Retrofitting small cabinet smoker

[Saskattak]

Hello. I am rebuilding a old propane smoker into a higher temp smoker using lump instead of propane. Are there any resources where i can figure out my draft design? EverytIbhave found is for offset/RF type smokers.

Hoping to use this for things like wings, spare ribs and other small appitizer type cuts of meat.

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[Dirtytires]

Not sure of any resources for a propane to charcoal conversion but I’m sure we could help out with a few ideas if you posted up a detailed sketch of your intended pit.

[Big T]

I agree with DT, if you could post a picture of the smoker that you're trying to convert or a simple sketch of what you have, someone may have some ides to help you out.

[Saskattak]

Here are some photos and the dimensions on a sketch. The green i the one photo is tape over the oem vent. I'd like to close them off and run a centered stack.

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[Pete Mazz]

Looks like the existing would be enough exhaust.

[Saskattak]

Wouldnt a top center stack be a better location for draft? My thinking is that the heat/smoke will go evenly across the racks. I may be wrong to. For the bottom i was thinking a pipe coming off the bottom that 90s out to the front where i have a slide on the end. Thinking 2" pipe, would that work?

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[Dirtytires]

You could just cut your air vent into the door or on one of the sides making it as low as possible. A bottom I take would work but risks getting clogged with ash as it falls. You will need to plug up all the original air vents as most propane setups have a ton of them.

You are most likely going to run charcoal, right? I would put in a basket and get a inch off the bottom for a bit of airflow and better burn.

Wouldn’t touch the top vent till you run it a few times. Your idea of a pipe off the top would definitely work but not sure the existing setup needs altered as it is already exiting at the very top of the chamber. Can always fix it if needed.

Thinking your pit is going to be hot...might consider a plate on the bottom of the cook chamber to even put some of the initial heat blast.

Just my thoughts.....

[Saskattak]

I did actually build a firebox already. Bottom vent idea was goint tonhave th pipe protrude up under the box with a cap and slots cut around it. Centered draw tonthe firebox and ashes can drop into it. Just was the sizing, thinking 2" exhaust 90 deg bend (wife works for an auto parts store so these are super cheap).

As for other vents, the bottom was almost cutout completely then replaced with 3/16" plate tight to the edges. Only the one top vent know. I also sealed the doors with a felt gasket from Island Outdoors (firebox rated). This thing should be airtight now lol.

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[dacolson]

I think a simple rectangular vent right at the base of the side or door with a sliding cover would get you plenty of air right under the coal bed. Less materials, easy to control and access. Pipe idea is cool though.

[Brisket Envy]

Just some off the cuff ideas:
I would make that bottom 25% the fire zone, with a loose plate sitting on a couple of rails at the 7 1/2” mark. I would make the plate 14x13, and start with 1” space all around. If you leave the exhaust where it is, you might want to slide the plate back a bit, because the heat at the back will have a tendency to slide right up the back, and out the exhaust. Sliding the plate (heat shield or baffle) backward would mitigate that somewhat, depending on whether you leave a 1” gap at the back, 1/2”, or 1/8” gap.
Additionally, I would weld deflector strips (or sideways angle) around the inside walls, about1 to 1 1/2” Above the level of the plate, to help redirect the smoke/heat toward the center of the cooker. The plate can be used to sit a foil pan on for water, if desired. The plate will need to be at least 3/16” thick, 1/4” would be better. I built a couple insulated cabinet smokers and would place charcoal around a split of oak, to make kind of a consumable minion style path for the charcoal, and had excellent results with both smokers that I did that way.
The two I built were reverse flow vertical cabinets, but am pretty confident good results could be had in a direct- flow such as yours.

[Saskattak]

I think a simple rectangular vent right at the base of the side or door with a sliding cover would get you plenty of air right under the coal bed. Less materials, easy to control and access. Pipe idea is cool though.

Moving to side vents. I over think things at times.

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[Saskattak]

Just some off the cuff ideas:
I would make that bottom 25% the fire zone, with a loose plate sitting on a couple of rails at the 7 1/2” mark. I would make the plate 14x13, and start with 1” space all around. If you leave the exhaust where it is, you might want to slide the plate back a bit, because the heat at the back will have a tendency to slide right up the back, and out the exhaust. Sliding the plate (heat shield or baffle) backward would mitigate that somewhat, depending on whether you leave a 1” gap at the back, 1/2”, or 1/8” gap.
Additionally, I would weld deflector strips (or sideways angle) around the inside walls, about1 to 1 1/2” Above the level of the plate, to help redirect the smoke/heat toward the center of the cooker. The plate can be used to sit a foil pan on for water, if desired. The plate will need to be at least 3/16” thick, 1/4” would be better. I built a couple insulated cabinet smokers and would place charcoal around a split of oak, to make kind of a consumable minion style path for the charcoal, and had excellent results with both smokers that I did that way.
The two I built were reverse flow vertical cabinets, but am pretty confident good results could be had in a direct- flow such as yours.

