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New 80 gallon RF smoker build


Smoke Blower
Joined Nov 25, 2016
Hi, I've got some new 24" pipe that I want to build an RF with.  I would really like to get some feedback on the dimensions before I start. I have two lengths of the pipe, (43.3 inch) for the cook chamber and (16 inch) for the firebox. 

 DaveOmak, Legend.  I've read your tutorial on RF Smoker build and used your calculations to arrive at the below.  (Great resource - thanks for taking the time to put this together).

ActualCook Chamber inside diameter (inches)                23.51
ActualCook Chamber inside length (inches)                43.31
ActualDiameter X Diameter X 0.7854 X Length = Volume in cubic inches18,802
RecommendedVolume in cubic inches X 0.004 = FB/CC opening in square inches                75.21
RecommendedVolume in cubic inches X 0.004 = Area under the RF plate in square inches                75.21
RecommendedVolume in cubic inches X 0.004 = Area required at the end of the RF plate in square inches                75.21
RecommendedVolume in cubic inches X 0.33 = minimum volume of the Fire Box6,204
RecommendedVolume in cubic inches X 0.001 = FB air inlets in square inches...                18.80
ActualFirebox inside diameter (inches)                23.51
ActualFirebox inside length (inches)                15.75
ActualFB Diameter X FB Diameter X 0.7854 X FB Length = Actual Firebox volume in cubic inches6,837
Question 1. From the above I'm proposing to make the firebox volume 10% over the min recommended. Is this enough?

Re the stack, the below is what I came up with using Dave's calculations.
RecommendedVolume in cubic inches X 0.022 0.017  = Exhaust Stack Volume in cubic inches              413.66
 Exhaust Calculation..  
Proposedexhaust stack length (inches)                23.62
Proposedexhaust stack diameter (inches)                  5.12
ProposedESV in cubic inches  = Stack Length in inches * 0.7854 X Stack Diameter X Stack Diameter              485.54
Question 2 - I prefer the look of the fatter shorter stack but should I use a narrower pipe for the stack and make it longer instead?  

Question 3 - I' m proposing to make the stack volume 17% over the recommended. Is this ok?

I'm proposing to a round FB and CC so again on the recommendation from Dave, I will overlap the FB and the CC so that the football opening opening is made up of two segments.  Below is the calculation from the circle calculator. 

Total FB/CC opening will be (2 x 40.47) just under 81 cubic inches, against a recommended min volume of 75.

Question 4 - is this ok or should I increase it?

Putting the RFplate above the overlapping segments, the volume under the RF plate will be larger again.  (Is this to allow for the longer path and the additional friction?)

The RF plate on the above calculations will be just over 7 inches up from the bottom of the CC. (as each segment is 3.5 inches high. 

Question 5 - Is this OK? should it be higher?

Lastly, I'm proposing to put the exhaust stack above the CC so that I can put a door on the CC to double it as a grill. I was proposing to make the bottom of the exhaust stack the top of the CC. From the diagram on the tutorial, this looks wrong. 

Question 6 (and the last one from this long post!) - How far down into the CC should the exhaust stack go?   

Thanks guys, I really appreciate the input.

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