# Will this work? Has anyone tried an undersized fire box.?



## bjons (Jul 12, 2011)

My only fire box I've been able to get my hands on is 5000 less cubic inches than the calculator says it should be. My cooking are is round with a dia. of 29inx82in. the fire box i want to use is dia of 19inx47in. Can this work? any help would be welcome as im getting pinched for time.


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## daveomak (Jul 12, 2011)

Bjons, evening.

Someone spent quite a bit of time figuring out the calculations for making a great smoker.

That being said......I would not change the ratios of fire box to cooking unit. I'm not that smart.....but you already knew that.....Dave

PS Welcome to your new home.


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## got14u (Jul 12, 2011)

Don't go below 1/3 of your cooking or smoke chamber....and that sure seems like a LONG fire box to me any ways, almost 4' if I am reading it right


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## solaryellow (Jul 12, 2011)

There are plenty of undersized fireboxes in some of the builds here. It will work but will consume more fuel.


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## got14u (Jul 12, 2011)

How does it consume more fuel?


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## solaryellow (Jul 12, 2011)

GOT14U said:


> How does it consume more fuel?




Think of it as a tank full of hot air. The smaller your tank of hot air is, the easier it is to cool that tank of air with the introduction of cooler fresh air thus needing a hotter fire to keep the hot air flowing. Put an ice cube in a small glass of warm water and then put an ice cube into a large glass of warm water and see which one gets colder. Does that make sense?


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## talan64 (Jul 12, 2011)

Are you completely stuck on using a round firebox?  If you were to go with a square fire box, you should be able to get away with (roughly) 29x25x25 (correct my math if wrong). 

Of course the experts here on the site can tell you better, but I do agree that with the canister style firebox you are suggesting it seems rather long.


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## lovinspoonful (Jul 12, 2011)

What configuration are you contemplating? SFB? If so, the smaller diameter of the firebox and the long shape of it present problems as far as the draw is concerned you may get a bit of a "venturi" effect and burn even more fuel than you need. If I were you I would consider building a square firebox to suit and ditching the pipe.


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## meateater (Jul 12, 2011)

Here you go. It doesn't open you need to save it somewhere. 
https://statich.smokingmeatforums.com/7/7f/7f0795bb_timplatebbqform2.xls


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## bjons (Aug 8, 2011)

Ok, we did our first test burn to check draft. worked great with the exception that i was unable to throttle the temp down enough. I used a bad of kingsford for this test burn. Will using wood allow better control of the temp?


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