LSG IVC Uneven Charcoal Burn

[Texcoonazz]

2nd cook on my IVC today and had some odd things take place and hoping to gain some insight from the experience here.

After my first cook using kingsford I noticed not all the charcoal or hickory blocks burned thru during the first cook. The hickory was charred pretty good but not all burnt complete. I had the S Plates installed and for most part it followed around the channel as designed. Since I had some charcoal left, over half, I just left in the tray and figured I would use in my second cook. Do this all the time with lump coal in my Egg. I have a BBQ GURU but did not use the fan on the first cook.

Today I loaded up charcoal into the basket to fill it back up. As mentioned I still had over half of the charcoal remaining from last cook and just left it in place. Today I did use the 25CFM fan. When I finished the cook I opened the bottom tray to see how even the burn was and to see if it followed the snake around and was surprised to see even more unburied charcoal in the first 1/3rd than I observed during the first cook. Each briquet burned but not complete. About 1/3 of the center remained. Same with the hickory. Charred but not burned complete. Also noticed the burn had travelled completely around the snake. The top coals were not really burning though. It appears the bottom coals burned pretty good and worked its way around burning the bottom coals first and not completely burning the top coals. I was able to maintain temp but the way the coals burned has me a little stumped.

I am thinking the hickory chunks placed on top did not fully burn because the charcoal on the surface never really ignited?

Is it possible what I am seeing it due to leaving the coals in the pit since last cook a week and a half ago? Effected by humidity or moisture somehow? I cleaned out the water from the last cook so no water was left in the pit. And that Does not really explain why they did not burn completely during first cook.

Any thoughts?

 

[pjtexas1]

Incomplete burn leads me to think not enough oxygen. Then again maybe bad charcoal. How much lit charcoal did you start with? I find it best to start with less lit. Too much lit and you end up choking the fire down (less oxygen) to keep temps down. Honestly I've never seen this before.

Sent from my SM-G955U using Tapatalk

 

[Texcoonazz]

Incomplete burn leads me to think not enough oxygen. Then again maybe bad charcoal. How much lit charcoal did you start with? I find it best to start with less lit. Too much lit and you end up choking the fire down (less oxygen) to keep temps down. Honestly I've never seen this before.

Sent from my SM-G955U using Tapatalk

I started with about a half a chimney load. The climb to 200F took about 45 mins and the climb to 245 was slow and steady. When it got up to 245 it held steady for several hours.

I had a bit of a learning curve with the fan today and did have some swings later in the cook. After wrapping at 165F Food temp I saw a spike of 265F cabinet(Was set for 245F). Totally my fault I forgot to reduce the opening at the the valve and it was drafting thru the fan. It took a little time to get the temps back down but when they come down it had trouble recovering and dropped to 230 before climbing again. It took about an hour or so for things to even back out. Maybe what I seeing is the result of the fan shutting off to bring temps down and then running hard to get it back up from 230. Not sure why it only burned the bottom coals and not the top though. OR why the first 1/3rd did not burn complete.

The top was closed to 1/2”. Is it possible I had that closed to much and to your point reduced oxygen?

 

[pjtexas1]

How deep did you pile the charcoal? Once up to temp it doesn't take much of a fire to keep temp unless you use water. Mines not a LSG but here's how I run my maze. The pic is old. I use firebricks now. I don't fill the charcoal basket to the top. Hopefully some LSG owners will know better than me.

Sent from my SM-G955U using Tapatalk

 

[onemanlan]

I have maze pieces for my Humphrey's IVC. I've abandoned it in favor of using 2 of the maze pieces to shorten the firebox. When I did the maze like you described I got uneven cooking on one side of the grill or the other as the fire worked it's way around the bends. I also ran into issues like you described with incomplete burn of chunks and charcoal. My solution was to reduce the total horizontal area for charcoal to meet the need of length of burn & maximize the depth of the bed wood + charcoal bed to encourage continuous burns. It has helped a lot. Because I also lay the first set of coals accross the front of the firebox & it burns toward the back I get a more even smoke distribution than when I was using the maze.

 

[mcyork28]

I used to see this a lot when I had Humphrey's Long Weekender. Never got to the bottom of it.

 

[JAKs Q & brew]

I have this problem sometimes as well, though I think you probably burned more than you think.

