Center Firebox Build

Discussion in 'Reverse Flow' started by hephaestus, Jun 29, 2013.

  1. Hello Everyone,

    I’ve been smoking meat now for 4-5 years and watched Dad do it many more. I’ve been using a modified Charboiler and I think its time for a Cadillac smoker. At some point I’m willing to do some kind of charity work with it. So I’ve managed to find a compressor tank so I don’t have to mess with that propane pain. I’ve been doing a lot of research on here and find I really like the center firebox. I want to build one like real57vetteguy and Dragons Breath. So I’ve added a few of the drawings that I’m planning on doing. On the front side drawing I forgot to add that those are bricks strapped to the firebox.  That is going to be done as a fire shield. If anyone has any questions or suggestions can you please speak up.

    Thank You



    Last edited: Jun 29, 2013
  2. Brian

    Looks like it will be a nice plan. I look forward to seeing your build.

    Happy smoken.

  3. I have two questions here.

    1. Has any one ever had a tank warp on them when smoking and if so what would you do to prevent it?

    2. Does anyone think using charcoal on a burn out of the tank would work?
  4. I've been removing the old red primer with a strong paint remover and grinder. I did a lead test on it and it came up negative. My thinking behind getting it off is better safe then sorry. But still have the back side and the bottom to do so I'm 2/3 done. When I was grinding the threads off the top I managed to start a smoldering fire. This tank is a old compressor tank wasn't going to mess around with propane but still manged to have fire. After I get the primer off going to patch the holes and then cut doors.

    I got lucky the other day I got 1/4 inch steel for 40 cents a pound for the fire box

  5. This might be my last post on here because I'm getting no interest in this build. For some reason I ask a question on here and no response. So let me ask one more question here.  I see that most smokers doors are built at 12 o'clock and 3 o 'clock position. But my problem is that the doors will fall right down the middle of where a patch is on top. So the question is there going to be a problem with me cutting the door there. Thanks in advance
  6. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Hephaestus, evening......   Well, you have had 195 views of your thread....   someone is interested....   I think the reason there are no responses is you are building a smoker that does not fit the "profile" we are accustomed to....    I have no idea how I can help you...   Probably the same for others....   If you were building a "conventional" style smoker, the folks have taken the time to run calculations for, or a reasonable facsimile,  someone would jump in and help......    Liken it to the Wright brothers.....   "I'm building this airplane and am going to fly it....  help me with my design".....    Heck, no one has seen that design before.....  maybe it will work ..... maybe not.....   I, like others stop in here to learn something.....  You are the instructor, we are the students that came here to learn......

    Take it for what it's worth.....   

    cbennefield likes this.
  7. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Last edited: Jul 19, 2013
    • Hephaestus, Dave has a point, its the old saying."if you cant say something nice, don't say anything at all".
    So...either I don't say anything for risk of offending you,...or offer you my best advise, and that is to re-think your design.  There may be some builds out there of this style, and because the builders put so much effort into the build they will triumph their build as the "holy grail" of smokers, this design is flawed from the beginning, instead of trying to redesign the wheel, go with a design that is tried and true and one that have have hundreds instead of a handful of previous builds to pull information from.

    And I paused for a minute before submitting this post, but then I thought, these words may be just what this thread needs to start getting you some feedback...everyone loves a good debate right?
  8. First thing first, I want to apologize if I offended you. My reasoning behind my frustration is that I feel that I'm just writing a blog. And everyone is reading it but there is no place for comments. I do understand that my build is out in left field and I'm thinking outside the box.  I think that this way makes sense to me. We can go back to the caveman days where one caveman decided to make a fire in between bunch of rocks. While the others are cooking over a direct fire, the odd ball is trying to make the fire more efficient. So everyone is over there looking at that one caveman saying his idea is lame while he is all by him self. But then they start realizing that he is gathering less firewood. So what happens next… they all start using his method.  But then that same caveman down the road figures out that if you stick a fire a small crevice that it uses way less wood then the previous method. And then they go through the same cycle of thinking the guy is nuts, until they realize that his new idea is better again. But now I'm going to break this down in smoker history, which goes from a firebox on one side to a chimney on the other end. (Cooking over a direct fire caveman style)  Next there is the baffle/ tuning plates and also reverse flow. (Cooking in between rocks method) Then you go with method I'm planning center firebox (Small crevice).  So, the point I'm trying to make is that the other ways are less efficient then this design I’m trying to create.  I don't think the evolution of the smoker is going to stop at the reverse flow method. And the way I see reverse flow is that it’s heating one end to send to the other. That is not very efficient if you think about it. But the way I see it is that the reverse flow is like a V-12 engine with 500 hp and I'm building a 4 cylinder with 500 hp.

