after some first promising results I decided to post some infos on my cooling unit here.
I want to say that this is not my invention, even the way of diverting the parts from its intended use is not my idea. But maybe new to some of you, and maybe some others find my way of documentation helpful .
Is cooling really worth it?
Well, that was exactly my question. Of course I had no doubt that it would be useful, because of the great difference in the temperature constants of assimilation and dissimilation rate in the highland plants.
But worth it to go all the effort and money that a cooling unit would bring? As I have other highlanders that come along fairly good without it, and the prices for special terrarium equipment are outrageous, I chose to pay more attention on the other cultivation parameters as light, substrate and so on.
But especially with my highland Utricularia, and esp. those that werent already adapted over years to our living room conditions, I did not find a satisfying way. Their years growth mainly occurred in those few weeks in March and October, when (what I like to interprete now) the temperature range was suitable.
So finally I decided to give it a go.
As cooling element I use a water cooled radiator with a 12 cm fan behind, that blows the air through the radiator. Thanks to the modders that have to cool down their cpus, there is now a market for these, so prices went down significantly, and there are many ready-to-use solutions to buy. The modders use it in a different way, to cool down the circulation water heated by their cpus to room temperature, but why not the other way round? As I said, not my idea, just my way to put the components together.
Water as cooling medium
So how to cool down the radiator? Water with a 30% amount of Glysantin ( the antifreezer you use for your cars) is an excellent medium, it prevents corrosion inside the radiator and lowers the freezing temperature of water. But how to get it cool?
After my first and frustrating attempts with a Peltier camping thermo box I bought a little compressor freezer where the pump and a copper cooling coil is placed in. My freezer has 85 Watt, seems to be enough by now.
Even better, but still much more expensive, are flow coolers. Maybe because they are still most commonly used by professional cooling in gastronomy, or aquarium / terrarium cooling. A little bit cheaper than those cryostats used in laboratory, but still too expensive for me. But I am putting my high hopes in the modders here, they have already discovered these flow coolers to get under room temperature. Time and prices will tell. Another way may be to get a cheap, used beer cooler or sth on ebay. But you never know in what condition the compressor is, esp. its coolant
I use the pump that was included in the watercooling set. There are cheaper pumps to buy, no idea if they stand the cool water for a long time. I insulated the hoses outside the freezer, that seems to be quite important, and kept it short.
I first did no insulation, just as a try I have now put Styrofoam boards under and around the terrarium except the top and front. It has not shown that great effect, but I did not really seal it, as I wanted to avoid heat build-up during the day, when the lamps are on. Anyway, it brings some light reflection too.
Maybe a bit too early to give a résumé, but I had already some promising results. Many plants are beginning to go off now, in a time of the year where most of them just ceased before. And some of them even started to flower, that have never bloomed in summer. Or never bloomed at all in all the years, like my U. humboldtii x quelchii
The tank is placed in my storeroom, where temperatures did not fall below 25°C already on some warmer May nights, with a temperature inside the tank even one or two degrees higher. I now get night temperatures inside the tank of around 15 degrees Celsius, the lowest this summer was 10°C, the highest 17°C, taken in the early morning. So the cooling effect is about 10 degrees down.
What would I do different next time?
Well, first of all skip that nasty camping thermo box. Waste of money. For those who would doubt that I still have a quite unused one to offer for your try in my cellar
Then: maybe not a complete watercooling set, the single components are cheaper to get maybe. But the set has one advantage all components fit to each other, so difficult to say.
Next I will try is a flow cooler, because those freezers' compressors are not made for continuously running (even though I run it only though the night, and some hours in the afternoon), and my compressor smells and sounds a bit like it wont live forever but first the prices have to fall down a bit more.
The watercooling set was 140, and 150 for the freezer. The rest is altogether maybe another 20. Current draw is somewhere around 90 Watts.
Happy highland growing
Edited by Martin Hingst, 29 April 2009 - 11:08 AM.