DIY chiller from mini-fridge

[mmelnick]

I have 2 tanks side by side. My 55 fresh and my 20H salt. I only had the 55 last summer and it was getting into the 90's. I have added 260watt PC's since then too, so I know that I will have problems with both tanks come summer.

 

My thought is to get an old mini-fridge and put it under the stand for the 55. I would then run a long coiled up hose from each tank through the fridge; possibly my sump return or something similar. I could set the fridge to a certain temp and hope that the water ran through it long enough to make a difference. The problem w/ a DIY like that is that a fridge is meant to operate constantly and at a lower temp than I want my tank. The only solution I can come up with so far is to use the offset of the fridge and heaters to maintain the correct temp.

 

Has anyone done anything like this before? And as always, thanks in advance.

[lakshwadeep]

Yes, I've read about this. Let me look if there's something online.

 

http://saltaquarium.about.com/od/dyiprojec...ydonchiller.htm

 

http://www.wetwebmedia.com/diychilrfaqs.htm

[mmelnick]

Yes, I've read about this. Let me look if there's something online.

 

http://saltaquarium.about.com/od/dyiprojec...ydonchiller.htm

 

http://www.wetwebmedia.com/diychilrfaqs.htm

 

Yeah, that's pretty much the exact same Idea I have been playing with. I'm just worried that I might over chill the tank. I don't think that a fridge can be set to a temp as warm as 70 degrees. So I would have to cool it more than that and hope that in the case that the tank got too cold the heater could keep up. So basically the project iis hanging on whether or not a heather can heat faster than a fridge can chill.

[BKtomodachi]

These systems are usually very ineffective, so cooling too much probably will not be a concern.

[mmelnick]

they also have a freezer section, so a lot of hose near the colder section may be the way to go.

 

 

I was thinking.... maybe I could use my digital thermometer to shut off the fridge once the water temp gets too low in the tank.

[shiveley]

it's very difficult to maintain a specific temperature output with a refrigerator's cooling unit, and they're not as efficient as most aquarium specific versions.

[mmelnick]

I'm sure that't true, but my second consideration is that I have 2 tanks to cool. Is there any way that I can get a chiller that can do 2 tanks (or 2 chillers) for the price of an old mini fridge and some tubing.

 

A legitimate chiller to keep up with a 55 gal will not be cheap.

[BKtomodachi]

I'm sure that't true, but my second consideration is that I have 2 tanks to cool. Is there any way that I can get a chiller that can do 2 tanks (or 2 chillers) for the price of an old mini fridge and some tubing.

 

A legitimate chiller to keep up with a 55 gal will not be cheap.

I don't really know of any good way to cool both tanks, unless you wanted them to share a sump or something.

 

As for the chillers- AFAIK, a "real" chiller will likely be less expensive after several years if you pay for your own electricity. The fridge versions are very energy inefficient, and I doubt one mini-fridge could accomplish much cooling in both tanks with that total water volume.

[mmelnick]

I would spring for one chiller if I had 2 SALTWATER TANKS but the 55 is a freshwater. If I ran them together I would have a whole lot of pissed off fish.

 

 

 

so... is the general consensus that it won't work, or that it is not efficient? I'll put it this way. I can't spend over $100 and I ahve to cool 2 seperate tanks. The place that I am renting does not even have AC so I have to do something.

[jeremai]

Go to Wal-Mart and spend that $100 on an A/C for the window.

 

There isn't a cost-effective way to chill a tank more than with evaporative cooling - if there was, chillers wouldn't be so expensive. People have tried the tubing through the fridge idea, but like others have said, it won't work how you want because it's incredibly inefficient. Unless you could run glass tubing, or find some other way to keep the tubing suspended on all sides, it will only transfer heat where the tubing comes into direct contact with the surrounding air.

 

Save up for a chiller, or change the room temp with an A/C, those are your best bets.

[Coralkeeper]

Hey, everyone. I'm starting up a coldwater tank have and have a few questions similar to this. Here is the link to the thread. Thanks!

http://www.nano-reef.com/forums/index.php?showtopic=153156

[Chutsk10]

I don't see why the fridge idea can't work or be designed more efficiently. . . Just use more coils if need be. Also you can possibly hook up the pump feeding the fridge to a temperature sensor to shut off water flow if it happens to be too good of a system.

 

The plus side of this would be that you can cool both tanks and well, you can cool beer. Can a chiller do that for you? Don't think so.

[FateX9]

what about using titanium tubing in the fridge? i was thinking about trying to make a chiller using one of those thermoelectric coolers for cars to keep drinks cool and just fill the entire thing up with water and see how that works, youd need to use a controller to turn off the "chiller" but thats not a problem since you should be able to use a ranco single controller, but for materials alone would run ~200 which is how much a small chiller runs

when i save up some more money i may try out some of my wacky ideas but no spare change after setting up my tank and i still need more money for the fish i want

[BruiseAndy]

I'm sure that't true, but my second consideration is that I have 2 tanks to cool. Is there any way that I can get a chiller that can do 2 tanks (or 2 chillers) for the price of an old mini fridge and some tubing.

 

A legitimate chiller to keep up with a 55 gal will not be cheap.