    Just to make it clear I'm not the caveman that everyone is following. [​IMG] The one I'm following is real57vetteguy. So please take a look at his thread.

    And once again especially to Dave I'm not looking for enemy's and I'm sorry. So if you can please come out to left field with me here and there it would be gladly appreciated. Most of my questions will be general welding questions.

    If I have any problems with heating I'll ask
    Thanks Brian


    Last edited: Jul 20, 2013
  9. Hephaestus

    You didn't offend me, I was worried about offending you, but needed to get the conversation started some how, and just throw the ugly out there.

    But we did get the conversation going, so please let me continue....and I really am struggling , trying to not come across too arrogant.

    But Ive already gone through this train of thought your going through and built about four of these.  Thinking, look at those off set smokers, they burn so much wood and loose so much radiant heat, what a waste.....wouldn't it be so much more efficient to put the heat under the cook chamber and capture all that wasted heat , and would it cook so much more evenly with the firebox centered?

    But it don't work out that way, your going to end up with a hot spot in the center of your cook chamber, your going to need to deflect the heat, and even a drip pan is going to get so hot it going to smoke up all the grease and taste like crap. So then you have to separate the firebox and the cook chamber and plumb them together with pipe, or move the firebox further back so that its not directly under the cook chamber, but all we have is a funny looking offset smoker that you have to walk around back or lean way up under the front to load the firebox. So now we got to go back to engineering again. What if we double wall the entire cook chamber, direct all of the heat to the very edges, then install another drip pan/baffle plate inside of that. Well that works, and the one I ended up with did cook very well, but I had a ton of time into it,  I still had to load the fuel from underneath, standing and cooking the food was hot because your standing right on top of the firebox, instead of beside it, etc etc etc. and well, IT JUST DOES NOT WORK OUT LIKE YOU THINK IT WILL. So I chopped it up and actually #19's firebox came from the last one I made, the cook chamber is still in the garage.

    There is a reason the off set, or reverse flow style smoker is the most popular for stick burners, They are more fun to cook on. You got your fire off to the side, not right under your feet, its easy to maintain your fire with out having to bend over , easier to clean everything out.etc etc .

    Yes, they are less efficient, but if you read through some of the threads, there are ways to make these things way more efficient than those dept, store models. Wish you were near enough I could let you borrow one of mine, just to see what I'm talking about.
  10. If someone didn't get out of the box every now and then, we would still be using horses for transportation.[​IMG]

    I like your design and I believe you will end up with more consistent temps throughout the cook chamber.  I would suggest though that you scrap the idea of the dampers between the firebox and cook chamber. I know you are thinking about temp control, but intake vents in your firebox will work much better. A low intake for better burn and more heat, and a higher vent for cool air to mix with your heated air to lower the temp.

    I went the route with the dampers between the FB and CC only to never use them.

    Good luck with the build and I will be lurking.
  11. jarjarchef

    jarjarchef Master of the Pit OTBS Member

    I am courious to see where this goes. I like the theory and have had the same thought myself.

    As Ribwizard pointed out there are some issues to address that will cause you headaches later. He is the expert in the building department in my book. He puts a lot of skill and experience in all of his builds.

    I am not a metal fabricator or engineer, but I have cooked a lot on many different styles of equipment in my professional and personal career.
    Just a few observations.

    As pointed out you will have a hot spot over the firebox. If you look at vertical smokers there is a heat deflector of some type. Most have water pans, but some use stone, sand or other types of safe matter for this. I have seen some mention of a second plate just under the RF to take the brunt of the fire heat. I know you have tubes/vents allowing the smoke and heat into the chamber with dampers. That may help, but still will create hot spots.

    Air flow with the vent tubes may be a challenge. I would use the same formula for firebox opening as a traditional RF smoker. Easier to choke it down then to increase the air flow after built.

    Bricks strapped to the fire box and doing some charity work. As a catering Chef the thought of moving a smoker with bricks strapped to it kind of freaks me out. However I think the thought of the visual of this tank sitting on brick in my back yard is very cool!

    Good luck and happy smokin!

  12. First off I respect every ones opinion on this especially Ribwizzard  and Dave they have great respect around here.  You'll never sound arrogant to me, it'll just sound very blunt[​IMG] OK so I've left out how I plan on curving this problem with hot spots. First I'm going to start with the firebox. The plan is to kind of fabricate a square funnel to the out let to the CC. I'm going to angle it on all four sides with sand in them. (As seen in the drawing.) Now with the Cooking chamber I'm going to have a damper hooked up to a hi and low thermostat to open and close it with a motor. Then over all that I'm going to make a heat shield then my baffle plate over that. All that is going to be removable on the inside. I was also concern with heat around my legs and that were I insulated it with brick. I'll also have fans in there to blow heat out if it gets to hot or to draw more heat in.

