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Building fire in bottom of firebox

Lynn Dollar

Lynn Dollar

is Blowin Smoke!
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In large propane tank smokers, it seems to be the rule to build the fire in the bottom of the firebox. Aaron Franklin and some others I've seen on Youtube are doing this in backyard offsets without using a grate.

I've tried it twice now in my OC Brazos. It builds a good coal bed. Using a fire grate, I usually have to rebuild my coal bed halfway through a cook with lump or charcoal. That's not a problem.

But I'm havin trouble getting new splits to catch flame. And I'm using small 7 to 9 inch spits and they don't stack as well as the 14" splits used in larger smokers. They bury in the coals much easier.

Anyone else doing this ?
 
Most of the people I know that do this line the bottom with firebrick first. Helps hold the heat, protects the bottom of the firebox.

I think you already found the downside, which is ash management over longer cooks. I think you’re gonna have to use a shovel or rake to keep the deeper stuff at bay.
 
I always try to prop one end of the split up on something when I add them, even if that something is another burnt log or piece of coal bed. I find that a small gap of air on at least a portion of the log helps it catch quicker, burn cleanly, and make the coal bed underneath it hotter instead of smothered. My Shirley technically has expanded metal “basket” above the actual bottom of the firebox, but within an hour or two of starting a cook the metal is fully covered in ash and coals and performance is probably similar to directly on top of bricks or the bottom of the fire box until I knock some of the ash down by shaking it.
 
sudsandswine said:
I always try to prop one end of the split up on something when I add them, .
Click to expand...


Yes, but with a small split, that can be difficult.


I've tried adding two small splits and just live with the spike in temps. If I don't, I end up opening the lid to the FB to get enough oxygen to fire up the split and sooo, I get a big drop in temp instead of a spike.


I made an expanded metal grate and when I use that, I build the fire to one side and set a split on the other side. Those catch on immediately when moved to the fire.


I do like when not using the grate, that the fire is lower in the FB, in relation to where heat enters the cook chamber.
 
I've started doing this on my last 5 cooks and I'm not going back.
I have put fire bricks in my fire box but it works fine without them.

When adding a split, I ALWAYS rake the coals and put them so there's a little tunnel in the middle of the firebox. Coals in a U shape and them I just put the split sideways on top of that. It allows for a good airflow and the new split will catch quickly.
 
LordRiffenstein said:
I've started doing this on my last 5 cooks and I'm not going back.
I have put fire bricks in my fire box but it works fine without them.

When adding a split, I ALWAYS rake the coals and put them so there's a little tunnel in the middle of the firebox. Coals in a U shape and them I just put the split sideways on top of that. It allows for a good airflow and the new split will catch quickly.
Click to expand...


I like this idea.


What are you using for a rake ?
 
Are you keeping your firebox door wide open? With the Brazos I've found that's the best way to keep the fire burning clean and hot. I don't use a fire grate also because of losing coals to the bottom of the firebox.
 
Here’s how my fire looks. I do use longer splits than 7-9 inches however.

6d1abc2e2f18851443a5b1a73dcac153.jpg



Sent from my iPhone using Tapatalk
 
If I ran that set up, considering the split is around 12" long, my Brazos would be running over 300* and air flow would be pushing the heat to the stack end. There would be a large imbalance, end to end. I put digital temp probes on both ends of the meat.

I keep the door open, but I vary the opening to regulate air flow, depending upon cook chamber temps. Its usually around 2 to 4 " open, with a clean fire. I don't try to get even temps end-to-end, but I don't want a large diff.

My only problem with no grate, is getting the new split to catch flame, which can cause spikes in both directions.
 
Last edited:
ferdelious said:
Are you keeping your firebox door wide open? With the Brazos I've found that's the best way to keep the fire burning clean and hot. I don't use a fire grate also because of losing coals to the bottom of the firebox.
Click to expand...

Have you noticed that the stack on the Brazos is 6" OD , but the exhaust port inside the cook chamber is 4.5 " ?

I'm puzzled why they did that ?

I've thought about getting a welder to put a collector on mine ........ but then I think I probably just need to invest the money in a better stick burner.
 
If you notice with Aaron Franklin and some of those other enormous smokers they'll generally put the splits in the rounded firebox where they sit "left to right" in the firebox. The rounded firebox holds the splits a few inches above the coal bed to create good airflow and still allow for enough heat to ignite the wood. You could do the same thing by cutting your splits down to the appropriate size so they will rest on the edges of the inside of the firebox, above the coal bed.

If you check out this video at about the 16:15 mark you'll see that Aaron has a piece of wood going "left to right" and then he's doing a "lincoln log" pattern on top of that with the new wood. That "left to right" piece of wood is elevated above the coal bed by the shape of the rounded firebox...works very well.

https://video.klru.tv/video/bbq-franklin-episode-5-fire-smoke/
 
Lynn Dollar said:
I like this idea.


What are you using for a rake ?
Click to expand...

When I bought my offset they included 2 scrapers/rakes to clean out the fire box. Small shovel should work? Or perhaps you could look at fireplace tools, they usually have a shovel and something to rake the embers/coals.
 
LordRiffenstein said:
When I bought my offset they included 2 scrapers/rakes to clean out the fire box. Small shovel should work? Or perhaps you could look at fireplace tools, they usually have a shovel and something to rake the embers/coals.
Click to expand...


Do you think the fire bricks help the new splits catch flame ? Or help hold heat ?
 
Lynn Dollar said:
Do you think the fire bricks help the new splits catch flame ? Or help hold heat ?
Click to expand...

I always have six fire bricks on the bottom of my firebox, but I only use them to extend the life of the metal. I truthfully haven't noticed any difference in fire/heat quality.
 
Lynn Dollar said:
If I ran that set up, considering the split is around 12" long, my Brazos would be running over 300* and air flow would be pushing the heat to the stack end. There would be a large imbalance, end to end. I put digital temp probes on both ends of the meat.

I keep the door open, but I vary the opening to regulate air flow, depending upon cook chamber temps. Its usually around 2 to 4 " open, with a clean fire. I don't try to get even temps end-to-end, but I don't want a large diff.

My only problem with no grate, is getting the new split to catch flame, which can cause spikes in both directions.
Click to expand...


Have you considered using the fire grate inside the main chamber as a baffle? It works really well and my temperature differences from end to end are minimal. Plus it will keep the temperature down. That fire in my picture produces 250 degrees.
 
ferdelious said:
Have you considered using the fire grate inside the main chamber as a baffle? It works really well and my temperature differences from end to end are minimal. Plus it will keep the temperature down. That fire in my picture produces 250 degrees.
Click to expand...


I had tuning plates. They were more trouble than they're worth.


and really, they turned the smoker into somewhat of a reverse flow. I don't want that.
 
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