Intro and build question

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geo1

Newbie
Original poster
Mar 29, 2017
10
14
Caseyville, IL
Hello everyone, long time reader first time poster. I have had an 18" WSM for about 7 years now and try to use it as much as possible. I've always wanted a larger smoker and about a year ago i was ready to pull the trigger on a 24 X 48 backyard cooker from Peoria Cookers. Well shortly after deciding i wanted this i found out i was having a baby so spending that much money on a smoker was out of the question. Over the past year i have been slowly building a smoker from a 250 gallon propane tank.

So my first question for this forum is about the exhaust stack.

Smoker specs:
CC:         250 gallon        57,750 cubic inches
FB:         24.5 X 24.5 X 32    19,208 cubic inches
FB/CC opening:    8" tall            222 square inches
FB air inlet:    two 4"X8"        64 square inches    
end of RF plate:  not yet installed, estimating 222 square inches

Exhaust stack:    57,750 X .022 = 1,270 cubic inches
    6" pipe 45" tall   
    or    8" pipe 25 1/4" tall

The issue i'm running into is i am locked into a 22 inch max height to get my smoker in and out of my garage. The 8 inch pipe is almost right on the money but everything i've read has said i want to be somewhere between 30 - 40 inches in height. 
will this smoker not draft correctly if i use an 8 inch pipe that's only 22 inches long? if this is the case i will need to look into a removable extension or possibly a hinge half way up.

Thanks in advance!
 
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To the SMF geo1!  You're on the right Smoke Meats Forum to find the answers to your questions, while having fun!  

Can you post up any pics? that is a really good first step for any of us to be able to see your project and possible spot your issues right off. 

Draft and or Draw is very important and understanding the concept behind it first helps greatly with your build. Many different design solutions for these custom builds to overcome obstacle in order to have a properly functional Smoker.
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 Custom smoker builds are fun and cool, but they all have to still be able to function correctly in the end! 
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FYI, congrats on the little one, If this is your first? just know this, a sibling play mate will soon follow and you're going to need a second job over having time to play with your Smoker project! LOL  

No worries, the little ones will grow-up before you know it and back to your smoker project you go.Just remember, they are only little once. Keep us all posted, on your progress, Smoke on, Mike
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Thanks 416bigbore. Yes, this is my first and she hit 6 months last Friday. It already seems like its going by too fast. 

I did end up welding in a 1/4 inch plate 1 inch from the top of the firebox to insulate the cooking chamber from the firebox, hopefully help save paint on top of firebox, and to help with even temps. i hope the cooking chamber to firebox opening height going from 9 inches to 8 doesn't hurt the flow too much.

Ok, here's a couple pictures(don't mind the messy garage), really hoping i can get away with a 22 inch tall 8" stack.




Thanks.
 
Dropping your heat deflector plate 1" really reduces the effective area of the FB/CC opening.....   I would lower it to ~1/4" or so....  and suspend it...  welded in permanently will subject the plate to extreme temps and warping and weld breaking could result....   You can measure the opening now and plug it into the calculator and see what you've got for sq. in. and compare it to recommended....

 
 
Thanks! Yes it will be reverse flow. 
No question about it , you have it all going on with your build! 
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 I did notice something in your second pic that stuck out like a sore thumb to me. look at the weld on your frame down from your jack right above your JD Mower deck. It's where your two frame tubes meet.

YOU CAN NOT WELD ACROSS STRUCTURAL INTEGRITY LIKE THAT. It will no fail today and or tomorrow or even in a week or two. But you just created a stress point on your trailer frame for a potential failure over time.

If you bounce that Bad Boy up and down the roads hard every day and or weekend? The problem with present itself sooner over later, and it will start to crack down from the end of the weld on the frame and not up, due to the stress at that point!

I am not trying to and don't mean to be super critical on your build, You have a very nice build going on and that  compromising weld on your frame stuck out for me. Now you're wondering how to fix it? LOL 

No worries, leave it alone and don't try to grind it out or you will end up with a bigger  problem. All you need to do is weld in a small gusset, that will go across your compromising weld and on down center of your trailer frame tube.

Take a 3/16 or 1/4 x 4" square plate, cut it diagonally then nip off a little of the corner of the right angle of your triangle plate and place it in the center of your tube over the weld, and weld it up. FIXED !
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Awesome build, can't wait to see your build breathing fire and smoke !
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Mike 
 
 
Dropping your heat deflector plate 1" really reduces the effective area of the FB/CC opening.....   I would lower it to ~1/4" or so....  and suspend it...  welded in permanently will subject the plate to extreme temps and warping and weld breaking could result....   You can measure the opening now and plug it into the calculator and see what you've got for sq. in. and compare it to recommended....

I've got that plate welded in there solid and don't think i could get it out of there without causing severe damage to the firebox. i turned the firebox upside down, welded in angle around all sides of the firebox top except the cook chamber opening, then set in the heat shield in and welded it out before attaching the firebox to the cooking chamber. I think the best i can do at this point is heat it up with the torch and take the BFH to it and regain some of the opening. This might also help with flow as the heat shield will be at a slight angle directing the heat in the direction it needs to go? I'll try to get out to the garage tonight when i get home from work to get some measurements.
 
 
No question about it , you have it all going on with your build! 
yahoo.gif
 I did notice something in your second pic that stuck out like a sore thumb to me. look at the weld on your frame down from your jack right above your JD Mower deck. It's where your two frame tubes meet.

YOU CAN NOT WELD ACROSS STRUCTURAL INTEGRITY LIKE THAT. It will no fail today and or tomorrow or even in a week or two. But you just created a stress point on your trailer frame for a potential failure over time.

If you bounce that Bad Boy up and down the roads hard every day and or weekend? The problem with present itself sooner over later, and it will start to crack down from the end of the weld on the frame and not up, due to the stress at that point!

I am not trying to and don't mean to be super critical on your build, You have a very nice build going on and that  compromising weld on your frame stuck out for me. Now you're wondering how to fix it? LOL 

No worries, leave it alone and don't try to grind it out or you will end up with a bigger  problem. All you need to do is weld in a small gusset, that will go across your compromising weld and on down center of your trailer frame tube.

Take a 3/16 or 1/4 x 4" square plate, cut it diagonally then nip off a little of the corner of the right angle of your triangle plate and place it in the center of your tube over the weld, and weld it up. FIXED !
welder.gif
 

Awesome build, can't wait to see your build breathing fire and smoke !
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Mike 
Thanks for pointing that out. I've got some extra 1/4 inch plate i can use to make a gusset. I'll work on getting her fixed up this weekend.
 
You have a very impressive Built going on that you and your new Family should have years of enjoyment from !
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 Keep up the great work and we all want to see that Bad Boy breathing smoke and fire ! 
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 Mike 
 
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