"Geothermal Chiller" Construction and Progress

[aquatictec]

FWIW my project was to cool the water in our greenhouse by passing the actual tank water through a ground loop with a low
wattage pump. We will eventualy have 2 systems with 8000 gallons of water on each system. Each loop
holds approximately 50 gallons of water. On a hot day the systems go up about .5 degrees per hour so I need 8000 gallons *.5 degrees
per 1 hour of cooling= 4000gallondegreesF per hour (how do you like those units) The groundwater loop can return water
at 55 degrees F. If the tank is 82 degrees F that is a 27 degree drop so we would need to run 4000/27 gallons per hour
through the loop= 148 gallons The water would have a dwell time of approximately 20 minutes in the loop. It might work.
Even it doesn't it should cool the tanks down overnight.

Regular geothermal plastic tubing seems to be extremely thick which would cause low heat transfer rates so I I had some
made with a thinner wall. I asked the manufacturer why the wall thickness was so big and was told they do vertical loops
and the pressure is extreme in them. I was trenching it in the ground so that wasn't a concern with me. I needed 2 loops
so I laid 3 to have a spare. They were buried 6-7 feet deep in a 4 foot wide 400 foot long trench. The loops went out
and back 800 feet total each loop.

I hooked the loops up and was able to blow in one end and feel the air coming out the other end but it was delayed a few
seconds. On the first loop I hooked up the hose to fill it and bubbles started blowing out the other end. The water
never made it out and it stopped blowing. I hooked up the second loop and the same thing. I let it sit for a few days
and hooked up a small pump to each of the 2 loops. After a few days one loop started flowing water at the full rate of
the pump. The other loop nothing. I tried hose pressure on the other loop and again nothing. Recall it worked with
just me blowing on it. I still have the back up loop to try.
Nothing ever came out of the working loop other than water and the water is clear. I did not lay the pipe myself so
it is possible they kinked it but I would think they would have told me and I would think if you could blow air through
it easily with your mouth, that water at 40 psi could flow something through it. I also reversed the flow directions
in case there was an object trapped inside.
Even though the tubing is thinner than standard geo tubing you cant budge the tubing by jumping up and down on it and
absolutely no water will go through at 40 psi pressure. I
still have my back up loop. I will probably hook it up first and hope that it works.

I am thinking of trying compressed gas of some sort or an air compressor or water booster pump on
the non working line and getting the pressure up to 100+ psi and seeing what happens. I have CO2 at 1000 psi available
but I have used it before and was lucky to survive what happened. Fortunately for me it blew a gasket on a filter
before blowing up the filter.

I am still trying to get the other 2 lines to work. I ordered a 160 psi diaphragm pump to try to open up the one line.
In the meantime I will work on plumbing the spare line. Now for the good news:

It is 93 outside I hooked up one line to a 2000 gallon system and it has dropped the temperature 1.3 degrees in 43
minutes. The goal was to stop the .5 degree per hour temperature rise on the future 8000 gallon system

1.3*60/43=1.81 degrees per hour plus the .5 heat gain it overcame or 2.31degree *(2000) gallons /hour cooling=
4620 degree gallons/hour

I calculated I will need .5*8000= 4000 degree gallons per hour so it looks like it will work


btus/hr = 2000gallons/.1198lbs/gallon*2.31deg F/1hour=38564BTU/hour or the equivalent of a 3+HP chiller

assuming the math is correct

all for less than 100 watts of power

This not a standard "Geo system" I am cooling the tank water by passing the tank water through the ground. No heat
exchanger or compressor. It cost less than $3000 for the 3 loops installed pumps and controllers. If I can get all
3 loops to work that would be 9 tons of chilling for $3000. Way LESS than the cost of 3 3 ton chillers. Less initial
cost and practicaly zero opearating costs.

I installed 3 loops on the other side of the building in 97 but someone crossed the loops up so we only ended up using
one of them. It has worked fine. We purge it with hose water every few years to kill whatever grows in there. It does
not cool as well at the end of summer as it does at the beginning due to it heating the ground up. I dont think there
has been any creep over the years thank to our Ohio winters. We cant use the loop for heating since we are running
the tank water through it.

Greg Smith
Aquatic Technology
26966 Royalton Road
Columbia Station, OH 44028
(440) 236 8330
www.aquatictech.com

[evilpsych]

it's also possible that a mole or other animal has chewed a hole in your tubing, and you've just been pumping the water into its burrows.

Any wet spots popping up some feet/yards away from the trench?

[Vinny Kreyling]

Well if I paid someone to do that & I had a problem I would call them back to "fix"the problem.

[Curious George]

I have been thinking about this very thing for a while. I thought about the faucet. You only need energy to heat water, not cool it. Coming through the ground pipes, brings the water in cold to the house. Same can be applied to a reef tank and I would think that it wouldn't be that hard to do, as long as you have the space and time to dig/plumb.

Good write up. Thanks for sharing your experience.

[aquatictec]

Our tap water is at 70 degrees in the summer. I had looked into using it in an emergency situation by slowly running it through a large coil. It is much more efficient to run the tank water through the ground. You ecxtract 100 percent of the cooling this way.

I suppose it is possible that a line was broken but i dont think so. The hose pressurizes the system so if you remove the hose you get backflow for around 7 seconds. The loops connect in a manhole so I was planning on disconnecting them there and checking them out.

I also considered digging to wells one for water and one for returning the water to the ground. Running the well water throgh a large loop in the sump. It would be nice to have the money to try it.

If it works out the "GEO" route will be the most economical.