Kiln Temperature Help

[Davo]

So I have started my kiln run and I’ve noticed that I’m struggling to get consistent temperatures above 50c.

It’s still dark here, but I can upload a picture later today to show set up. I am using an commercial drinks chiller as my kiln. I have not added any further insulation as I felt it’s factory specs would have been sufficient.

I have a slow cooker set on low, and it is creating a lot of humidity. It is also using the entire dish of water in about 20hours.

My thoughts for trouble shooting are either:

1) the slow cooker is too small of a heat source for the size of the kiln

2) I need to turn it up to high

3) I am letting too much steam out and should put lid on properly.

any other ideas?

 

[Knucklehead]

I suspect the door seal.

edit: try taping the door gap closed with some vapor proof tape and see what happens.

 

[Davo]

Ok will give that a go and monitor. The seal is about and inch thick and seems solid. I must admit (embarrassingly) that I am only using the kiln in this first instance to bring my leaf into a good case for sweating and then I am sealing it in vapour proof bags. This has meant I haven’t bothered to fully wire up the slow cooker properly yet. Instead of running the cable through the pre drilled bung hole, I am running it through the door seal. I didn’t appreciate the extent this slight cracking of the seal may compromise the temperature

 

[ChinaVoodoo]

I felt it’s factory specs would have been sufficient.

Dropping temperature 20° VS raising it 30° should require around the same amount of power since heating is more efficient than cooling. A fridge is usually about 150W. Look at the power output for the crockpot. The low setting may be too low.

 

[Davo]

Here is a pic of kiln



I checked just now and temp was at 51c. Leaf feels moist.There is pretty much the same amount of water in the slow cooker as there was this morning, so I wonder if part of the issue was that I was over filling the dish?

I have filled it 3/4 this time and have our lid on slow cooker properly. I’ll monitor this. Will check out wattage of low setting when next up there

 

[Davo]

Dropping temperature 20° VS raising it 30° should require around the same amount of power since heating is more efficient than cooling. A fridge is usually about 150W. Look at the power output for the crockpot. The low setting may be too low.

Slow cooker is 225-250W. I’m starting to get worried about mould growth given the case of the leaf and the lack of temp so I have put it onto high for the time being at least to get it up to 55.

 

[Knucklehead]

Nice kiln!

Do you have a circulation fan in there?

 

[Davo]

Chur bro. Scored it for free from our local farm store.

I don’t have a fan running in there. My leaf is all sealed in bags now and spaced somewhat evenly on the shelves.

I positioned the sensor for the controller about 2/3rds of the way up.

I welcome any advice or pointers.

 

[ChinaVoodoo]

I welcome any advice or pointers

Get a fan.

Add insulation to the door. Even if it isn't necessary, it will save power. Even a simple thing like bubble wrap (the smaller the bubbles, the better) would have an impact.

 

[LeftyRighty]

For the size of your fermentor kiln, smaller than an upright freezer, whether the crock pot is on high or low should not matter, if just fermenting (not flue-curing). Heat output should be adequate, just a bit slower at startup. Even the smallest-made crockpot will produce sufficient heat. I have a full-size upright freezer kiln and the smallest crockpot, on high, works for fermenting.

You are getting excess humidity because you have not vented the kiln. The crockpot will continuously output moisture, even with a tighter lid, without venting, the moisture has nowhere to go, will just buildup.
My kiln has a piece of 2-inch pvc pipe for air intake near the bottom of the kiln, and a valved 1/2-inch pvc pipe exhaust near the top, both thru drilled holes on the side of the kiln. These are caulked/sealed so moisture does not get into the kiln wall insulation.

My air intake pipe has a piece of screen stuffed into it, to prevent bugs/rodents/whatever from getting into the kiln, in the garage. This seems to have never been a problem, but one never knows when it might in a garage.

On the exhaust pipe, I partially close the valve for the 1st day of a new batch, to get it all up to the proper temperature, after that, adjust to whatever. I suggest some plastic hose from the exhaust pipe to a pot or jug, as you will get constant dripping from this exhaust, unless you want a puddle on the floor.
(Note) if the crockpot is empty or very low with water, use hot tap water, or allow the crockpot to cool for about 1/2 hour before adding water, or you'll crack the ceramic pot.

Yes, you are losing heat thru this exhaust pipe, but that's why I used the smallest 1/2-inch pipe, not losing enough heat to matter, your crockpot will just cylce more often. If you use the larger 6-7 quart crockpot on high, it will produce enough heat to get to the 165 degress for flue-curing, if you're into that. Also, a larger crockpot will allow less frequent opening the kiln to re-fill with water.

