Whole Leaf Tobacco

Dr. Bob's multi purpose curing chamber in planning

DrBob

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I am a lucky fella. My ferment curing chamber is actually a metal lined upright freezer. The only plastic panel was in the door. I removed that plastic and replaced it with aluminum sheet during the original build. It is insulated with foam and I believe that it is urethane foam which should be safe to 240 degrees as far as I can find.
My ehxaust pipe and control valve is sch 40 pvc this I might need to change, no big deal.
I am still using the water heater thermostat As much as I preached the virtues of a ranco 111000 I never got one for myself. I am thinking now of getting a PID-rs-r-h thermostat as it is programmable. and only costs $79.00 from thermomart. It is designed for temps up to over 1000 degrees and as low as -100 f It is designed for kilns of all sorts.
As far as heat goes I am thinking a magnetic oil pan heater in the 750 watt range. I already have one and I used it in the original testing of my curing chamber. In my testing i just put it on a 12" x 12" x 3/8" steel plate. it performed very well but was replaced by a crockpot as a better solution. I anticipate actual heating needs of 300 watts or roughly 1,000 btuh.

My circulating fans are computer fans they may or may not take the heat. But I could use one as a draft inducer. I picked up a couple of dozen of them for free so I guess I can spare a few for testing.

Deluxe stogie and leverhead have made great testing of the trash can flue curing chamber and meybe with a little help the design can be improved. I got 7 months to get it ready, plenty of time to sort it out

Any advice will be appreciated

Dr. Bob
 

Knucklehead

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The first stumbling block that pops into my numbskull is the door seal. Will the existing seal hold up under heat? What top temperature are you shooting for?
 

DrBob

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180 would be the max. The door seal may have to go. I bet someone may have the answer
 

FmGrowit

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I don't remember ever seeing a commercial refrigerator, cooler or freezer ever being anything but lined in stainless steel. What's nice about a metal liner is you can use the curing chamber for making Fire Cured and Latakia also.

You'll have to drop a couple of bucks for a commercial unit, but I'm sure any scrap dealer would be happy to work with you...maybe make a trade ;)

The door seal can be replaced with an oven seal. It might take a little fooling around, but I'm sure it can be done.
 

DrBob

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I just did a little checking and silicone sponge tape is good to 350 degrees and is available in .500" thick and is self stick to boot. I only need 20' to do the job. The door seal is going to have to be changed. It has alwats been a problem and if I could get some material 1/2" thick by 1" wide I would be good to go
 

LeftyRighty

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My freezer box has a plastic liner. I tried to determine what temperature would soften the plastic using a clothes iron, but test was inconclusive - couldn't accurately measure the temp, but know it's well over 200 degrees.
2nd test was a large 4 gallon pot of boiling water. After 20 minutes (temp dropped to 190), no softening or smell on the plastic. For me, plastic liner are fine for 165-170 degree flue-curing.
 

johnlee1933

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180 would be the max. The door seal may have to go. I bet someone may have the answer
Not quite as elegant would be stove gasket rope. it is not magnetic so you would have to figure out another was to keep the door closed. It is VERY heat resistant and flexible enough to do the job. Until I test my setup I won't know if the magnetic seal will stand up or not. For 3/4" stuff from Amazon it would cost about $20 for the rope. I have some gasket cement so that would not be a problem, -- John
 

LeftyRighty

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DrBob - I wish you well with the dual purpose fermenting/flue-curing chamber. I considered that with mine, but figured I could only get about 100 leaves in this smaller freezer box, and I want more.
My 2nd freezer box is about 23 cu ft - hopefully about 200 leaves.

Am going to set mine up for at least 2 crockpots, if I need that to get enough heat for stem-drying phase. Whether or not the computer fans will take the heat is of concern to me also. Am thinking I'll just set it up to remove them for the final high-temp drying, and use gravitational convection or draft for air exchange.

I really like the Ranco ETC, so getting another for this box.
I am currently cleaning my freezer box, gutting out all the useless refrigeration parts. Plan to set the box on a cheapo Sears moving dolly, so it will be easier to jockey around while working on it.

This freezer box is a chest-type freezer, with a torsion bar spring on the lid - the door pops open when it is standing on it's end. I am going to use draw latches to keep the lid/door closed, and tight against the seal. I did this with the fermenting chamber and it works well.
 

leverhead

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Dammit, I take a few nights to work on my marital situation and you guys want to talk about interesting stuff!

