geothermal chiller

I too am starting to consider a Geothermal Cooler. Can the pipe, which exits the house, exit the house above the ground and then go into the ground outside? Is this what others are doing or are they drilling through the floors of their houses.

I have a basement and was considering exiting through the siding (wooden area) and then going into the ground from there. I been considering runing the pump 24/7 and use the heater to raise the temp if needed.

Does this sound good?
 
Looser,
Running your well pump to circulate a small bit of water is a big waste of electricity. Well pumps are usually 3/4 hp minimum.
Better to make a coil of tubing and stuff it down your well so the tubing simply sits in the water down there. Then use a small pump to circulate the water when your tank is calling for cooling. Much easier than digging a ditch:)

Falconut,
The pipe can go through the wall, just insulate the piping for the exposed portion.
Using a heater is a waste. Just turn off the circ pump for the loop. DO NOT RUN TANK WATER THROUGH THE LOOP. You need to run freshwater through it, then run another coil of tubing in your sump.
 
H20ENG - Actualy its a 1HP pump. But it feeds into a air bladder tank so the pump would barely ever run on a account of circulating water through a coil in my sump. Regardless of the pump size, the energy required to move water out of the well through the coil and back to the well, would be the same as moving the water from the tank to the well and back. Maybe a little less friction running a smaller pump a lot more often but otherwise I don't think the cost would amount to much.
 
I see where your going, but remember that for good heat transfer you'll need at least 3/8" - 1/2" tubing. That'll drain your pressure tank fairly quick.
You could definitely test it out just to see how much heat gets removed, but if your like me, with little pumps laying around, use one of those:)
 
H20ENG- But assuming I get the same cooling power from X amount of cool water it shouldn't matter how big the tubing is right? Bigger tubing might just mean a bigger coil (faster cooling) or longer dwell time to remove the same amount of heat from my tank. Your right though I do have little pumps laying around, but to use them I would need to get a pipe from my house to my well and deal with getting a coil in the well, and who knows what else. The other way around I can just tap into the cold water supply on my work sink behind my tank, add a flow control valve to my temp controller, a coil in my sump, and run a drain line out just about anyplace. I know what your going to say next (maybe). In that case I know it wouldn't be closed loop so I would be pushing the water up out of the well and then just draining it off, but maybe I can find a good use for it, that I would have had to pump it for anyway, like watering my garden (more water on hot days). Either way I don't think it would require a whole lot of water. I'd like to find a cooling expert/engineer to help me figure out required flow rates, coil size, btu transfer, etc.... then I would know up front just how much water I would be pumping and what size coil I would need, and all that other good stuff. Thanks for your input though. I have another thread going on the subject looking for a cooling expert, but haven't gotten any responses yet.
 
if you digging the ditch why not just put in a big potable water container like 250-500g one tube in ...one tub out closed loop.
 
looser - I don't have a well, mine is municipal.

H20ENG - I'm really confused, I thought the idea was to pump tank water out of the house and through the pipe in the ground to disipate the heat. Are you saying that we're supposed to be pumping a freshwater closed loop outside and then through a coiled pipe in our sump?
 
You dont want a long dwell time because the water in the loop will absorb the heat, then no more heat transfer will occur. You need a fairly high velocity in the tubing to get good heat transfer (Laminar flow in the tubing will not let the heat transfer as easily as turbulent flow).

Also the colder the water, the better, as faster heat transfer occurs with the greatest deltaT.

You could set up your flow rate so that the temp leaving the tubing does not quite approach the temp of your sump. This way, you know the water is not heat saturated, but are still getting enough flow to do the job.

PM ChemE or Cseeton, those guys know their thermo. I only know enough to run equipment efficiently, not quite at the design level... :sad1:

Hopefully you can use all that water. My RODI waste goes to a barrel that gets sucked out via venturi when my sprinklers run:)

nyvp,
This is correct, (and several people have used this method) but not the most efficient heat transfer method. If the barrel is circulated well to have good flow along all sides of the barrel it would help a small system. Think of how much water is NOT in contact with the walls of the vessel contacting the earth. Then look at buried tubing, much more surface area.
 
falconut
Some people DO run their tank water through the loop. Heres why I wont and do not feel it is a good practice:

Growth inside the tubing walls will occur, affecting heat transfer.

If you shut down the flow to stop cooling, all that growth and organisms in the water use up all the oxygen. The water becomes anerobic and quickly produces hydrogen sulfide.

When you turn the loop back on for cooling, the whole loops' worth of (now) 55 deg sulfide laden water slug loads into your system, at minimum- temperature shocking the system. At worst killing everything from the anerobic water.

People counter this by running the heater to compensate for the extra cooling. You may as well dig a hole and put your heater in it. Its the same waste of electricity as far as I am concerned.
If I am going to dig up my yard for a geo loop, it is strictly to save electricity dollars.

