500 gallon reverse flow build

[James659]

Hello, great sight and info here. I have been building a reverse flow 500 gallon smoker for my brother. I'm a fabricator/ welder and have experience with metal but not smokers. He came to me a few months ago with a 500 gallon diesel tank and a websight , feldons pit calculator and said use it to get my measurements. Fast forward a few months and I'm 2/3s done with the project and was doing some research on calculating double stack heights cause feldons web doesn't say anything about using 2 stacks. While researching I came across this sight that is saying that feldons websight is flawed for reverseflows and all my measurements are wrong. My question is what effect will this have on the smoker? From what I can tell my intake dampers and hole going to the cooking chamber is a little smaller than it should be. To fix this it will be allot of work I wasn't counting on and really don't want to do it unless the smoker won't work as is. Second question is doing my research I found out 2 six inch pipes have the same carrying capacity as an 8 inch pipe. So I used 8 inch pipe measurements in the calculator and it came to around 3 foot for the 6 inch double stacks. Does that sound about right?Thanks to everyone that puts out the effort on these sights so ppl like me can build our dreams.

 

[gary s]

If using the 8" stack (Which I recommend over using 2-6") the length should be about 44 inches

Gary

 

[HalfSmoked]

James welcome to the sight glad to have you on board. Sorry you have problems but experience guys like Gary and others on here should be able to help you out.

Warren

 

[James659]

Thanks for the welcome. I'm using 6 inch cause that's what I have. My brother is wanting this for his church and the materials are donated for the most part and it's up to me to make it work. I do have some extra plate I could make a rectangle box stack.

 

[gary s]

I understand, why din't you use what you have, but build it with the intent of modifying and changing it in the future.
Now in saying that if it performs well and he is happy with the look, leave it alone.
I was just thinking about the overall finished look and performance. And most important What YOU and your Brother Like

I'm sure it will be great and you Brother and Church members will enjoy lots of great BBQ

Gary

 

[James659]

Thanks Gary,
So you think I should go 44" height on the double stack then? As far as performance do you think with me going by feldons calculator measurements it
will be sufficient? It will be easier to fix now then later if I have too change anything.
The church mainly uses their smokers for fund raising, church picnics and at times local bbq competitions. It doesn't have to be the best out there just needs to produce good grub.
Thx James

 

[gary s]

That was for the 8" let me recheck for you

Gary

 

[gary s]

If using two 6" I would go with 38"

Gary

 

[James659]

Thanks again Gary.

 

[James659]

New question. I made the changes to the firebox to conform to the measurements this sight recommends. Made bigger Fb intakes including 1 in the top of the door, and i cut the opening to the cc bigger to get the recommended opening. My new question is I have a downward slope going to a drain on the baffle. I was originally going have a drop of 1" over 5ft sloping away from the fb. But because of the changes that drop will be 2 " over that 5 ft length to the drain. Is a downward slope of 2" over that 5ft going to hurt anything?. It will be allot of work to change, but I want this smoker to work properly. Thx

 

[gary s]

Are you talking about your RF Plate ?

Gary

 

[James659]

Yes sir.

 

[gary s]

That slope won't hurt anything

Gary

 

[kmmamm]

So long as the clearance area under the bottom and around the edge of your rf plate is at least as large as the opening between fb and cc, you should be fine. One simple way to check is to trace the cc/fb opening onto a piece of stiff cardboard or 1/4” plywood and then see if it will pass under the lowest point of the rf plate and around the end into the cc.

 

[James659]

Thanks for the replies. This tank is wide and there's plenty of space under the rf plate. I had to trim some of the rf plate where the drain is to get enough room at the end going to the cc, I'm pretty close to what is recommended there just a little shy.

 

[James659]

I'm about to start on the cooking grates. I plan on making upper and lower levels that slide out. Im using 1" angle iron and expanded metal. I looked for a good forum thread that would give me a basic how too but couldn't find one.I got in my head how I think they should be made but would like to see how ppl with more experience have made them. Does anyone have a link to a tutorial or build I can read over? Also these grates will be 4' x 5' and is expected to hold a whole hog. Should I split them up so they aren't so big, for example 2.5' x 4' and have two
Thanks.

 

[kmmamm]

Unless you are using thick (3/16” or thicker) angle, 1” is kind of light for grate frames. I use either 1.5” or 2” x 1/8” thick for the grates. The 1” angle will work well for the slides that the rack sits in. Provided the cc chamber has one door, I would use a full size rack rather than splitting them up. Makes it a hole lot easier to cook large chunks and whole hogs.
Building the actual frames is straight forward cut angles to size, and tack together using a frame jig to insure square rack. You can mount the expanded metal on either side of the angle, I prefer mounting it so that it is on the bottom rather than the top as it makes for smoother edges. What size/style expanded metal are you planning to use?

 

[James659]

I have 3/16 angle 1 by 1. The expanded metal looks to be 3/4" flat expanded metal. Not sure on the gauge but it's around an 1/8". I can measure it ltr if needed. I like the look of the expanded metal on the bottom of the angle the best as well. I can buy different angle if needed, I was hoping this 1" angle will work as that is what I have. I get the building of the rack itself but where are the stops recommended to be put. How far out should the racks slide out and still be stable for the weight?

 

[kmmamm]

3/16” is pretty stiff, but 1” will still flex quite a bit when fully loaded. I Would recommend picking up some 1.5” or 2” -3/16” angle for racks that size. Use the 1” for your rack support/slide assembly. With a heavier frame, 11 gauge expanded metal is plenty strong enough for the racks and should work well. So far as stops, I simply weld another piece of angle 1/4” above the rack slide. That keeps the rack in place when pulled out about 3/4 of the way, but still allows racks to be removed completely for cleaning and loading/unloading.
Good luck

 

[James659]

Thx everyone for letting me pick your brains.