DIY fridge chiller

Hamp

New member
I am planning on building a chiller out of a small fridge by running a water line to a bulkhead then a coil inside of clear tube and back to the tank. I want to take apart the freezer walls so the thermo will control inside temp. Then a heater in tank...I saw this somewhere...How well do you think it will work?
 

QuagmireMan

New member
put on your flame suit........


To answer your question, not very well. There is a link someone will put up soon about how a fridge cannot dissapate heat rapidly enough to keep an aquarium cool.
 

fishy_business

New member
This has been discussed in the past numerous times and has been proven not to work.
If a chiller isnt in your budget you should consider fans blowing across the top of your tank,as evaporation will bring down temperature.
 

smcdonn

New member
Save your money and buy a 1/20hp JBJ chiller. Im not going to get into why the fridge idea doesn't work, just believe me its been tried 100 times without much success.
 

Hamp

New member
Yea, a long shot. I'm in Texas and it is starting to get hot. I have 150w HQI on my aquapod and even with fans on it gets up to 81 in my tank(and its only march). I am also loosing over a gallon to evaporation every day. I have 2 small fans from around the house set on the back. I have seen small DC type fans online that I think are built for nano tanks. Anyone have reviews on these?
 

TIMMYE

New member
A gallon a day is not bad. I evap about 3.5-5. I also run up 82 degrees. So I woul d not worry about 81. I would save your money and get a good chiller if you are really worried.
 

ABATTLEDONKEY

In Memoriam
i gotta disagree here with the general consensious here. i have used a small fridge to chill water with MUCH success. essentially, what is a water chiller? its a shophisticated frige with the focus on chilling running water.

the trick is this: direct contact with the evaporator coil!

the evaprotator coil is the cold part for those who dont know. the odea of running a water line through a fridge is very bogus as the heat cannot disapate very well. the reponse time is also VERY long between cooling the entire fridge and alllowing the heat to be pulled from the water. the thing you want to do is to find a fridge that has a VERY loose confiuration. pull all the cooling fins out of the evap coil so that all you can see is the coil is self. then take your water line and run it(zip tie ti directly to) right on top of the coil, matching its distance with your line. heck, coil it around if you want to. that water will get COLD is an instant and youll have a very fast response time. i did this to chill anti-freeze to a nice 10F as a project to prove this very point to my air conditioning instructor(it was a class i was taking). its a lot more work, but its doable.

this is also VERY easy to screw up and it something goes wrong its never an easy fix. if possible i would definatly just BUY a chiller, but im setting this up for my brother and im not gonna worry about it one bit. if you DO decide to do this, make sure you know EXACTLY what your touching and messing with cause like said, you can mess this up royaly. good luck!
-Paul
 

MayorOfWhoVille

New member
Has anyone seen a fridge chiller design with the tank water tube coiled in another body of refrigerated water? So basically the heat transfer would be much more efficient and the water in the 'heat sink' would have time to exchange heat with the cool air in the fridge...at least on paper. Any thoughts?

Also, ABATTLEDONKEY, cool idea!
 

BeanAnimal

Premium Member
<a href=showthread.php?s=&postid=12199991#post12199991 target=_blank>Originally posted</a> by ABATTLEDONKEY
i gotta disagree here with the general consensious here. i have used a small fridge to chill water with MUCH success. essentially, what is a water chiller? its a shophisticated frige with the focus on chilling running water.

the trick is this: direct contact with the evaporator coil!

With all due respect, that has nothing to do with it. The problem with a "dorm fridge" is not the ability of the unit to transfer heat. The problem is the overall cooling capacity of the refrigeration system in general. I would be more than happy to explain in detail, but have also authored an article to help people understand the basic physics and math that need to be applied to the question.

http://www.beananimal.com/articles/dorm-fridge-aquarium-chiller.aspx

This is not one of those subjects that can be argued with opinion. It is a simple matter of the capacity (lets say in BTU/hour) of the refrigerator in question versus the heat load of system to be cooled. If you have a heat load on your tank of 1000 BTU/hour and your dorm fridge is capable of moving 500 BTU/hour, then it is not going to work, no matter how much water you run directly over the evaporator.

Anybody who claims to have built a successful chiller from a dorm fridge is blissfully unaware of the basic physics involved and the fact that their heat load was minimal to begin with.

So back to the question at hand. Can you use a dorm fridge as a chiller? Sure, for a nano tank.
 