Now, a closed loop with tap water and a few drops of chlorine doesnt care if it sits for months not moving. Its easy to control your cooling. When called for cooling the circ pump starts, then shuts down when it is satisfied. The unit is not cooling your tank while you are also trying to heat it. You do need a second exchanger in the sump to transfer the heat to the loop.

A few more parts, but really the best way to do it. (IMO, of course :D )
Chris
 
Chris... you beat me to it.

Seems that "dwell" time is something everybody wants to build into their chillers or loops. The exact opposit is what we want! The faster the water moves, the more turbulant it is and the greater the Delta T for any given cross section of contact.

Bean
 
Yep.
IIRC, anything greater than 6 foot per second velocity through the tubing will keep the flow turbulent enough to work well, but some large chillers (and I mean 1000 ton, not 1HP:) ) run at super high velocities to eek every bit of cooling out of the tubes, at the cost of early tube replacement from wear.
 
Bean, H20Eng,

What do you think of this plan.

I will put a few hundred feet of 1 inch poly pipe in the ground in a trench that is aprox 75 feet long. At the end of the trench I want to burry a 30 to 55 gallon plastic container (a barrall if I can find one), and use this as a basicly the cooling system, in the barrall will be heat exchangers from the systems that will need cooling. I have 3 tanks systems that I want to be able to cool. For the heat exchangers I was planning on having a line from each tank system going into the barrall, but after reading more I think tha loops from the barrel going to each tank system with a powerhead running them would work better. Then the main loop would have a larger pump recirculating water through it. This way I would have a fairly large body of water at 55 degrees to cool the tanks down.

With this setup how fast would I need the water to flow through the ground loop to keep the system cool? I don't have any idea what the load is, but I know it is pretty high one of the systems is 200 gallons of coral tanks with 3 400 watt halides and 2 250's. The other 2 systems are not to bad, but if it works out and has extra cooling I would like to add the home tank into the system also.

My whole reason for doing this of course is to save money, so all of the extra pumps need to be pretty small to keep the power consumption down otherwise I could just add a larger AC to the shop.

Kim
 
H20ENG - Could you describe the 2nd exchanger in the sump a little more? Are you talking a titanium coil or simply some pvc pipe.
Thanks,
Craig
 
My tank is 90 gal. and I would like to keep it around 78 - 80. I was wondering what the smallest size PVC pipe was to run under the ground?

Could I run 1/2" PVC Sch. 40 under the ground about 3' deep (frost line is 30"). Then continue to use the 1/2" PVC up to the sump. Then just before the sump convert to 1/4" Stainless Steel Gas Pipe for the exchanger in the sump? Would this work for a closed loop Geo Chiller?

If it's good, how do I determine the length of feet (PVC) needed under the ground and the length of feet (SS) needed for the exchanger in the sump?

Anybody know how to do this?
 
<a href=showthread.php?s=&postid=7256574#post7256574 target=_blank>Originally posted</a> by H20ENG
falconut
Some people DO run their tank water through the loop. Heres why I wont and do not feel it is a good practice:

Growth inside the tubing walls will occur, affecting heat transfer.

If you shut down the flow to stop cooling, all that growth and organisms in the water use up all the oxygen. The water becomes anerobic and quickly produces hydrogen sulfide.
Click to expand...

first i agree with your observations. but, as a comparrison the heat exchanger in the tank water would suffer the same growth thereby also lowering heat transfer rate. so as a comparrison they would both be the same. but only if efficiency was the same to start with. im am sure that would not be the case. flowing tank water directly through the geo loop would be more efficient.
 
The big problem I see is the long term growth in the loop. Have you ever cut apart OLD tank plumbing and see how thick and clogged it becomes with critters and other nasties? I would just be afraid to do all the work and then have to run a pig through it every few years and risk a clog.
 
How do I determine if 1/2" PVC is big enough and how many feet I'll need for my buried pipe and if 1/4" SS will work and how much I'll need to work? Both of these are for a closed loop setup.
 
I'm preparing to put some loops under a new building too.
The plan is for 6-250 gallon tray systems,
is anyway to estimate tubing size and length without having the bebenefitf running the system first?
From what I'm reading here 1/2" is the safe bet...? true?

I'll be following along, foe more heat exchanger ides too.
Thanks for the great thread guys
Marc
 
<a href=showthread.php?s=&postid=7291376#post7291376 target=_blank>Originally posted</a> by BeanAnimal
The big problem I see is the long term growth in the loop. Have you ever cut apart OLD tank plumbing and see how thick and clogged it becomes with critters and other nasties? I would just be afraid to do all the work and then have to run a pig through it every few years and risk a clog.
Click to expand...

good point. it would be easier to clean a drop in heat exchanger.
 
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