Thanks for this! I was going to put a plate above the basket at the same height you mentioned. For the vent I ws thinking of sealing the oem back vent and putting a center one as noted above. But pinching the diffuser plate at the back would alleviate that some what. And the deflector plates are a great idea, will add them to the design.

For my firebox vents I am thinking a 3-4" opening on either side with a slide style door for tuning. Cut them low in the firebox.

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[dacolson]

I think you're on the right track.

[Pete Mazz]

A vent at top above the food may introduce some nasty dripping onto the food.

[Saskattak]

A vent at top above the food may introduce some nasty dripping onto the food.

I never thought of that, thanks for bringing it up. I will pilot it with the current OEM back vent. I will tighten the gap along the back when the deflector plate is adde and add deflector plates as mentioned above and see what happens .

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[Saskattak]

I finally did a test run without the deflector plate. It wrapped my thermometer but im guessing into the 500s with a full hot firebox and top vent open and firebox door open for 5 mins. Back vent was shut and it dropped to 300 and stayed there for hours. Again no other vents (less minimal air gap on bottom plate I sent inside to cover hole from corrosion) and no deflector. I have since built the firebox deflector plate and need to build side vents next.

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[dacolson]

Nice test. Promising. Did you have to keep the FB door open?

[Saskattak]

Nice test. Promising. Did you have to keep the FB door open?

Thanks. No, I shut the firedoor after it was rocketting passed 300, then it went beyond the range of my temp gauge. Once shut it slowy dropped. I actually just finished cutting my 2 side vent holes and will be adding 1/2 a chimney of hot coals to see what that does. No covers on the vent. Also gonna start seasoning it now to.

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[Dirtytires]

500 degrees is way too hot for a smoker and you may start to see warpage at that range. Start your fire small and don’t let it get out of hand. As you found out, it can quickly get hot but takes a long time to get it back under control.

[tinspark]

I have to start my center feed with no more than 12-15 charcoal briquettes from a charcoal chimney, then I add a few 2 half fist sized splits in order to keep my temps down. For my initial test fire I used a full chimney of charcoal briquettes and my temps spiked to over 400 deg. F. before I opened my lid and let the heat out until my blazing inferno cooled. Once I figured out how small of a fire to keep, things worked really well, The only thing that I noticed with such a small fire, is that I am feeding it about every 1/2 hour instead of 3/4 hour in order not to lose my small coal bed..
Fire management will be key for your too. The upside is that you will likely use less fuel

[Saskattak]

500 degrees is way too hot for a smoker and you may start to see warpage at that range. Start your fire small and don’t let it get out of hand. As you found out, it can quickly get hot but takes a long time to get it back under control.

I know, but thanks for the tips. This all function tests if you will to see where it will go. And I also understand what thermal energy does to carbon steel in the form of distortion. This little smoker isnt made for sustained high heat. I ran a half filled basket with my two 2"x3" vents cut and it got to 350 easily. So know I know where it will get to or sustain.

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[Saskattak]

I have to start my center feed with no more than 12-15 charcoal briquettes from a charcoal chimney, then I add a few 2 half fist sized splits in order to keep my temps down. For my initial test fire I used a full chimney of charcoal briquettes and my temps spiked to over 400 deg. F. before I opened my lid and let the heat out until my blazing inferno cooled. Once I figured out how small of a fire to keep, things worked really well, The only thing that I noticed with such a small fire, is that I am feeding it about every 1/2 hour instead of 3/4 hour in order not to lose my small coal bed..
Fire management will be key for your too. The upside is that you will likely use less fuel

Nice! It appears after yesteday i will need to add fuel for longer cooks BUT this isn't for that. This is for wings and riblets and other smaller appitizer type foods I own 2 Weber WSMs and am building a Legacy 4800 reverseflow from these great gents at Smoker Builder. I just like cooking options lol

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[Rodcrafter]

I understand liking the cooking options statement. We have called it the "bug" around here, once people catch the bug they build all sorts of cooking stuff. Yes, I'm speaking from experience.

[Saskattak]

I understand liking the cooking options statement. We have called it the "bug" around here, once people catch the bug they build all sorts of cooking stuff. Yes, I'm speaking from experience.

I have the "bug" for a few things in my life. The wife wants to spray said bug with a whole bunch of Raid I am certain. But she hasn't as of yet!!

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[Rodcrafter]

Oh that sounds familiar.


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