Questions on a Reverse Flow Smoker Grill

[426Hemicuda1]

I've been intrigued with the theory and Reverse Flow idea for the smoker / grill, on a horizontal unit, with the fire box. I've got some questions, so please bear with me and please respond if my assumptions are right or wrong. I'm looking at building something similar to one of Bob Lang's hybrids, but to have a 20" diameter x 36" to 42" long horizontal, with a fire box, the fire box will also have a vertical box for warming, slight smoking. The inception of the reverse flow idea verses the tuneable plate idea in the barrel is what intrigues me. I've often thought WHY NOT create a pit that can be converted to either. First, am I correct in that the tray that covers & sits above the inlet from the fire box, should be sealed or sit in a set of channel tracks with the end opening the same size or slightly larger than the inlet opening from the fire box? Second, the tray that serves as the reverse flow plate;.....can it also serve as a drip pan &/or water tray for keeping the humidity when smoking using the reverse flow method? IF SO, then why not make the tray with hang-over lips to fit into a channel at the sides and end over the inlet (thus sealing out smoke pass-thru); yet have the tray have a recessed area of about 2" or so, with the thru-grill exit pipe for draining the tray of liquid with a ball valve at the end of the exit pipe, mounted at the end. Is it feasible to use the tray as a water tray, or to drop in some fruit juices or RC Cola, to aid in the moisturization during the smoking? If this is feasible, shouldn't the liquid you use in the tray/pan be ambient, so that it wouldn't suck heat away from the interior, and would come up to smoker temperature faster (or even slightly boil)??? I really would appreciate some thought on this one.

However, if you reached under the tray at the end where the smoke would escape and had the thru pipe mounted there, using a pipe coupler, instead of a solid connection; it would or could be easy to disconnect the coupler and remove the reverse flow tray from the pit entirely; and replace it with either tuneable plates/deflectors for a tuneable pit design, OR some drop in trays half the width of the horizontal unit, to serve as charcoal holders, should you want to use the horizontal unit as a grill (be it small with one tray, or large grill using both trays). Using this theory, you could wind up with a reverse flow smoker using the fire box with lots of stick produced heat & smoke, OR, a tuneable plate smoker with a side fire box, OR a small or large grill, for those days you just want to BBQ. Does this sound feasible? Thanks in advance.

[Frank_Cox]

On a small pit like you are talking about, you will not have too many troubles doing that kind of setup. because it is smaller in size it is very forgiving. Now if you were to get into a large pit you may have some control issues depending on your cooking preferences.
I always say "depends on your cooking style"
For starters, Most important thing to remember when you are talking about anything removable in the cook chamber is the grease and juices from the meat. You got to keep them from building up and draining into the firebox which could cause a grease fire.
Next, The tray you are referring to in the cook chamber, we refer to it as the Baffle plate, is used as a heat sync to help even out the temp in the cook chamber. this is done by building up heat and then radiating evenly. If you put water or juice in the baffle plate and fill it up, it will come up to temp gradually but will take a long time to come up to temp once it finally does (212*F at sea level) it will quickly boil off and need to be re filled. once you refill it you will start the process over again and the pit temp will drop a lot. thus you will lose control of the pit. if infact you then forget to fill the pan back up about every 45 minutes or whatever it would take then the pit would run out of water and skyrocket out of control. for this reason I do not recommend using water directly in the plate. Instead, use a pan of water placed on the plate which will produce the same result of more moisture in the C.C. without the other problems.
as far as the Gap in the plate goes, it just depends on the "tune" you want for your cooking style. I design all my smokers at a tune that I feel works best for me. here's a basic run down how it works....
Bigger plate gap= less restriction under the plate=less time the flue products spend under the plate= less heat transfer to the plate.
smaller plate gap = more restriction under the plate= more time the flue products spend under the plate= more heat transfer to the plate.
IMPORTANT= too small or too big of a gap leads to improper combustion on the small side or no control on the bigger side.
WINDOW OF TOLERANCE- big side= size of firebox to CC opening
Small side= size of smoke stack diameter in square inches.

Hope this helps! Did I answer all your questions?

[Gizmo]

Since you brought it up Frank - I've always wondered why someone couldn't put on a drip-oiler (converted for water) and deliver water a drop at a time to the baffle plate via 1/4 inch copper tubing to get the moisture into the cook chamber? No heat loss - boils on contact - nothing inside the cabinet to refill... as long as it doesn't boil in the tube ...

[Frank_Cox]

Rick- You could do that no problem. just need to keep the end of the tubing clean of lime build up and never have the water feed in a closed container! I don't think the water in the tube would be able to boil off because it would have water at or below the boiling point right above it....

[The Czar]

....you guys make my head hurt.....

[Smokeone]

[maccas66]

Cuda.........I think so!

