Thermoelectric wine cooler drying and curing - DIY

beer30 said:

I finally said screw it and pulled the trigger on ordering all the parts to build something. Still not decided on exactly what size to build the box. Found someplace that said the cannatrol is 2.49 cu ft which is roughly 70 liters which is a bit bigger than the koolatrons. So makes me lean towards a bit bigger box. Seeing how my spare room temp is pretty low for a first test I'm leaning towards just putting everything in a tote. Or heck I could go full ghetto and put it in a cardboard box LOL. My thinking is the cooling peltiers really just need to counteract the heat from the dehumidifier peltier if my room temp is in the right range. From hunting around the net it seems that peltiers make roughly 1.75 times as much heat as they do cold. So 2 cooling modules and 1 dehumidifying module, as everyone here appears to be using should work out fine. I'll have 2 extra modules if cooling really turns out to be an issue.

Still lots of coding left but I did knock out all the variables and if statements. So if again big IF everything works correctly I shouldn't have any of the freezing problems some here have talked about. I coded for reducing voltage if the dehumidifier or cooling modules freeze, back off dehumidifier voltage if the box temp gets too high, etc. Hoping to have the code usable by the time the parts arrive.

Click to expand...

I think a lot of people looking into this think of the dehumidifier fins getting ice on them is a real problem, it’s not a big deal. To overcome it all you would need to do is put a recurring timer in between the Inkbird power out and the dehumidifier power in to turn the dehumidifier off for 10 minutes every few hours. I even have a spare timer, but it’s not worth the 5 minutes for me to get it and put it in operation, that’s how little the freezing is a problem. Now if you want to make a new product commercially yes you would build something like that in, but for the average diy user you just unplug it for a couple minutes if it happens, raise your settings and all is fine. The freezing only happens if you set the rh too low initially. I believe the cannatrol has the same issue according to the manual, and they didn’t bother to fix it on their commercial product. That said, you don’t have to do a bunch of programming to solve the problem if you view it as a problem.

Most of the dehumidification is done by the peltier of the cooler. The dehumidifier acts mostly as a heater, allowing the cooler to work more and remove more water. If you put the contraption in a cool place the dehumidifier heats more because less heat is coming from the outside.
The Klarstein cooler has a defrosting cycle where it reverses the polarity of the peltier. Heating the cold side and removing the ice.
If the dehumidifier freezes it does not matter. It still generates heat. And keeps the cycle going.

Hook Daddy said:

I think a lot of people looking into this think of the dehumidifier fins getting ice on them is a real problem, it’s not a big deal. To overcome it all you would need to do is put a recurring timer in between the Inkbird power out and the dehumidifier power in to turn the dehumidifier off for 10 minutes every few hours. I even have a spare timer, but it’s not worth the 5 minutes for me to get it and put it in operation, that’s how little the freezing is a problem. Now if you want to make a new product commercially yes you would build something like that in, but for the average diy user you just unplug it for a couple minutes if it happens, raise your settings and all is fine. The freezing only happens if you set the rh too low initially. I believe the cannatrol has the same issue according to the manual, and they didn’t bother to fix it on their commercial product. That said, you don’t have to do a bunch of programming to solve the problem if you view it as a problem.

Click to expand...

I probably have went a bit over board on fail safes but I ultimately want a set it and forget it type of system. Something I can load up and leave for a week if I want. So putting some sensors on the cold side fins to attempt to keep them from freezing seemed like a good idea. Or at least know when they are frozen so they can be thawed. One of those better to have and never need vs wish you had it sorta things. Much like I may put sensors on the hot sides too just in case a fan dies. Sensors are cheap and data is handy especially when testing.

Lou66 said:

Most of the dehumidification is done by the peltier of the cooler. The dehumidifier acts mostly as a heater, allowing the cooler to work more and remove more water. If you put the contraption in a cool place the dehumidifier heats more because less heat is coming from the outside.
The Klarstein cooler has a defrosting cycle where it reverses the polarity of the peltier. Heating the cold side and removing the ice.
If the dehumidifier freezes it does not matter. It still generates heat. And keeps the cycle going.

Click to expand...

That is what I've come to understand too from my research. I almost went with a small heating element instead of a peltier module but they were about the same price so I figured the bit of extra dehumidification is a good thing specially in the beginning of drying. With the controllers I'm going to use I could reverse and heat if need be too but I'm hoping with my code set to reduce power when the fins get close to freezing that it won't be needed. Just have to wait and see what testing shows me.

