chocked out by ash - what happened?

dgaddis1 · December 2016

I cooked a pork butt this weekend and for the first time ever my fire got (mostly) chocked out due to ash build up. Here's the set up:

Large BGE
Kick Ash Basket
No grate
Cleaned out Egg before the cook, including pulling the ceramic pieces and cleaning behind them
Used Rockwood Lump. Lit the fire by placing a starter cube at the bottom and center of the basket, lit it, and then piled the charcoal on top. Filled the fire box with the biggest pieces from the bag first, then added some medium size pieces on top of that about 3/4 of the way up the fire ring.
One big chunk of cherry, a few small pieces of hickory for smoke.

It ran for ~9hrs or so just fine with the temp sitting around 235*F. Then the temp started going down, I opened the vents more, and the temp kept going down. Eventually temps hit 200*F and I pulled everything out and bottom of the basket was pretty much clogged with ash. Still had lots of lump left. Shook the basket, stired the coals, added another handful of lump and put it all back together and temps came back up.

Never had that happen before. Now, on other low and slow cooks I've done I started the fire with a chimney to get a decent amount of lump lit, then dumped it in, spread it out around the bottom of the basket, and added more on top. I wonder if starting the fire in a single spot was part of my problem? The vents in the firebox weren't clogged. Temps were really cold that night (dipped into the 20's I think), but I don't see why that would be a cause.

Do you think the big piece of cherry is to blame? It was about the size of a baseball.

Any thoughts? Comments? Suggestions? Got my first brisket cook coming up in a few weeks and don't want to be dealing with my fire going out!!

Legume · December 2016

Doesn't sound right, you have all of the right toys. One chunk of wood shouldn't be able to choke a fire unless it's a stump.

VB_egger · December 2016

I would think the initial fire was not large or hot enough.

chuckytheegghead · December 2016

Sounds like you need a flameboss.

Hans61 · December 2016

Sometimes weird things happen. I wouldn't worry unless it happens again

JohnnyTarheel · December 2016

Question I have is why light the starter cube at the bottom of the basket on a low and slow? If it's lit at top you know air is moving up like it should.

pgprescott · December 2016

Analysis is off the mark. No way. Maybe a black hole, but no way is it ash snuffing out the coal. No way.

HoustonEgger · December 2016

Agreed with @pgprescott it's not an ash problem. This problem happens when the fire is lit in one place and not allowed to spread correctly - which happens a lot if you don't let the egg hang out at a higher temp for a bit. For example, if I only light in one place and then only let the egg come to 250 or so, I can pretty much bet this will happen. But if I let the egg get to 400-500 for a bit and then bring it down, no problems.

Either that or a bad stacking of your lump.

StillH2OEgger · December 2016

If you have enough lump, you should be able to light in one spot on top, bring the temp up slowly to 250 range and stabilize there for a while and be good to go all night.

lousubcap · December 2016

As mentioned above, it has to be an air-flow issue given you have enough fuel which you did. So somehow you managed to clog the source of air. Don't have a basket but if all you did was clear the ash and then all was fine that's what had to happen. Hard to believe given the many ways for air to get to the fire but...

SaintJohnsEgger · December 2016

This is one reason I always light int two places and that I'm not a fan of lighting at the bottom of the lump.

JustineCaseyFeldown · December 2016

HoustonEgger said:

Agreed with @pgprescott it's not an ash problem. This problem happens when the fire is lit in one place and not allowed to spread correctly - which happens a lot if you don't let the egg hang out at a higher temp for a bit. For example, if I only light in one place and then only let the egg come to 250 or so, I can pretty much bet this will happen. But if I let the egg get to 400-500 for a bit and then bring it down, no problems.

Either that or a bad stacking of your lump.

No need to let the fire grow and spread out. That can actually be problematic

if you want a 250 fire for example, it's going to be fairly small. Better to have that condensed into one small compact fire than to reach 250 by creating a bigger fire, then choking it back to hold 250 with a thinly spread out fire

smokeyw · December 2016

Like some have said, put your lump and wood hunks in and then light the top. The fire will burn down toward the air source. It's called the "Minion Method".

JustineCaseyFeldown · December 2016

Welp.

Seems to me that lighting the fire at the bottom and piling the 'largest' lump on top of it first reduced the places for your fire to bridge to new lump

big chunks on the bottom are the old rule for max airflow, but that's assuming the fire is on top. Among smaller lump

if you take a look at a low and slow fire, it is small. No flames. Just glowing lump

It travels to new lump by contact

if you ended up with a cold fire that didn't burn upward, it has to be because it couldn't.

Imagine large chunks. Few contact points.

Now, if the fire is on the bottom, that lump can actually fall away from the lump above it. This is similar to when you put a chunk of smoking wood on the fire and get good smoke, but a half hour later find that the fire burned down away from it, leaving the chunk high and dry

fire has a tendency too to find or 'look for' the air. In a BGE it will burn downward. With fuel in all directions, the thing that steers the fire is where the air is

light on top next time. If you want big chunks on the bottom, keep on keeping on. But the amount of air required for a low and slow is hard to block with even small bits of fuel. The most stable cook i ever had overnight was topped off with the tailings in a bag. Chips and dust. The fire had plenty of fuel and air from below

fires in the BGE want to go down and they want to travel to new lump. Put the fuel between the fire and the lower vent and don't obsess over large lump. It has its own issues

stlcharcoal · December 2016

It wasn't ash, the fire just failed to move onto the next chunk of charcoal. If you have a huge chunk and the next piece isn't close enough, it's not going to light. It's not like fire wood where there's a flame touching. The glowing piece has to hit the next closest piece with at least 670F to get it to light. With a metered amount of O2, this can be a problem. It's also a problem in the XL's with that wide & shallow firebox--fire can wander to one side and not come back. You think it's bad in a BGE, try a kiln with 120 tons of wood in it after a week--fire is an amazing and baffling creature.

In any case, light from the top on low and slows. Lighting from the bottom can cause a runaway temp as well if you don't choke the O2 fast enough.

GATraveller · December 2016

I'm from the "light on top" camp.

dgaddis1 · December 2016

Good info folks, thanks!

HoosierBBQ · December 2016

I've always started from the bottom. Good information here, going to light from the top next time.

chocked out by ash - what happened?

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