Help! I think my egg is possessed :-)

UKMatt · December 2009

Can anyone explain to me what on earth my Egg is up to.

I have it set up for indirect roasting with the platesetter as I am going to roast a pork rib roast.

I have two thermometers in there (the dome and my ET-73) and it seemed to be taking an age to get up to temperature (aiming for 400ish dome temp). I've tested the thermometers and they're accurate.

When I went out to check, the dome was only showing 350 but the coals were glowing very bright through the bottom vent.

After that, three weird things happened:

I burped it a bit and then looked inside - when I closed the lid I had flame shoot out the top of the egg.

When I closed down the top vent more, the egg appeared to be breathing fire from the bottom vent - about 20 or 25 'puffs' of flame!

Finally, I had to put a probe into the meat so I burped it especially carefully - glove on, lift the lid a couple of inches and down, then a few more inches, then about a foot. Finally, thinking the danger had passed, I opened the lid up and reached for the probe - at that point I had a fairly major ball of flame coming up around the plate setter.

I am aware of the science behind flashbacks (or whatever we call those things that remove eyebrows!) and of the normal precautions. I have generally only seen them after grilling direct at high temperatures and then closing the vents down.

So for some reason, I am getting really bad flashback at a relatively low temperature and they're consistent - every single time I open the dome I get one.

Is there something that causes this at lower temperatures?

Thanks
UKMatt

Unknown · December 2009

sounds like your air flow is really restricted, did you have a lot of small pieces of lump in there, & maybe dust? I have seen similar things happen with this, Marc

Humphrey Chimpden Earwicker · December 2009

you likely have a lot of fresh lump.

Panhandle Smoker · December 2009

I agree with Zippy it sounds like you have a blockage likely on the fire grate. Use a wiggle rod or a coat hanger with a 90 bent into the end through the bottom vent and clear the holes in the grate.

BBQMaven · December 2009

If you have checked the fire grate and used a wiggle stick and still have problem...seems that air flow is issue...When you open top and get flashback it is from extra fresh O2... things to check after this burn... does the firebox opening line up with lower vent opening, are the small holes on side of firebox stopped up, is there a build up of ash behind the firebox?
Only other thought is if you used the bottom of a bag of lump and it has tons of dust that are stopping air flow.
I'm sure those smarter than me will chime in, please update with what you find!
ktm

Eggsakley · December 2009

AS others said, wiggle the grate. Or maybe it is posessed. The first seems more likely.

2Fategghead · December 2009

It sounds like the movie back draft.It seems like you have a fire with a lot of fuel and restricted air flow and when you open the dome you get a rush of air and flames dance out of there. Be careful or you will get a new kind of hair cut. :ohmy:

UKMatt · December 2009

Thanks to all for the comments.

To address some comments: It was a new bag of Royal Oak. It did not appear all that broken up when I poured it in but it may well have been more small pieces than normal I suppose.

I don't have a wiggle stick handy but I will find one for next time.

In the end, it did settle down after about an hour and I am about to eat the results :-)

Thanks again!

UKMatt

BBQMaven · December 2009

Glad to hear it worked out...
Coat hangers make great wiggle sticks when nothing else is around!

Humphrey Chimpden Earwicker · December 2009

low temp flashbacks that occur multiple times (when opening the lid) or repeatedly shoot out the bottom vent most often are caused by lots of VOCs and dust with not enough oxygen to really burn and be driven off.

the lowest fires (like 250) don't involve enough lump to generate the flashover. higher temp cooks (like 450) effectively drive off the VOCs quickly enough that it's never a problem.

very high temps can have flashbacks for other reasons, but never really because of VOCs.

but a 350 fire, on a full load of ump, is the sweet spot for repeating flashovers (not really flashbacks in this case).

there's enough lump burning to ignite the VOCs and dust when just enough extra oxygen is involved. the fire is low enough to not drive them off, so you can get these flashovers half an hour into a cook. a hotter fire would have driven the VOCs away by then. a lower fire wouldn't gain anything by the extra oxygen from opening the lid. and the fire isn't aggressive enough to seek out oxygen from the lower vent.

it ain't blocked airflow. it's a giant pile of fresh lump with only a small bit of (but just enough) lump to provide an ignition source for all the potential fuel. the oxygen starts the party.

Humphrey Chimpden Earwicker · December 2009

proof that it wasn't a clog is that the problem went away. clogs only get more clogged...

a wiggle stick is a good tool though, regardless. especially for just before you go to bed prior to an overnight cook

Grandpas Grub · December 2009

There is not enough air getting up into the burning lump.

The heat from the lump will burst into flame in any direction free air is available. Flashback when opening the egg or flash back down through the vent.

Usually a wiggle rod will resolve the problem. You can buy a wiggle rod and have it shipped over there or you can make one out of a wire cloths hanger. You might use another term other than hanger.

You could go to a shop and buy a 3/8" diamater aluminum or steel rod and bend the end to clear the air path underneath and up through the grid in the bottom of the fire box.

GG

[Deleted User] · December 2009

I would agree with stripsteak.

The only times that I have had Flashbacks are when I had an accellerating fire and opened the dome. Usually a full load of fresh lump and the temp is rising but may have stopped along the way (maybe due to lack of O2?)

The mass from the platesetter will keep the dome temp from rising rapidly, but that doesn't mean the coals below aren't going beserk. I also find that the platesetter obstructs airflow somewhat. Not a lot but enough to delay your flashback until you have the dome open.

I would think that that you had an airflow problem if you weren't getting flashbacks . Because you are, I think the cause of your odd symptoms are due to the combination of new lump, maybe some charcoal dust too, cranking it up to speed and having a platesetter in place.

I have had a similar but not exactly the same, experience on a 650 degree pizza cook. temp was sticking at about 500. I have also had 600 degree pizza cooks where flames were shooting out the chimney and others-same temp- where there were no flames just the warm orange glow of the coals.

2Fategghead · December 2009

Matt, You may want to have a well established fire and wait an hour after your egg was stabilized at your desired temp with the plate-setter in then put the food in. Just my $.02 cents worth.

A wiggle stick may help after you dump in the lump and lite the fire you can wiggle the stick up through the bottom vent and make sure you have a good air flow.

Help! I think my egg is possessed :-)

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