Geothermal Chiller

[4RJN]

Hi Everyone, I finally have a chiller that works great and does not cost a ton to operate. After making several different attempts at home made chillers (dorm fridge, ice box, large container on cement floor, small air condintion unit with titanium coil) I have found the simpliest and cheapest alternative and it works far better then any other I have tried. I installed a geothermal loop of 3/4" pipe 400' total length. It runs on 1 mag 3 pump that is electronically controlled. The pump only runs about 5 minutes total per hour to hold my system at 76 degrees. I used to battle the tank up to 82 degrees everyday with other chillers and fans running. Now the tank it quiet as can be and it has not gone above or below the 76 degrees in 2 weeks. I can not believe how stable the temperature is now. I would highly suggest trying this basic concept and the monthly electric bill will make you almost as happy as having a nice stable temperature.

[mfinn]

I'd be interested in exactly how you did this. Got any pictures?
Details please.

[Hef]

I'm assuming there is a long explanation with pictures and detailed parts list coming soon.

[BeanAnimal]

I would imagine there is not much to the system but one butt load of digging in the yard, and a temperature controller.

Either the kids helped, he is a tired man, or he rented a trencher...

Bean

[lmsrch]

how the heck do you protect agaisnt leaks ...
i wish i could do it but i live in fl

[jayson_219@yahoo.com]

i am also interested in how this is done. what is a geothermal loop??????? im battling 84's and 85's

[BeanAnimal]

As I eluded to... He likely burried 400' of thinwall pipe in his yard. If glued properly then there is no need to worry aboutr leaks. The soil a 18" or so down is 70 or so degrees. The pump runs the water through the coil, transfering the heat to the ground (cooling the water). A temperature controller turns the pump on and off just like it would a chiller or heater.

Pretty simple if you can find the room and time to burry the line.

There are plenty of variations you could attempt.

Pouring the coil into your slab.

Burrying 3-4 55 gallon drums (plastic type) with a hundred or more feet of thinwall tubing in each. Fill each barrel with water and loop them together.

Using a crawl space with a few hundred feet coiled back and forth.

Use your imagination...

For what it's worth, the slower the flow rate (in general terms) the better the cooling. Youi could do the math to determine the perfect flow rate... given the length of pipe, its heat transfer coeficient and its diameter. Trial and error will likely work just as well.

Bean

[Lammy]

The premiss is that below a certain depth the ground is a constant 55 degrees. So by running a length of plastic tubing through the ground you can heat/ or cool water in the tube.

[gpajon]

Easier said than done. IN the deep south (Broward county Florida) I went 7 ft deep and reached the water table. The water coming out of the ground is 81.1 degrees. 81.1 degrees is still just cool enough to bring 94 degree tank water down to say around 85 or 86 deg.

[pvtschultz]

I guess you all down in the deep south can't if the water table is so high, but us in the far north can benefit from this greatly as well. As long as you bury the tubing below the frost line (around 2' or so would do it) you won't have to worry about freezing during the cold winter months and then during the hot summer days, you'll be able to take advantage of nearly free aquarium cooling.

[niko5]

Thats a neat idea... I cant beleve the water is 81 comming out of the ground wow... Im in Houston and I have dug holes before and the dirt always feels cool... I may have to try this.. im going to dig a hole and throw a thermonitor and cover it up to see what happense

[Lammy]

the only problem I see is how do you get to the ground outside your house??

gpajon, seven feet is far deeper than you need I think. Water also holds different thermodynamic properties than soil, so it could be carrying heat from somewhere else. So while that water was warm, the ground at say 3 feet deep may be cooler.

[axlerod]

Frost line in maine is about 4 feet and this past winter it was about six feet realy cold winter with no snow cover

[reeftechie]

This might sound dumb but do you run your system water through this? Or do you run fresh water through this, and then add some of the pipe into a holding tank with the salt water and this in turn cools that water? I am a bit lost here. If you do this, is there any worry about contamination from running that system water all through the tubes below the ground?

[reeftechie]

double post

[axlerod]

it sounds like he is running his system water thru the pipes buried in the ground. but you could also make the pipes in the ground a closed loop with just fresh water in them and run it thru a heat exchanger and run your tank water thru the other side of the heat exchanger the second way would require a second pump to pump tank water thru the heat exchanger

[reeftechie]

ahh ok so it sounds like his way is better, I dont know anything about a heat exchanger and it sounds expensive haha... So I will just run the system water through it, save me some time, money, and another pump.

Thanks bro.

[Lammy]

also ads a few extra gallons to your system depending on how much tube ya put in the ground.

[niko5]

Just be sure the tube in the ground is one piece with no cuplinks and you dont have a problem with contamination... but if you do have to do cuplinks seal them some how.

[niko5]

Iv got an idea that will save even more money and make this think virtually FREE to run.... Install a "T" fitting in your return line and take your input for the tubing ( im guessing 1/4" tube and install a solenoid on that line so every 5 mins or whatever the solenoid opens and water rushes through it then the solenoid shuts off and the new water in the line cools down.

[niko5]

Oh He used 3/4" pipe I dident catch that... wow 400' total of 3/4" that must have been a big hole.. I wonder what kind of preasure that puts on the pump... hum... Ied sure like some pictures

[gpajon]

http://archive.reefcentral.com/forum...5&pagenumber=1

[Hef]

Just read a bunch of old posts on Geothermal chilling. Seems like every post that starts stirs up a lot of interest. It sounds great.
I've got a crawl space under my house. It's dug out about 3 ft. down already, so I could get in there and dig a trench. Looks like about 100 to 150 feet of 3/4" pipe should do the trick. A small Mag 3 pump to move the water out of the sump and back in.
Everyone talks about Thin Wall PVC. Anyone know if the Flex stuff would work? I would like to do this without using so many fittings.

[niko5]

Use 1/2" thats what a Mag 3 comes out with anyway... go with thinwall adn you can get bags of fittings CHEEP

[Toast_Man]

Frost line at 2' lol I wish...Up here in the great white north it can be between 8' & 12'

still it is an interesting Idea....

Joel