Reverse Flow Smoker Design Questions

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TexasForever
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Reverse Flow Smoker Design Questions

Post by TexasForever » March 26th, 2020, 5:31 pm

New to the forum but have been looking around for quite sometime. I have been researching ideas for my first smoker build. I had a design all picked out then talked with a friend about it and he steered me in a slightly different direction. Wanted to get everyone's opinion on which design would work best. (Poorly drawn sketch included. My friend is going to put them in CAD when he gets a chance)

Both designs are insulated built with 1x1 16ga frame.

Firebox will be 1/4" inside wall 16ga outer skin
CC will be 16ga inside and out
Insulated with 1" Rockwool


My original idea was a vertical offset reverse flow design

Cook Chamber Inner Dimensions 46H x 22W X 22D
Firebox Dimensions 18H x 22W x 22D with angled sides
FB Inlet 2x10 lower and 2x4 upper
Firebox to Cook Chamber opening would be 22W x 6H
1/4" Reverse Flow plate 22x6 opening to cook chamber
4" x 4" Exhaust on Firebox side of CC 6-8" Tall

My friend expressed concern that the short travel of the smoke along the reverse flow chamber (18" or so) would cause there to be hot spots in the CC and not have equalized temps.

Which lead us to discuss a reverse flow cabinet smoker . So I came up with the following based on this and other posts on another forum



Cook Chamber Inner Dimensions 46H x 30W x 22D
Dual 2" x 22" inlet from FB into CC (See diagrams) (Could also use back wall if necessary?)
Firebox Dimensions 18"H x 30W x 22D
4x4 Exhaust at bottom of CC (Length TBD, need help/advice on this) 1 or 2 exhausts?

Some things I am unsure of:
1. Length of exhaust stack on both pits? Its my understanding that on a vertical pit you can count the cook chamber for the length of exhaust?

2. Firebox intake - I see a lot of the insulated cabinets just using a single 2" ball valve. After reading the information on here everyone recommends 2 inlets at at 80/20 ratio? How are these guys getting by with a single ball valve? The calculators reccomend 26 sq inches of intake?

3. I am concerned about getting the proper air flow on both designs. If you guys could check my calculations and make sure I followed instructions properly.

I would greatly appreciate any feedback. Thanks in advance.



TexasForever
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Re: Reverse Flow Smoker Design Questions

Post by TexasForever » March 26th, 2020, 5:46 pm

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Big T
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Re: Reverse Flow Smoker Design Questions

Post by Big T » March 26th, 2020, 5:47 pm

Welcome aboard!! I can't answer all of your questions but I'll try to help you out on a few. The pit calculators are designed for an offset smoker so they aren't very helpful when designing a vertical cooker. I don't think anyone has designed a calculator for verticals but I'm sure there's a formula for them somewhere. As for the intakes I think most insulated verticals are designed to be ran using charcoal instead of wood so the amount of air needed is extremely less than required to burn wood. This allows them to use a 2'' ball valve and usually some type of draft controller for really long burn times. I believe that Franks has a set of plans at smokerplans.net for a vertical RF cooker, the come with tech support that's unmatched anywhere and they're also tried and true plans. If you don't see what you're looking for then you can give him a call and he'll be happy to answer any questions that you have.


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Pete Mazz
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Re: Reverse Flow Smoker Design Questions

Post by Pete Mazz » March 27th, 2020, 4:59 am

Welcome . Keeping the FB under the CC makes for a much easier build . A vertical really only needs a FB large enough to hold a decent amount of wood or charcoal . RF verticals are overly complicated for my taste . Intakes can be oversized as they can always be closed down . Multiples are handy if the wind isn't cooperating . Stack can be a simple opening with a damper.


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TexasForever
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Re: Reverse Flow Smoker Design Questions

Post by TexasForever » March 27th, 2020, 11:50 am

Is it possible to design a cabinet to be used with wood? Just increase the intake size?



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Pete Mazz
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Re: Reverse Flow Smoker Design Questions

Post by Pete Mazz » March 28th, 2020, 4:05 am

Intakes can be oversized as they can always be closed down


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