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My cooling unit


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#1 Martin Hingst

 
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Posted 03 August 2008 - 19:48 PM

Hi,

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 weren’t 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.

Cooling element

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 cpu’s, 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 cpu’s to room temperature, but why not the other way round? As I said, not my idea, just my way to put the components together.
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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…

Water circulation

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.
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Insulation

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.

First experience

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 :bad:
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 :D
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 won’t live forever…but first the prices have to fall down a bit more.

Costs?

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 :P

Martin

Edited by Martin Hingst, 29 April 2009 - 11:08 AM.


#2 Cas

 
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Posted 04 August 2008 - 00:26 AM

Thanks Martin.. this is really useful!

I've been trying to cool my 2ft tank that is insulated all round with styrofoam.. first attempt is with a 90W+ peltier cooler but that only managed to bring the tank temp down by 3C+.

Now I use 3 Coleman cooler blocks hung from the top of the tank each night. This brings the tank temp down by about 10C. By morning, however, temp in the tank's about 24-25C (our mornings are typically 28-29C this time of the year).

..Now very tempted to try what you've done..

#3 LJ

 
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Posted 04 August 2008 - 09:28 AM

Very interesting Martin :thanks: I would love to have something to cool my growing area down at night a bit more, unfortuntely I wouldnt know where to start trying to put something together like that. Well done!! The results sound very promising too :smile:

Heather

#4 Martin Hingst

 
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Posted 04 August 2008 - 09:45 AM

Hi Heather,

sorry if I kept it too confusing, but these watercooling sets are already ready to use, and the instruction that comes with it are for customers like ordinary PC users - not all of those are experienced tinkerer :thanks: To bring it to the point:
All I had to do is to integrate this cooling coil into the water circulation and place it together with the pump inside the freezer. The coil was one of the easiest - and cheapest :smile: things, I made it by just bending a 3€ copper tube from the superstore to the desired shape.

But those units would not be of any great help in a conservatory or sth., just for a smaller, closed volume like a terrarium.

Snuffy, 29degrees in the morning? And I thought I got it bad already... good luck and

regards

Martin

Edited by Martin Hingst, 04 August 2008 - 10:04 AM.


#5 LJ

 
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Posted 04 August 2008 - 10:18 AM

Hi Martin

Well, its my indoor growroom (coverted cupboard!!) that would benefit from some additional cooling rather than the greenhouse or conservatory. You almost make it sound easy putting that together - you have to remember though I'm a woman without practical DIY skills :thanks:

Perhaps one day I'll be brave enough to try something like that :smile:

Heather

#6 Cas

 
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Posted 04 August 2008 - 11:58 AM

Hi Martin,

I'm wondering if you'll enjoy higher efficiency if you place the copper coils (presumably those are your heat exchanger?) as close as possible to the top of the freezer/cold plate? Possibly enclose it in plastic container and seal it off from the rest of the fridge? I'm thinking of all those hotel room mini-bar fridges, they have those tiny ice box compartments as close to the cold plate as possible - water freezes in them.. while the bottled drinks below never do.

#7 Martin Hingst

 
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Posted 04 August 2008 - 13:03 PM

No brother or father with DIY skills, Heather? :smile: grandfathers are also well known for being extremely helpful - whenever they are asked for, and even when not :thanks: provided you were a good granddaughter :wink:

Snuffy, in the beginning I screwed the coil on the metal plate at the back of the inside, that is in close contact to the compressor. But it gave a bad resonance when the compressor started... so I untightened it, with no remarkable loss of efficiency. But when I need to, I will try that again - the really hot nights are yet to come.

#8 UtricSeb

 
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Posted 04 August 2008 - 17:57 PM

Hello Martin. Your cooling setup sounds very interesting and your results seem to be quite good. It is a little hard to imagine it from just words. Do you think it is possible for you to show some pictures or a drawing showing how to assemble it?

