Can someone look over my math?

M

Mankussm

Found some matches.
Joined
Jun 27, 2014
Location
DFW/29Palms
Thanks in advance for any constructive criticism! I am starting a build on a 110GA propane tank.

CC volume = 25410 cu. in. actual
FB volume = 8470 cu. in. recommended

Chimney volume = .05 x 9680 = 484 cu. in. ( 4" ID stack X 38" tall above the CC )

FB to CC recommended opening = .008 X 9680 = 78 Sq. in. ( 12" r x 5.5" height )

RF plate area 78 X 1.5 = 116 sq. in. ( 12" r x 7.25" height )

 
I dont have a clue on the design and numbers end of it but looks like you figured it out. Just build it and smoke it up!
 
I don't know the formula for calculating the area of a partial circle like that. What I did on my cut out was to draw a 1" square grid pattern on a piece of paper, then drew the radius of the bottom of my CC, then counted the number of squares to match what Feldons said I needed. Hope this helps, it's all my simple mind could figure.
 
mikemci said:
I don't know the formula for calculating the area of a partial circle like that. What I did on my cut out was to draw a 1" square grid pattern on a piece of paper, then drew the radius of the bottom of my CC, then counted the number of squares to match what Feldons said I needed. Hope this helps, it's all my simple mind could figure.
Click to expand...


Thats a good idea. Thanks!
 
It worked for me. I tried looking up online how to do it mathematically and it was way over this country boy's head.
 
All your calculations match the pit calculator. The only thing is the reverse flow plate should be even with the firebox. I would raise the fire box to height of RF plate. I built my RF smoker 1 1/2 years ago out of a 250 gallon tank. I used the same pit calculator. Everything came out and works great . I put a rack in the fire box at 4" high. I have my intakes under the rack. So air goes through the fire . I believe it gives you a better burning fire. Also it is always better to go bigger with your openings . I have adjustable vents on my intakes and leave the exhaust wide open. Control temp by intakes. Remember it is all about the draft. If you can not get the right draft the pit will not get up to temp. Also I made the mistake to take my exhaust to my first grate level. Bad idea , I had to cut it off to the top of the tank. From top rack to bottom rack I had a 70 degree difference. Once I cut it off , I am not more than 10 degrees. Here is a link to my build video. [ame="https://www.youtube.com/watch?v=42S30S2lMr8"]My First Smoker Build - YouTube[/ame]
 
buttburnersbbq said:
All your calculations match the pit calculator. The only thing is the reverse flow plate should be even with the firebox. I would raise the fire box to height of RF plate. I built my RF smoker 1 1/2 years ago out of a 250 gallon tank. I used the same pit calculator. Everything came out and works great . I put a rack in the fire box at 4" high. I have my intakes under the rack. So air goes through the fire . I believe it gives you a better burning fire. Also it is always better to go bigger with your openings . I have adjustable vents on my intakes and leave the exhaust wide open. Control temp by intakes. Remember it is all about the draft. If you can not get the right draft the pit will not get up to temp. Also I made the mistake to take my exhaust to my first grate level. Bad idea , I had to cut it off to the top of the tank. From top rack to bottom rack I had a 70 degree difference. Once I cut it off , I am not more than 10 degrees. Here is a link to my build video. My First Smoker Build - YouTube
Click to expand...

The main reason I wanted the reverse plate above the FB was to prevent a hot spot on that side. All else looks great. Thanks for the advise.
 
Nice build buttburner! Enjoyed the video. One question re: smokestack location, is there a reason behind your decision not to center it on the c.c.?
 
One thing to consider is the ultimate temp you wish the cooker to achieve.
Most cookers are designed to cook at around 250. That's where my lang 84 is happy.
If I were to remodel it I would increase the firebox size by maybe 50% and place the door on the side so the intake vents could be located in the back like a Geer. Also I would place two 6 inch vent stacks and make the intake vents 100% larger. Ben Lang advises cracking the cooking chamber doors and opening the firebox door to get to 300. Many people are cooking higher than in the past and I would like for my lang to do so. I am seriously considering a redesign.
 
mikemci said:
Nice build buttburner! Enjoyed the video. One question re: smokestack location, is there a reason behind your decision not to center it on the c.c.?
Click to expand...

I off centered stack due to I left the original hooks on tank so I could lift and put on my trailer. It is not that far off center and I have no issues.
 
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