Geothermal Cooling idea/questions

[gman2]

Come June my home addition will be starting. I am going to have a fish room with an 8' 450 gallon tank built into the wall of the game room. The fish room will have a 200 gal sump and a 120 gal fish only tank. I will have a 300 gallon separate prop system as well.

I live in southern California and am interested in the idea of the geothermal cooling as to save electricity and to have a stable tank temp.

My idea is to run an unknown number of feet underground outside. I will have a heat exchanger in the sump with a 5 gallon tank that the heat exchanger empties into. Some type of external pump will pump from the 5 gallon tank into the line leading to the outside and back to the heat exchanger in the sump. This system will be using only fresh water and controlled by a Neptune controller just as a chiller would, but using less power in theory I hope. This will only be used for cooling and not heating.

Now my questions.......

1) What type/size of pipe to use for the outside lines?

2) How many feet of the pipe is needed fo the outside lines?

3) How deep do I bury the lines? The lines will not be servicable as they will be under a concrete walkway when the construction is done.

4) I guess a titanium heat exchanger is what I should use, but what type, brand and size?

5) What type of pump should I use and how many GPH should it be?

6) Are there any website of people doing this? I mean with using fresh water instead of the tank water.

7) Any other issues I should be aware of or is this just a stupid idea?

Any ideas and suggestions welcom since I have a few months to prepare for this.

Thanks
Tony

5)

 

[Anonymous]

take a look at this thread:
http://www.reefland.com/forum/printthre ... eadid=6763

 

[gman2]

I saw that link, but I believe he pumps the tank water thru the lines. I was hoping to have it separate from the tank and use fresh water like a close system.

I guess that it would be just like a cars colling system with a radiator.

Anyone else have suggestions??

 

[liquid]

I would say it's a *big* no-no to run the tank water thru those lines. They're eventually going to foul with cryptic critters. Somehow you're going to have to find a heat exchanger that you can fit on the tank side of the geothermal portion.

Shane

 

[gman2]

Anyone have resources or a conact person that I could speak with about this???

Thanks
Tony

 

[Mouse]

One good way of making a cheap chiller is to have a small "drinks" size fridge with a bucket of water inside. What you do is run tubing in a coil inside the bucket and then connect both ends to your tank. Provided the water is constantly pumped through the tubing and the water in the bucket itself is circulated (with an aditional pump) youll have no problems. Only tricky bit is getting the temperature right, or thermostating the fridge. But then again i suppose youd only use it on a hot day, and the heater should compensate if you get into any real trouble.

 

[taikonaut]

Mouse, did you actually run this DIY chiller setup, or you are just passing the info along?

 

[shr00m]

that is a common DIY chiller that works really well if implemented right. use copper tubing and make as large of a coil you can fit in the small fridge, silicone up the holes you drill also.

 

[Len]

If you don't mind Tony, I'm going to move this over to the DIY forum with a shadow left in the GRD (which means double exposure). We're trying to encourage usage of our special interest forums

 

[Anonymous]

that is a common DIY chiller that works really well if implemented right. use copper tubing and make as large of a coil you can fit in the small fridge, silicone up the holes you drill also.

Copper tubing would be bad, bad, bad. This would only work on a small tank. "Dorm" sized fridges do not have enough power to make a dent on a large tank.

 

[Fl_Seagull]

Interesting Idea.

I might be a little late with a reply but I am looking for ideas for my own setup and my experiment might be of interest.

While I have not seen anyone run line outside to cool a fish tanks, but it has been done to cool a house or two. I would search for ideas on radiant heating/cooling. Twenty + years ago in Iowa people were looking at this using air and pipes buried 7 ft in the ground. The thought was that the temperature was a steady 55 degrees F. At least one house that I know of was built and successfully cooled through the 90+ degree summers.

Since then people (mainly in the Northeast) had loops put into wells drilled About 100 ft into the ground with the water used by water-to-air heatpumps to cool and heat their homes. One house I looked at was using 1" pipe about 250 total feet long. Since this was a close loop the head pressure was the frictional loss of the system. I don't remember the pump size. Seems like it was bigger than my 1.5 hp sprinker pump.

My experiments.
1) Equipment: little giant TE-4 ~800gpm @ 0', 100 ft of 1/2 inch irigation pipe. Too much back pressure/no flow .
2) 1.5 hp sprinker pump good flow but high pressure :? .
3) place pipe in lake and measure temperature difference between lake vs pipe water. pipe water temp is 5 to 7 degree higher. With the lake temp. running 72 degrees (It is higher during the summer when I will need the cooling)
4) ground temp in the middle of summer @ 4 ft in Melbourne, Fl 73 Deg.

I would suggest that unless your ground temp is closer to 55 deg. F that this would be hard to be cost effective. Usually, a 10 to 20 deg F temperature difference is need to keep the heat transfer useful. Even at 55 degree F. I would think you would need some form of heat pump. A good air conditioner contractor might be able to give you more localized data on the possibilties

 

[shr00m]

yea, stupid me... im thinking of pc cooling copper would be a no no.

