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Building a custom smoker but have questions on flue

post #1 of 7
Thread Starter 

Hi all, I have been smoking in store bought smokers for about 25 years and as many of you I have had to make modifications to just about all of them in one capacity or another. I have recently decided to design and build my own smoker. I know it's not rocket science but there is a question on the flue that I wanted to see if anyone else had experimented in this area and what you have learned. I am working on a water pan manifold design with multiple smaller ports from heat and smoke source to try and develop a cooking chamber that does not have such a large temp differential side to side and shelf to shelf. I have the water as regulator to reduce most of the need for intake damping for cleaner burn the manifold and multiple smaller ports from firebox to more evenly distribute heat and smoke. Now after that dissertation what I have always done in the past is to insure the flue was at or slightly below the bottom grate on off set smokers or RF smokers, But to keep from losing smoke faster from on side, the other or from the center, what would you all think is the best location and design for drafting the smoke out?

 

Thanks in advance for any advice,

HogWaller

post #2 of 7

Hello hogwaller.  huh.gif  Can you do that again in English?  Seriously; I was a fabricator for many years and  I THINK I know where you are going here but I am going to wait a while before I give you my opinion.  I'd like to see what other folks have to say and I'm not sure folks would agree with my opinion.  I will be watching.  BTW welcome to the fun.  We look forward to your contributions.  Keep Smokin!

Danny

post #3 of 7
Thread Starter 

I am building a prototype using a 55 gal barrel as the cooking chamber and a 30 gal as a fire box. They are both horizontal on a stand. The 55 gal has been cut for a quarter cut lid with 2 level grates. I took another 55 gal barrel and cut top and bottom 3" up and across the centerline then took 4" out of the center and welded it back together to use as a deflector an a water pan in the bottom of the cooking chamber on 3" risers. I have the 30 gal fire box all but underneath the 55 gal cooking chamber and there are 3 3" tubes going from the top of the fire box to the bottom of the cooking chamber and penetrating about 1" to prevent possible grease back flow into the fire box. The three heat and smoke inputs spread across the cooking chamber about 6" apart. The deflector shield filled with water keeps the heat from going directly up to the meat by sending it up the curved sides creating a convection type circulation and the water helps maintain a more constant and moderate temp in the chamber. I know the flue is best located equal to or lower than the bottom grate. I am considering using 2 4" flues that penetrate the back of the cooking chamber just below the bottom grate and going inside about 10" to try not to unbalance the heat from one side to the other then on the outside elbow 90 degrees and go up 26"-30" for proper drafting. I hope this makes a little more sense and sorry for the vagueness in the initial info. I am looking for suggestions as to a better flue design or confirmation that this is the best option. I have modified already built grills but this is my first from scratch. As I mentioned above I am using barrels as prototype ( cost effective ) and will eventually build a heavier model.

post #4 of 7

Hello hogwaller.  I did too much reading between the lines on your first post.  :hit:  That's why I was withholding my opinion.  My first opinion was that you were WAY over complicating this and I didn't want to say that.  Your second post explains exactly what you are doing and it sounds great to me.  In my opinion 2 4" flues are maybe more than you need but as long as you have a damper in the flues I see no problems with your design.  You may never use the dampers but is nice to have the option.  I usually over build my own contraptions and smokers but I would rather over build and not need it than have to tear the thing back apart.  You may also find you don't need the water pan BUT the option is nice to build in originally.  Should I EVER get caught up I have a fridge waiting for conversion.  I plan a couple things added to that I may never use but is nice to have options.  Your build seems sound and I can't see why it would not work really well.  This is only my opinion.  Others may have different advice.  Good luck and don't forget to post some picts of the build.  Keep Smokin!

Danny

post #5 of 7
Thread Starter 

Thanks for the input. My thought process is hoping not to have to use dampers on either end that way the fire burns cleaner and less creosote and the smoke crosses the meat then out so to not create the bitterness and keep the heat inside to do the cooking. I'm also trying to eliminate rotation of meats due to hot spots you get with side mount fireboxes even with tuning plates. The water pan is a need during our summers here when it over 100 degrees and 20% humidity the meat tend to move into the jerky side unless you foil and then that steams off your rub and reduces the smoke absorption. I only try and use foil for the relaxing period. I'm already white boarding my next challenge in building a dugout cold smoker to process hams, fish and cheeses. I'm sure this will lead to lots of questions

post #6 of 7
Quote:
Originally Posted by hogwaller View Post
 

Thanks for the input. My thought process is hoping not to have to use dampers on either end that way the fire burns cleaner and less creosote and the smoke crosses the meat then out so to not create the bitterness and keep the heat inside to do the cooking. I'm also trying to eliminate rotation of meats due to hot spots you get with side mount fireboxes even with tuning plates. The water pan is a need during our summers here when it over 100 degrees and 20% humidity the meat tend to move into the jerky side unless you foil and then that steams off your rub and reduces the smoke absorption. I only try and use foil for the relaxing period. I'm already white boarding my next challenge in building a dugout cold smoker to process hams, fish and cheeses. I'm sure this will lead to lots of questions

 

Hello hogwaller.  I am originally from south Tx. so I feel ya with the heat humidity thing.  I understand about the smoke exchange and creosote but if I read correctly you plan no damper at the intake or the flue?  So how do you control the heat?  Or just no damper on either flue?  Either way; IMHO I would put the dampers into the original build.  You may never use them but if you need them and don't have 'em that means cutting it apart, screwing up the paint job and etc..  Just my opinion.  Good luck.  Keep Smokin!

Danny

post #7 of 7
Thread Starter 

I will have an intake damper and dampers on the flues but with the water pan and the lower flues I should be able to maintain the heat inside at a more constant level. Thermal transfer through the steel of the barrels will be the majority of the loss of heat. The air temp below the bottom grate should theoretically be the coolest air in the chamber and it will be what is exhausted first and using the first rule I learned in smoking "keep the door closed damn it" the temp inside should hold balance without using a flue damper, once I do some test fires to find the right coal level range the intake damper should be needed for slight adjustments through the burn and at the start and at the end.  The flue dampers I just don't see a lot of need unless its a windy day you might close down your draft some but that's it.

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