 

 

Could do single loop and pump in a titanium coil with a couple three way valves but that would cost the same as buying two chillers most likely.

[qbical]

yea, but it also depends on what kind of material you are using INSIDE the fridge for piping/water flow. some materials have really poor thermal transfering properties, so maybe u can use that to your advantage. if u use a material that has poor thermal transfer inside the fridge then it wont be cooling the liquid so much. contact time will make a big difference too. between the tanks heater, the material used and contact time, i think it is totalyl poss.

[kingwintergreen]

Save up for a chiller, or change the room temp with an A/C, those are your best bets.

 

I agree. Throughout the 10 years I worked in LFS's one of the things I could never understand is how the same hobbyist who would have no problem slapping down hundreds of dollars at a crack for a lighting fixture (and oh so much more to regularly replace bulbs) would not even consider purchasing a chiller, however great the need (despite the fact that it is a one-time purchase). I could never see the gain in risking sometimes thousands of dollars of livestock to avoid the peace of mind a good chiller provides.

However , I don't mean to belittle your DYS spirit. In fact, if some manufacturer could produce a DYS kit specifically for the purpose of converting minifridges to chillers, the world would be a better place... at least better for those of us who don't have the real thing. Keep us posted.

[AquaticEngineer]

I made myself one of these several years ago with a mini fridge for a cold water marine tank. I could keep a 20 gallon tank consistantly in the 50's, my 55 gallon was in the mid 60's.

 

I tried slowing the current down through the tubing inside the fridge and that helped a lot, but the biggest thing I found that helped was completely by accident. I was trying to figure out a way to coil more tubing inside the fridge and stumbled across a vinyl tubing that had aluminum coil molded into the vinyl tubing ( not in contact with the water) It made the tubing more flexible while eliminating the kinking of regular tubing. It also increased the transfer of cold since the metal would get colder much faster then the vinyl.

 

I even tried putting all of the coiled tubing inside of a large tupperware inside of a mini freezer and filling that with a high salinity water mixture to lower the freezing temperature of the water inside the freezer so it would transfer better to the coiled tubing running up to the tank. The freezer I never got to seal right after I drilled a couple 3 inch holes in the top. lol

 

If I had it to do again, I'd probably buy a chiller. If I had to do it again on the same $$ I had, I'd go ahead and trash a 40 mini fridge from college.

 

Again, my goal was to get as low a temperature as possible, not maintain one.

[Kraylen]

Find someone who makes Kegerators and ask them to drill it out for you! If you do it wrong you can mess up the coils.

[Sctn4Elk]

Find someone who makes Kegerators and ask them to drill it out for you! If you do it wrong you can mess up the coils.

 

I thought about this at one time long ago when I lived in Boise and Home Depot had a sale on those mini fridges for 49.00. The problem I ran into was trying to keep the water in the fridge long enough to even cool the water 1 degree. There are a lot of articles out there on the internet about this and they all seem to say it won't work. Another idea was to get one of those portable AC units and just point it at the tank, they are cheap, like 70.00, and would be far less than the chiller. I would have to do some research to see which one would be more cost effective over the long haul..as I recall, those chillers tend to pull some power too.

[Fraggy]

Hi. I'm new to the forum and I'm doing the exact same thing you are. My tanks range from nano to 125. My 75 and 29 overheated so bad the other day, I lost half my coral. In my city, it hit 107, a record high for this early in the year and then spanned for a week that way. Fortunately, it's back to the low degrees, and I have time to do the dorm fridge thing also.

 

I feel for you...I had to bury my 21" colt coral tree (it was 21" WIDE not tall...height was about 16".

Its two brothers are dead as well...a really horrid loss, and my Yumas may still not recouperate. My bubble coral is having a hard time also.

[BruiseAndy]

Hi. I'm new to the forum and I'm doing the exact same thing you are. My tanks range from nano to 125. My 75 and 29 overheated so bad the other day, I lost half my coral. In my city, it hit 107, a record high for this early in the year and then spanned for a week that way. Fortunately, it's back to the low degrees, and I have time to do the dorm fridge thing also.

 

I feel for you...I had to bury my 21" colt coral tree (it was 21" WIDE not tall...height was about 16".

Its two brothers are dead as well...a really horrid loss, and my Yumas may still not recouperate. My bubble coral is having a hard time also.

 

It might work for the nano, for the 125 you will definitely need a chiller.

Quick math

Mini fridge with a 1/12 hp compressor can remove 666 btu/hr

70W pump would transfer almost all its energy to water=239 btus

70W light probably about 30Watts transferred to water=102 btus

 

Already over a 1/2 capacity of the fridge is taken with a small light and pump.

 

The transfer of energy from ambient conditions would be a bit harder to calculate due to glass thickness and me not knowing the U value of the glass in a tank and would also have to factor in humidity to see how much evaporative cooling you could get.

 

My best suggestion would be using copper tubing in fridge then buying and 18" section of titanium and swagelok the two together with an open loop resovoir and a pump. Can buy 3/8" annealed tubing then bend a U out of Ti to place in tank.

 

Regardless of how well the heat transfers through the tubing you are using you have to remember you are limited by the amount of heat the fridge can remove.

 

1/12HP is probably overestimating as I have seen some of these with 1/20HP compressor in them.