    The angled lines are what I'm talking about

  13. They would be removed before I hit the road. I'd sure hate to a have fundraiser for someone I killed.
  14. Hephaestus I like you're idea!

    Oh yeah I built one similar.

    I'll share some of my smoking experience.

    Been out of the country for the last couple of weeks but I can see you do need some positive response.

    Yesterday I smoked 19 turkeys all at once on my center fired. Turned out to be over the time limit and everyone had to wait 2 1/2 hours past lunch time.

    My center fired is about 20 to 25 degrees hotter in the center! This allows smoking of different size birds, or meats, and still have them come out at approximately the same time.

    I put the larger birds in the middle with the smaller on either side. We're talking from 11 to 21 pounds. I found this to be an amazing feature. Can't use it all the time but it does come in handy.

    One important element is to keep an air space between all the turkeys. Then my smoker will cook 1 or up to 16 in approximately the same amount of time. I found my smoker's limit is 16 turkeys, more and the birds are stuffed into the smoker making one solid rack of meat. Really extends the cooking time. I'm sure most of you smoking gurus already new this, but I'm still learning.

    Another thing is the grease drain on a center fired. I did list it down hill to facilitate the flow, and this does effect the temperature on the ends, but while cooking the whole smoker can be raised or lowered to get the heat and smoke flowing relatively evenly.

    I put 2 9" diameter dampers between the firebox and cook chamber. I used sheet metal on stand offs for heat shields and they work just as well as brick! lighter and permanent.

    Another feature of my smoker is I have to remove the grates and clean the burnt build up on the reverse flow plate. Especially in the center. This is more of a chore than a feature. ha ha 

    Still, I believe that because of the heat being under the smoke chamber this design is a bit more efficient. 

    With the Minion Method, Dragon's Breath will run about 6 hours on one 40 pound bag of mesquite lump charcoal plus the fruit wood limbs I put in from time to time for the smoke.

    If I can help let me know and keep on smoking.

  15. I can be blunt, I know.....

    But it doesnt mean I wont share what I learned from those builds with you, Im just going to include all of what I learned, good and bad.

    Think about adding a air gap between the firebox and the cooking chamber, even if only a couple of inches, this will do more to even out your temp than twice the steel invloved in water pans and diverter plates.

    The air is naturally going to want to rise straight up, anywhere it contacts steel will be a hot spot. Try to direct it to the farthest edges of the cooking grate, letting the heat rise to the left, the right and the rear of the meat, then roll up and come back down onto. I moved from a single exhaust stack in the center to one on each side about six inches from the top of the chamber.

    Also, head my warning about the fire being at your feet and having to bend over to mend the fire, it will get old. Also, if you want a rack in front of the cooker, it will make it worst.

    And because unlike a offset firebox that looses heat when the door is open, when you have your door open on this one it will actually raise the temp very fast , so design it for very quick loading, the flames wont have anywhere to go when they get that burst of fresh air but towards you.

    But that air gap is the most important info I can try to sell you on.
  16. First off thanks to Dave for the post. And I hope I don't offended you about me picking apart your smoker now that I know a few details. I'm going to admit I'm a little concern about the center being that hot like everyone is saying. But the one thing I see on Dragon Breath is that there is a lot of firebox connected to the cooking chamber. And like your saying Ribwizzard is that there needs an air gap in between the FB and CC. But here is my thinking and please elaborate if you think different anyone. But what if I raise the CC up higher off the fire box and then have a heat shield or second chamber besides the baffle.

    Thanks again

  17. Making the firebox very tall would help, but think about working height and convenience. The air gap was a solution to keep the height of the cooking chamber as low as possible. But your right, with a tall enough firebox, and baffle plates, you can create the same effect.
  18. I guess that Wizard I was was being to blunt. What I'm trying to say is move the cooking chamber more off the fire.  What I think the object is to do is keep as much of the tank off the firebox as possible.At first I was looking at putting it about 18 inch across and 4 to 5 inches deep. But now I moved it up and now its two to three inches deep and 16 to 17 inch width. I built a redneck model of it yesterday and took some pictures maybe it will share some light on this or not. (No offense to the redneck you know how do things and so do I) I hope that it can by seen in the picture as I see it. 

    One more thing is a have question on your door flanges and I'll ask that there. (by the way Wizard that is genius on how you did that)


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