# Homemade geothermal cooling



## Dahc

Well, summer is coming again and my electric bill is already unacceptable. $218 last month just for a single mobil home. Last year at this time, we had the same usage but the bill was $150. I don't know about ya'll but I can't afford my projection for my summer electric bill.

So... Last year I found a website and someone there suggested taking thinwall PVC, burying it 2' or 3' deep in the ground and pumping air through this into the house. I came across another website that actually had prints for this. The PVC needed to be anywhere from 4" to 6" and it would cost about $900 or more just for the PVC. I compared this with aluminum piping and steel and with the pipe joints, dope and a strong coating to resist corrosion, it would cost well over $3000 for the cheapest option.

I'm thinking for my 16'x80', I may be able to do this for less than $2200. That means that at the present cost of energy (which is going to go up), the thing would pay for itself in two years because the in hottest months, most of the bill is for air conditioning. Without it, my house easily reaches 95 F inside. It's very inefficient. I am making plans to do some things to make it more efficient but I think in the long run, traditional heating and cooling is out.

Has anyone considered this or had any ideas along these lines? How would you build your (air) pump station? Would you build a box with fans in it or maybe try to get some inline fans? Any ideas are welcome.


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## MELOC

it sounds like you have one of those electric trailer furnaces.


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## WisJim

Burying it 2 or 3 feet isn't deep enough. To make it worth while it should be 6 to 8 feet deep at least, so that the soil around the pipes stays cooler all summer. Aso, the bigger diameter pipe, the better. Even 8 inch would be better than 6 inch. I have a couple of friends who have tried this over the last 20 years or so, and will try to get more details if possible.


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## 12vman

Lots of reading but..

http://mb-soft.com/solar/saving.html


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## Dahc

12vman said:


> Lots of reading but..
> 
> http://mb-soft.com/solar/saving.html


Yes, that's one of the sites I found that really got me thinking about this last year. I'm ready to try and start but I looking for a few more ideas about how to move this air in and out of the house. It really needs to tie in where the central h/a does now to save me from having to tear things up and rebuild.

I also have a pond about 20' from the house. If I could only figure out how to hold down 4" pipes filled with air, I'd use that... lol.


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## 12vman

There's 2 ways to install the above system. You can either CIRCULATE the air inside the home through the tubes OR pull outside air through them and bring that cooled air inside. If the tube were buired and the air was pulled from the outside, you could configure your cold air ducts to pull air from the tubes and blow it throughout the house via the existing ductwork.


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## Jim-mi

Ya the geo-thermo stuff is great, but remember that any air circulation motors are going to be running a long time which will be $$$$ on your electric.
It'll take some hefty motors to suck/push enough air thru "lengths ? " of pipe.


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## 12vman

If I read it correctly, It should be designed with enough pipes (area) so not to cause any restrictions to the air flow. They get into the math of it but I'd rather sit on a cactus than try to figger all of that out.. 

Around here, the air would be coming in at around 54 degrees from the tubes. The thermastat would control a blower motor only and not a compressor for the freon. I figure that alone would save a bunch of power..

I plan to use this idea in my home in the future. I'll use a solar chimney to draw air from the inside and replace it with cooled air from the underground tubes. No power required..


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## Dahc

12vman said:


> If I read it correctly, It should be designed with enough pipes (area) so not to cause any restrictions to the air flow. They get into the math of it but I'd rather sit on a cactus than try to figger all of that out..
> 
> Around here, the air would be coming in at around 54 degrees from the tubes. The thermastat would control a blower motor only and not a compressor for the freon. I figure that alone would save a bunch of power..
> 
> I plan to use this idea in my home in the future. I'll use a solar chimney to draw air from the inside and replace it with cooled air from the underground tubes. No power required..


I think if we could find out what a particular blower was designed to push and then figured up the volume of a single stick of pipe it would be easier than what they have.

The map says that my air would be around 68F but I figure with the slight inability of PVC to shed all the heat energy, maybe I could get some 76F air into the house. That would be great in winter as well.

What's a solar chimney and how does it work? I'm thinkin' it's a hole in the top of your house that the hot air can escape from but I have been wrong before.


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## tamilee

Dahc said:


> Well, summer is coming again and my electric bill is already unacceptable. $218 last month just for a single mobil home. Last year at this time, we had the same usage but the bill was $150. I don't know about ya'll but I can't afford my projection for my summer electric bill.
> 
> So... Last year I found a website and someone there suggested taking thinwall PVC, burying it 2' or 3' deep in the ground and pumping air through this into the house. I came across another website that actually had prints for this. The PVC needed to be anywhere from 4" to 6" and it would cost about $900 or more just for the PVC. I compared this with aluminum piping and steel and with the pipe joints, dope and a strong coating to resist corrosion, it would cost well over $3000 for the cheapest option.
> 
> I'm thinking for my 16'x80', I may be able to do this for less than $2200. That means that at the present cost of energy (which is going to go up), the thing would pay for itself in two years because the in hottest months, most of the bill is for air conditioning. Without it, my house easily reaches 95 F inside. It's very inefficient. I am making plans to do some things to make it more efficient but I think in the long run, traditional heating and cooling is out.
> 
> Has anyone considered this or had any ideas along these lines? How would you build your (air) pump station? Would you build a box with fans in it or maybe try to get some inline fans? Any ideas are welcome.


