DIY Chiller Experiment

[GreenThumbSucker]

Hey,

Im doing a DWC grow using 27 gallon toughbox totes, one for each plant. The problem I am having is excessive heat in the solution. It sits at about 78 degrees. I made one chiller using an old mini-fridge with plastic tubing coiled up in it. It goes 15 minutes on then 15 minutes off. It only dropped the temp 2 degrees, not enough to make any difference. I have been having issues with roots not liking the excess heat, thus it affects my yields. My friend is getting 1 - 1.5 lbs per plant using this method (undercurrent.) His system runs at about 65 degrees. I have a 27 gallon reservoir with a 27 gallon auto-top off system I made with a float valve and another tote.

My solution: I am building a chiller from a chest freezer. I just bought one on Craigslist for $70. Here is the plan:

I will put a five gallon bucket in the chest freezer filled 2/3 of the way with water.
I will run plastic hose in through the side of the freezer, which will coil up inside the bucket, then back out the top and back out the side of the freezer to the reservoir.
I plan on coiling about 50 feet of hose in the bucket.
Here's the catch - once the hose is in place, I will turn the freezer on and leave it until the bucket freezes solid, at this point the plastic hose will have no water in it and will be encased in ice. Once it is frozen solid I will hook it up to the reservoir and start pumping solution from my reservoir, into the chest freezer and back into the reservoir. I will experiment with timing it, don't want the solution to freeze solid in the plastic hose so I will just run in 24/7 the first day and see how much melt I get in the bucket/lower my temp gets. I will be happy with anything between 55 and 65 degrees.

What do you guys think?

 

[nick88]

Hey,

Im doing a DWC grow using 27 gallon toughbox totes, one for each plant. The problem I am having is excessive heat in the solution. It sits at about 78 degrees. I made one chiller using an old mini-fridge with plastic tubing coiled up in it. It goes 15 minutes on then 15 minutes off. It only dropped the temp 2 degrees, not enough to make any difference. I have been having issues with roots not liking the excess heat, thus it affects my yields. My friend is getting 1 - 1.5 lbs per plant using this method (undercurrent.) His system runs at about 65 degrees. I have a 27 gallon reservoir with a 27 gallon auto-top off system I made with a float valve and another tote.

My solution: I am building a chiller from a chest freezer. I just bought one on Craigslist for $70. Here is the plan:

I will put a five gallon bucket in the chest freezer filled 2/3 of the way with water.
I will run plastic hose in through the side of the freezer, which will coil up inside the bucket, then back out the top and back out the side of the freezer to the reservoir.
I plan on coiling about 50 feet of hose in the bucket.
Here's the catch - once the hose is in place, I will turn the freezer on and leave it until the bucket freezes solid, at this point the plastic hose will have no water in it and will be encased in ice. Once it is frozen solid I will hook it up to the reservoir and start pumping solution from my reservoir, into the chest freezer and back into the reservoir. I will experiment with timing it, don't want the solution to freeze solid in the plastic hose so I will just run in 24/7 the first day and see how much melt I get in the bucket/lower my temp gets. I will be happy with anything between 55 and 65 degrees.

What do you guys think?

use a big cooler instead of a tote. Stays cold a whole lot loner. I put a frozen 20oz bottle in every 2 days. and have no probs with my res temps.

 

[GreenThumbSucker]

use a big cooler instead of a tote. Stays cold a whole lot loner. I put a frozen 20oz bottle in every 2 days. and have no probs with my res temps.

My room is very warm. I have a lot of solution to cool, about 100 gallons. I use the tote for auto-top off, not cooling.

Here are some pics:



Im debating how much hose to coil up in the bucket, and what size hose to use.

 

[polyarcturus]

wahh ithought we where doing some real DIy work over here....... i would dismantle assembly build exhaust box for the evap coils and heat pump and bend the cooling/condensing coils in into a large insulate cooler or waterproof box. add pump and pipe(personally i would try to pressurize around 10-25 psi) and hook up a wort chiller, a transmission radiator in a ducting setup, all types of things lol. i have yet to get my hands on afre freezer, bu when i do....

 

[GreenThumbSucker]

wahh ithought we where doing some real DIy work over here....... i would dismantle assembly build exhaust box for the evap coils and heat pump and bend the cooling/condensing coils in into a large insulate cooler or waterproof box. add pump and pipe(personally i would try to pressurize around 10-25 psi) and hook up a wort chiller, a transmission radiator in a ducting setup, all types of things lol. i have yet to get my hands on afre freezer, bu when i do....

