BBQ Fire Box Size Help

[Notaguide]

Looking to the green screen for opinions towards revamping the firebox on a custom pit I built 20yrs ago. It was built with a lot of material and parts laying around on hand as many are. There wasn't a ton of information out there at the time like Feldons or bbqpitcalcuator that's avaible now but did the best I could with what I had (which was limited). It's been a great pit and like the layout but have never felt it cooks as good as it should. It takes too long to get consistent temperature with low smoke while using more wood than it should.

The pit is your basic 250gal propane tank, 6" stack, and 22"dia fire box (pipe), all being 1/4" thickness. The firebox is almost half of what is recommended for the volumn of the 250gal. chamber which is in my opinion the main issue from what I've read.

My first thought was to cut the round firebox off and replace with the correct size square box (26.5"square). It would work but recently came across a few pits that Mill Scale in Lockhart have built using very large tanks with small insulated fire boxes. I had the opportunity to actually see one at Meat Church BBQ this past weekend while discusing how they perform.

So the new idea is to leave the existing 22" firebox (pipe) and then place a outer 24" pipe with 1" of ceramic insuation in between including the front and back sides as well. I figure doing this or building a new square box will be about the same amout of work but the outcome is in question? There is very little info reqarding firebox volumn if insulated. Wrapping the existing pipe box would be my choice asthetically if it would work. If it's no improvement, I'll wish I had just gone square and not wasted the effort. Hoping someone may have experience with insulated fire boxes. I'll also be relocating the smoke stack to the end with a horizontal box to help evenly distribute heat across the chamber.

Any opinions or thoughts are appreciated.

[bbqfan5909]

Give a fire management basket a try, have a lonestar grillz smoker and really like this basket: Fire Management Basket – Lone Star Grillz

[Hardware]

I would move the stack as stated above, get boiler insulation and wrap current firebox as best you can and then do a test run and see if the current firebox insulated works. Once confirmed then proceed with current insulated if not add the bigger. Insulated is going to help a bunch. I have a 24" X 7Ft pit with a 24" X 30" insulated firebox with 8" to 6" smoke stack like on a moberg pit and it cooks great.

[Notaguide]

The Moberg 90deg long elbow would be a easier install than what I was considering. The round end of the tank should help with the design as well I would think. I also like the idea of the Lone Star Grillz fire management basket.

Trying to locate a 26" dia. piece of pipe to help add a little more insulation value iif going that route. If anyone has a lead on something that diameter let me know.

[Dale Moser]

I don't think insulating the fire box is going to produce the results you're after. I think relocating the stack will help, and I'd also take a close look at the firebox to cook chamber transition, as well as a way to manage your coals (like the basket mentioned). 1/4" Plate should be fine for heat retention in Texas, it sounds to me like you have a draw issue.

Most times, this can be helped a lot by regulating your temp with the damper on the stack, rather than the carburetor on the fire box.

[Palmetto]

I designed my offset pit per Feldon's calculator, and it cooks great.
I have also reworked problem pits like this for people, and I always go back to square one. Run the calcs on feldons, and adjust accordingly. Always seems to work out perfectly.

[bowhuntercoach]

I agree with Dale. Make the hole between the firebox and the pit larger. That box is plenty big for that pit. Since you will be moving the stack anyway, go with a larger diameter of pipe to get more draw. We've built a lot of pits in my Ag shop and we never use the calculator. We just make everything bigger than need be and then you can always dial it down once you get a good clean fire going. Making pits is a lot of fun and each one turns out a little different.

[Notaguide]

Appreciate all the recommendations! The opening between the tank and firebox is as large as it could be. Not knowing the correct opening size originally, I welded the fall off piece on a pivoting arm in order to adjust the flow. It runs mostly wide open unless there is a huge spike in heat and can shut it down instantly. It actually works well at times but is technically unnecessary.

When I have some free time, the 4" flu will come off, patch the hole while moving the stack to the middle of the front end with a 8" long elbow transitioned to a 6" stack at least 42" tall. I can regulate the flow with a cap on the stack I figure as much as needed. I'll try this out first but leaning towards cutting the entire box off and going square. Square fireboxes seemed to be proven. The "Mill Scale" pit designed just got me looking at other alternatives.

The pit does cook and will produce good results but feel it could be much easier for fire management and getting a good coal bed going as previously mentioned.

[Notaguide]

Update on the changes made to the pit in the last couple of days. Trying to get something complete before the 4th.

Went ahead a used the idea Hardware mentioned with the 8" long elbow reduced to 6" for the smoke stack. Also had sheets custom cut to size for a new firebox. 1/4" for the sides and top and 3/8" for the bottom of the box. I also had them cut the door and vent while at it. I have a few loose ends to finish but the hard part of cutting the old firebox off and building the new box is complete. Excited to see how it cooks after it gets a fresh coat of paint.

Appreciate the previous opinions and help.

[dbaio1]

I know nothing about building pits but that sucker looks sweet. Like that firbox and smoke stack re-do. That thing is huge.

[Texas Grown]

I bet it rolls smoke now!

[gonehuntin]

I bet the changes you made on the fire box and stack make a huge difference, let us know how it cooks David.

[Dale Moser]

Looks great!