LOTS of smoke = Low Temp Flashback

Charcoal Mike

Hi all -[p]Was cooking a couple of spatchcock chickens last night. I previously had a bunch of small pieces of lump left in the bottom of the firebox. So I *completely* cleaned the firebox (and the holes), and filled to the top of the box with fresh BBQ Galore lump. There were a few small pieces, but not many. Mostly 2-3 inch pieces and larger.[p]Lit with a Weber firecube on top. Bottom vent wide open, no daisy or any other lid on top. Did not have any wood for smoking - just the lump. Was shooting for 350, but for whatever reason she kept stalling at 225 after 20 minutes. Man the smoke was absolutely POURING out of the top - the neighbors yard looked like it had a bad case of morning fog. I was even able to look through the bottom vent and see smoke moving around underneath.[p]Well, I put on my handy gloves and CAREFULLY opened the lid - POOF!! a nice flashback. This of course immediately burned away all of the smoke. Not 15 seconds after I closed the lid I had a RAGING fire, and the temp had rocketed to 360 and was still climbing. I actually had to close the daisy wheel completely and close the the bottom vent to just 1/8 of an inch to slow it down.[p]Anybody else ever seen anything like this before? Flashback at **225** ? I actually saw the SAME thing the last time I did chickens, but I took it as a result of the old lump I had in the egg.[p]- Mike[p]PS.....Chickens turned out great. Leftovers tonight.

Unknown

Charcoal Mike,
I've had the same happen to me. It happened when I lit a starter cube and then closed the dome. What I do now is lite the cube, open the bottom vent all the way and keep the egg dome open until a few pieces of lump are glowing. Word of warning tho.......keep a close eye on the egg with the dome up. Once the lump catches, It'll crank up REAL fast.

Unknown

Charcoal Mike,
Although I haven’t experienced this in the egg yet, I have seen it happen in a house with a fireplace. It would seem a fairly decent amount of heat must be generated from the get go in order to create the necessary suction/draft/siphoning effect in the chimney. A cold smoldering fire will continue to smolder and stay cold while the house fills with smoke choking everything in it. To prevent it, fireplace owners are recommended to ignite some newspapers on top of the wood fuel they are using to ensure that there is enough draw.[p]Perhaps next time you notice this you could simply place a small fan in front of the lower vent to encourage proper air flow. Or use more than one weber cude to generate more heat.[p]Matt.

Bordello

lo n' slo,
That is the way I light my egg, it just seems to work better for me, it also lets the smoke dissipate into the air less noticeably then being concentrated out of the dome vent until burning clean. I live in an area that somewhat frowns upon burning wood. Only gas fireplaces allowed in the houses but they made no mention of burning wood in barbecues.
Happy Egg-n,
New Bob

The Naked Whiz

Charcoal Mike,
Based on research I did a while back (see my web page below), I seriously doubt the smoke was the culprit. You said you loaded it up with fresh lump. Fresh lump contains volatile organic compounds which are flammable in themselves. When you heat fresh lump up, you drive off the VOC's which are then available for combustion. Obviously, fresh lump contains the highest level of VOC's and thus the risk of flashback is greatest with fresh lump. In my experiments, I used old lump, heated it up to 700 degrees, threw on some smoking woods, closed up the egg, let her sit for a couple of minutes, opened her up and absolutely nothing happened. Like I say, I'm sure the culprit in your case was fresh lump.[p]TNW
[ul][li]The Naked Whiz's website, look for the link to flashback info.[/ul]

Charcoal Mike

The Naked Whiz,
Not saying the smoke was a culprit - just an obvious symptom that something was a bit out of whack.[p]What surprised me more than anything was the low temp at which I got the flashback - usually (in my limited experience) you see this more on a high temp dwell, when oxygen is severely limited. I was quite surprised to see it at 225, with both vents wide open.[p]The information about the VOC's is great stuff. Thanks for the research![p]- Mike

The Naked Whiz

Charcoal Mike,
I've had a flashback at around 400 once. Again, it was new lump and it was small pieces that didn't allow the air to circulate very much. The temperature isn't as crucial as one would think. You just need enough heat to drive off the VOC's something to ignite them. My low temp flash wasn't as low as yours, but the other contributor is lack of air circulation. You said you had mostly relatively good size chunks, so I wonder why the air wasn't flowing and the VOC's could build up. Truly wierd.....[p]TNW

fiver29

Charcoal Mike,[p]I thought I would share. I had a reverse flashback this past weekend. Scared the bejesus out of me![p]I was following Tim M's (thanks Tim) recipe for the 3-1-1.5 ribs at about 250. So I get Mr. Humpty up to around 250 in about 15 minutes somewhat stabilized no problem. I was thinking to myself how I hate to wait for the temp to get back up with the firebricks I have because they are pretty thick and they eat up quite a bit of lump.[p]Anyway I decided to not use firebricks. I used the large pizza stone in the large egg with a firebrick on each side to set my grate on top of. There was still some area around the pizza stone left so I thought 'what a great idea!'. [p]I had the bottom and top vents wide open. I had just poured some fresh lump on the fire before putting the pizza stone on *key*. And there were a lot of small pieces being its towards the bottom of the bag.[p]I'd say maybe 2 or 3 minutes later I hear a 'whoosh' noise. Then another. I'm thinking 'what the ..... is that?' I bend down and look into the bottom vent. Its a nice orange glow and the temp up top is still about 250. Then I saw the 'whoosh'. A nice big flashback sent downward. I seriously thought the thing was going to blow up on me! By the way, lots of smoke was pouring out of the top.[p]I closed off both vents and slowly opened both. My internal temp eventually stabilized and I smoked some great ribs.[p]In retrospect it wasn't such a great idea to use the setup I had in combination with wide open vents. I'm just glad things turned out the way they did. Anywho, the point to the story is to be careful. You can get a flashback at a high temp, low temp, and the key ingredient seems to be the fresh lump each time.[p]CHEERS![p]Fiver29

The Naked Whiz

fiver29,
Yep, fresh lump and restricted air flow. The pizza stone was no doubt impeding air flow up and out the top. If you have seen my video, I dumped a bunch of fresh lump onto an already red hot fire. That egg was just aching to blow when I opened it up! I really need to do that again sometime. :-) I'll try your setup sometime and see if I can recreate the reverse flashes....[p]TNW