[dr. umido]

greetings everyone hope your day is going well!

I read through the DIY res chiller threads but did not find a DIY res chiller like this one so I thought I'd share this poor man budget res chiller. The summer & fall temps were pretty bad this year and knew I needed some form of a res chiller. I lacked the funds to buy one new or used, already played the frozen water bottle game and all I had was a used 5000 BTU window AC sitting around. I realize how shody & bubble gum & duct tape this looks but with a $0 budget everything was made with parts I already had laying around. I don't have any pics of the system installed, but here are some prior to moving it hence the control panel sitting unsafely on top of the ice chest. The control panel was mounted on a wall well above the water line.

**A few warnings** this involved the dissassembly of an air conditioner, exposure to electrical hazzards & the potential release of ozone depleting refrigerants in to the atmosphere. This can result in bodily harm, take all necessary precautions & safety procedures & use the right tools always bring a helper if youcan.



This diagram shows the concept of the system. The AC unit is dissassembled, the fan / blower assembly removed & unplugged from the control panel. The Cold side (evaporator) from the window AC is mounted "safely" in an ice chest. Inside the ice chest is a sacrificial annode and a coil of 3/8" or 1/2" copper or titainium tubing, last the ice chest is filled with plain water. The AC cools the water in the ice chest, the nutrients are pumped through the copper/titainium coil which removes the heat & cools the nutrients.

A manifold was constructed around the hot side (condensor) out of thin sheet metal from home depot with all sides enclosed & sealed except for one. This ensures enough airflow is moved across the coils to remove the heat. Inadequate air flow across the hot side will result in compressor shut off & no cooling capacity. A 265cfm dayton blower was used to "pull" air out of the mainifold. I used a can of spray foam that I had laying around to seal the manifold to the top, sides & bottom, you can see the excess in the rear.











Here you can see the cold side of the AC (Evaporator) and the copper coil. I used a piece of 1/2" thick foam rubber under the evap to insulate against vibration. A 125gph pump was used to pump the nutes through the coil, this was more then adequate for 25 gallons. The downside to this system while on a low budget is temperature control, you either need to A. wrig up a new underwater thermostat to the AC panel or purchase a Tempstat from Acquaticeco. The tempsat will turn on/off the water pump which is used to control nutrient temps.

After mounting the evaporator in the ice chest & safely securing the control panel, I filled the ice chest with water & turned the system on. Within 45 minutes the water temp reached 39 degrees...burr too cold! This was without any load on it other then the water contained in the chest. After some testing I basically came up with the system on a timer, 25 minutes 4x per day while air temps are 84+. The chilled water in the ice chest would remain cold for quite some time and since I was using another ice chest as a quasi reservoir, I was able to maintain consistent 67 degree nute temps despite ambient air temps.

The reason why i chose to mount the cold side of the AC in an ice chest & then filled it with water is 1. water is superior to air for thermal transfer, 2. copper has one of the highest thermal transfer properties next to silver & gold 3. an ice chest full of "chilled water" with a copper coil that has nutes flowing through it will be 10x more effective then mounting a coil in a freezer which relies on "chilled air" coming in contact with the coil. Freezers & their compressors are not intended to be run with load in that they work on principle of chill over time. There is not enough refrigerant, the evap & condensor are often undersized & the compressor can not handle removing an external high heat load. As far as safety, the computer overclocking community has been using this method of "water chillers" for years. Using common sense & taking all necessary precautions makes this safe.

Frozen bottles of water while somewhat effective involves human labor which means you are physically obligated to be there at consistent schedules to 1. make frozen bottles, 2. exchange melted for frozen bottles & repeat all over again. During a hot summer, bottle replacement is a PITA I suppose an improved version of using frozen water to cool your res would be to use an ice chest with a coil of copper inside then keep the ice chest full of ice. Pump your nutes through the coil, with this method at least the cooling element is "insulated" against the ambient temp better then a frozen bottle in a bucket.

While ugly I hope it was of some use If this is of any interest, when I get the funds I'll be building a better water chiller that is capable of chilling seperate reservoirs while keeping the nutrient mixes seperate and will then post the pics.

d.u

[pontiac]

Nice, i added this to the link-o-rama: https://icmag.com/ic/showthread.php?p=678179

Nice man. Very homemade looking...but hey...it works. Everything is insulated and looking good for an A/C unit turned chiller.

[dr. umido]

Pontiac - wow had no idea it was link worthy I'll try to clean it up some.

Jam Master Jaco - You know I felt a little ashamed at how sloppy it looks since I normally do not do anything that half tilted but like you said it works thanks for the kind words.

d.u

[Boerman]

Just a word of caution: if you are running your nutes through copper tubing, you risk developing copper toxicity. Believe me, been there-done that! Plants over-dosed with copper don't recover.

[Liam]

Switch that copper out for stainless steel, it ain't cheap but it lasts forever!

[cocktail frank]

nice job!!!
funny the things you build when stoned

[GreenBush 420]

Instead of switching the tubing for stainless, try dipping in a plastic coating. They sell this stuff as tool dip (like the handle on your pliers). It would be much easier and cheaper than switching the tubing and replacing the coolant.

[GreenBush 420]

Ooops, I guess I read that wrong. If you dip the copper you can place the copper tubes directly into the rez so the nutes never have to travel thru the metal in the first place. Am I wrong?

[shorttimer]

If the tube is insulated with plastic, there will be little thermal transfer. I say go stainless