Lou66 said:

Most of the dehumidification is done by the peltier of the cooler. The dehumidifier acts mostly as a heater, allowing the cooler to work more and remove more water. If you put the contraption in a cool place the dehumidifier heats more because less heat is coming from the outside.
The Klarstein cooler has a defrosting cycle where it reverses the polarity of the peltier. Heating the cold side and removing the ice.
If the dehumidifier freezes it does not matter. It still generates heat. And keeps the cycle going.

Click to expand...

I’m not sure I agree 100% with this statement, I’ve heard the theory in this thread before and couldn’t prove one way or another, but I think now I can and here’s why. First if you watch the Inkbird graph you can see the system cycling when working. Once the dehumidifier fins freeze and ice forms that cycling stops and rh is shown as a flat line. Also during that time much less water is caught in the drip tray, which tells me less water is being pulled out of the unit. 1/4 cup of water can accumulate on the fins, which of course makes it out once thawed and into the drip tray, but a lot of the dehumidification is done by the dehumidifier, not just heat generation. Here’s what the Inkbird tells me when frozen



And running properly



I have also noted that if left frozen for a long period more ice slowly accumulates but only to a point, but no extra water is in the drip tray, meaning the cooler itself is pulling very little humidity out. In fact the biggest flaw with the cooler design is probably the size of the drip tray as @gooshpoo pointed out earlier, if the cooler is packed the tray will overflow if not manually emptied, which is just like most home dehumidifiers. I agree the cooler itself helps remove some moisture, but otherwise just a heater would suffice, and it doesn’t. This week I loaded both of mine up packed with fairly large colas, all fans removed but still some large stems in the bigger buds as shown here.



This is the most fresh just harvested bud I have put in at once. I intentionally set one cooler up with a target rh of 65%, and one at 72%. The one at 65% froze up within the first two hours, the other one never froze. I let the one ride overnight frozen to verify what would happen. The rh stayed about constant, the fins stayed frozen, no water at all in the drip tray, the first graph above show this test. The other unit set at 72% had over 1/2 cup water in the drip tray, so the dehumidifier is doing a lot of the water removal in my opinion. I thawed the fins on the one by unplugging it from the Inkbird for 10 minutes, it had about 1/4 cup on the fins. I raised the target rh to 72% and it’s running like a champ pulling way more water out. So, I believe the dehumidifier does the majority of water removal, not the cooler.

Hook Daddy said:

I’m not sure I agree 100% with this statement,

Click to expand...

Which statement do you mean exactly?

In my case the cooler draws 60 W and about 4 w for a small fan circulating the air inside. The dehumidifier has 20 W and a on duty cycle less than 50 %. So overall the cooling power of the dehumidifier is 5 times lower than the cooler. Thus having 5 times less dehumidifcation.
But i did it different as said above. I use a Thermostat primarily to keep temp below 16 C and humidity below 60 % secondly. But I don't that changes as much.

Seeing the rate of ice deposition declining is what I would expect. Peltier create a temp difference between both side. Initially the cold side is below freezing and accumulates ice. Then it gets increasingly insulated as the ice stacks up. The temp increases and no more ice forms. At the same time the hot size gets warmer to maintain the temp difference.

I would imagine if you had the koolatron in a warmer room then the cooler itself would possibly pull more moisture. But if your room temp is close to your target temp then the cooler does not work hard enough to get the fins cold enough to collect moisture. I also wonder if the cooler cold side having a fan vs the dehumidifier cold side not having a fan makes the difference. Will be interesting to see some data on how hard the cooling modules work vs the dehumidifier, how cold everything gets, etc. Plan on trying some wet towels soaked in maybe a half gallon of water as a first test just to see how it all works. I need to go look at some numbers to see just how much average weight is lost during drying as that will give me a target for the amount of water this thing needs to be able to handle moving.

Lou66 said:

Which statement do you mean exactly?

In my case the cooler draws 60 W and about 4 w for a small fan circulating the air inside. The dehumidifier has 20 W and a on duty cycle less than 50 %. So overall the cooling power of the dehumidifier is 5 times lower than the cooler. Thus having 5 times less dehumidifcation.
But i did it different as said above. I use a Thermostat primarily to keep temp below 16 C and humidity below 60 % secondly. But I don't that changes as much.

Seeing the rate of ice deposition declining is what I would expect. Peltier create a temp difference between both side. Initially the cold side is below freezing and accumulates ice. Then it gets increasingly insulated as the ice stacks up. The temp increases and no more ice forms. At the same time the hot size gets warmer to maintain the temp difference.

Click to expand...

