DIY geothermal chiller

I am not technical so I am asking some newbie questions. I have a chiller and I think the part that cost a lot of $$$ is running the compressor.

So am I correct that after you layout the $$$ for the parts and installation, the only "operating cost" will be the cost of the water pump running? Also, with your layout, there wont' be a compressor in your setup.

Again, not knowledgeable in this area. Just trying to understand what part of the chiller that makes it expensive to run, versus having nature chill the water.

Also, I do understand that by not having the water actually be exchanged, that it won't be as efficient.

Is there anyone, on the Web that has done this kind of thing and can you get some kind of calculator to actually figure out how much coil you will need to place in the sump, to keep the water cold?

It just seems like by not actually cooling the water itself and exchanging it, that there probably is a lot of "inefficiency". I understand that you know this. Is there a way to measure the differences?
 
Yeah thats pretty much it. The compressor is very expensive to run and dumps all that heat it remove from the tank and then some back into the room. Running a circulation pump only will use a fraction of the energy.

I wish i had answers to those questions. I have been discussing it with other people on the DIY forum and I can't get an equation to calculate btus.

It depends on so many factors. I am trying to maximize the length of the coil in the tank to increase cooling capacity. I might be the first one to document and share this actual design. many people use similar designs tho and have success. I know dave was happy with his PVC open loop design.
 
This is a great project!

I've heard of this possibility years ago and always wanted to do it. (don't own a house yet).

To whoever said that he is being a cheapo, you are very wrong. The operating costs of the chiller could far exceed the initial cost of the unit. Being efficient is smart - NOT cheap. Using the geothermal properties of earth is great, provided you have the means to do it.

Go for it!
 
That was John, he was just busting my balls.

I just ordered 100 ft of Titanium tubing in 5-6ft lengths. It was the only way to get it at $5 a foot. He said he recieved other emails about the tubing from people on RC in the last few days so i'm going to try to sell the extra for what i paid for it to all the people in DIY forum that were looking for it.

I guess i'll be the guinea pig to see how well this works and how hard it's going to be to bend up a coil. but the titanium guy told me he bends it up with a little heat without a problem. I also might buy some bar stock a little bigger than the tubing and try to machine couplings to make it easier to weld the pieces together. So if anyone local thinks they might want to try this, let me know and i'll hold on to some tubing for you.
 
I am setting up a 225 in the corner of my house and I also thought about setting up a cooling system utilizing a 50 gallon plastic drum buried in my backyard. I was going to pump aquarium water through the drum - but now I am thinking that i can pump the cooler water through some titanium tubing in the sump.
 
One thing that I thought of was depending on how the tube is entering your house, you may need to drain the system in the winter.
 
Yeah mine wil be in the basement so i dont have to worry about freezing. But if putting it outside you will want to blow out the lines with some compressed air. or....... fill the lines with antifreeze, assuming it's a closed loop.
 
I wish I had any idea chris. I'm thinking in 3/8" tubing even 50-100 gph will flush the water through the titanium coil in a matter of seconds. the 18ft coiul will probably only hold a few cups of water. I think thats the critical thing, that the water doesn't warm up too much while still in the titanium coil, otherwise i wont get the full advantage of the long coil.

I also want a pump that will not draw a lot of power. a taco circulator draw 80watts. I think that auto pump will draw less, but i will lose some efficiency when converting to 12v. So i'm really at a loss.

If you haven't noticed i'm pretty much guessing on all my pipe lengths and flow requirements
 
Scott,

How are you going to figure out how much titanium you will need. Or will you just put as much as you can into the system?

Oh scratch the question, I did not see the previous post.
 
I was wondering how you were basing lengths etc. I would think you wouldnt want to fast a flow thru the tubing to allow for more contact time with the water to cool and heat the tubing. Heres a random thought but maybe some kind of pump used for hot water heating systems.
 
CB747,

Not sure about fast GPH. On my chiller, I have a slow gph and it is very quick to cool. I use the slow GPH because I also run a UV through my chiller.
 
Ok i just realized the math on this isn't difficult. inside diameter is .331" and i'm going to use 18ft of tubing. That puts the volume in the coil at 18.5 cubich inches. Which is .08 gallons.

This means at 60gph the water will make it all the way through the titanium coil in 5 seconds. That sounds good to me. :) But again i'm just guessing.

My plan once i get it running is to fill 2 buckets with 90 degree water and put the titanium coil in one bucket and run the pump. se how long it takes to drop the temp 10 degrees. use the second bucket as a control. I have to think i will be able to calculate btus from that somehow.
 
I had a chiller and had a decent flow thru it but not a ton. Sounds like its similiar to your flow thru yours. I dont think Scott will want fast flow thru the tubing to allow for more contact time and more efficient transfer of heat/cooling. Id agree that slower is better for his application. Just need tro figure out the point where it becomes too slow.
 
i'm sure there is some flow rate that will be perfect, but i have no idea. to slow and it will warm up to tank temp before it leaves the coil and the last few feet in the coil it wont be cooling anymore. I dont want too fast because it might not cool enough in the ground coil, and will cost more energy to run the pump. I mentioned a taco circulator like used in baseboard type heating in houses, but i think it's too much flow.
 
i'm going to use as long a coil as i can afford :) . an adjustable rate pump would be ideal but i dont think thats going to happen
 
Why not experiment with copper and when you have what you need then upgrade to titanium. Might save you a few bucks in the long run
 
because i'm impatient :)

thats not a bad idea, i might try my bucket experiment with all copper. but actually copper is 2 bucks a foot so it's not even that much cheaper. sure is easier to bend though.
 
I am not sure how tight a radius you can bend the copper to, but you sparked an idea. You can rent a gas post hole digger and dig a pretty deep 12" hole. If you could bend the copper around a 12 inch tube of some sort, you could just drop it into the hole. The copper would eventually be connected to the pump and titanium drop in chiller by some type of rubber / flexible tubing. If the titanium tubing can be wound tight around a 2 inch piece of pvc, that would be perfect for heat transfer. Not sure if you can bend titanium tubing that tight.
 
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