I do suggest that you install at least a couple of small fans in the kiln, to circulate air for uniform temperate throughout. I use small 110v computer fans (available online).

 

[deluxestogie]

My leaf is all sealed in bags now and spaced somewhat evenly on the shelves.

If it's all in case, and is sealed in bags, then you don't really need any water in the slow cooker.

Bob

 

[ChinaVoodoo]

If it's all in case, and is sealed in bags, then you don't really need any water in the slow cooker.

Bob

Depends on the bags.

 

[Davo]

These are the bags I am using

Vacuum Sealer Bags | Trade Me Marketplace

Vacuum Sealer Bags Foil Open Top Bags Aluminum Foil Vacuum Sealer Bags Zip Lock Storage Bag Heat Seal Sample Packets Clear Front Multi Size Sealable Powder Food...

www.trademe.co.nz

I am going to open one or so in a weeks time to check the case

 

[deluxestogie]

I am going to open one or so in a weeks time to check the case

No need. Just squeeze it. Vacuum seal bags are usually laminated poly-nylon, and should be vapor-proof.

Bob

EDIT: Your stuff is PET polyester film, which is also vapor-proof.

 

[Davo]

Pleased to report kiln temp is sitting in desired range. Have returned to low power setting to see if it can maintain the heat.

really appreciate all of the comments. It’s actually much easier to understand the kilning process when you are doing it. Kinda daunting from the outset but really simple in practice.

I will get some fans set up and may do the inlet/outlet vents next season. I have all of the materials required for that anyways.

 

[Davo]

If it's all in case, and is sealed in bags, then you don't really need any water in the slow cooker.

Bob

Does having water or not in the slow cooker impact it’s efficiency as a heat source? (Appreciate the water helps with humidity but in my case is not required)

 

[deluxestogie]

Without water, a slow cooker's ceramic crockery acts like a ceramic heater. [When I flue-cure, I ramp the temp up with a dry Crockpot.]

Bob

 

[Knucklehead]

Pleased to report kiln temp is sitting in desired range. Have returned to low power setting to see if it can maintain the heat.

really appreciate all of the comments. It’s actually much easier to understand the kilning process when you are doing it. Kinda daunting from the outset but really simple in practice.

I will get some fans set up and may do the inlet/outlet vents next season. I have all of the materials required for that anyways.

How did you get the heat up?

 

[Davo]

How did you get the heat up?

I dunno. Haha

I think by sealing the bags I removed the need for humidity factor so I had to stop filling up slow cooker and opening the door. I also turned it onto high so that might have just helped get it up faster. Curious to see if Low setting can maintain that heat or not.

Without water, a slow cooker's ceramic crockery acts like a ceramic heater. [When I flue-cure, I ramp the temp up with a dry Crockpot.]

Bob

Do you remove the glass lid when you do this?

 

[deluxestogie]

Everybody on the forum who uses a slow cooker for a kiln has a different approach to:

• cooker size (wattage and water capacity)
• lid management
• insulation
• door closure seal
• cooker power setting
• ventilation

I am sure that the specifics each choses depend on the mix of all those factors, as well as the ambient setting of the kiln (indoors, outdoors, etc.). In my case, even when I'm filling the crockery with water (every 3 days in winter, to every 5 days in summer), I simply omit the lid. I leave my 7 quart Crockpot set on "High", which I believe is about 300 watts. This raises the temp rapidly when it cycles on, and remains off for a long portion of each cycle (set point 128°F, with 5°F hysteresis). Each time I refill the water, I mark it on my wall calendar, and leave a symbol on the next future date it will require refilling. Since my kiln sits on my enclosed back porch, I can see the digital temp display on the controller each time I enter my kitchen. I kiln my tobacco in huge, open plastic bags. I can also hang small strings of leaf in there, and even a wire basket for holding smaller items. At my kilning temperature, vegetative growth of mold is not possible, so long as the fan keeps the heat distributed uniformly. So I never measure the relative humidity within the kiln.

In the somewhat distant past, I used a 2 quart Crockpot (max 100 watts), which was able to reach even flue-curing temps, though it struggled for that. The larger Crockpot minimizes temperature fluctuations, and the frequency of refilling.

So just play with it for a few weeks, and figure out an approach that requires the least attention on your part. There is no magic formula, or a single, correct way to do this. (Think of the thermostat in your bedroom. You just fiddle with it until you know how it should be set intuitively.)

Bob