BeanAnimal

Premium Member
<a href=showthread.php?s=&postid=12201650#post12201650 target=_blank>Originally posted</a> by MayorOfWhoVille
Has anyone seen a fridge chiller design with the tank water tube coiled in another body of refrigerated water? So basically the heat transfer would be much more efficient and the water in the 'heat sink' would have time to exchange heat with the cool air in the fridge...at least on paper. Any thoughts?

Also, ABATTLEDONKEY, cool idea!

The "heat transfer" is not the problem. The problem is the overal capacity (in BTU/hour) of the refrigerator and the fact that refrigerators are NOT designed for the duty cycle required to chill a tank. Their compressors are designed to be cooled by the refrigerant under a low duty cycle. Leave the door to your fridge open for a day or two and see what happens (the compressor will die because it will overheat).

Do yourself a favor and purchase a small purpose built chiller. Also note that for every gallon of water that you evaporate, you get over 8,000 BTUs of cooling!
 

BeanAnimal

Premium Member
<a href=showthread.php?s=&postid=12195362#post12195362 target=_blank>Originally posted</a> by Devil Man
yea and bean is giving me a hard time... look at this... gezze.

Look at what? Somebody asked a question and people have kindly showed up to answer. Once again, if you don't like repetitive questions, ignore the threads instead of complaining.
 

ABATTLEDONKEY

In Memoriam
ok bean
lets loose the hard on shall we? geez. nice article, nice rant, but all of it is jjust a waste of time. im going to say this is plain english and without any complicated words for you : i have made this work to an extreme degree. thats right bean, i made on one these puppies cool a 200 gal system, sitting in a 100 degree room to 10 degrees F(this was antifreeze, not an aquarium). i have also gotten an aquarium to cool using the same manner when the ambient temp was 120! its a cheap alternative but i also suggested a water chiller because it is alot of work. i understand ALL the physics very well, and have worked with this stuff for 5 years as a fun side job. the idea that there cannot be enough BTU consumption with this process is insane. this is EXACTLY how one of you water chillers works. AC sytems are ALL the same in concept, no matter that they are cooling, or how cold they are getting it. just be happy that theres new ways of doing things rather than getting defensive of an ill fated idea.

for alll the rest, no im sorry, i dont have any pictures. im sure you can find easy illustrations or cut outs on line of a system like this. if you study how an AC system realy works(all the physics and equitment) it'll be no problem in finding out how this works. good luck
-Paul
 

stugray

Premium Member
OK ABATTLEDONKEY:

I run a 1/3 HP chiller on my 300 Gal system. It is capable of 4000 BTU/hr.

A dorm fridge is capable of about 100 BTU/hr.

I would ask you to do the math but......

At $800 for my chiller compared to 40 ( yes FORTY ) dorm fridges to get the same heat capacity, that would cost ~$75*40 = $3000.

So go ahead and build a tank chiller from dorm fridges ( not A Dorm fridge ).

Stu
 

brent.carroll

New member
I have a unique setup I'd like to share.

I live in eastern Virginia, home of the 3 foot crawl space under the house. I'd been under there many, many times and noticed how cool it was. As interior space was lacking for every piece of equipment under the sun, I decided to run a PVC loop to the garage (about 30 feet) and run some of my equipment out there (chiller, UV, CA Reactor) and take advantage of the fairly constant chilly atmosphere under the house. I was shocked after setting this up (nearly two years ago) that my chiller rarely kicks on now (and I'm running 900W of lighting on my 180!). At first, it was too chilly and my heaters ran constantly. So, I went back under and insulated them which seemed to be the perfect balance. So after one full seasonal cycle, I am glad I did it (and kicking myself for the $700 chiller I bought when $30 in PVC did the trick).

I guess my whole point here, if you can, use Mother Nature where you can...

Next... figuring out how to get rid of 1 TON of heat the fans on my lights exhaust into my air conditioned house in the summer.... which reminds me... we pay to heat water (lights) AND pay to cool it at the same time... jeez....
 

BeanAnimal

Premium Member
Paul,

I find your comments rude and uncalled for. My post was kind and meant to help the OP with an answer to his question.

As for the validity of your comments, the thermal capacity of ANY phase change cooling system is finite and predictable. If we know the capacity of the system, we can determine how much water it can cool over a given period of time. It is that simple.


The fact remains the same, a "dorm fridge" does not have the capacity to act as chiller or cool down a 200 gallon tank of water in 120F room.

