geothermal chiller - Page 2

looser · 04/26/2006, 06:57 PM

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.

nyvp · 04/26/2006, 09:08 PM

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.

falconut · 04/26/2006, 09:19 PM

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?

H20ENG · 04/26/2006, 10:06 PM

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...

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.

H20ENG · 04/26/2006, 10:19 PM

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

)
Chris

BeanAnimal · 04/26/2006, 10:19 PM

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

H20ENG · 04/26/2006, 10:28 PM

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.

kgross · 04/27/2006, 02:09 AM

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

falconut · 04/27/2006, 05:26 AM

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

falconut · 05/02/2006, 02:13 PM

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?

douggiestyle · 05/02/2006, 03:02 PM

Quote:

Originally posted 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.

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.

BeanAnimal · 05/02/2006, 03:07 PM

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.

falconut · 05/02/2006, 03:25 PM

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.

Marco67 · 05/02/2006, 05:10 PM

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

douggiestyle · 05/02/2006, 05:17 PM

Quote:

Originally posted 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.

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

Cuby2k · 05/02/2006, 05:35 PM

Hey I love this thread, fun stuff. There are many great thoughts and some not so but it is a cool forum.

falconut made a great point about the growth, something that I hadn't considered. AND running the water through an exchanger will reduce efficiency - some.

As far as the black poly pipe lasting, I am not sure. I believe it is NOT code approved for use inside of the house because of some major catastrophes and huge lawsuits a few years back.

Now PEX the radiant heating tubing is much better, stronger, has an oxygen barrier, and can withstand a broad range of pressure. But, it is costly compared (I think) to the black poly stuff. Runs around $0.45 to $0.60/LF. The most typical size used for radiant heating systems is 1/2" and the pipe is not really well known for it's thermal transfer properties, which are poor. But it does the job with enough pipe out there and a big enough temp diff.

So just crunching a few numbers . . .at a velocity of 6 FPS in a 1/2" line you can expect a pressure drop of around 20 PSI/100 feet of pipe. Say you put out 200 feet, that translates to 92 feet of head! Most aquarium pumps are rated for high flow and low head. Your GPH at 6 FPS is 210 or 3.5 GPM. This doesn't look good.

So what if we lowered the flow to say 1.5 GPM (90 GPH) which translates to 4 PSI/100 feet of pipe. That would drop the total head to around 20 feet which is manageable.

Now at 1.5 GPM and an entering water temp (via the exchanger) of around 75 deg F you could expect a temp drop of maybe 10 degrees through the loop then you will lose a couple of those degrees again at the exchanger. So if you were able to get 1.5 GPM at a 6 deg F drop you will be dumping 4500 BTUH to the Earth. (Provided you were deep enough to get constant temp which would have to be from 2' to 6' and it's better if the ground is WET). One watt of electricity equals 3.4 BTUH so you are getting rid of about 1323 watts.

I think this is starting to look attractive but cost is going to be a factor. 200 feet of 1/2" PEX = $100. A heat exchanger of titanium will run around $100 (I am now officially WAGGING) and a decent pressure circulator will run $225 and you had better add another $100 for what if's. Still $600 for essentially FREE cooling isn't bad. You still have to provide the labor and misc stuff but I am liking it.

Unless of course you have a day job and kids and a bad back . . . well maybe working a few hours overtime to pay for that $600 chiller doesn't look so bad either.

Sorry for the run of the fingers here, I kind of dig this stuff.

UPDATE INFO. I just noticed on Ebay, 500 LF of 3/4" PEX for $150 which includes shipping. 3/4" could handle a higher flow rate and maybe it would end up at a lower PD. Velocity at around 1.5 FPS is enough to elimate laminarity as I recall.

Cuby2k · 05/02/2006, 05:37 PM

One more thing, stay away from the tank idea, there is such poor thermal transfer and do not use less than 1/2" pipe. If it is going to be buried under a building consider the heat gain from the building and FOR SURE use PEX under a slab.

Marco67 · 05/02/2006, 05:49 PM

nice info chuby2k,
when you say "under the slab " do you mean directly under or just inside the perimeter?
Frostline here is 32". footings are dug at 48", I can burry inside or outside. Inside being a bit easier of course.

Cuby2k · 05/02/2006, 06:24 PM

hmmm ,not sure I understand your question completely Marco.

Under the slab anywhere is what I was getting to. So if you were to bury the pipe under your footings or basement floor, that would be "under the slab". The problem is the earth heats up from the indoor space temp so your transfer would not be as good. Your bigger concern would be a less than high performance pipe that could easily shear or get damaged during the installation. If that happens and you have poured the floor you are up the creek, so to speak.

