Reverse Flow Sizing

[jiwjake]

Just a question, I know the reverse flow calculator says roughly the firebox should be 1/3 of the size of the cook chamber, how does Lang Smokers get away with such a small fire box?

 

[daveomak]

It all depends it you are BBQing or 24 hour slow smoking.... For a 4-5 hour BBQ, you don't need a big firebox...

 

[jiwjake]

I had the opportunity last summer to spend some time with Keith Allen at his original place outside of Chapel Hill, he explained the difference to me between his style of BBQ (which he states is “roasting over a fire” and mine which is smoking, can you explain the difference between a slow smoke and a 4-5 hr. BBQ, Dave? I have cooked a bit of pork in my day and I can definitely say that unless cooked in a controlled environment, a decent sized shoulder cooked over any kind of fire takes relatively the same amount of time.

 

[daveomak]

When I smoke pork butts, they take about 16+ hours in the smoker.. BBQ, uses a hotter fire...
If you think "a decent sized shoulder cooked over any kind of fire takes relatively the same amount of time. "
I can't help you...

Boneless butts....

 

[jiwjake]

Sorry, let me clarify my comment, I meant any fire at roughly 225 - 250 degrees. Cooking temps...
When I cook butts 16 hrs +/- is about what it takes me. I guess back to my question, reading through some threads about reverse flow builds, the theory on the firebox is 1/3 or bigger, how does Lang smokers get away with it? From what I have read you can BBQ or slow smoke on Lang, do the require a lot of fuel in order to maintain the desired temp?

 

[SmokinAl]

I'm no builder, but I do own a Lang.
And I can tell you from experience it will run anywhere from 210- 350, simply by changing the size of the fire I build, and the size of the splits I add when needed. Obviously if your running at 225, your not going to use as much wood as you would running at 300. I like to run mine around 270-280 most of the time, and at that temp it will need a split about as big around as a beer can every 45 minutes or so.
Al

 

[jiwjake]

Thank you Smokin Al. I often measure life's trials and tribulations by the amount beer it takes to get around it!

 

[JckDanls 07]

Are you planning on building a smoker ? as to why you asked that question...

 

[jiwjake]

No, just looking at the calculators and realized that the Lang goes against what the calculator says. Well maybe. I have cooked on a Weber Kettle for awhile but it’s about patched out, great smoker for $100. I have some material to make a reverse flow but I really enjoy the roasting/smoking cooking thing that I do without the firebox.

 

[uga fan]

In my experience, yes I agree Lang fireboxes are undersized. An undersized firebox will still cook your meat, they will still range in temperatures from 200-400 degrees. They "give" in the situation is the amount of attention the user has to give to the firebox. The size of the firebox isn't a direct correlation to the temperature of the cooker until u reach extreme examples. An undersized firebox will just make u add wood more often. I've built 5 cookers with fireboxes around 125% and they will run 4-5 hours with no adjustments or wood added

 

[jiwjake]

Thank you. I have a 60” x 24” piece of pipe and I have a 24” x 42” tank, the 60” pipe is thin less than a 1/4”, the tank is 5/16”, I have enough material to make a 20” square fire box 3/8” thick. Curious about the fire box size, as you said just more work if I go with the 60” pipe.

 

[uga fan]

The goal in pit building is make a cooker that works for you and not works you. Understanding the dynamics of cooking and heat and airflow. Understanding combustion. I can take a 20x20x24 firebox attached to a 48x23 tank, fill the firebox packed solid with wood and get cook times like a pellet cooker. Because it's not an issue of how big the firebox is. Its giving it only enough oxygen to burn just enough wood to give u the heat u desire. That can be accomplished with dampers and or an exhaust damper. U can nearly close the firebox dampers yet open the exhaust and suck air into the firebox. U can also choke the exhaust open the dampers and run the firebox hotter. My point is, no calculator, thread, fellow cooker or pit builder can give you a cookie cutter formula for size. It's about understanding smoking and designing a pit that meets your cooking style. But no matter what, u have to understand the dynamics and principles relating to air flow and combustion before u can be a successful pit builder. Look at it as an engine or carburetor. If u take a 350 V8 engine and put it in a VW Beetle, it will be fast as hell but not efficient because the design of the larger engine. If u put a 2.0 4 cylinder in a Ford F350 u will over work ur engine trying to go anywhere because its underpowered. So determine what u want the cooker to do first, then design it with that goal in mind