I tried on time where I put in 10lbs of fule for a 8 hour cook. I use the plates to make an L shape, with 1 layer of briquettes then a layer of wood chunks then full to the top with lump (fairly small pieces so there are no gaps).

I finished the cook and then shut the pit down. The next day I cleaned out the box, it looked like less than 50 of the fuel was burned, but then I weighed the remaining and it was less than 2 pounds left.

You are probably burning more of it than you think.

Also, I try to never reuse briquettes as I find they just don't burn well the 2md time. I will usually use whatever is leftover in the chimney starter to get the next cook going.

 

[onemanlan]

Also, I try to never reuse briquettes as I find they just don't burn well the 2md time. I will usually use whatever is leftover in the chimney starter to get the next cook going.

Great post overall. I find this use of old briquettes the best. I see chimney charcoal as sacrificial charcoal since you're not generally cooking with it, but rather getting other coals lit & the grill to temp. That's a perfect use of that left over material. I'm more than happy to use $5-6 a bag new charcoal to the same end.

 

[Texcoonazz]

How deep did you pile the charcoal? Once up to temp it doesn't take much of a fire to keep temp unless you use water. Mines not a LSG but here's how I run my maze. The pic is old. I use firebricks now. I don't fill the charcoal basket to the top. Hopefully some LSG owners will know better than me.

Sent from my SM-G955U using Tapatalk

I have been loading to the top. Fully loaded with just enough room to put wood Chunks on top. I will be firing it up again this week end and plan to put the wood in bottom and load charcoal on top. I’m also going to place a slightly larger gap in the maze plates.

 

[Texcoonazz]

I have this problem sometimes as well, though I think you probably burned more than you think.

I tried on time where I put in 10lbs of fule for a 8 hour cook. I use the plates to make an L shape, with 1 layer of briquettes then a layer of wood chunks then full to the top with lump (fairly small pieces so there are no gaps).

I finished the cook and then shut the pit down. The next day I cleaned out the box, it looked like less than 50 of the fuel was burned, but then I weighed the remaining and it was less than 2 pounds left.

You are probably burning more of it than you think.

Also, I try to never reuse briquettes as I find they just don't burn well the 2md time. I will usually use whatever is leftover in the chimney starter to get the next cook going.

.

I think you may be right. Yesterday I dumped the coals from pan yesterday and there was not near as much as it appeared. Thanks for opinion of re using coals also. No more for me other than maybe saving for the chimney.

 

[nweave2614]

Here is my method for the LSG Mini, I have the fireboard fan and have used it every time but I think the person I stole this off of uses a guru.

All credit to the guy on page 147 of the LSG IVC thread, I forget the name and im to lazy to look it up, starts with an H.

I load up my maze, FWIW Chris says always load to the top of the basket, I know the guy above has a successful method by loading only half way to the top so maybe that is BS but I always load to the top.

I always load coal on bottom and wood on top, I tried wood on bottom once and the food tasted nasty, dirty smoke flavor. Im sure it does not matter and I just screwed something up on that cook but its a mental block now.

I take my hand held blow torch and I hold in in the corner near the intake port for about 2-3 min, just get 2 or 3 bricks starting to ash over. The key to a good fire on a IVC is the smallest hottest fire possible for your temp

let the smoker come up to temp, takes probably 2 hours.

Normally I get solid combustion, but even with this method there will be a few bits of charcoal and wood left over like you mentioned. Normally these are very small pieces that were in the corners of the basket so I always assumed it was harder to get full combustion in those locations.

 

[Texcoonazz]

Here is my method for the LSG Mini, I have the fireboard fan and have used it every time but I think the person I stole this off of uses a guru.

All credit to the guy on page 147 of the LSG IVC thread, I forget the name and im to lazy to look it up, starts with an H.

I load up my maze, FWIW Chris says always load to the top of the basket, I know the guy above has a successful method by loading only half way to the top so maybe that is BS but I always load to the top.

I always load coal on bottom and wood on top, I tried wood on bottom once and the food tasted nasty, dirty smoke flavor. Im sure it does not matter and I just screwed something up on that cook but its a mental block now.

I take my hand held blow torch and I hold in in the corner near the intake port for about 2-3 min, just get 2 or 3 bricks starting to ash over. The key to a good fire on a IVC is the smallest hottest fire possible for your temp

let the smoker come up to temp, takes probably 2 hours.