Thanks for the reply
Im going simple and cheap. If this doesn't work then I will rethink it.

 

[nick88]

My room is very warm. I have a lot of solution to cool, about 100 gallons. I use the tote for auto-top off, not cooling.

Here are some pics:

View attachment 2193903 View attachment 2193904View attachment 2193905View attachment 2193906

Im debating how much hose to coil up in the bucket, and what size hose to use.

My fault.. I didn't catch the 1 for each plant part.. I was thinking just a single system not a recirculating one.. sorry

 

[superstoner1]

get the aluminum bubble insulation at lowes and wrap the strongbox twice and use a couple of bungee cords to bind it tight. then make a top blanket with slits that allow u to slide it around the stalks. this helped my vegger considerably that uses the strong boxes.
also, instead of rubber hose, that has poor heat transfer, get a 50' wort chiller made from stainless steel(used for home brewing beer). i use these in all of my res's and never a temp issue.

 

[Afistakis]

wahh ithought we where doing some real DIy work over here....... i would dismantle assembly build exhaust box for the evap coils and heat pump and bend the cooling/condensing coils in into a large insulate cooler or waterproof box. add pump and pipe(personally i would try to pressurize around 10-25 psi) and hook up a wort chiller, a transmission radiator in a ducting setup, all types of things lol. i have yet to get my hands on afre freezer, bu when i do....

Crap, I had my hands on a hydronic heat exchanger for use with a heat pump but I had no idea what to do with it. I had no need for chilling water at the time. Now I have a 1/4hp chiller to make a dent. With a used outdoor unit, some line set and balancing the system I can only imagine how many gallons that would chill at what flow rate. It would require a good amount of power and a 10ga hookup but 20oz frozen bottles might not melt... Oh well. I know what to look for now though. They are copper though. I haven't seen one stainless steel. Shouldn't hurt things too much I'd guess.

good luck with fridge idea

 

[GreenThumbSucker]

good luck with fridge idea

It isn't a fridge. I tried that and it barely dropped the temp 2 degrees. It is a big chest freezer. This time the plastic tubing inside the freezer will be completely encased in ice.

 

[GreenThumbSucker]

Hmmmmm, what if I just fill up the freezer half way with water? I can immerse the tubing in it and freeze it solid.....

 

[Metasynth]

First of all, wouldn't copper tubing be way more efficient for heat exchange? Secondly, have you thought about using a wort chiller for brewing? Hear me out...

Instead of running your nute solution through tubing encased in a block of ice inside the freezer, what if you instead had a reservoir of antifreeze in your freezer, below freezing, and you pumped that through tubing into a copper coil inside your control bucket. That way, you have the coil in the control, and when the temp gets too high, the pump kicks on and circulates antifreeze that is below freezing in copper coils in your control, instead of pumping your nute solution through the chest fereezer.

 

[GreenThumbSucker]

First of all, wouldn't copper tubing be way more efficient for heat exchange? Secondly, have you thought about using a wort chiller for brewing? Hear me out...

Instead of running your nute solution through tubing encased in a block of ice inside the freezer, what if you instead had a reservoir of antifreeze in your freezer, below freezing, and you pumped that through tubing into a copper coil inside your control bucket. That way, you have the coil in the control, and when the temp gets too high, the pump kicks on and circulates antifreeze that is below freezing in copper coils in your control, instead of pumping your nute solution through the chest fereezer.

So that is how a wort chiller works? I have read about them, I thought they were air cooled.

 

[superstoner1]

do not,do not, do not use copper in ur res. stainless steel only. copper will leach into ur res.. a good 50' wort should be aroumd $70-75.

 

[GreenThumbSucker]

do not,do not, do not use copper in ur res. stainless steel only. copper will leach into ur res.. a good 50' wort should be aroumd $70-75.

I have read that copper will slowly poison your solution and kill your plants. Something about the nitrates oxidizing the copper.

NO matter, I am going with my original plan for now. Should have int finished by tonight. Here are some pics of the $70 chest freezer I am using:



The tubing I plan on using is hard plastic. It should be fine for what Im doing. As you can see, I have a lot of room inside, will be easy to put a five gallon bucket full of water in, could probably fit two if I felt like it.

