New guy first time builder 250 gallon reverse flow.

[cclark]

Hey guys been looking at the site for a while now. Learned a lot of great things you guys know your stuff. My name is Cody I'm from east Texas area. Me and my grandpa bought a 250 gallon propane tank a couple weeks ago from a propane place and about to try out our hand at this. Grandpa was a pipeline welder so he will be doing most the welding. I will be doing the cutting grinding etc. my tank is 88" in length and 30" in diameter. I googled a firebox calculator and it said I needed 20724 cubic inches. I do not know if all calculators are the same but does this sound right? It comes out to like 27.4" squared. Another question I have is does the baffle plate have to be a certain thickness like 3/16" or can I get away with 1/8"? We plan on starting this weekend and picking up the plate and other supplies Friday. Thanks for the help.

[Gizmo]

Welcome cclark! - Looking forward to seeing your build...
Mass is your best friend when it comes to the baffle plate so most will recommend at least 1/4 inch - the more massive the steel the better it helps stabilize the heat over time...

The calculations are done by smart smokerbuilders - not me - but they'll be along soon ...

[alleyrat58]

Welcome cclark! Can't wait to see your build! Take lots of pics for DCMAN the "photo czar."

Frank is the guru when it comes to calculations, but off the hip you sound close. I believe the volume of the stack will be of more importance.

I will echo Rick's comment about the baffle plate - go big or go home - LOL. I just put a baffle plate in my smoker, 1/4 inch, and definitely would not go less than that if I had to do it over.

[cclark]

Ok well in that case I may go with 1/4" firebox as well. I'll be sure to post pics of progress.

[Smokeone]

Welcome cclark!
Calculations are not me either, but I think you are close.
I would go with 1/4 for the baffle and the firebox (if it is not insulated). That is just my .02.
Good luck, and dont be scared of DC he is a creampuff.

[cclark]

Thanks guys for the help will be picking up a 1/4"plate tomorrow or friday.

[RDRASH]

Baffle plate should be no thinner than 1/4, firebox should be roughly 1/3 the volume of the cook chamber. Oh take lots of pics or

[The Czar]

..... .....and I will be watching....

[k.a.m.]

Welcome to the site cclark. Your tank size hits on the calculator but your firebox comes in a little small at 27.4. Personally I would increase to 28" square but I like slightly larger fireboxes.
1/3 volume of your tank is 20724.00 while a 27.4 square firebox is 20570.82. A 28"
square firebox will have a volume of 21952.00.
With the 28" firebox the ff/cc opening needs to be 175.62 Sq.in. A half moon of 21.5" x 10" 3/4" will give you an opening of 181.5 Sq.in. The added room will allow for a grease bridge on the bottom to keep accidental overflow into your firebox.
I would use 1/4" minimum for my R/F plate.
Make sure you leave at least your firebox to cooking chamber opening at the opposite end of the of the R/F plate so no bottle necking occurs.
I would add a secondary drain in the lower chamber for clean out.
I hope this helps.

[cclark]

yea i was probably gonna round up to a 28" firebox...a little extra cant hurt. When you say a "A half moon of 21.5" x 10" 3/4" will give you an opening of 181.5 Sq.in" Im assuming you mean 21.5" wide and at the highest point being 10" tall? Just trying to get all this right before i begin. Thanks again

[cclark]

This was the tank when i picked her up. She is airing out and getting flushed with water right now

[k.a.m.]

cclark, yes the cut would be a half circle 21.5" wide x 10" 3/4" tall.

[mdesmond6275]

Sounds Like you and I are on the same page cclark. After some calculations from a pit calculator, k.a.m. is on [as always ]
Here is what I am gonna be doing for mine. My tank is the same size. I thought it was a 350 but looks like it is 250 instead after some research of dimensions.
- Firebox 29 x 29 x 29 a little over according to the calculator but I am gonna chop off a little on the front plate to make it look like an old wood burner.
- 6 inch exhaust pipe 44 inches tall [fatty] if I can find a bigger one I may use it!
- Fire box to cook chamber opening 28 x 7 or 30 x 6 gonna do a rectangular one... if it works! I may have to do the half moon depending on how it fits in my opening...
- Air inlet ports 6 inch calls for 2 ½ I am thinking 4 rather have symmetrical overkill than not enough oxygen to the box. They are gonna be screw adjustable. SO temp regulation will not be a problem.
1/4 inch for the baffle? that sounds a little much to me. I was thinking a little thinner. and by baffle are we talking the plate running the length of the smoker with the drip channel in the center correct? Still figuring this out

[cclark]

yes mdesmond that is the baffle plate....everyone here seems to think you need at least a 1/4" there. At first i was going to try and save some money and go thinner, but after listening to everyone, I am going to go 1/4"

[k.a.m.]

yes mdesmond that is the baffle plate....everyone here seems to think you need at least a 1/4" there. At first i was going to try and save some money and go thinner, but after listening to everyone, I am going to go 1/4"

More commonly called R/F plate or reverse flow plate. Thinner metal works fine on cookers in the 16" to 18" diameter because the heat required to run them is minimal. When you rise into 20" and up the heat required to fuel them is more intense and the firebox box side of the R/F plate takes a beating. I have seen 3/16" plate turn into a roller coaster near the firebox on a 250 build. Between the heat and area to support it cant take it.

[Gizmo]

Well put kam - makes perfect sense ...

[cclark]

Think it Would help to a couple of uprights under the RF plate to help support it?

[Gizmo]

That might be overkill cause if you weld a 1/4" plate around 3 edges there is nowhere for it to go ... just sayin'

[k.a.m.]

cclark, Mine is supported in the middle and end.
I hope this helps.

[cclark]

Tha KAM that does help. I'll do something similar to that. I am not sure on the 28" firebox anymore. If I go 28" I will have a strip of 20" left over. I was hoping to have a big enough strip so that I can use whatever of it I can for the RF plate. So I am now thinking about a rectangular box so that whatever I have left I can use for the RF plate. I realize I'm gonna pick up a few inches with the angle drain setup. What's the width of the RF plate usually on a 250 gallon tank? I realize it depends on how high I put it up. This tank is 30" diameter.Thanks again for the help.

[k.a.m.]

cclark, my plate is set about 4.5" below the 3:00 mark. With the angle iron I am guessing my two plates were about 13" wide. I can get more accurate if you need. I will just have to raise the wings and measure it when I go to my son-in-laws this evening.
Here is a link to my build.
viewtopic.php?f=11&t=270

The build is also posted on the smokering it has a lot of detailed pics but you have to wade through the posts.
http://www.thesmokering.com/forum/viewtopic.php?t=32283

[TuscaloosaQ]

Kam i just saw that thread on your build for son in law it was jam up wish I had found it a long time ago

[k.a.m.]

Kam i just saw that thread on your build for son in law it was jam up wish I had found it a long time ago

Thank You TQ, it was a fun build.

[cclark]

Here's a few pics from this weekend. We laid and cut out the pieces for the firebox...need to get another piece of plate to finish out the top piece. That one sheet off in the distance is going to be the front but I'm not sure how I want to do my doors so I didn't tack it up. Papal is still good with a torch at 70 years old. More to come soon hopefully. May be brave enough to start cutting I to tank this weekend.

[rlmax02]

your off to a great start. good luck with it and keep the pics rollin