I was simply stating that from what I have observed the dehumidifier, at least in my setups, is doing much more of the moisture removal than the cooler itself. I think the cooler keeps the cool side regulated to keep it from freezing, but in doing so maybe it doesn’t condensate as much, which is what we are looking for and what the dehumidifier does. You are equating watts used to cool vs moisture removal, but I don’t believe that is accurate as the dehumidifier does no cooling at all, they are separate and so is the power used. It’s just the dehu fins getting in the zone between condensation and freezing that removes the moisture from the air. If the fins never get cold enough to condensate then they won’t remove moisture either, which I don’t think the coolers fins do even with the heat generated by the dehumidifier. That’s why the coolers drip tray is so small, it’s not designed to pull moisture. Also the cooler would draw a lot more moisture out once the dehumidifier freezes but is still running generating more heat than cool, but it doesn’t pull any more out. Now that I am thinking about it next time I don’t have anything drying ill load them both up with equal amounts of moisture and run one with a dehumidifier and one with it unplugged, then again with one having a heater instead of a dehumidifier.

beer30 said:

I would imagine if you had the koolatron in a warmer room then the cooler itself would possibly pull more moisture. But if your room temp is close to your target temp then the cooler does not work hard enough to get the fins cold enough to collect moisture.

Click to expand...

That is why we add the dehumidifier. It heats the cooler, so it has to cool to keep the temperature at the set point.
I recommend to set the cooler 2 °C below the target temp to have it run at full power.

Hook Daddy said:

but I don’t believe that is accurate as the dehumidifier does no cooling at all

Click to expand...

Sure it does. One side gets cooled and then water condenses on it. This water then turns into ice. The ice water used to be in the bud and now is in a form that can be removed from the 'closed system' that is our cooler.
I saw water condensing on the back side of the cooler, around where the cooling element is installed. That led then to the drip tray.
It is so small because of the design purpose. You put it full of bottles. The air volume is small and the bottles don't give off moisture. So there will be little water evaporating, little water to collect.

Equating power usage to condensing power is valid if the efficiency of both units is the same. And they are both peltier with off the shelf DC power supplies to so I think that is fair.
When water condenses it gives of a certain amount of heat. This heat is then either given back into the water, causing evaporation and having a net zero effect or the heat is removed (either to the outside or the hot side of the dehumidifier) then the water stays at the surface. More water condenses because it is still cold and eventually a drop flows into the drip tray. The rate of moisture removal depends on the supply of wet air, that is facilitated by the fan and the rate of heat removal. Heat removal is proportional to power usage of the device, so water removal is it too.

Lou66 said:

That is why we add the dehumidifier. It heats the cooler, so it has to cool to keep the temperature at the set point.
I recommend to set the cooler 2 °C below the target temp to have it run at full power.



Sure it does. One side gets cooled and then water condenses on it. This water then turns into ice. The ice water used to be in the bud and now is in a form that can be removed from the 'closed system' that is our cooler.
I saw water condensing on the back side of the cooler, around where the cooling element is installed. That led then to the drip tray.
It is so small because of the design purpose. You put it full of bottles. The air volume is small and the bottles don't give off moisture. So there will be little water evaporating, little water to collect.

Equating power usage to condensing power is valid if the efficiency of both units is the same. And they are both peltier with off the shelf DC power supplies to so I think that is fair.
When water condenses it gives of a certain amount of heat. This heat is then either given back into the water, causing evaporation and having a net zero effect or the heat is removed (either to the outside or the hot side of the dehumidifier) then the water stays at the surface. More water condenses because it is still cold and eventually a drop flows into the drip tray. The rate of moisture removal depends on the supply of wet air, that is facilitated by the fan and the rate of heat removal. Heat removal is proportional to power usage of the device, so water removal is it too.

Click to expand...

In my statement above about the dehumidifier doing no cooling at all, I meant overall in the big picture. The cooler has the cool side of the TEC inside and the hot side outside the insulated box which is the cooler itself. It is only cooling the cooler, it does remove some humidity, but very little and my guess is it is designed not to. My point is the dehu is inside the insulated box, both hot and cold sides, so is providing little to no real cooling effect, in fact it is generating more heat than cool at most times.

I would agree that power is a constant all things the same, but the power usage is not linear since the hot side of the coolers TEC is outside the insulated box, and not that of the dehu, so efficiency in regards to cooling and removing moisture are no longer one for one. I’m not trying to argue, just want to come to a consensus that is correct,

I can't follow you?

The thermodynamic principle is explained above. If I was unclear at some point I can elaborate.

Lou66 said:

I can't follow you?

The thermodynamic principle is explained above. If I was unclear at some point I can elaborate.

Click to expand...

I understand what you are saying, no need to elaborate. I have been an electronic engineer for the past 35 years so understand Watts and power consumption very well.

Hook Daddy said:

I understand what you are saying, no need to elaborate. I have been an electronic engineer for the past 35 years so understand Watts and power consumption very well.

Click to expand...

