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First Pit - Reverse Flow

post #1 of 15
Thread Starter 

I have been reading about pits and especially reverse flow smokers. I am just now thinking through what I want to build (or have built). I have a welder, but don't really know how to use it well, so hiring that out. I do want to spec out what I want the pit builder to do. Reading the posts has been very informative.


 I have two pieces of 50 '' 24" diameter 1/2 inch pipe. I have one piece of 42" 20" diameter pipe, also 1/2 inch. These will be my starting blocks. I think I have more pipe than I need and was hoping to trade one of the big pieces for some plate and square tubing. What do you think trade value is?


I kind of like the idea of having a really big (long) fire box with a lid so you can cook over the fire box (steaks/burgers). Any downside to that?


I will primarily use this pit in my yard, but would like to be able to move it once or twice a year for picnics and such. Has anyone seen a rig that doesn't look like a trailer in your yard, but you can fairly easily add an axle or wheels? This could be small wheels that I could use to get it onto my big trailer, or a narrow trailer that maybe you can actually use and detach from the pit. I am afraid if I put it on a permanent trailer I won't use it as much, and certainly don't want to pay rent on it.


Pipe is HEAVY! I was seeing starts when we lifted the "little" one on the trailer. I had to get a big forklift to get the big ones out of my truck. 


My starting blocks:



How I got them on the trailer:




That's big pipe!


Thanks for any advice.

post #2 of 15

well here is what i think 1/2" is overkill the weight is going to be excessive ,if you want  a backyard pit you will need to mount trailer tires on it to carry the weight  as far as the fire box you can use the main cooking area for cooking also just put a piece of expanded metal on the bottom for charcoal or wood  and cook burgers or whatever this will keep your weight down another option is get a jet ski trailer and build you pit on that, this is what i did i had a smoker that was designed for a backyard the wheels were too small and it was difficult to move around ,if you have the room in your backyard this would be a great option then you could trasport it anywhere if you needed to hope this helps.

post #3 of 15
Thread Starter 

I had a couple of people tell me 1/2" was overkill, but if that's what I got for no cost, should I use it or try to downsize? Is the weight or size really prohibitive? Anybody know how to calculate the weight?


If you use charcoal in the cooking chamber, any special technique for cleaning out? Add a door at the end or just shovel it out through the "regular" door? Is there enough room to do this with a reverse flow?


Thanks for the input. I appreciate it.

post #4 of 15

jsi- About that 1/2 inch thick pipe; here's my thoughts; 



1-That sucker is going to take a lot of fuel to reach your desired cooking temps.

2-Going to be heavy to haul around



1-Once you reach thermal mass, your recovery times will be very quick (recovery time is the time it takes the smoker to return to your target cooking temps after you open and close the doors)

2-Going to be so heavy that the bad guys will have to really thing twice before stealing your cooker.



This is another RF build that I'm looking forward to~



post #5 of 15

Right on Dutch with your pros and cons. 

Justsmokeit, if 1/2" was free, then that's what you got, free is always good.  I like the idea from DoubleRR with the jetski trailer, that would work well.  Or Harbor Freight sells a cheapo trailer that might meet your needs, since you probably won't be taking it out for a spin except in your backyard, or you could have your welder custom build you a trailer that could be small enough to move around your backyard. 

As far as cooking with charcoal inside the main chamber of a RF pit, you can, I would worry about burning off some of the good seasoning that your trying to build up inside.  A better idea would be to incorporate a open top for your firebox with a drop in grate for charcoal cooking.  Make a charcoal basket that can adjust on some slides in the firebox higher or lower depending on what kind of grilling your looking to do.  A number of pit builders incorporate this into their fireboxs.  

post #6 of 15
Thread Starter 

I found this weigh calcualtor online. It basically says the weight for 24" diameter 1/2" pipe is 125lbs per foot. That sound correct? 



post #7 of 15
Yes, that's about right for the weight.

I would use it and be glad to have it. Free stuff is good stuff.
post #8 of 15

justsmokeit i have a clean out tool that is a plate cut out to the curve of the pipe with a handle works good ijust scape into fire box then out into a bucket ,good luck with your build, i agree to use what you got metal  prices are really high right  now aside from the weight issue your pit should cook excellent and hold in the heat well using heavy pipe post some pics when you get started

post #9 of 15
Thread Starter 

I have been using the BBQ calculator to figure out some of the options based on teh material I have.  I was having trouble figuring the fiebox opening. I used the excell calcuator, but it says just 1.72 inches high and 20 inches across on a 30 inch pipe. Sounds short/small to me. Seems like the ones I have seen are bigger. Any input on how to measure or place a round firebox?


30x52 cooking chamber (36738 cubic inches)

24x36 round fire box (16285 cubic inches)

5 inch 41.9 inch chimney

8 inch diameter fire intake (48.86 square inches).

Firebox to cooking chamber opening, half moon 18.21 inches (130.28 square inches)




30x52 cooking chamber (36738 cubic inches)

30x24 round fire box (16964 cubic inches)

5 inch 43.22 inch chimney

8 inch diameter fire intake (50.89 square inches).

Firebox to cooking chamber opening, half moon 18.59 inches (135.71 square inches)




24x48 cooking chamber (21703 cubic inches)

24x24x24 square fire box (13824 cubic inches)

5 inch 35.22 inch chimney

8 inch diameter fire intake (41.47 square inches).

Firebox to cooking chamber opening, half moon 16.78 inches (110.59 square inches)



post #10 of 15

I used a round firebox on my build. It was 30" also. When calculating the opening to CC you have to put half the opening in the calculator as segment height. If you have a 9" vertical opening between the two, put in 15" radius and 4.5" segment height and then double the segment area. In this example it would be 66.487 x 2 = 132.974.


Here is a pic from my build of how it looks from inside the cook chamber under the RF plate.


It is not complete, but you can see how I put it together here.http://www.smokingmeatforums.com/t/133841/rf-smoker-planning-and-the-build

post #11 of 15
Thread Starter 

Thanks. Sounds like exactly the info I needed. Met with my pit builder last night. Based on the materials I have, he recommended going with the 30 inch round firebox.  I think this measurement will work for me...


Thanks again for the help.

post #12 of 15

No problem, glad I could help.

post #13 of 15
I am building my first ever smoker and I am doing a reverse flow. I am building it from a 500gal propane tank I got for free from the propane company I work for. It is an odd shape it is shorter in length and bigger round in diameter. In the calculator do I figure it in the cylinder or the tank part?
post #14 of 15

I don't want to hi-jack this thread. I suggest you start a new thread. Measure your tank, diameter or circumference (around the outside) and length, we can calculate volume from there....post a few pictures, they always help. See if tank has manufacturer plate that's good info to know as.well.

post #15 of 15
I'm new to forums and thought I was starting a new thread lol sorry. Thanks for the help. I'm going to measure it and put up picks
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