# Reverse flow smoker in Lexington nc

Discussion in 'Reverse Flow' started by bigtodd, Apr 19, 2014.

1. ### bigtoddNewbie

Hello everybody I'm new to the smf. Looking to build my first smoker with a buddy if mine. I have a 260 gallon tank I snagged for free and a trailer I bought for \$75 it's a little big but the wheels in my head are spinning as what to do with the extra space pics will follow as we build I know the basic concept and design just need some info and ideas please

My tank is app 7' by 36".
I ran a quick number my fb will be 24x24
As I have read many of yals threads my fb opening and the gap at other end need to be the same
My question is does my cooking plate have to be a certain distance from my cooking surface and from bottom of tank
Does my cooking plate need to be a certain distance from actual cooking area

Any and all help is appreciated in advance

2. ### daveomakSmoking GuruOTBS MemberSMF Premier Member

Your FB needs to be at least 30x30x30 .... to meet the 1/3 CC size recommendation

4. ### ribwizzardMaster of the Pit

He's talking about a 260 lb propane tank, not gallons.

6. ### bigtoddNewbie

Sorry guys it's a 325 gallon tank again I'd appreciate any help as far as placement of heat plate and cooking grill. I know I not not calling them correct forgive me this is first tw posting something not net and so excited to be building a smoker

Also is there a certain size opening I need on fire box?

7. ### lendecaturalSmoking Fanatic

No problem, it just didn't compute there for a minute. Click on this link.

http://feldoncentral.com/bbqcalcula....87&fi=6,3,0,81.00,4.50&fc=16.59,23.45,216.00

It shows you need a firebox to cook chamber opening of about 216 sq-in; however, it is recommended to use 1.5 times that value to assure it will flow well. Therefore 216 x 1.5 = 324 sq-in needs to be the size of the cutout and the area under the cook chamber plate. To get that number, you need to cut the tank opening up about 12" from the bottom when you look at the tank from the end. If you put your cooking grates on the 9 o'clock or at the tank midpoint (18" up), there will be 6" of clearance from the grate to the cooking plate. You need the same 324 sq-in at the opposite end of the cooking plate from the firebox for the air to make the turn towards the cooking grates. The calculator link shows the exhaust pipe size needed and you can play with the inlet dimensions to make the vents work like you want, but I plugged in 6" x 3" as an example and you would need 4 and a half of them, so go with five, three low at fire grate level and two in line with the cutout to the cook chamber. Play with the firebox intake box so you get them like you want. There are lots of really nice examples of both round and rectangle within some of the builds. Hope this helps and keep us posted on your progress. Nice score on the tank!

Len

8. ### bigtoddNewbie

Thanks a bunch Lin is there a magic spacing from the cooking plate to the actual cooking surface

9. ### bigtoddNewbie

Sorry Len for misspelling your name

10. ### lendecaturalSmoking Fanatic

No problem and no magic number, 6" will work just fine.

bigtodd likes this.
11. ### bigtoddNewbie

So Len you're saying go up 12" from bottom and cut the Entire half moon shape to bottom and that's my fb to cc opening and I'll need the same on opposite end

Question on future item. What if I don't get even heat across my heat/baffle plate

12. ### daveomakSmoking GuruOTBS MemberSMF Premier Member

Todd, morning...... We need some dimensions of the tank (Cook Chamber.. CC) to get you some good numbers for your build...

Dave

13. ### bruno994Master of the Pit

BigTodd welcome to the wonderful world of smoking on a RF pit!  Anywhere from 4" to 6" should be fine on the gap between your reverse flow plate and bottom grate.  Mine is 4 1/2" and works just fine.  At a 250 center of bottom grate temp, a 12 to 15# brisket cooks to toothpick tender in less than 8 hours (panning and wrapping after 4 hours).  Looking forward to your build!

As far as even heating across the pit, the thicker the RF plate (at least 1/4"), the better.  Mine will run around 10 degrees hotter towards the firebox end depending on the size of fire I have going in my FB, which is nothing.  For the most part it stays within a few degrees.

Last edited: Apr 22, 2014
bigtodd likes this.
14. ### bigtoddNewbie

Thanks for the info guys. This is my first rf smoker. I've cooked bbq shoulders briskest and chicken for about 18 years in my previous life lol now I'm doing this on my and for fun my cooker will be used mostly for church functions I've started a boys group called ACTs (apostolic Christian troopers) hope to raise money for them if this on goes well I'm gonna build a home model

15. ### bigtoddNewbie

Hey Dave my tank measurements are 87" long with a circumference of 96" which I think will be a diameter of 30" so my ha daughter says lol my gas man says it's a 325 gallon tank.

16. ### daveomakSmoking GuruOTBS MemberSMF Premier Member

Closer to 250 gallon empty, holding 200 gallons propane..... (20% margin for expansion)

That changes some stuff..... Back later....

17. ### bigtoddNewbie

Hello fellow smokers just want to clarify my opening from the fb to cc is go up 12" from bottom and make a half moon shape cut out since my tank is round. I just bought a sand blaster and hope to get that done this week end and also my cut outs pics to follow soon

18. ### daveomakSmoking GuruOTBS MemberSMF Premier Member

FB/CC opening...245 sq. in. ... seg. height 12".... use a radius of 15" for the semi circle, same as the tank..... RF plate 29" wide..

And the tank is 250 gallon based on your measurements...

Great info

20. ### bigtoddNewbie

Does any one know where I can get handle guards for handles