Wine Cooler for Cloud Forest Orchids

I have been working on converting a wine cooler into an environment to grow some true cool growing miniatures. I thought I would use this thread to document my progress. My goal is to build a unit big enough to hold 50 miniatures that require cool temperatures. What I am targeting is a low of 50-55F and a high of 65-70F. I want to be able to maintain 70%+ humidity and good airflow. I want the environment to be fully automated so I can go away for a week or two on vacation without having to get a plant sitter to come water everyday.

Once done, if things work out well, I intend to stand up additional units so I can cover different conditions. I also intend to run it off of an advanced controller so that all of aspects of the environment can be controlled and monitored from my phone. I can chart my variables, set up alerts to text me if the temperature gets too high, or even push a button to run the misters on demand. But that will be toward the end of this project.

 

Choosing a Cooler

There are two types of stand-alone wine coolers, Thermoelectric and Compressor. A compressor cooler is just like your refrigerator at home. It has a cooling chemical, a compressor that pressurizes the chemical and radiator cooling on the back of the fridge. It can cool down really well, but makes a lot of noise and is expensive to run. Here is an example of a compressor model:

NewAir 33-Bottle Compressor Wine Cooler-AWC-330E - The Home Depot

A thermoelectric cooler runs using a Peltier chip. When electricity is applied to the chip, one side gets really hot, one side gets really cold. The cold side is in the cooler and the hotside it outside. Fans blow on both the hot side and cold side so that the inside stays cold and the hot air goes out into the room. It doesn’t cool as well as a compressor fridge, but it is much quieter and cheaper to run. Also, there are a no complicated parts so it is much easier and safer to modify. The only concern I had was if it could get and stay cold enough. There is a lot of talk online about Peltier cooling not being sufficient. One thing to keep in mind with thermoelectric coolers is that they can only cool so much below room temperature. If you keep one in a 90 degree F garage, it isn’t going to cool anywhere close to one you keep in a 72 degree house. The compressor coolers don’t have that same limitation.

You can find these used on craigslist or second hand stores pretty easy. I was looking for a large unit 28+ bottle capacity and one where the controls were on the door instead of inside the fridge. I figure with all the humidity and spraying going on, it would be better. I ended up buying two units for $50 each on craigslist.

NewAir AW-281E: NewAir AW-281E - 28 Bottle Thermoelectric Wine Cooler

Vinotemp VT-28TEDS: VT-28TEDS Wine Cooler - Scratch n Dent - Vinotemp

Something was likely wrong with the Vinotemp. It cooled, but I could only get it about 10 degrees F cooler then room temperature. The NewAir worked great and would get down to 53F or almost 20 degrees lower than the room temperature.

If I were to have bought one brand new to covert, I would have probably tried this one:
New 32 Bottles Wine Cooler Fridge Cellar Storage Holder Chiller Bar Rack Cabinet | eBay

It appears to have dual Peltier coolers, and claims to be able to get down to 40 degrees F where most only claim to go down to 50 F or so. It is cheap, simple, and has the controls in the door.

Here is a picture of the New Air unit I will be modifying. You can see a little blue light that I can turn off or on. My plan is to leave that in place to kind of act as moon light when the bright light goes off. It will likely do nothing for the plants, but I think it will be neat.

 

Lighting


I knew to maximize my low temperatures, that I would want the heat from any lighting to be outside of the box. I knew I would want to cut as small of a hole as possible to minimize the impact to the insulation. I also needed a pretty bright light to punch down over 2 feet to the bottom of the cooler. I decided to go with a single chip, high intensity LED light. This allowed me a 3 inch hole in the top and more than enough light (at least I believe).

I built a 17-164 Watt unit based on the following components:

· Vero 29 chip BXRC-50G10K0-L-24(light bulb): BXRC-50G10K0-L-24 Bridgelux | Optoelectronics | DigiKey

· Meanwell LPF-90D-42 Driver (ballast): LPF-90D-24 Mean Well | Mouser

· SSTX Passive Heatsink: SST X Passive Heatsink

· Cooper Controls 0-10V Dimmer: Cooper Controls SF10P-W Slide 0-10V Dimmer - 120/277V, White: Amazon.com: Industrial & Scientific

Effectively the same equivalent light can be built with much cheaper components, but I wanted the passive cooling so there is no part to break, and the 0-10v dimming because I wanted to control the intensity of the lights and I need the more expensive dimming when I finally build in the automatic controller.

Other than that I just re-purposed a drip tray from a stove to make a little reflector, and some other wires and stuff I had on hand. Later on I will show how I integrated it all into the cooler box.

 

Thanks for the correction of the link! I actually just drew a circle around it with a sharpie, then cut it with a Dremel tool.