I just remembered another type of piping called multicore. It is an aluminum corrugated pipe with a PVC like jacket and it's thermal conductivity is much better than PEX or poly. I think it is cheaper than PEX by a bit too.

Tell you what, I will look up some pricing and thermal conductivity stuff and post it back here. This idea is starting to make better sense to me and if nothing else it's fun.

I do know a little about piping, pumping and thermal and fluid dynamics but when it comes to LPS or SPS or trying to keep reef tanks alive, I am going to need MUCH help friend.

I'll get back here after I gather a little info.

Oh and one more minor detail, It's CUBY, not CHUBY. Just a small item. ahem.

Cuby2k · 05/02/2006, 06:26 PM

If someone has info on titanium heat exchangers I would love to hear about them.

hsvtoolfool · 05/02/2006, 07:54 PM

Quote:

Originally posted by Cuby2k
If someone has info on titanium heat exchangers I would love to hear about them.

http://www.sw-wilson.com/prod04.htm

http://umii.net/hx.htm

Cuby2k · 05/02/2006, 07:59 PM

Oh that is perfect hsvtoolfool, this is really getting to be fun.

Thanks for the info!

falconut · 05/02/2006, 08:21 PM

I've heard of people using 1/2" Sch. 40 PVC for to piping buried and to run to the sump for the tank water systems. Wouldn't that work for the closed loop?

Shouldn't I be able to bury say 200' of 1/2" Sch. 40 PVC and run it to just outside the sump, then connect it to some 1/4" 304 Stainless Steel Tubing (in the sump for exchanger) and then switch back to 1/2" PVC to return back to the ground?

I've found 1/4" 304 Stainless Steel Tubing for $1.99/ft and 1/2" Sch. 40 PVC is cheap and the seals won't leak. All I would need is to determine a pump size and get a controller.

douggiestyle · 05/02/2006, 08:29 PM

Quote:

Originally posted by falconut
I've found 1/4" 304 Stainless Steel Tubing for $1.99/ft and 1/2" Sch. 40 PVC is cheap and the seals won't leak. All I would need is to determine a pump size and get a controller.

i love you man. jk

try 1/2 ss flex gas line connector.

http://www.laundryparts.com/sunshop/...s/zgasline.jpg

easy to bend and ribbed for heat transfer pleasure

i feel like a walmart greeter. lol

hsvtoolfool · 05/02/2006, 08:31 PM

You're welcome. I plan to use one of these exchangers to
build a chiller from a $100 window A/C unit like ReefRelated
pioneered...

http://reefcentral.com/forums/showth...hreadid=177020

Besides geo-thermal, I suspect the above window A/C trick
is the most cost effective long-term chiller solution. The
heat and noise is dumped outdoors where they belong
and the total cost is about the same as a store-bought
chiller with the same capacity. The hard part is finding a
magician who will do all the technical A/C stuff for a
reasonable price.

04/26/2006, 06:57 PM	#26
looser Registered Member Join Date: Feb 2003 Location: Central MA Posts: 933	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. __________________ "Honey, get the kids out of the house. . . . the fish tank is about to explode!" Current Tank Info: 225 with 75 Fuge

04/26/2006, 09:19 PM	#28
falconut Registered Member Join Date: Dec 2003 Location: Blackwood, NJ Posts: 3,813	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? __________________ 180 Gallon FOWLR, 40 Gallon Sump and 10 Gallon Refuge. (2) OceanRevive S026 LEDs, ASM G2 Skimmer & SCA-302 Skimmer. Setup since July 2017.

04/27/2006, 02:09 AM	#33
kgross Premium Member Join Date: Nov 1999 Location: Nampa, ID Posts: 5,870	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 __________________ Proud Member of the Idaho Marine Aquarium Society America will only be the Land of the Free as long as it is the Home of the Brave. Current Tank Info: AGA 180gallon tank, VHO/MH lighting, DSB, calcium reactor, Also a 7 Gallon Nano softy tank, and a 32 gallon cube

04/27/2006, 05:26 AM	#34
falconut Registered Member Join Date: Dec 2003 Location: Blackwood, NJ Posts: 3,813	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 __________________ 180 Gallon FOWLR, 40 Gallon Sump and 10 Gallon Refuge. (2) OceanRevive S026 LEDs, ASM G2 Skimmer & SCA-302 Skimmer. Setup since July 2017.

05/02/2006, 02:13 PM	#35
falconut Registered Member Join Date: Dec 2003 Location: Blackwood, NJ Posts: 3,813	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? __________________ 180 Gallon FOWLR, 40 Gallon Sump and 10 Gallon Refuge. (2) OceanRevive S026 LEDs, ASM G2 Skimmer & SCA-302 Skimmer. Setup since July 2017.

