Cheap air cooling of buckets

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purklize

Active Member
Well it's that time of year: it's getting warm outside and soon we're going to have to worry a lot more about pythium/root rot in our DWC buckets.

Here's the solution I came up with last summer. Instead of buying $500 water chillers that don't allow you to have different nute solutions in the different buckets... or keeping the room freezing cold... I just put the air pump in front of the air conditioner. The air there was 50-55F, and it kept the water temp at 60F even when it hit 80F in the room.

This year I'm going to salvage a crappy old dorm/box fridge, drill holes in the side for air lines, and put the air pump in there. I could keep it a lot colder, as cold as I wanted, and it'd use a lot less energy. The biggest problem with the A/C method is if it gets cold outside the A/C refuses to do anything but recirculate air, so paradoxically if it's cold outside, the water temps go way up and the room gets hot and humid. Cracking the window isn't good enough in these situations, there's not enough air flow.
 
dbkick

dbkick

Well-Known Member
careful of the refrigerant lines but then you already knew that I'm sure. I just modded a chest freezer to supplement the chiller, its costing a fortune to run but it def cools the light plus has a little left over to cool the room a bit, running an icebox heat exchanger on the light.
 
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purklize

Active Member
How is it impractical? All you have to do is drill a few holes in the side with a metal cutting bit and you're done...
 
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purklize

Active Member
If you can't support your statements why post them in the first place?

"It won't work"
"Why?"
"Cuz... I don't have to explain it"
 
missnu

missnu

Well-Known Member
I would think that the cost to run a minifridge would be an issue, but if you are running an AC and you did away with that and just had the fridge then it probably wouldn't be terribly different
 
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purklize

Active Member
They're a lot cheaper to run than air conditioners. You can get box fridges that only pull 90 watts, and they're insulated, so the cool air builds up, unlike an air conditioner where it has to run continuously because it's venting straight into the room. Air conditioners also pull a minimum of 400-500w, usually a lot more unless it's the smallest model in the store.

90w box fridge: http://www.amazon.com/Danby-DAR195BL-1-8-cu-ft-Refrigerator/dp/B000FAR33M/ref=sr_1_2?s=kitchen&ie=UTF8&qid=1335297684&sr=1-2
 
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psari

Well-Known Member
Depending on the location of the fridge it will add heat to the inside as it exchanges. Especially if you need to vent it (you will) to allow the pump its air source. This forces the fridge to run constantly and makes it incredibly inefficient.

Also watch for starting AMPs needed on even those little guys on where you place this on your circuits. Some of them have a start hit that can be well over 10 AMP on those little compressors they use. Larger ones can be even higher (12+) depending on who made the core.

Dont get me wrong, I'm not here to rain on your parade. (Just thinking some food for thought might be helpful.) Using fridges for this and that is not the most efficient method and why you dont typically find it stickied/FAQ'd/printed in books/etc. And not just for this application. Sideline into the aquarium forums on cooling air-pumps and their output and the like for some examples of this.

Thousand ways to get creative though and if nothing else you can learn a great deal while having some fun in the process.

Cheers.
 
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purklize

Active Member
I'm failing to see how this is less efficient than my air conditioner idea, which worked great last summer... the point of this one is to lower power consumption drastically... yes a pump will produce some heat in the room, but if the water temps are perfect an extra 1-2F in the room isn't going to hurt. Even if a 90w fridge had to run 24/7 to keep up (which seems pretty unlikely) it would only cost about 5-10 bucks a month depending on your power rates. You could put some containers of water in the fridge to keep it colder when it turns off so it doesn't have to turn on/off constantly.
 
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psari

Well-Known Member
Ah, translation issue on my part ...

I assumed you were needing/using the AC unit regardless and that this would be an increased cost for your setup or an alteration. I merely wished to express considerations for helping you make it work as you appeared committed to this solution.

The only point I felt was of importance was that this "is not the most efficient method" for accomplishing the goal but it is not pointless or without basis for potentially working while reducing your costs depending on other factors. As well as the idea that start draw on some devices needs to be kept in mind. Key point being that things that may work in other realms often dont even apply to this as stealth and space are often more of a problem. That and other solutions may cost more up front and not fully realize their potential savings until much later as you've indicated is to be avoided.

Like all text based exchanges there is far too many details missing to try and flush out anything more than generalities here. Asking a thousand questions about being able to locate X component in Y space (putting fridge and pump combo in another room) or anything else usually is just spinning wheels unless you're fully up to speed with the poster etc.

As to efficiency, I was not thinking your AC solution was more efficient. Indeed, it is very likely far less. Especially with the disclaimer that you can have times where it will not run. Comparison was in regards to other cooling methods potentially used for the air pump. Fairly long list of other things that could be attempted that may gain similar results without the same power consumption and added heat. Since dissipating heat from anything that exchanges is always an increased cost. Whether it is an exhaust fan or having to rework things, this is a major factor.

Combinations of cooling bother reservoir and air would probably be a best long term solution, and inherently the most efficient.

I know tone may be a problem here. Just disclaim this as a translation problem from my end. I am not dismissing any potential here. Just sharing some thoughts.
 
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purklize

Active Member
Sorry, I hope I didn't sound rude or pissed in the last message, you are right when you say the written word can be tricky like that. I do appreciate feedback and I'm just trying to figure out the best way to do this, if this ends up being a terrible idea I wouldn't be surprised, I've had bad ones before. :D I didn't take your words the wrong way, it's obvious you're doing your best to be helpful - thanks.