 

I am running tests right now to see if I can get away with a single pane of glass between the light and the interior of the box, or if I need to double pane it to keep it more insulated. So far when the light is full blast (which i am sure is too much), then the temperature stays at 70F until the light goes off then it drops to 55F. With the light on 50%, the temp stays at 55%. I am running tests at 70% power now (which is what I think I am going to want to run the tank at.)

 

The heat sink and drip pan get good and warm, but I can keep my hand on them. Directly under the light it feels like 90 or 100. I will have to take a reading. I was worried I didn't get full coverage of the artic silver because none squished out the side. I don't know how to tell without taking it back off.

I think the increase in temperature has a lot to do with the interior being black, and the single pane of glass between the light and cooler. I think the black just adsorbs all that energy.

It does take a couple hours to get up to 70%.

 

The cooler can only go down to 55 due to a restriction of the controller that is built in. When the light is off, The cooler only occasionally runs to keep it at 55. I suspect that once I override the built in controller it can go much cooler.

My plan is to see if It will work without an override initially, but eventually I will fully control the high and low temperatures. Meanwhile, I will mess around with the second box, and install a new peltier chip and see if I can get that one working the way i want.

 

Testing the Light

I ran tests this weekend to determine the min/max temperatures with the cooler running and the light set to different intensities.

Room temperature was held at 70 degrees Fahrenheit. There was only a single thin layer of glass between the light source and the cooler. With the single pane of glass, and without the light on, it would maintain a low of 54.5 F. With no cooling, and the light at 100% intensity, the Max temperature was 93.9 F. With the cooler running, the max temperature was determined by the intensity of the light going into the cooler. I believe if I add a dual pane glass, I can lower the max temperatures, but I can’t find a cheap, small, prebuilt dual pane window. Also, I am worried that if I make one it will quickly start fogging.

Here are the Max Temps:


Based on this, somewhere between 85% and 100% would be ideal. A low of 55 and a High of 65 is just what I was hoping for.

Next I tested the light intensity to see where we stood. I used a lux meter and measured different distances from the bottom (25 inches) to the highest point on the wall where I think Plants will sit (5 inches). Here are the Lux readings:


If I use the light scale you typically see, High, Medium and Low light look like this:


Based on this, I would think that I lucked out, and 85% may be just right.
However, my experience running under these High intensity LEDs is that it is probably way too much light. For example I run one on my office tank. My Specklinia grobyi is at 6000 Lux, which should be way into the Low range, and it is awfully pink on the top of the leaves. It was a very consistent dark green when I got it.


This has me thinking that 85% will not likely let me grow as many low light plants as I am planning. Ideally I would be able to have low light plants in 2/3rds of the tank and medium in 1/3rd.

I would love to hear what peoples own experiences are, growing under artificial lights, and what I should expect at these Lux levels.

 

Great info Naoki, that leads me to believe I am in the right neighborhood. I have read some of what you have written around PPFD, I need to spend some more time learning more about it.

The temperature in the office is High of 76F (ish) and Low of 69F (ish). I don't get the fluctuation I would like, but the High isn't too hot (I don't think).

 

Here is a picture of the tank with the light on medium. You can see from the shadows that it is pushing out some pretty good light.

 

Modifying the Cooler

I needed to cut a hole in the top of the cooler for the light. To determine how big the hole was, I used the fact that the LED chip has a 120 degree spread, along with the height the chip would be from where I wanted the light to fall on the inside of the tank. I wanted it to fall on the side walls about an inch from the top. I learned that I needed a 3” x 3” hole in the top tapering out to 8”x8” on the inside ceiling of the tank. I ended up cutting the hole a little wider just in case. I just drilled holes in the corners and used a jig saw to cut out between the holes.



Then I used a razor knife to cut the plastic on the inside of the tank.
It appears the wires were in the way of a hole cut in the center of top. This is the one thing you will need to rewire once you get in there if you cut through the wires making a hole.


Also, it turns out the interior blue light was directly in the way of the hole, so I had to make a little cut out to the side and move the light over from Center.



Here is a picture with the blue night light on.



I then covered over the exposed insulation with some white plastic sheeting. I used some clear silicone to hold it in place and seal the seams. I think I could have just left it alone, but I thought it would make it look cleaner, and would help prevent water leaking down inside the walls down the road.

I took off the back cover and cut a hole for the dimmer switch, and the power cords. I just drilled the corners and then used a metal cutting bit on my Dremel to cut between the holes. I have since learned that using a sheet metal nibbler, would be way cleaner, faster, and easier. I will buy one of those next time:
Amazon.com: Nickel Plated Nibbling Tool (1): Power & Hand Tools

Finally I installed the dimmer, driver, and cords on the back cover and re connected it.

I could have just left everything on the outside and it would have been easier, but I like the idea of trying to make everything more self-contained. Here is a picture of the dimmer:

 

I will be honest, I have never heard of low-e glass before you mentioned it. I googled it, and it sounds like a GREAT idea. Now where can I find a small piece of it? Can you buy a piece at just a home store?