# New build ?

Discussion in 'Reverse Flow' started by tgrimmett, May 21, 2014.

1. ### tgrimmettFire Starter

I am goin to build a reverse flow offsett smoker. My cc is 67in x23 round ,my fb will be 24x24 square . My question is were does the rf plate need to be right at the opening or a few inches above, an does it come straight across or does it need be angled. An my chimney does it need to go out the top or down a few inch inches on the cc.

2. ### daveomakSmoking GuruOTBS MemberSMF Premier Member

tg, evening...... Below is a calculator for proper sizes.... Ignore the FB size calculation.... it is a minimum and your FB is perfect...

..... click on pics to enlarge .....

Used to calc. the FB/CC opening and area under the RF plate and the width of the RF plate...

http://www.1728.org/circsect.htm

Work out what ever details you can...... Question everything.... and we will help when ever you have questions.... From your post, you have looked at what has been built here.... lots of good info and ideas.....

Dave

3. ### tgrimmettFire Starter

Thanks a lot, I'm goin to try to get started this weekend I'll let you no how it goes

4. ### tgrimmettFire Starter

Ok I I figured out the height in cu inches how do you figure out how many inches it is I'm not to good at math lol

5. ### tgrimmettFire Starter

Also Dave, does the fb to cc chamber have to be half moon shaped can I just cut it square or is it better moon shaped.

6. ### daveomakSmoking GuruOTBS MemberSMF Premier Member

If you look at the drawing of the half moon, using the radius of the CC for the half moon, that lowers the opening as low as can be giving more room in the CC for food racks....

CC = 23x23x0.7854x67 = 27,837 cu. in.
FB = CC x 1/3 = 9278 cu. in. minimum
Stack CC x 0.017 = 473 cu. in.
FB air inlet = 28 cu. in.
FB/CC opening and area under the RF plate = CC x 0.004 = 111 cu. in.
Stack size and height 473 cu. in. / .7854 x 16 = 4" stack 38" above the CC
473 cu. in. / .7854 x 25 = 5" stack 24" above the CC

FB/CC opening.... 111 cu. in. 11.5" radius..... 7" segment height ED...... Seg. Area = 107 cu. in. ... Chord AB = 21 1/4" for the RF plate width....

Dave

7. ### tgrimmettFire Starter

Thanks Dave that helps a lot .