Something that just occurred to me:

Evaporative cooling can bring the temp down a lot, either by using a fan or an airstone, but the problem is that air pumps run hot and are probably pumping hot air into the reservoirs... maybe the reason putting it in front of the a/c was so helpful was partly/entirely because the air pump was cold to the touch?

It shouldn't be expensive to implement. I intend on fishing a box fridge of a dumpster when all the students leave town in the next week or two. I had two, but they got stolen. Long story. :evil:
 
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psari

Well-Known Member
Air temp from pumps does increase a fair degree. Depends on the pump from what I recall on just how much. Come from the soil/hempy world so I've never paid this much attention.

Key examples I noted previously were where people were trying to reduce all factors for maintaining salt fish tanks in comparison of course. Evidently it's not cheap to run those nifty salt tanks. GIGO though. Was curious reading but it didn't stick.

Main gain was still more likely from your intakes that were drawing in around that 50-55 F range and translated as passive transfer into the water.

Without measurements of the output and all the rest it would be hard to determine.

All the noise I read on using freezer/fridges was about how they exchange heat and how they are engineered to only deal with a small volume of air. VS your air-conditioner which has to run and bled more heat quickly.

As for potential changes/experiment consider the fact the intake temp will be passing through the pump and exiting quickly. Running your intakes around a cold core or similar may help here to allow the air more time to cool.

Similar to how the drain to waste water coolers use a coil to increase their contact. Using something like alcohol or even oil should be considered. Not likely to have a freezing problem, but just a water core or solid metal core device may not be ideal for such a modification.

Intake air temp can easily be reduce using a simple tower evaporative cooling system. Up to and including running the water used for this through the fridge to help take advantage of the juice being used and to offset the pumps byproduct heat.

Most pumps can handle a fair amount of condensation, but also watch for this I would think. Especially if you'll be passing moist air with that temp differential in an enclosed space.


Only comparative thing I've seen done was to muffle and cool a ballast for stealth and heat control. Buzzing easily explained as small fridge at a glance and all that. Slightly different but similar application direction.
 
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purklize

Active Member
psari - great idea about the alcohol. Thanks again for your feedback, I'm pondering this stuff.

BigBuddahCheese - why are you posting in this thread? So far you've said nothing. Not helpful and annoying to anyone reading, it's just clutter. I am not going to be crushed because Mr. Physicist won't tell me the imaginary flaw in my idea. Either post something useful or butt out.
 
IN33DW33D

IN33DW33D

Active Member
Don't worry about BBC, he's a straight to the point guy. No reason to write essays on obvious observations. ;)

Anyways, what I did was build a huge box wrapped in mylar to trap all the cold air and I use a booster fan to blow cold air from my AC set on a thermostat to keep all my buckets at 60 degrees. It costed me the price of a booster fan, 2x2's, and white and black mylar wrap which was all already located in my grow room when I started the idea.
 
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purklize

Active Member
Unfortunately you are the one that started down this path, but yet like the impracticality you cannot see so is the way this thread has derailed. Trolls usually do...

toodles tough guy.
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Don't worry about BBC, he's a straight to the point guy. No reason to write essays on obvious observations.
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I'm not asking for an essay, but rather a statement of what these "obvious observations" are. To enter a thread and say "Your idea won't work" and then if asked why, to say "It's so obvious I shouldn't have to say" is rude and arrogant.
 
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purklize

Active Member
Another trick I've seen work is to place your air pumps inside a dorm refrigerator. The air pumps will then pump cold air through your rez. Just drill some holes through the side for the air tubing and one through the top for a small intake (warm air from the pumps goes up). Works like a charm.

http://www.icmag.com/ic/showpost.php?p=1202404&postcount=14
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I have seen people put their air pumps into freezer sections of mini fridges, and think I might try this eventually, and definitely so If I have to take extended leave from the plants.

http://www.icmag.com/ic/showthread.php?t=66112
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Well, looks like it works...

Another possibility would be to cool the pump with a fan, and have the intake go through the box fridge... have a coil of copper or aluminum tubing in a container of alcohol (like psari suggested) so that the air enters the pump freezing cold... or if a fridge isn't available, a cooler full of ice/brine.
 
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psari

Well-Known Member
Not sure where to find a source on how much power a fridge with freezer or for that matter a standard freezer. But there is a thermodynamics rule or two involved here. The amount of time and calories being exchanged to create that ice at whatever rate vs the power requirements needed to constantly do the same thing or to do it nearly instantly.

Even my water dispenser for the other fridge I use has a simple coil of tubing. Running it "dry" so to speak means I'm waiting a couple of hours before I get that nice cool water. And in the meantime I can listen the fridge run a little extra. Always wondered how much my ice and cold water cost me in the desert in power. Go through enough of it plus the cost of the RO system ... Pointless side commentary.

Far too long away from that sort of math to work out other factors like the contact with the floor as a heatsink by surface area, effects of ambient air temp, insulation factor of the buckets and res, etc. As a minor aside, I see a lot of uninsulated reservoirs and that only seems to make sense if you wish them to try and maintain ambient air temp ...

Now I'm wondering how flash freezers work ... hrmmm.
 
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