Firebox size confusion

[bzprod]

Hello builders!

I've read tons of posts here, and first off -- thanks so much for the treasure trove of data!

I'm about to embark on my first custom offset, and I'm having a bit of a hard time wrapping my head around the firebox dimensions. I'd love a pointer or two!

According to the calculator:
-- 20" x 42" cook chamber
-- 20" x 16" firebox

This firebox would be 114% of the chamber. As I understand it, this is on the higher end of what's acceptable, but should be fine.

But... it seems really odd! I'm not sure I've ever seen a smoker like this, with such a short firebox. Am I missing something, or would this be optimal regardless of my smoker-brainwashing ?

That said, what would be the difference in fire management between 20" x 16" and 20" x 20"?

Thanks for the help, I really appreciate it and I can't wait to cook on my dream smoker! The calculators and advice have been eye opening!

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Some extra info:
I currently have a Klose 20" x 30" pit, with a massive 20" x 20" firebox (250% of the cook chamber!). If I build a raging fire, I can cook at 350-500 degrees fairly easily. But, I'm into briskets and ribs and such, and if I try to build a small compact fire, the wood smolders and smoke comes out of the firebox instead of drafting properly. I've tried extending the chimney a few feet, fire baskets, etc. Heck the most effective method was simply placing a charcoal chimney starter inside the firebox and tossing a log into it every once in a while.

So, my goal is to obey the laws of physics and thermodynamics, and to let nature do its thing. I'm a bit nervous, but ideally I'd solve these issues and have a pit that's enjoyable to use.

[Big T]

Welcome aboard!! The best piece of advice that I can give you is to trust the calculator. I would also recommend that you take a look at a reverse flow if you haven't already done so, they're the best option for the 200-325 degree in my opinion and the temps are pretty even across the cook chamber. With that being said, there's nothing wrong with a well built traditional offset.

[ajfoxy]

Welome!

[Dirtytires]

remember, the calculator gives you the size of the box but you can customize the dimensions to some extent. For instance, my wood supplier cuts standard to 18 incheson his logs. If I had a 16 inch firebox, I would either need to pay extra to have him custom cut mine shorter. I, obviously would want a 20 inch firebox front to back so would shrink the other dimensions to keep it to the square inches specified.

[bzprod]

Welcome aboard!! The best piece of advice that I can give you is to trust the calculator. I would also recommend that you take a look at a reverse flow if you haven't already done so, they're the best option for the 200-325 degree in my opinion and the temps are pretty even across the cook chamber. With that being said, there's nothing wrong with a well built traditional offset.

Thanks for the tip. I never really thought about reverse flow, but I've heard great things about them.

remember, the calculator gives you the size of the box but you can customize the dimensions to some extent. For instance, my wood supplier cuts standard to 18 inches on his logs. If I had a 16 inch firebox, I would either need to pay extra to have him custom cut mine shorter. I, obviously would want a 20 inch firebox front to back so would shrink the other dimensions to keep it to the square inches specified.

Good point, it looks like 18" x 19" would also work well, and give me a little extra length in the firebox. I'll keep playing with the calculator for the perfect ratios and dimensions!

[Brisket Envy]

You have run into the same issue many have, when building a smoker with a relatively short cooking chamber, while using the same diameter pipe for the firebox.

Sometimes rectangular fireboxes can be more adaptable, because they can be made narrower, while maintaining the desired length and height.