Kind regards,

Sebastian

#9 mobile

 
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Posted 04 August 2008 - 18:34 PM

Just a thought - I wonder if it would be possible to connect the cooling element directly into the refrigerant system. That way it would eliminate the losses in the air to water heat exchanger. It would need a refrigeration engineer to do it though as it would involve removing the existing refrigerant, soldering copper pipe into the existing circuit and recharging with refrigerant.

#10 Mantis

 
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Posted 04 August 2008 - 19:51 PM

Your results are better than mine!!
I used a Waeco Compressor cool box (minimum temperature -15°C), a slightly bigger radiator (39x12 cm), 1 fan (couldn't place more) and pvc tubing.
First I placed the pump in the cool box but the pump generated too much heat. Next I placed the pump outside the box and placed tubing (in a spiral) inside the box with a small reservoir so there would always be enough liquid in the system.
I used cooling liquid mixed with demineralised water. After many tests I gave up on this setup. I think the problem was that the cool box wasn't capable to process the warmth enough of my growing chamber and that my growing chamber and tubing wasn't insulated at all. Or that the water in the tubing didn't spent enough time in the cool box to cool down.
In the end I would let the box cool the reservoir and tubing to the point of freezing but as soon as I switched on the pump the temperature quickly became 10°C with no real effect on the temperature inside.

The next thing I want to try is to get the cool air from the box in the growing chamber with fans and piping.

The days during my tests I noticed that I would size up all those nice open refrigerators in the supermarket and I even looked into the option of dry ice and liquid nitrogen :tu:

#11 Martin Hingst

 
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Posted 04 August 2008 - 20:52 PM

Hello,

Mantis, I would not give up, but use a stronger freezer. -15°C as given from the manufacturer seems not very effective. Mine gets around -25°C before the thermostat switches the compressor of, without that switching off it would get much deeper I am sure. But when I start my system, even my freezer gets not deeper than zero degrees, with a temperature of the circulation water at about +8 degrees.

mobile, you are absolutely right - with both your suggestion and your

It would need a refrigeration engineer to do it though

:tu:
Maybe when the system has to be refilled anyway (what may be sooner than I hope...) I will think about that. But my first hope is that the flow coolers (that do in princible what you suggested) are more affordable at that time.

Sebastian, sorry I have taken no pictures in the built-up process, and drawings - well please believe me when I say you would not like to see that, and it would make it only more confusing :smile:

So maybe some more words and some links to pictures of others:

First I mounted the fan at the radiator's back and fixed the radiator at the top of the terrarium (with some wires :roll: it has a perforated dressing there for air exchange). The radiator has already the two adapters for connecting the two water hoses for in- and outgoing water. These two hoses I fed into the freezer - I drilled two holes in it (without hitting its essential parts :smile:). One hose I connected to the inlet adapter of the pump. The other one to one end of the copper coil, the other end of the coil is connected to the outlet adaptor of the pump - thats it.

To be more correct, there was another cooling piece in the setup - the cpu cooler. I also integrated it into the circulation, after the coil, in the same way, but you can forget about that - and can spare the money when buying the pieces one by one. It makes about a third of the setup's price...:roll:

Here a picture of the cooling unit of Martin Reiner Posted Image at drosophyllum.com The english version is under reconstruction at the moment, but I can suggest that as interestiong reading. I got my first inspirations from his page.

I know that "the devil lives in the detail" what we say in German, and I did not want to let it sound as it was nothing. So if you have further questions, please ask.

Regards

Martin

#12 gardenofeden

 
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Posted 06 September 2008 - 11:49 AM

Just a thought - I wonder if it would be possible to connect the cooling element directly into the refrigerant system. That way it would eliminate the losses in the air to water heat exchanger. It would need a refrigeration engineer to do it though as it would involve removing the existing refrigerant, soldering copper pipe into the existing circuit and recharging with refrigerant.



yes, why not dissect an old fridge, remove the cooling "plate" and put it in the tank with the compressor etc outside? Linked to a thermostat you could get any temperature you liked.

