How about a Geothermal Chiller burried in the ground?

[cwegescheide]

Hey I have a question for you all. It seems to me that I have read somewhere about people expiramenting with burrying a large sealed tank underground (I live in Tampa Fla) to act as a geothermal chiller. Do any of you know anything about this? I am thinking about setting up a larger tank in the new house and cutting a hole in the wall (fiancee is gonna throw a fit!!) and digging up the yard LOL.

Anybody tried it? Could you explain how water is circulated thru it? Any problems? And IS IT WORTH IT? Thanks!

Chris

[tashier]

Hmm, interesting.

[Tim224DT]

Hmmm depending on where you live in tampa you might have all muck for a ground or all sand......... For this geothermal chiller to work you would most likely need to have some nice dark soil but at the same time you will be having to run pipes into your yard back into your home and in hopes it will work......

How big of a tank are you planning on going in wall?? Because you can buy a nice chiller from Pacific Coast 1/10 hp chiller for around $400 that includes a pump and i know someone that is running that chiller on a 200 gallon tank i think it is with 1000 watts of light and the chiller keeps up.



Tim

[cwegescheide]

Originally Posted by Tim224DT

Hmmm depending on where you live in tampa you might have all muck for a ground or all sand......... For this geothermal chiller to work you would most likely need to have some nice dark soil but at the same time you will be having to run pipes into your yard back into your home and in hopes it will work......

How big of a tank are you planning on going in wall?? Because you can buy a nice chiller from Pacific Coast 1/10 hp chiller for around $400 that includes a pump and i know someone that is running that chiller on a 200 gallon tank i think it is with 1000 watts of light and the chiller keeps up.



Tim

Hi Tim,
The tank I am planning would be about 500 gallons total water volume. Not including of course the resivior that would be burried. I thought I read something where people did this as a matter of a fact in Fla. I think it would be tough to justify being the guinea pig drilling a hole in the wall of a cement block and digging up the yard and all to see if it would work. I'm hoping to learn from others before I tear up my house.
Thanks,
Chris

[wharyat]

I would think it would take a while for it to pay for itself. Your looking at a multiple thousand dollar price tag versus a good chiller for less than 1,000.

[cwegescheide]

Originally Posted by wharyat

I would think it would take a while for it to pay for itself. Your looking at a multiple thousand dollar price tag versus a good chiller for less than 1,000.

I don't think so... I'm just talking about some sort of a "sealed" tank burried in the ground and PVC routed from my sump to pump water thru the tank burried in the ground to circulate cooler water thru the system as required. I have an ACIII and all I would need is a pump to circulate the water thru the system and back into the sump. You think this would cost a few thousand dollars? I guess I'm just thinking in the long run this might be a cheaper alternative to more electricity consumption and less to possibly go wrong maybe???

Thanks,
Chris

[wharyat]

I havn't don any reaserch on this (yet ) so I'm not sure exactly how well it would work.

I was assuming you would need to rent a peice of equipment to dig a hole big and deep enough for a reservoir for a 500g system (around 100-300g).

An array of piping would be the most efficient way to cool the water, since it gives a large surface area for maximum thermal dissapation.

I think I'm going to do a bit of reasearch on this to see how well it would work.

[Geoff]

i read somewhere where someone tried this. it did not work as well as they thought. i think they attributed it to the pipe they used for the cooling field. the problem is that plastic is horrible at conducting heat. it insulates the tank water that you want cooled from the ground that would be helping it cool. if you could find a good conducting material, like titanium, that you could bury all over the yard than it would work quite well.

not sure burying a large tank would work. may be if it were a many thousand gallon tank, but than you would have to worry about cleaning out all of the detritus that would settle on the bottom of that thing. piping would be the way to go.

G~

[stefan.bruegeman]

You would not necessarily need to build the array of pipe in the yard out of plastic.

The idea is to exchange heat, not volume of water.

You could build the array in the back yard out of copper (or any other horrible metal that would destroy your reef), and do not use reef water to run through the array. Use distilled water or what ever you other cooling medium you choose to circulate through the array and then have a small titanium exchanger that then exchanges the cooled medium that circulates through the array with the salt water in your reef such as a titanium array heat exchanger which would be very small.

This is in theory dangerous because you could spring a leak and leak some of the cooling medium into the tank which would be heavy with copper so how you exchange the cooling medium with reef water to cool the reef water would have to be very well designed. Think of a nuclear power plant using multiple sets of water to heat and cool the water heated by the nuclear core.

Further up north you may even need to have an element in the cooling medium that prevents your buried array from freezing, or the pipes going to it (anti freeze or sugar)

This way you keep your costs down by making the large part of your construction from things available at your local hardware store and then anything touching your reef out of reef safe materials.

The only other consideration to take into account is thermal control (thermostat). The rate at which you pump the cooling medium through the array will be proportional to the amount of cooling you can achieve which is also effected by the amount of heat which can be dissipated into the ground through the array. with a properly build array and exchanger you could be able to over cool the reef with only a few watts of energy used to move the cooling medium so there would have to be some kind of physical flow control system.

-Stefan

[jenglish]

JMHO but I still think a DIY system based on evaporation would be simpler and more cost effective. But I haven't tried to do either so thats just a shoot from the hip observation.

[Jadinop]

It's been tried before but as mentioned above it didn't pan out. You can find more info on Reef Central about it but the basic problems are hard to overcome. Here are a few of the big ones.

The plastic tubing acts as an insulator and there is not enough heat differential between the ground and the tank water to overcome it, especially here in Florida. Copper tubing might sound like a good idea but you are looking at needing a few hundred feet of tubing. Plus you will still need to buy titanium tubing for the heat exchanger. Not exactly cost effective anymore.

It takes a really big pump to push water through 500 feet of 1/2" plastic tubing to attain even a small constant rate of flow. The added heat of this pump will negate any cooling effects you might pull out of the ground. The additional electricity needed to run this pump will also excede any potential savings over a chiller.

The whole thing will also act as a giant denitrator as bacteria populates the inside of the tubing. While that might seem beneficial, you can never shut off the flow of water through the tubing without it going toxic quickly. When the power comes back on you are loking at gallons of now toxic water dumping back into the tank. The tubing coil will also strip oxygen from the water but that can easily be ovecome by placing the tubing output close to the skimmer input.

Burying a large tank in your yard will also have similar problems. Larger pumps, detritus buildup and temperature control will all be a problem. The other thing to consider is that increasing your total water volume not only affects tank temperature. Everything will need to be on a larger scale. Protein skimmer, calcium reactor, water changes and any chemicals dosed will all have to be increased to take the total water volume into account.

I wouldn't start drilling those holes in your house just yet. Evaporative cooling is the most cost effective and easiest method of cooling a tank. If you find that you need a little more cooling power a chiller is your best bet.