Need recomendation on adding RF plates

[castiron]

My smoker has a baffle plate where the heat comes directly out of the fb, because it was to hot right there but I have been contemplating adding an inverted V the length of the cook chamber and stopping it short on the opposite end, so I got on here looking at builds and found that apparently this is done regularly and called "reverse flow".  The firebox is propane to cook with, with a log on top for smoke

1.  How short should I stop it from the end?

2.  Does it need to be a certain distance from the cook grates?

3.  I was planning on laying it in so it could be removed if wanted, since it is 66" long I was thinking of making it in two pieces.

Cooking chamber is 24" dia. by 66" long.

fire box is 24x24x20

Thank you

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• castiron
• May 11, 2013

 

[castiron]

more pic

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• castiron
• May 11, 2013

 

[castiron]

I guess I can only do one at a time.

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• castiron
• May 11, 2013

 

[castiron]

More pics

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• castiron
• May 11, 2013

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• castiron
• May 11, 2013

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• castiron
• May 11, 2013

 

[doodleq]

Dimensionally, your rig is similar to mine. My RF plate is two pieces, the one beginning at the FB end is about two thirds in length, and the other is a third. Each narrows slightly (the narrow ends meeting at a 1.5" gutter with a drain), so they in effect create a valley...downhill from the FB to the gutter, and uphill from the hotter to the end of the plate. I ended the plate about 8" from the end, aiming to have slightly more area open at the end of the rf plate than there is between the firebox and cook chamber. The distance from the grate to the rf plate varies with this slope, of course, but just call it 5" at max. My plate is fully welded in, so the grease is guided entirely to the drain.
Looking at your rig, you'd have to close off two of your stacks, or the smoke wouldn't make the whole circuit and you'd have a "stale" section I'd think. You'd also need to check the volume of the remaining chimney, I believe, in order to make sure you have sufficient flow to keep things moving. You can use the feldon calculator to determine that.
My last smoker wasn't rf, and after even a short time with my new one which is, it's just another world as far as being able to control it. If you want a rf rig, it seems like you have a good starting point. I'd say you're less than $200 and 5-10 hours from being able to make it reality. Good luck and post what you come up with!

 

[castiron]

How did you make your plate is it?  Is it just a flat plate laying in or what?

I've only got 2 stacks and they are 4", so I had figured I'd be keeping the one opposite the firebox closed.  There's a power pole in the background, that appears to be a center stack.

 

[doodleq]

I'll try to get you a pix or a drawing later in the day. I used 3-/16" plate ( or maybe it was 1/4"), and measured the widths just above the FB opening. That was my width on one end. Then I measured the width approximately 1-1/2" lower and that was the width on the other. The two pieces (one longer and one shorter) met in the middle at a downward slope to one another for the drain. These particular pieces I had sheared due to being a bit more difficult to lay out and since I wanted a really good fit for welding, and putting them in and out repeatedly for grinding would have been difficult and time consuming. Worth the $20 in cut charges IMO.

 

[doodleq]

image.jpg

• doodleq
• May 13, 2013

don't know how helpful this will be...this is the 2/3 closest to the FB...22" on one end, 21" on the other. There's a gutter on the short end. The other section is also 22" on one end and 21" on the other, and since it is shorter, has a more of an aggressive incline over it's length...my thought is this would increase velocity on the open end...seems to work.

 

[castiron]

Thanks DQ,

I not planning to weld them, I'll just cut a tight fit, so the grease can run front to back if it wants, but it still may not be a bad idea to taper them to help it flow toward the drain end.  I originally thought about breaking a shallow inverted V in them, but maybe I won't bother.