[426Hemicuda1]

I've been looking pretty hard at a Rankam Farmer's Grill, with a RiverView label on it, sold @ Home Depot. They've got one they call "beat up" I can get at a steal. I went by this evening and took the measurements. The fire box is 18.75" wide x 18.5" long x 20" high. The Round drum grill part is a 20" drum x 42" long, 1" lips on the ID on each side to support the porcelian grills. I hate those grills, and intend to immediately replace them with 9 gauge x 3/4" Stainless expanded metal grills, with 1x1 304 tube borders. The one thing I didn't care for is the opening between the firebox & grill drum. 10" high x 11.5" wide, football shaped, I almost think this thing ought to be re-sized smaller to a half moon shape. I did note that this thing bolted together, and I can easily fix that with some seal welding. I saw a thread on this site that showed some real neat tuneable plates, (3/8" thick, sitting on some angle, with a square tube guide at the bottom). I'm thinking about doing this sort of conversion, with the tuneable plates mounted as low as possible, but higher than the firebox to grill opening. I was going to build some 2" deep drip pans that could sit on top of the tuneable plates, to catch the grease & drippings. Unfortunately, this unit has a far left side flue exit with 4" diameter pipe x 12" long. Moving the exit back to the right side, above the fire box is possible, but it will cause the elimination of the top opening lid of the firebox & FB grill, no real problem, it can be fed from the side. The Firebox has no carcoal box to speak of, so I'm making one similar to a milk crate, built from expanded metal with a standard footing grate below. The milk crate style charcoal box will have 1x1 square rod at the corners and around the top border. One side will have a dipped "U" shape, which will face the FB door, so once the door is open, stick slivers can be dropped in without pulling the fire box charcoal box out of the door. I intend to put some 9" x 4" x 1.5" fire brick inside the Firebox, for the grate to sit on, and if I can arrange it inside the grill, under the tuneable plates, i'll do that too. Once that firebrick gets heat into it, it holds it quite well, and that should lead to more even heat temperatures??? With the Stainless flattened expanded metal grills (I may add a top slide-in/slide-out grill), tuneable plate, re-located chimmney flue, fire bricks, drip pans, etc. I should end up probably matching what the thing cost, but hopefully, this should work quite well, if what I've read on here about the styles & types are true. Any comments, suggestions??? Please keep sending them!!! I think I'll let that full reverse flow idea with the solid plate, float for a while.

QUESTION: SHould the tuneable plate style ALSO have a chimney flue mounted on the same side as a Reverse Flow style grill/smoker, or does it matter on the tuneable plate's grill chimney flue location???

[Buck]

Here are some considerations if you want to be able to run your cooker reverse flow and standard offset (tunable plate). First, you are going to need a stack that your can seal really well on both sides. If the heat/smoke is going out the wrong stack, it's not going across your food. If you are going to make removable tuning plates, you are going to need to make the gap between them as close to air tight as possible (when you run your cooker as a reverse flow) if you want to have your cook chamber close to the same temp on both sides. I tried a temporary baffle plate on a reverse flow with a less than 1/16" gap at the firebox end and all the heat went straight from the firebox to the stack and I couldn't get the cooking chamber hot enough to smoke. Sealed it up, cook chamber got hot. If I was you, I'd save myself a ton of headaches and just go reverse flow but what you want to do is possible so if you want it both ways, do it ... but plan well.

As far as the stack on the firebox side goes, you can have it come out the top of the cook chamber instead of the side and keep the firebox as it is. I would make sure the firebox is about 1/3 the size of the cook chamber ... if it isn't close to that, you'll need a plan to somehow make it bigger if you don't want to be constantly fiddling with it during cooks.

As far as converting a store bought smoker, you need to think of what you're going to end up with when you're finished. I just did a bunch of mods on a cheapo char-broil (check out my thread ... should be able to find it by looking up my profile and looking for my most posted topic) and it works 20x better than it did but I still have a cooker with a cooking chamber that is too small for more than 10 people and has metal that is too thin. It works real well but uses a ton of fuel and needs to be re-fueled often. I did this build with learning in mind more than the final project so it was well worth it to me but if I had have put the money and time into a build, from scratch, I'd be 3/4 of the way into something that has no compromises. Also, the thin metal on the cheapos is a huge pain to work with. I ended up with some really gnarely welds in a few places. I was planning on making the existing firebox bigger but ended up making one from scratch after working with the metal it was originally made of. If it's under 12 gauge, you may want to consider something else. Just some things to think about.

[Gizmo]

I have to agree with Buck here - he makes some very good points.
There is enough free knowledge on this site alone to get you right where you want to be and all of your money and effort will go directly into a better finished unit.
Whatever you pay for the store-bought unit should be compared directly to what you can buy a tank for that's heavier steel and a longer life product that's a lot more readily worked into what you want.
You might finish it up quicker by going the store bought route but I'm afraid we're talking about saving a couple weeks now for a unit that your grand-kids should be using.

I'll get off my soapbox now - just my opinion ...

[Smokeone]

[DUAYNE B]

what does all of this have to do with square dancing,,,,,,,,,,,,

[Gizmo]

I was thinking the same thing Duayne...!