Lets put this very simply and kindly. If you can show where my math and/or article is wrong, then please do so. I would welcome the learning experience. Yes Paul, HVAC systems are all based on the same concept, nobody said they weren't. The question here is capacity, not the efficiency of the contact between the water and the chiller. You are confusing the two.

As for your 200 gallon system example:
Firstly, antifreeze has LESS thermal capacity (about half as much) than water. It is does not help cooling, it actually reduces cooling capacity of a system (by about half). Why do we use it then? Because it does not freeze.

You mention that you understand the physics. Lets look at your 200 gal example and apply those physics.

The specific heat of water is 1 BTU per degree F per pound. There are 8.33 pounds in a gallon, so it takes 8.33 BTU to heat or cool 1 gallon of water 1 degree F.

The specific heat of 100% Ethylene Glycol (antifreeze) is about .6 BTU per degree F per pound and has a specific gravity of about 1.16 (at the 10F you indicated). So 1 gallon of Antifreeze weighs 9.66 pounds. It therefore takes 5.8 BTUs to heat (or cool) 1 gallon of 100% antifreeze 1 degree F. So you claim you pulled down a 200 gallon system 90F to a steady state temperature of 10F. Lets ignore the fact that the room will continue to try and heat the liquid back up and with a Delta T of 90 degrees, the heat transfer back into the Glycol would be VERY significant. So ignoring the reality that makes your example even harder, a straight 90 pulldown would take 104,400 BTUs. Again, that is ignoring the HEAT in the room that will continually try to heat the liquid back up.

You did not say how long it took to pull the liquid down or what size "chiller" was used. You did not mention insulation or any other aspect of the setup. Nonetheless, I am calling your bluff. If you had a 1 ton chiller (that is 12,000 BTU/hour) with NO external heat input (a perfectly insulated tank!) it would take nearly 9 hours of continuous running to pull the tank down to the 10F. In the real world it would take a 2 ton unit three times that long in a 100F room. Why? Because of the losses involved in the system and the ambient temperature that we are fighting against. Glycol cooling systems are used in buildings with resevoirs MUCH smaller than 100 gallons and they require compressors much larger than 2 Tons. How do I know this? I work with them.

Anyway, we can apply the same physics to your 120F room. If the target fish tank temperature was 75 degrees, then you are looking at a 45 degree pulldown from ambient. Again, we will ignore the heat being added back into the system, as it only makes matter worse. Lets take a 100 gallon tank as an example. To achieve a 45 degree pulldown we would need to remove 37,485 BTUs from that tank. It would take the dorm fridge over 75 hours of continuous operation to pull the tank down to the target temperature. In reality the 500 BTU/hour dorm fridge would never be able to keep up with the 120F heat load in the room and the tanks steady state temperature would only be a few degress less than 120F. Again, basic physics and the finite capacity of the dorm fridge.

As you can see it is all about the capacity of the system, not the efficiency of the heat transfer. Even at 100% efficiency, if the compressor is too small, then the system will not reach the target temperature. Getting upset at me is not going to change the physics.

I am sorry to call your bluff this way, but your assertions are simply not even remotely possible and you have responded in a rather condescending and rude manner with information that is simply not supported by any stretch of the facts or phsyics.

Now if you come back and tell us that you used a 2 Ton capacity compressor, then I will be more than happy to believe you.
 

stugray

Premium Member
Bean,

I think he must have been referring to the ECO-AQUILIZER-DORM-FRIDGE-CHILLER system.

It just happens to use it's very own "proprietarty blend of thermo-dynamic physics" of course ;-)



Very professional response on your side Bean.


And as for brent.carroll's response. That is a very doable cooling system. There are other threads on here that address the geo-cooling loop in the ground concept. You actually CAN do that your self for a few $100 and have nearly zero operating costs.

Stu
 

A.T.T.R

Active member
if you susspend the fridge with magnets the physic no longer apply lol


ppl are smart remember that


BTU OUT HAS TO BE BIGGER THEN BTU IN!
why are you guys fighting this


i guess i should go back and argue taht 1 +1 = 19


now for a small system it can work ( under 20 gallons) any thing larger then that no

and yes you could cool 1000 gallons of water witha dorm fridge if there is NO HEAT INPUT AND PERFECT INSULATION but guess what
that isnt out tanks
1 watt is = to 3.41 ( i think) BTU's
therefor a 100 watt pump makes 341 BTU's and hour
alot of that is lose to evap and 'heat shed to the room' so lets assume only 200 of those btu;s stay in the tank... still out of range for most freezers lol
 
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