So what is your reasoning that a cooler with 5 times lower power consumption causes more water condensation than a larger unit?

I think it really depends on outside temperature, I mean if the cooler doesn't have to work hard to keep the temperature its not going to pull as much water as it potentially could. You also have a fan on the cooler Peltier air blowing across the cold-sink might effect how much moister it could collect.
Wile the dehumidifier is working at constant cycle, with only a fan on the hot side. I would have to say its doing more work in the overall process.
The dehumidifier has not had much of an impact temperature wise in my Koolatron, I always looked at it as like a kinda neutral temperature aspect because its effects negate one another.

Lou66 said:

So what is your reasoning that a cooler with 5 times lower power consumption causes more water condensation than a larger unit?

Click to expand...

You’re comparing apples to oranges. What you’re saying is equivalent to saying since both the Toyota Corolla and lotus Elise have the same engine they must run the same speed. The koolatron TEC is designed with cooling as its purpose, it does not run full out non stop but has a temperature controller. It generates just enough cool to keep the insulated section of the unit at a steady specific temperature. In its normal operation it doesn’t pull much humidity at all.

The dehumidifier TEC is designed to get the cooling fins as cold as possible to condensate moisture, and basically runs full out non- stop, the only controlling is what we do by turning it on and off with the Inkbird.

Then there is the fact that the TECs in the Koolatron are larger and there are two running together, so yes they CAN pull more power when needed, but just because a unit is rated at 40 Watts doesn’t mean it is always pulling 40 Watts, that’s just the maximum it should pull, in normal use once the cooler is at temp it will only pull 5-10 Watts, and the heat sink fins are cool to the touch, not cold enough to generate condensation in large amounts as the dehumidifier does by design.

I hope you get what I’m saying. It’s in the design and operation of the TEC chips, and mainly the temp controller and the size of the heat sinks that makes the difference. One is designed to cool and not to generate condensation, the other is built with the sole purpose of generating condensation.

beer30 said:

I probably have went a bit over board on fail safes but I ultimately want a set it and forget it type of system. Something I can load up and leave for a week if I want. So putting some sensors on the cold side fins to attempt to keep them from freezing seemed like a good idea. Or at least know when they are frozen so they can be thawed. One of those better to have and never need vs wish you had it sorta things. Much like I may put sensors on the hot sides too just in case a fan dies. Sensors are cheap and data is handy especially when testing.



That is what I've come to understand too from my research. I almost went with a small heating element instead of a peltier module but they were about the same price so I figured the bit of extra dehumidification is a good thing specially in the beginning of drying. With the controllers I'm going to use I could reverse and heat if need be too but I'm hoping with my code set to reduce power when the fins get close to freezing that it won't be needed. Just have to wait and see what testing shows me.

Click to expand...

Wonder if a safe dehumidifier would work, the bar style that heat up.

Drb63 said:

Wonder if a safe dehumidifier would work, the bar style that heat up.

Click to expand...

Would work for what? The dehumidifier we are using works great, what are you trying to find a dehumidifier for?

Drb63 said:

Wonder if a safe dehumidifier would work, the bar style that heat up.

Click to expand...

In theory that would work. I’ve always suspected the cannatrol unit uses a small heating element like those. The little dehumidifier we cut up is nice since it’s heating and stripping moisture.

Drb63 said:

Wonder if a safe dehumidifier would work, the bar style that heat up.

Click to expand...

I thought about using one of those just for the space savings. But I always come back to the fact the dehumidifier peltier provides heat AND helps remove moisture.

I decided to just go with the trusty 27gal tote as a test "box" after seeing someone use a wardrobe box on YT. Figured if it's too big I can always cut down the size by filling it with foam. Bought some 1/4in dowel rod and binder clips so I can just hang branches. Seemed like way less hassle than making racks.

pahpah-cee said:

In theory that would work. I’ve always suspected the cannatrol unit uses a small heating element like those. The little dehumidifier we cut up is nice since it’s heating and stripping moisture.

Click to expand...

speaking of the dehumidifier, Walmart has the Pohl Schmitt dehumidifier for $20 currently. Half of the price I’ve seen it most other places.

I have the safe “dehumidifier” bars already, might try them and run some tests while waiting for the TE dehuey to arrive.

Has anyone ran their dehumidifier with the cooler off just to see how much it raises the inside temp?

I'm running an old peltier out of a cooler as a test to see how much heat they build while I wait for my new ones. So far 3 hours into the test and the temp has seemingly leveled out at 10°F above ambient temp. That is in a standard black and yellow 27gal tote. So if one had a space cool enough, basement, garage, etc but didn't want to hang plants in the open this could possibly work with nothing but a tote, dehumidifier, and controller.