I saw a great unit once, someone used an old chest frezzer with a sheet of glass and lights on top, now that would be cold!

#13 adams

 
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Posted 07 September 2008 - 03:11 AM

yes, why not dissect an old fridge, remove the cooling "plate" and put it in the tank with the compressor etc outside? Linked to a thermostat you could get any temperature you liked.

I saw a great unit once, someone used an old chest frezzer with a sheet of glass and lights on top, now that would be cold!

that may have been me

#14 adams

 
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Posted 07 September 2008 - 03:13 AM

yes, why not dissect an old fridge, remove the cooling "plate" and put it in the tank with the compressor etc outside? Linked to a thermostat you could get any temperature you liked.

I saw a great unit once, someone used an old chest frezzer with a sheet of glass and lights on top, now that would be cold!

that may have been me

#15 mobile

 
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Posted 12 September 2008 - 11:24 AM

yes, why not dissect an old fridge, remove the cooling "plate" and put it in the tank with the compressor etc outside? Linked to a thermostat you could get any temperature you liked.

Like these?: http://pitcherplants...x...6419&page=1

#16 adams

 
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Posted 12 September 2008 - 21:05 PM

what is the utricularia with the largest leaves in the picture?

#17 Martin Hingst

 
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Posted 29 April 2009 - 10:38 AM

Hello,

after about a year, maybe a good point of time for a first conclusion.

Fist the technical things :
the freezer works still good - maybe I was a bit too scared in this point :sarcastic_hand: The pump is continuously running, day and night, for a year now, without any problems. No corrosion in the radiator, and the fan is doing its job well, despite the humid environment.

Then the plants: I have never had better looking highland plants. Most of the plants are starting to flower, it will become very colourful in my tank in some weeks :JC_cupidgirl: among the flowers some firsts - like U. longifolia and others. I will post some pics soon.

As my description above was maybe not too clear, here a drawing of the principle. Hope that helps.

Posted Image

Adams, the plant on the right is U. alpina 'Pittier Moon'.

I will show you the results in flower soon - bye for now

Martin

#18 Dicon

 
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Posted 29 April 2009 - 15:32 PM

Martin,
Have you considered filling the freezer with bottles of water to inprove efficiency.
After the initial freezing of the water, the system would become easier to balance and the compressor could rest.
An empty feezer is least efficient!

#19 Sebulon

 
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Posted 05 May 2009 - 12:20 PM

Martin, can you post some picture sof your highland utrics by now. Can't wait to see them! :D I have U.alpina in a roomtemp terrarium, growing decently, but not as well as it could. I also have a few more highland utrics ordered, so I really need to make some cooler unit like this.

Where did you get that cooling element in the first pic, did it come with the set you ordered? Where did you order the set?

Do you use a fridge or freezer? I think I saw you telling it to be both in some paragraphs. :D Or maybe I was getting dizzy while reading the whole topic. :D

Thanks for posting this useful topic, I have found it to be my lifesaver!

Greetings,
Jarkko

#20 Martin Hingst

 
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Posted 11 May 2009 - 12:48 PM

Hi,

thanks Dicon for the idea. I am sure you are right - that would buffer the cooling capacity, and the freezer could indeed rest. In terms of efficiency, something that has to be proven first. Worth a try.

Jarkko, I use this cooling set here: http://www.webshop-i...40-AM2-AM3.html

and a link in English http://www.trend4pc..../19/language/en

I still use a freezer, but the prices of flow coolers (aquarium chillers) are going down now - I am not sure if I really need the higher cooling efficiency, but it would make the setup more professional - and more compact. And I could mix in more air from outside for better ventilation. Maybe some day.

BTW, the first flower has opened up - U. alpina x campbelliana :woot: Not the shiest flowerer among the highland Utricularia - but a first for me. And I spotted some new stalks - U. jamesoniana among it. Maybe I will find the time for some pics this weekend.

Regards

Martin