 

[superstoner1]

if plastic worked as a heat transfer than it would be used for condensors and evaporators, it doesnt. yes, it will help but the amount of energy used will be a waste.

 

[GreenThumbSucker]

if plastic worked as a heat transfer than it would be used for condensors and evaporators, it doesnt. yes, it will help but the amount of energy used will be a waste.

Yeah but I don't want to get into a situation where the tubes freeze solid either. I just want to cool my system

 

[Afistakis]

I'm sorry if I sounded condescending earlier. I just re read what I wrote. My bad.

The issue you are running into is energy loss in conversion. The compressor is exchanging heat as efficient through the condensing and evaporating coils to change the temp inside the freezer using refrigerant under pressure in copper or aluminum coils with as much surface area as possible to transfer the heat efficiently as possible/cost. A rubber hose does not have sufficient surface area or heat conductivity to transfer the heat quick enough for your application. Eliminating an extra conversion of transferring heat energy from the compressor to coil to your new coil system you propose will make it considerably more efficient. Even if you were to evacuate the system, braze on a new efficient coil in place of the built in coil, recharge and drop the coil directly in your nute solution which is force circulated through the coil, I am not sure you would have enough btu to accomplish your goal.

I might try lining your chest freezer and recirculating a large amount of fluid in there and using a smaller control bucket on the outside to pump into. The system would need 2 pumps though. You should be able to adjust the thermostat to not freeze your nutes or switch it out with a fridge one.

That's all I got for using your freezer. If you want to do a heat pump conversion to hydronic chilling, I may be able to help you there.

Good luck

 

[GreenThumbSucker]

I'm sorry if I sounded condescending earlier. I just re read what I wrote. My bad.

The issue you are running into is energy loss in conversion. The compressor is exchanging heat as efficient through the condensing and evaporating coils to change the temp inside the freezer using refrigerant under pressure in copper or aluminum coils with as much surface area as possible to transfer the heat efficiently as possible/cost. A rubber hose does not have sufficient surface area or heat conductivity to transfer the heat quick enough for your application. Eliminating an extra conversion of transferring heat energy from the compressor to coil to your new coil system you propose will make it considerably more efficient. Even if you were to evacuate the system, braze on a new efficient coil in place of the built in coil, recharge and drop the coil directly in your nute solution which is force circulated through the coil, I am not sure you would have enough btu to accomplish your goal.

I might try lining your chest freezer and recirculating a large amount of fluid in there and using a smaller control bucket on the outside to pump into. The system would need 2 pumps though. You should be able to adjust the thermostat to not freeze your nutes or switch it out with a fridge one.

That's all I got for using your freezer. If you want to do a heat pump conversion to hydronic chilling, I may be able to help you there.

Good luck

Thanks for your reply!

I am going to do my original idea for now. The tubing I am using is thin hard plastic, not rubber. I will run it and see what the result is, then go from there. If it gets it to 65 degrees or less, I will be happy. If it doesn't, I will go with plan B and maybe try to make a wort chiller from the freezer parts.

I am going downstairs now to build this contraption......more pictures forthcoming soon.....

 

[GreenThumbSucker]

OK, I built it. Was a LOT easier than I expected. I positioned the side of the freezer (where the heat comes out) against a doorway that goes to the furnace area. I sealed it up with black plastic. No heat gets back in.



I drilled two holes for the half inch intake and exit tubes to come through. I put the 5 gallon bucket in the freezer, then put in 75 feet of coiled up hard plastic 1/2 in tubing. I put the ends of the tubes through the holes, and sealed them with silicone. I poured ice all around the coiled up tubing in the bucket and filled it to the top with ice cubes. I then filled it about 2/3 with water.

I then ran one tube to a pump in my reservoir and a 1/4 in tube from the exit hole back into my reservoir, to slow down the flow. There was too much air in it so I disconnected the pump and forced water through the tubing to purge out all the air. Once the air was out, I hooked it back to the pump and turned it on. The water that came out was icy cold.

The solution temp was 76 degrees before I turned on the unit. I will check it again in a couple hours when it has had a chance to circulate and cool down.

 

[GreenThumbSucker]

I just went down and checked the temperature and it is at 71.5 degrees. Quite an improvement, but I was hoping for better than that. Hmmmmm.....