04/26/2006, 09:08 PM	#27
nyvp Registered Member Join Date: Sep 2005 Location: Hollywood Florida Posts: 3,633	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.

04/26/2006, 10:06 PM	#29
H20ENG Pro builder/aquarist hack Join Date: Jul 2002 Location: NORCAL (Vacaville, CA) Posts: 5,125	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... 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.

04/26/2006, 10:19 PM	#30
H20ENG Pro builder/aquarist hack Join Date: Jul 2002 Location: NORCAL (Vacaville, CA) Posts: 5,125	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 ) Chris

04/26/2006, 10:19 PM	#31
BeanAnimal Registered Member Join Date: Feb 2003 Location: Pittsburgh Posts: 20,772	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

04/26/2006, 10:28 PM	#32
H20ENG Pro builder/aquarist hack Join Date: Jul 2002 Location: NORCAL (Vacaville, CA) Posts: 5,125	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.

05/02/2006, 03:07 PM	#37
BeanAnimal Registered Member Join Date: Feb 2003 Location: Pittsburgh Posts: 20,772	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.

05/02/2006, 03:25 PM	#38
falconut Registered Member Join Date: Dec 2003 Location: Blackwood, NJ Posts: 3,813	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. __________________ 180 Gallon FOWLR, 40 Gallon Sump and 10 Gallon Refuge. (2) OceanRevive S026 LEDs, ASM G2 Skimmer & SCA-302 Skimmer. Setup since July 2017.

05/02/2006, 05:10 PM	#39
Marco67 RC Sponsor Join Date: Nov 2000 Location: Cape Cod Posts: 2,733	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 __________________ Complicated yet simple Frustrating yet rewarding The more you think you know...The more you need to learn Current Tank Info: Too many tanks, Need to buy stock in the eletc co

05/02/2006, 05:35 PM	#41
Cuby2k Cuby2k Join Date: Mar 2006 Location: Salt Lake City Posts: 982	Hey I love this thread, fun stuff. There are many great thoughts and some not so but it is a cool forum. falconut made a great point about the growth, something that I hadn't considered. AND running the water through an exchanger will reduce efficiency - some. As far as the black poly pipe lasting, I am not sure. I believe it is NOT code approved for use inside of the house because of some major catastrophes and huge lawsuits a few years back. Now PEX the radiant heating tubing is much better, stronger, has an oxygen barrier, and can withstand a broad range of pressure. But, it is costly compared (I think) to the black poly stuff. Runs around $0.45 to $0.60/LF. The most typical size used for radiant heating systems is 1/2" and the pipe is not really well known for it's thermal transfer properties, which are poor. But it does the job with enough pipe out there and a big enough temp diff. So just crunching a few numbers . . .at a velocity of 6 FPS in a 1/2" line you can expect a pressure drop of around 20 PSI/100 feet of pipe. Say you put out 200 feet, that translates to 92 feet of head! Most aquarium pumps are rated for high flow and low head. Your GPH at 6 FPS is 210 or 3.5 GPM. This doesn't look good. So what if we lowered the flow to say 1.5 GPM (90 GPH) which translates to 4 PSI/100 feet of pipe. That would drop the total head to around 20 feet which is manageable. Now at 1.5 GPM and an entering water temp (via the exchanger) of around 75 deg F you could expect a temp drop of maybe 10 degrees through the loop then you will lose a couple of those degrees again at the exchanger. So if you were able to get 1.5 GPM at a 6 deg F drop you will be dumping 4500 BTUH to the Earth. (Provided you were deep enough to get constant temp which would have to be from 2' to 6' and it's better if the ground is WET). One watt of electricity equals 3.4 BTUH so you are getting rid of about 1323 watts. I think this is starting to look attractive but cost is going to be a factor. 200 feet of 1/2" PEX = $100. A heat exchanger of titanium will run around $100 (I am now officially WAGGING) and a decent pressure circulator will run $225 and you had better add another $100 for what if's. Still $600 for essentially FREE cooling isn't bad. You still have to provide the labor and misc stuff but I am liking it. Unless of course you have a day job and kids and a bad back . . . well maybe working a few hours overtime to pay for that $600 chiller doesn't look so bad either. Sorry for the run of the fingers here, I kind of dig this stuff. UPDATE INFO. I just noticed on Ebay, 500 LF of 3/4" PEX for $150 which includes shipping. 3/4" could handle a higher flow rate and maybe it would end up at a lower PD. Velocity at around 1.5 FPS is enough to elimate laminarity as I recall. __________________ Rod "Cuby" Current Tank Info: 180 display, 100 gal DIY fuge/sump, DIY skimmer. Last edited by Cuby2k; 05/02/2006 at 06:35 PM.