Magnetic seal strip (that came with my fridge and appears to be run of the mill) worked just fine, for me. Physical dimensions are more important than cubic feet, both are important. Being able to get whole green leaves loaded evenly is the trick. The loading density is limited by the available pressure to move air through the load and how to keep the door(s) closed. A thermostat can be made to work, but a ramp function is very desirable.

I'll start a separate thread soon about the detail and changes I made to my fridge, where I've been and places you probably don't want to go. This should be a fun project! If you think harvest and curing can get to be a bit much, getting curing crammed into a week, multiple times is a blast! I think the end product is worth it.

Steve
 

Markw

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My circulating fans are computer fans they may or may not take the heat. But I could use one as a draft inducer. I picked up a couple of dozen of them for free so I guess I can spare a few for testing.

Dr. Bob
Hi Dr Bob I love your chambers. The fan will fall over with the heat the bearings get too hot. When I worked in the hospital they used kilns. The way they got round this was to mount the motors on the outside of the kiln and the fan blades were fixed on an extension rod that went through the kiln wall. they used ceramic wool insulation so it rotated very easily, could be worth a try.

Markw
 

johnlee1933

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Hi Dr Bob I love your chambers. The fan will fall over with the heat the bearings get too hot. When I worked in the hospital they used kilns. The way they got round this was to mount the motors on the outside of the kiln and the fan blades were fixed on an extension rod that went through the kiln wall. they used ceramic wool insulation so it rotated very easily, could be worth a try. Markw
Great idea Mark. A squirrel cage blower with the motor bolted to the outside and the cage screwed to the inside with a short shaft extension might work very well. I'd guess no extra bearings would be required. -- John
 

LeftyRighty

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leverhead ...... how many air changes per minute/hour did you find effective during the yellowing stage? I am trying to figure out number/location of fans. FAC's would be a more effective way to determine this, rather than box size/density, unless you can define appropriate density.
 

DrBob

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here is the deal. I tested my chamber with a 290 watt crockpot and a 100 light watt bulb in my 20 degree garage today. 180 degrees was not a problem. this is a 160 degree rise. I stopped the testing in 30 minutes. nuff said. 200 watts should do the job for flue curing at 70 degrees. A crock pot should handle the job.
 

Markw

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Hi John yes a squirrel cage blower would be fine. If you wanted to get technical and not have any holes in the kiln wall you can use a couple of ferrite magnets as these would take the temperature and make a through wall magnetic drive. you should be able to get them from scrap parts they are easy to make.

Markw
 

DrBob

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Hi Dr Bob I love your chambers. The fan will fall over with the heat the bearings get too hot. When I worked in the hospital they used kilns. The way they got round this was to mount the motors on the outside of the kiln and the fan blades were fixed on an extension rod that went through the kiln wall. they used ceramic wool insulation so it rotated very easily, could be worth a try.

Markw
I like your input mark. I thought about that too. that Idea is a good idea. where can I find one of those long shaft motors for almost free?
 

leverhead

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here is the deal. I tested my chamber with a 290 watt crockpot and a 100 light watt bulb in my 20 degree garage today. 180 degrees was not a problem. this is a 160 degree rise. I stopped the testing in 30 minutes. nuff said. 200 watts should do the job for flue curing at 70 degrees. A crock pot should handle the job.
There's heat lost to evaporation and then to ventilation.
 

DrBob

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thanks mr leverhead. evaporation should be 144 btu per pint/or pound of water. ventilation is the wild card here It is t minus 7 months before the first test run of my chamber. YOU know a lot more about flue curing than me. You done it! I am just talking about it.
 

leverhead

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leverhead ...... how many air changes per minute/hour did you find effective during the yellowing stage? I am trying to figure out number/location of fans. FAC's would be a more effective way to determine this, rather than box size/density, unless you can define appropriate density.
I put a bunch of useful stuff in "Leverhead's Flue Cure experiment " post #79. In one link there, there's a pamphlet that goes into loading density and pressure to get a given airflow. You want at least 1/2 cu/ft of air, per pound of green leaf, per minuet.
 
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Markw

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Dr Bob and Leverhead or anyone, here is a good question. could you, or would it work heating the kiln by infrared. I still love the crock pot, but it is an interesting if it would work.

Markw
 
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