Need Help please take a look at my smoker figures

Discussion in 'Reverse Flow' started by jgunne, Aug 21, 2015.

  1. jgunne

    jgunne Newbie

    Can yall take a look at these figures? Do they look right? I used the calculator here, I did round the numbers for ease of cutting, measuring, etc. One of my questions is: It calls for at least 163.809 square inches at end of reverse flow plate, that tells me that if my RF plate is 27", I would need 6-7" between the end of RF plate and end of pit? that would make my RF plate approx. 27" x 56" or so, that seems like lots more than the recommended area of 163.809 square inches.  Also that puts the RF plate and the cut for the FB opening about 9.25" or so from the bottom of cook chamber and it makes the FB/CC opening 181.41 sq inches. Is that too big? Will those figures work together?

  2. jgunne

    jgunne Newbie

    I see one mistake in my firebox dimensions already, How about these dimensions: 24"H x 27"W x 26" L?
  3. jgunne

    jgunne Newbie

    Length of reverse flow plate 55"
  4. jgunne

    jgunne Newbie

    My drafting skills aren't too good but this will give you the idea. 27" RF plate just 9.25" up from bottom of the pipe seems off to me...Are my figures sketchy or is this close to right?
  5. is2326

    is2326 Fire Starter

    Here was my initial layout based on 30'' dia. I went with 6'' between the RF plate and the bottom of the rack. My rack sits at a 1/4 or what would be 9 o'clock. I also made the FB wider 29'' and a 5'' id pipe at 30'' above the CC. Hope this helps.
  6. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Morning..... your numbers look good.... Dave
  7. jgunne

    jgunne Newbie

    Thanks guys. Won't be starting til after hay season and it cools down, may even be January. But trying to get a solid plan now and start gathering materials. Already got my pipe.
  8. jgunne

    jgunne Newbie

    IS2326 how did yours turn out? Cook well and hold temp? Also have a question about my plenum. How low should it go in my cook chamber and how far below the top of the cook chamber to the top of my plenum? Dave, do you see any numbers you would tweak for better performance?

    Also I am planning on elevating the wood rack in my FB about 3", should I add heighth on my FB to compensate? The FB IS already over 100% according to figures but I want to do everything possible for excellent performance.

    Also plan to double wall and insulate firebox. Do you recommend cutting equal squares spaced equally in a line for air inlet or would just cutting a 10" x 3" slot and using a sliding plate on the outside work just as good or better?
  9. is2326

    is2326 Fire Starter


    I am still working on mine cause I am really trying not to over look anything. I decided that for more CC space the Plenum would be the way to go. I can not say for sure where you could or should put yours but on mine the bottom of the Plenum sits about 1.5 inches above my lower rack. The top of the Plenum sits 4'' below the top of the CC. And depending on the size of stack (4'' or 5'') will depend on the finish height above your CC.

    My FB is H22 D22 W29 that's about 199% larger than required. I asked on my post "can you make FB to big and Dave said no. So with that info my wood rack sits at 4.5 with a 2'' deep ash pan below.

    Because I don't have the experience with air flow numbers I will ask that someone with more knowledge on here help answer it for you. Mine is not insulated and I am using 10'' x 3'' slide plate that I got from BBQ Smoker Supply. 

    I hope this helps and look forward to your pics. Feel free to use any of my pics if they help. God knows I have used a lot of this site.... 
  10. jgunne

    jgunne Newbie

    Sorry to keep bothering guys but also have a question on the exhaust stack. Can I use a damper placed lower on the inside of the stack like a wood burning stove damper or would that impede flow too much and I should use the normal sliding plate on top?

    Also the pipe for cook chamber is 1/2 so I know it will be heavy but was wondering if you thought I could get away with one door and maybe making a counter weight? Or would this simply be too heavy to counterweight and cause problems with hinges and warping etc...

    Planning on using 1/4" plate to make the inner chamber of firebox then frame the outside with 1" square tubing, insulate with rock wool and was hoping to use something close to 1/8" plate on the outside skin of firebox. Would this work well or you think it's too thin of metal on the outside? Not sure how much heat will make it thru to outside firebox skin and I don't want it to warp for sure.

    Also any recommendations on hinges for those heavy doors would be appreciated. I made the ones for my first build of a small standard flow but not sure if I would rather use store bought hinges or not this time. I figure there may be some good ones out there for this kind of thing
  11. jgunne

    jgunne Newbie

    Thanks IS I really appreciate your help. I will be posting pics but unfortunately I won't be starting the actual build until winter months. Got to wait til hay season is done and can clean out the shop and recoup a little $$ lol. I'm just wanting to start early planning and gathering material. This is going to be my baby and much like you I don't want to leave out anything so I'm planning and re planning hoping that when I get started I'll have a solid plan and guideline.
  12. jgunne

    jgunne Newbie

    Anymore thoughts on this guys?
  13. smokejumper

    smokejumper Smoking Fanatic


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