 

[smaug]

I have gievn this some thought as well. If you go 3 to 6 feet bleow the suface of the ground you will have a pretty contasnt temp between 65 and 75. I would run 3/4 inch pcv in a loop and use freshwater. I would also add a small amount of bleach to the water to keep it free of ANY life forms.this would then empty into a 55 gallon drum and in the drum i would have a loop of PEX radiant floor tubing i would pump my saltwater through this. The salt loop would need a 2 stage pump one to keep a minuim flow so the water will not stagnate and a higher flow for cooling. i am planning this for a small greenhouse so i am also thinking of a solar water heater that would function in the same way for the winter. what i am not sure of is the length and the rate of flow thgrough the underground loop. I have looked into a couple of off grid forums and i get no responce.

Smaug

 

[Fl_Seagull]

Mission Viejo? Is this desert area? If the nights are clear and cool you might find a radiant pond idea would work better.

The idea is to have a pool of water open to the night clear night sky to release heat. Then insulate it during the day and use the chilled water to cool the house (tank).

Just an idea. 65-75 degree water doesn't give you much to work with for cooling, unless you can get the 65 degree most of the time.

 

[rabagley]

The "dorm refrigerator as chiller" idea is a pretty bad one. Noncommercial refrigerators are not meant to handle large cooling loads. They're generally designed to cool about two to three times as much as will leak through the insulation (100-200btu/hour max). Even a 1/10hp aquarium chiller will remove 500-800btu/hour and that's only enough to get a 10 degree drop on a 55 gallon tank. Larger and better substantiated article is here.

If you want to do a DIY chiller, start with a window A/C unit and learn from the same guy's notes and plans before you start.

Otherwise, just buy a chiller. I know it seems like a lot, but the materials are better than you're likely to DIY with (titanium and/or stainless instead of the copper, brass, and lead that are in the things you can easily procure), it will come with a controller of some sort, a decent quality chiller will last a lot longer than most of what you or I could build (unless you're really good), you'll get a warranty, and you're going to be able to get help repairing it and refilling it from lots of different people.

I'm a monster fan of DIY in this hobby, but a chiller is just complex enough and risky enough that I'm going to buckle down and spend the bucks when the temps start getting higher.

Regards,
Ross

 

[smaug]

The problem i see is in cooling say 400 gallons+. I agree with the drom fridge. I have read many threads on the idea and a lot of threads on how it does not work. The geothermal loop is a useable idea. i have read that by blowing air into a group of 4 inch pipes you can cool a whole house. My use of the idea has been done by coral farmers. the trouble is that they were not scinitficly documented. so it would be trial and error. I would like to use as little electricity as possible.

Smaug

 

[AnnArborBuck]

This is a simple heat transfer problem. The first thing you have to do is figure out how much energy you need to remove. That will be the baseline for your cooling system. Figure in house ambient temp, lighting, pumps, etc, etc. From there you will need to use some rather simple heat transfer equations to calculate the final pipe sizing, flow rates, etc.

Do a search for something like "Chemical Engineering Heat Transfer equations" and you should find some resources out there. It would be too hard for me to estimate what you would need without really knowing about your system (temp of ground at the depth you are going to burry, soil type (for heat transfer coefficient), etc, etc).

 

[down&dirty]

This is something that I have been looking into for my house that I would like to start building soon. Geothermal heating and cooling is very popular these days and is actually used in many larger buildings like schools and factories to reduce the cost of using conventional HVAC units. Take a look into earthships and geothermal heating and cooling systems. For a tank I would be concerned about actual sizing. Most systems are set up for cooling or heating a home and can actually provide hot water as a side effect. If it can heat the water for your shower why not for your tank. You would be looking at needing a large container(55 gallon food service ddrum) to hold the freshwater that you will heat/cool using the earth, a pump to move water through it, and a pump to circulate your tank-water through the drum. A simple heat exchanger could be built using flexible hosing wound through the freshwater. Most of these systems are buried anywhere from 6-12 feet underground where the earth maintains a constant temperature. Depending on the area you live this can range from 55-75 degrees, but hotter water can be removed from the system with the appropriate setup. Thermal mass shouldn't be to much of an issue since you are tieing the system to the earth which clearly has enough mass. Again, these systems are already being successfully used to heat and cool homes, schools, and factories around the country. Us reefers are just waiting on them to be successfully applied to our money pits. Imagine using nothing but the power of nature to run your reef tank!

 

[shr00m]

other than the tons of wattage used on pumps/lights/etc.

 

[smaug]

Thanks for the reply Ann i agree that it is to diffacult to just guess. i was thinking about 3/4 schd 40 pvc for my loop iand i think the goruynd temp at 4 feet stays around 65-70 degrees. i am looking into that now. Shroom i am not sure what kind of lighting you use but for the system i am looking at i would think i would need 2000 watts of lighting. my idea was to grow outdoors so lights would only be supplemental. this would get rid of the biggest cost in running a propagation setup so all that would be left is temp control and curculation. and salt and skimmer and ect...
But the idea is to come up with a effeciant cooler. and if you have looked into a chiller that would even touch a 400 gallon system the cost would be insane.
Maybe that is why a lot of people do thier prop systems in the basement. the temp is more stable. but then you need lots of lights. I would like to discuss this further so please feel free to add your comments and experiance. and yeah copper is a BIG no no.

Smaug