Florida Orchid Enthusiast

Hi, MJZ
I grow Dracula as well. After the problem of not being able to cool down the summer night temps with my evaporative cooler in my old greenhouse, I decided to remedy the situation in my new greenhouse. I realized that air conditioners won't go below 60 as well. So what I am going to do is use an aquarium chiller, and pump water through a product called an Ice Box, hooked up to an inline duct fan. The Ice Box is a radiator with duct fittings that is used to cool HID grow lights. If you are frugal, the chiller and inline duct fans can be found on Craigslist for very reasonable prices. You will need a controller. Other than that, You can pull away the Temp. sensor inside the front cover of the AC and insulate it to possibly get a lower temp. You will also probably need a humidifier as well. These plants are challenging to grow, but well worth the effort in my opinion.
Hope this helps

 

With regards to the Ice Box, sounds like a car radiator would work, too. Or, just a lot of fin tube for domestic heating...

 

You're very welcome, MJ. I hope you find a solution that works you.

My greenhouse is 10ft x 12ft with 7ft sidewalls, and a 10 1/2ft ceiling. It's small but feels very airy and open inside, and I love it!

Ryan

 

Hello!
Welcome!
Sorry for not replying sooner.

 

Great idea, carl! I considered a car radiator as well.

 

Has anyone had experience using a CoolBot with a compatible AC? Would think this would be fairly easy and seems like it would do the trick. They use it for DIY Walk in coolers.
https://www.storeitcold.com/coolbot-homepage-test-1-0/

 

that's not a hobby its a job!

 

Hi, MJ

I'm in a similar situation as well. Since we both live in areas that are challenging to accommodate cool growing plants, my orchid society only has a few people that grow them. The few that do, live right on the coast where the conditions are pretty much ideal for most of the year.

As for the equipment you mentioned, they all sound good. The controller sounds great. Here is the best part...a chiller is all you will need! If you get one that is powerful enough, it will be your a/c. They are much more efficient than a typical a/c, and will cost less to run. The controller you mentioned has separate day/night temperature settings as well. The humidifier you mentioned is what i use, and they are awesome. I have two of them, but only because I use an evaporative cooler (swamp cooler) that drops the humidity low and fast. One comes on with the cooler to buffer those effects, and the other is run by my controller. I'm not so sure you will need CO2 if you can provide a fresh air intake. The ice boxes come in 6" and 8" sizes ( I actually saw a manufactured dual 8"ice box/fan combo on it's own special stand yesterday while doing some research. IIRC, it was on the Hydro Innovations website). The fan I have is an elicent that is made in Italy, and is very high quality, efficient, and quiet.

Your limiting factor sounds like it will be providing enough light. While Dracula don't need much light, they do appreciate good quality, diffused light with a proper duration (photo period). Supplemental lighting may be a good idea.
All in all, your on the right track, and it is doable. If I were to do it over again, I would use a chiller as my sole source for cooling.

Best Regards,
Ryan

 

Great find, Chuck! I was just thinking yesterday that all I would need to do for a window a/c is pull away the sensor, and use a tiny preset aquarium heater that is used for Betta fish. Put the sensor and heater together, wrap em up, hook up the controller and be good to go. I already have a chiller from my reef aquarium days, and inline fans. To top it all off, someone just posted 6 ice boxes for $60 each on Craigslist! I'm hoping they will do 2 for $100

 

A labor of love

 

Ryan, do you happen to have a pointer to how/where to find the efficiency comparison of A/C vs chiller? This is something I have been wondering about the efficiency comparison for a while, but I haven't found an answer (or too technical to understand). They both use compressor based technology, and I have guessed that chiller has additional heat transfer steps (and possibly lose efficiency), so it may be less efficient overall. But I'd like to learn about it.

Here is a related topic, but I guess that for greenhouse, it probably needs something much more capable.
DIY Air Conditioner - Cooling Systems for Highland Nepenthes

 

Hi, naoki

It's basically water vs. air efficiency. With an a/c, the evaporator is surrounded by air. With a chiller the evaporator is surrounded by water. The chiller has the same components as an a/c, it's just that the evaporator on a chiller is in an insulated Titanium "barrel" with the coils inside.

Water has a thermal conductivity of 0.6 W (m *K)
Air has a thermal conductivity of 0.03 W (m *K) much lower than water.
Water has a much higher specific heat capacity than air.
Water can absorb and remove 4 times more heat than air nearly 20 times faster.
Only 30% of energy used in a/c is converted into usable cooling power, the rest is wasted.

That DIY article you linked is awesome, Thank you. I think the only difference is the price point between the DIY chiller and a manufactured chiller. That was the reason I suggested looking on Craigslist for one, which can usually be found for 1/2-1/4 of the retail price.

Hope that helps
Ryan