Normally I get solid combustion, but even with this method there will be a few bits of charcoal and wood left over like you mentioned. Normally these are very small pieces that were in the corners of the basket so I always assumed it was harder to get full combustion in those locations.

Thanks for the feedback.

I also reached out to Chris and he had the following to add. “ I have seen that and don't have an answer for you as to why that happens. What I will say is that the recycled charcoal never burns as good the second time as it does the first. I don't even bother saving the left over but if you do use it sparingly with new.“.

I Believe my primary problem is using left over / not burned or ignited coals. A few more cooks and I should have a good idea of how many pounds will be needed for the target temp / time.

 

[onemanlan]

If you use lump I'd absolutely re-use the lump a cooking fuel or chimney fuel. If you use briquettes I'd only sacrifice them for chimney fuel.

I find that lump has a bad tendency to not light adjacent pieces due to the irregular sizes. Often times at the end up a lump burn there are large pieces left over in odd places. It burns fine if you just pack over it with more charcoal.

Generally though I favor using briquettes in the IVC. They burn predictably & you can pack more in than you would with lump.

 

[AKMIMNAK]

Glad I stumbled across this! About to fire up my Mini for the first time very soon. Thanks all!

 

[pjtexas1]

Here is my method for the LSG Mini, I have the fireboard fan and have used it every time but I think the person I stole this off of uses a guru.



All credit to the guy on page 147 of the LSG IVC thread, I forget the name and im to lazy to look it up, starts with an H.



I load up my maze, FWIW Chris says always load to the top of the basket, I know the guy above has a successful method by loading only half way to the top so maybe that is BS but I always load to the top.



I always load coal on bottom and wood on top, I tried wood on bottom once and the food tasted nasty, dirty smoke flavor. Im sure it does not matter and I just screwed something up on that cook but its a mental block now.



I take my hand held blow torch and I hold in in the corner near the intake port for about 2-3 min, just get 2 or 3 bricks starting to ash over. The key to a good fire on a IVC is the smallest hottest fire possible for your temp



let the smoker come up to temp, takes probably 2 hours.



Normally I get solid combustion, but even with this method there will be a few bits of charcoal and wood left over like you mentioned. Normally these are very small pieces that were in the corners of the basket so I always assumed it was harder to get full combustion in those locations.

My theory on not loading to the top is less lit charcoal allows more oxygen (intake or exhaust open more / small hot fire). I always heard these cookers were too efficient and they needed to be choked down. With less charcoal I can let the fire breath. Besides, if I loaded up the basket it would run for 20 hours. I only need 7-8 hours max. But obviously its not the only way. I did find that putting the chunks on top works best for me too.

Sent from my SM-G955U using Tapatalk

 

[Porcine Aviator]

Interestingly, I just had a discussuion about this phenomenon myself.

So far, this is my theory:

Because the IVC or other high efficiency type smokers use very small amounts of air for combustion, there is a limited amount for combustion air called for at any instant of time.
Because the air( fuel) is scarce during the cook in an IVC, the charcoal that is easiest to reach or easier to ignite uses all of the available air first. In other words, the fire takes the easier route to fresh charcoal and starves out the remaining fire as it proceeds.

1. If the ash bin under the charcoal grate is relatively close to the grate, the ash can block the air from reaching the underside of the burning charcoal as that section burns and the coal starves for air. The fresh charcoal next to the burning coal is now the most available fuel and takes the oxygen. This process then proceeds for the entire cook.

2. If the fire isn't choked from below by ash build up under the grate, then the same process occurs on top of the grate. As the ash on the surface of the burning charcoal builds, the fresh bricket next door is easier for the air to reach and ignite. And so on, and so on.

We never see this in a normally aspirated fire because there is an unlimited supply of fuel (air)to burn any charcoal in its path.

If this does not make sense to you, try this test:

Set up your IVC as usual, without food in it, and open the vents during a test burn at 350-400°F. After a few hours shut it down and look at the burn box remnants.

 

[Kaptain Kadian]

I have been loading to the top. Fully loaded with just enough room to put wood Chunks on top. I will be firing it up again this week end and plan to put the wood in bottom and load charcoal on top. I’m also going to place a slightly larger gap in the maze plates.

Put the wood under the charcoal