimentation...I'll get back to you.

[swthorpe]

Old sarge.... I have only had the big belch occur once on any smoke, usually within the first 30 minutes, and then the smoke rolls normally.

[old sarge]

swthorpe - That sounds about right.