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Small patio reverse flow smoker design and build.

triax

Newbie
6
1
Joined Oct 18, 2019
Designing a reverse flow smoke from two gas canisters all going to plan based around the guide provided by dave on this forum. I have been trawling through threads but can't find an answer to what must be a common occurance.

Given I have two round cylinders for the FB and CC I'm wondering how the area under the RF plate is kept the same as the area between the FB and CC.

Does the area under the RF plate need to be the same as the CC/FB area? If so how is this normally accomplished since with a flat RF plate the area will be larger?

Thanks in advance.

Numbers below as starting point.


Cooking chamber volume 5661 cubic inches.

minmum Firebox volume (can be larger)
0.33 1868.13
Firebox to cooking chamber opening
0.004 22.644
Cross section of chamber under reverse flow plate
0.004 22.644
Area required at the end of the reverse flow plate
0.004 22.644
Exhaust stack volume above cooking chamber
0.022 124.542
Firebox inlet above and gelow grate total
0.001 5.661
 

Attachments

daveomak

SMF Hall of Fame Pitmaster
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Joined Nov 12, 2010
Good point.... Well, those 2 areas don't need to be the same, as you surmised..
The "football" opening is the area of concern... That allows for the smoker to breathe properly... The RF plate must be above that opening and any "extra" volume, is what it is... Doesn't hurt the operation of the smoke... Steals a bit of space from the cooking zone is all...
 

kmmamm

Smoke Blower
126
41
Joined Apr 30, 2016
Keep in mind you will need the same volume as the fb-cc opening on the opposite end of the plate where it rises into the main cc. Given the rf plate will need some degree of fall to drain grease and excess moisture, the rf plate will be mounted higher over the fb-cc opening and taper to a point such that the that opposite end is flush with the top of your fb-cc opening. As Dave indicated, archiving proper pitch and clearance on the rf can really eat into your available cc volume consequently effecting rack placement. Also be sure to account for the area between the end of the rf plate and the cc tank.
I have found the easiest way to insure your plate is the proper height is to trace the actual fb-cc opening onto A cardboard template and then use the template to cut out a couple plywood jigs. I use one jig to set the far side height of the rf plate and the other to check end clearance. I then cut a cardboard mock-up the rf plate and use it to check for clearance between rf and lower rack, determine drain location, etc. When everything is set, I will use the mock-up as a tracing template for rough cut of the actual rf. Granted, there are a bunch of different ways to do the same thing, but that is what works best for me.
 
Last edited:

triax

Newbie
6
1
Joined Oct 18, 2019
Hi, Basic layout complete.
Based on the numbers in one of the attachments or embeded images.
The only driving factors are the propane tanks which make up the cooking chamber and firebox.

I've plumed for 25% increase in numbers.
Firebox Approx 20% larger than it needs to be and a length so I can fit logs in a foot long minus the bark.

All suggestions welcome.
Next stage tweeking design and then sourcing box sections and wheels etc.

reverse flow smoker.200.png

Smoker section cad.png

Numbers used.jpg
 

daveomak

SMF Hall of Fame Pitmaster
OTBS Member
SMF Premier Member
25,252
2,864
Joined Nov 12, 2010
Looks like you've done your homework to get a great smoker built... Now comes the fun part...
 

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