Large Smoker Math

[Nickince]

Hey Guys,

I've built several smaller smokers (around 120 gallon) some standard and some reverse.

I'm now building some bigger stuff. Doing a 500 and 1000 gallon.

When I do the math for the 1000 gallon the firebox comes out insanely large with feldons. My gut tells me its too big. I know a lot of guys run a 250 cut in half. So I'm guessing the math doesn't apply the same way in this size.

That being said, 500's seem to use a 250 cut in half as well.

What's the going size for these smokers you guys have been building/seeing? Am i crazy? hahaha.

Also, lets say a 250 gallon cut in half is the right size for that firebox... Do I do the math for that size firebox for the opening between cook chamber and firebox or do I use the 1000 gallon number from the calculator. I think I need a smaller opening than feldons would tell me?

Hope this makes sense.

Thanks!

[sandro]

Half of a 250 tank is the outer shell, there's usually a 30" pipe inside that. However, I think the point is that above a certain size, "it's enough". Tanks bigger than 1000 gal aren't really a thing, and even without insulation a 125 gal firebox would be plenty. Even 250 gal use half of a 250 as a firebox if I'm not mistaken

[Nickince]

Yeah, thats what i figured. So I am going to use 250's. Next question is how do I figure oriface between FB/CC on an 'undersized' firebox. Not sure weather to use the original number or to use a small number that makes sense for the smaller firebox. I feel like the small number is the right one...

Thanks for the reply.

[sandro]

I never quite understood the mechanics behind throat size on mated tanks so I'll leave it to someone else to provide a clear answer

[SheffSmoker]

Just redo the calculations, will take you a minute using the ones provided on here.

[Pete Mazz]

Make the Throat the correct size for your CC.

[Frank_Cox]

Sorry I’m late to the game Here but here’s the standard I have used for years and these guys will attest to this accuracy.

I’ve always stuck to the numbers our calculator at bbqpitcalculator.com gives.
Start with the gallons on your cooking chamber.

If you’re building an offset, for the firebox use half of a 500.

The number will come up right at or slightly less than 100% and that’s ok in this case.
Offsets kind of break the rules since we don’t have a horizontal Baffle plate in use.











A 250 is way too small.
While a lot of builders are doing this I’ve not seen them get the results we get this configuration.

In the picture above you’ll notice our firebox throat is not very high up on the end of the cooking chamber.

This cooker runs great but the cooking rack is a little high for my taste.

I recommend you mount your firebox high on the end of your cooking chamber so your throat opening is approx half way up the side.

This won’t effect how the cooker runs.

Use a round throat opening and make sure you have a grease dam.

Hope this helps!


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