05/02/2006, 05:37 PM	#42
Cuby2k Cuby2k Join Date: Mar 2006 Location: Salt Lake City Posts: 982	One more thing, stay away from the tank idea, there is such poor thermal transfer and do not use less than 1/2" pipe. If it is going to be buried under a building consider the heat gain from the building and FOR SURE use PEX under a slab. __________________ Rod "Cuby" Current Tank Info: 180 display, 100 gal DIY fuge/sump, DIY skimmer.

05/02/2006, 05:49 PM	#43
Marco67 RC Sponsor Join Date: Nov 2000 Location: Cape Cod Posts: 2,733	nice info chuby2k, when you say "under the slab " do you mean directly under or just inside the perimeter? Frostline here is 32". footings are dug at 48", I can burry inside or outside. Inside being a bit easier of course. __________________ Complicated yet simple Frustrating yet rewarding The more you think you know...The more you need to learn Current Tank Info: Too many tanks, Need to buy stock in the eletc co

05/02/2006, 06:24 PM	#44
Cuby2k Cuby2k Join Date: Mar 2006 Location: Salt Lake City Posts: 982	hmmm ,not sure I understand your question completely Marco. Under the slab anywhere is what I was getting to. So if you were to bury the pipe under your footings or basement floor, that would be "under the slab". The problem is the earth heats up from the indoor space temp so your transfer would not be as good. Your bigger concern would be a less than high performance pipe that could easily shear or get damaged during the installation. If that happens and you have poured the floor you are up the creek, so to speak. I just remembered another type of piping called multicore. It is an aluminum corrugated pipe with a PVC like jacket and it's thermal conductivity is much better than PEX or poly. I think it is cheaper than PEX by a bit too. Tell you what, I will look up some pricing and thermal conductivity stuff and post it back here. This idea is starting to make better sense to me and if nothing else it's fun. I do know a little about piping, pumping and thermal and fluid dynamics but when it comes to LPS or SPS or trying to keep reef tanks alive, I am going to need MUCH help friend. I'll get back here after I gather a little info. Oh and one more minor detail, It's CUBY, not CHUBY. Just a small item. ahem. __________________ Rod "Cuby" Current Tank Info: 180 display, 100 gal DIY fuge/sump, DIY skimmer. Last edited by Cuby2k; 05/02/2006 at 06:37 PM.

05/02/2006, 06:26 PM	#45
Cuby2k Cuby2k Join Date: Mar 2006 Location: Salt Lake City Posts: 982	If someone has info on titanium heat exchangers I would love to hear about them. __________________ Rod "Cuby" Current Tank Info: 180 display, 100 gal DIY fuge/sump, DIY skimmer.

05/02/2006, 07:59 PM	#47
Cuby2k Cuby2k Join Date: Mar 2006 Location: Salt Lake City Posts: 982	Oh that is perfect hsvtoolfool, this is really getting to be fun. Thanks for the info! __________________ Rod "Cuby" Current Tank Info: 180 display, 100 gal DIY fuge/sump, DIY skimmer.

05/02/2006, 08:21 PM	#48
falconut Registered Member Join Date: Dec 2003 Location: Blackwood, NJ Posts: 3,813	I've heard of people using 1/2" Sch. 40 PVC for to piping buried and to run to the sump for the tank water systems. Wouldn't that work for the closed loop? Shouldn't I be able to bury say 200' of 1/2" Sch. 40 PVC and run it to just outside the sump, then connect it to some 1/4" 304 Stainless Steel Tubing (in the sump for exchanger) and then switch back to 1/2" PVC to return back to the ground? I've found 1/4" 304 Stainless Steel Tubing for $1.99/ft and 1/2" Sch. 40 PVC is cheap and the seals won't leak. All I would need is to determine a pump size and get a controller. __________________ 180 Gallon FOWLR, 40 Gallon Sump and 10 Gallon Refuge. (2) OceanRevive S026 LEDs, ASM G2 Skimmer & SCA-302 Skimmer. Setup since July 2017.

05/02/2006, 08:31 PM	#50
hsvtoolfool Premium Member Join Date: Jun 2004 Location: Huntsville, AL Posts: 307	You're welcome. I plan to use one of these exchangers to build a chiller from a $100 window A/C unit like ReefRelated pioneered... http://reefcentral.com/forums/showth...hreadid=177020 Besides geo-thermal, I suspect the above window A/C trick is the most cost effective long-term chiller solution. The heat and noise is dumped outdoors where they belong and the total cost is about the same as a store-bought chiller with the same capacity. The hard part is finding a magician who will do all the technical A/C stuff for a reasonable price.