Air intake and output

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Mo Smoke
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Air intake and output

Post by Mo Smoke » August 26th, 2022, 9:02 am

I have a propane tank that’s 6’ long 24” diameter. If I just want to put 2 air inlets that are 3”x3” openings on both ends of the tank, (no firebox), what size and length smokestack should I use?


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Re: Air intake and output

Post by Dirtytires » August 26th, 2022, 11:53 am

Sounds like you are making a charcoal grill and not a smoker. If so, remember a grill is hot and fast so excess oxygen is needed to keep the coals burning. I would first think that your intakes are too small for that but your question was the exhaust. If it is a grill, exhaust is irreverent but should be, in my opinion, at least as big as the intake so as to not cause a restriction.

I may be making too many assumptions....might need a bit more info.



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Re: Air intake and output

Post by Mo Smoke » August 28th, 2022, 3:08 pm

Yeah I guess this is more of a grill than a smoker. Didn’t really think of it that way until u said it. I saw something like what I described and thought it might be a quick cheap way to make use of this tank until I have enough money to start building a reverse flow. But one thing u said caught me. The size of the Intakes should be the same size as outputs. So what about length of the smoke stacks? How do u determine that number?


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Re: Air intake and output

Post by Dirtytires » August 29th, 2022, 10:38 am

Smoke stacks legnth on a grill is not a factor. In a smoker, you have a small fire and need to "pull" the smoke thru the maze of the pit. A grill is wide open and hot. No need to trap the heat as it just rises and leaves the grill. My grill has a 2 inch wide vent across the entire lid and the bottom is completely open.

You ever cook in a campground fire ring? It's typically nothing but smoke cause the ring is into the ground fire doesn't get enough oxygen to burn cleanly. Open up the bottom a bit by digging it out and the fire is Much cleaner burning. My point is, you don't want a restriction for the intake or exhaust...let the fuel be the limiting factor.



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Re: Air intake and output

Post by Mo Smoke » August 29th, 2022, 3:46 pm

Makes sense. My friend has a big grill with the same setup I described. Intake vents at the bottom on each side and just and opening at the top. No smokestack. That’s probably why he didnt work for him when he tries to use it as a smoker. There are 2 baskets on the ends that are meant to hold charcoal or wood but they are way too small for the size of the cooker, plus based on the science u just explained, there’s no way he could get enough draw to keep a good fire burning. So he just uses it as a grill and cooks direct over coals. But what I hate is that he puts the coals directly on the bottom of the tank. I told him he should put a grate in the bottom so the air can circulate underneath the coals and fire. He can cook but he always has fire issues.


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