24” x 72” reverse flow

Rollinsmoke · Post by **Rollinsmoke** » October 13th, 2019, 11:53 am

My first time building a smoker. Going with a reverse flow. CC will be 24”x72” and the firebox will be 24”x24”x24”. Hoping somebody can help me with the throat size. Having a hard time understanding the numbers on the calculator. Lol. Eventually it will be mounted to a trailer. I was reading somewhere that the baffle plate should be 5” below the cooking grate. If that’s the case I hope I can do a reverse flow with the cook chamber only being 24”. Any and all advise will be greatly appreciated.

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towtruck · Post by **towtruck** » October 13th, 2019, 4:44 pm

According to my calculation using the calculator here you need 110-111 square inches of throat opening. An opening 10"x 10" will get you 100 sq. inches. There are cals here to find the area of a quarter circle. You will need to make sure you get to that 110-111 number. Have the top of the fire box and the BP plate the same height and make the opening into the CC have a small lip on the bottom to catch any grease that may get under the plate and keep it out of the firebox.

I got a 4" stack diameter at 55 or so inches tall and two fire box openings of 2"x 10" for intakes.

I have not played with the other calculator for the quarter circles so mess with that a bit and see what shakes out.

edit...if your a hands on guy and not a math wiz tape two pieces of printer paper together end to end and grid them off with one inch squares. Hold that paper up to your 24" pipe end where you think you might want the BP to go and draw a line around the paper where the pipe meets it. Count up all the whole squares and then add together all the partial squares and see if you get to 111 sq. inches. It might take a few tries.

Post by **Big T** » October 13th, 2019, 9:45 pm

The range is 2-6 inches clearance between the BP and bottom rack. I prefer the 3-4 inches myself but anywhere in there will work. The closer to the BP the more radiant heat you'll get so it's possible to cook the bottom of your food before the top, too far away and you lose the benefit of the radiant heat.

Post by **Pete Mazz** » October 14th, 2019, 4:16 am

Rollinsmoke · Post by **Rollinsmoke** » October 14th, 2019, 6:09 pm

Awesome thank you guys very much. Next question, is 24x24x24 a good size for that size of a cook chamber. I just want to make sure I get everything right.

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Post by **Big T** » October 14th, 2019, 7:04 pm

That size FB is 127% of the recommended size, 115% is the max that you should go. If you go 24x24x20 that's 106% 24x24x21 is 111% 24x24x22 is 116% , the 106% FB calls for a 92 sq inch throat, the 111% Fb is 97 sq in the 116% Fb is 101 sq in throat.

Rollinsmoke · Post by **Rollinsmoke** » October 19th, 2019, 8:57 pm

Thanks for all the help. Here’s where I’m at so far.

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towtruck · Post by **towtruck** » October 19th, 2019, 9:27 pm

Coming along!

Post by **Big T** » October 20th, 2019, 8:47 pm

Rollinsmoke · Post by **Rollinsmoke** » October 21st, 2019, 11:09 am

Something I didn’t think about, if I use the top of my firebox plate as my BP I won’t be able to do 24x24x24. I’ll have to make some adjustments and go from there. Once I get those measurements I’ll have to get your guys opinions.

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Rollinsmoke · Post by **Rollinsmoke** » October 22nd, 2019, 10:57 am

Ended up going 24x24x21 which would be 111%. Thanks Big T for those calculations

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Rollinsmoke · Post by **Rollinsmoke** » November 14th, 2019, 11:39 pm

It’s coming along. Hoping to get a lot done over the weekend

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towtruck · Post by **towtruck** » November 15th, 2019, 11:49 am

looking good

Dirtytires · Post by **Dirtytires** » November 15th, 2019, 8:02 pm

Great!

Rollinsmoke · Post by **Rollinsmoke** » May 7th, 2020, 9:32 pm

Haven’t got much done since the last post. Work got in the way of any progress. I was able to get the trailer ready. Any ideas on mounting the smoker to the trailer?

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Dirtytires · Post by **Dirtytires** » May 8th, 2020, 9:07 am

Personally, I would cut out all the center supports and then build in what I need. Easier than trying to tie into the angled pieces that are on it.

Post by **Big T** » May 8th, 2020, 6:40 pm

On my first trailer build I worked it the math for the height I wanted my main cooking grate, subtracted my trailer height and then I built the stand that it’s mounted on. Once my pit was completed I sat it on the trailer and moved it back and forward until I got the tongue weight that I wanted. Then I welded the crossmembers to my frame rails. I have come to find that the FB is usually really close to the axle if you don’t have any extras built on the front of your trailer.

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Rollinsmoke · Post by **Rollinsmoke** » May 22nd, 2020, 11:58 pm

Ended up redoing the trailer and putting a floor on it. Then cut the saddles to set the CC in place.

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Dirtytires · Post by **Dirtytires** » May 23rd, 2020, 10:46 am

Looks like it’s going to turn out pretty slick.

Mankussm · Post by **Mankussm** » May 23rd, 2020, 4:43 pm

That looks great. What kind of trailer was that (boat, jetski)? Was the trailer non-galvanized steel?

I like the diamond plate floor that you put on it. That will look awesome when finished.

Rollinsmoke · Post by **Rollinsmoke** » May 23rd, 2020, 9:15 pm

Thanks guys. It was a boat trailer. It was not galvanized unfortunately. I had it sandblasted and a coat of primer put on it until all the fab work was done, then it will all be painted at once. Here’s a picture of it before anything was done.

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Post by **Big T** » May 23rd, 2020, 11:25 pm

dacolson · Post by **dacolson** » May 25th, 2020, 10:10 am

I have a trailer to tackle for my current build. Did you sandblast yourself or take it in?

Rollinsmoke · Post by **Rollinsmoke** » May 25th, 2020, 1:59 pm

I took it to a guy here in town that does it. He was able to flip it on its side and get the bottom.

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Rollinsmoke · Post by **Rollinsmoke** » May 26th, 2020, 9:47 pm

I’m trying to figure out what size I need for a stack. I have a 6” pipe just not sure what length I need. Tried to use the calculator, doesn’t seem to be working for me. Can you guys help me out

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