Hi Dahc;
Here's a link. Hope it helps. The system has info and detailed plans and was created by an engineer.
http://mb-soft.com/solar/saving.html

SORRY, didn't realize it was the same link.
tamilee


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## 12vman

Quote..
"What's a solar chimney and how does it work? I'm thinkin' it's a hole in the top of your house that the hot air can escape from but I have been wrong before."

Sure.. You can use the heat collected in the attic to make a vacuum in the house as it escapes. The attic would need to be sealed up and an opening made into the living area. Adding a chimney in the area where the heat is leaving would give you more pulling power. Your house would need to be pretty tight to get results and you would need to keep it closed up. An attic fan would work too if you allowed it to pull air from the living area and draw air in through the buried piping. This is in the event where you were pulling outside air through the piping..

The closed loop system wouldn't work for me. I would be required to run a fan all of the time to circulate the air through the piping back into the house. A solar powered attic fan with the piping getting air from the outside would. A chimney heated by the sun and the heat from my attic area would work great without any power..


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## 12vman

Here's some other ideas for cooling..

http://www.i4at.org/lib2/aircool.htm

http://www.i4at.org/surv/aircond.htm

From this link..

http://www.i4at.org/library.html


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## Dahc

12vman said:


> Here's some other ideas for cooling..
> 
> http://www.i4at.org/lib2/aircool.htm
> 
> http://www.i4at.org/surv/aircond.htm
> 
> From this link..
> 
> http://www.i4at.org/library.html


Very interesting links! Thank you for posting them. I couldn't do the cooling tower but it got me thinking about how I could maybe modify it to work for me. It would have to be a lot smaller and so it would use some electricity but surely not what I use now. Maybe an insulated tower, 3'x3'x16' with lots of little layers of tubing like the stuff on the back of a refrigerator, all stacked back to back with the water being pumped through them and a blower pushing/pulling air down the tower into the house. I wouldn't need a tower but if I ever went to a solar chimney type set-up like you describe, it would work right along with it.

I couldn't use the extra humidity like the the one in the article does. It appears that it is some type of desert compound. Here, in the winter the humidity gets down to around 30% but in the warmer months the winds blow up from the gulf over the FL panhandle and the humidity gets as high as 95%. Unfortunately I couldn't benefit from it in the winter. It doesn't get as cold as Ohio but we do have 17 and 18 degree days in Dec and Jan. This thread has really got my brain working.

12vman, you know anything about homemade alternators and coils? Like size vs. voltage?


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## chrisl

Here is food for thought. I've worked with a very large mechanical contractor here in the midwest. The guy I've worked with on quoting me bids for my employer, was telling me they did a large job for a phamasutical company down by Kansas City. The way they take care of there cooling needs is they dug a large pit or silo in the middle of thier campus ( very large campus close to 80 ac.). Any way they have several ice machines the comercial cube type that make ice 24/7. The ice falls in to the pit with a solution of saltwater. Inside the pit is rows and rows of pipe. They simply pump chilled water through the pipe to the cooling coils, cool there building then the water returns to the pit. They have saved according to this guy over 20 million in cooling cost over the last 15 years. The ice machine draw very little power compared to a mulit-ton chiller. The chilled water pumps would have to be used regardles. 
With all that said I wonder if a person would buy a small ice maker from one of these surplus outfits and do the same thing, you might be able to save money. I now we have a small 120v unit here at my job and it only pulls 4 amps. Just a thought.

Chris


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## 12vman

Quote..
"12vman, you know anything about homemade alternators and coils? Like size vs. voltage?"

Never messed with that too much. Check these guys out. They build them all of the time..

www.otherpower.com


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## Dahc

12vman said:


> Quote..
> "12vman, you know anything about homemade alternators and coils? Like size vs. voltage?"
> 
> Never messed with that too much. Check these guys out. They build them all of the time..
> 
> www.otherpower.com


Thanks. I've been a member there for about 3 years...lol. Mucho bueno info there.


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## momanto

What Kind Of Roof Does Your Mobile Home Have? Surely Not Tin.

Down Here Sometimes Folks Build A Pole Barn Over Their Mobile Home.

Some Fast Growing Trees Around It Would Help Too.

From - Low Tech, Low Budget Mom


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## SolarGary

Hi,

Here are some more ideas yet on efficient cooling:

http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm


There are a couple links on earth tube cooling here:
http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm#Other

The first is an EERE site has a blurb on earth tube cooling -- its not to optomisitic:

The other is a paper with some measured data on earth tube coolin -- its about the only real data I have seen (other than the Hait book below).

This guy did some real work with earth tubes, and has a book a good book:
http://www.earthshelters.com/

I was able to get the book on my interlibrary loan program -- you might be able to do the same.

Just my 2 cents, but I think I might try the more conventional stuff like more insulation, better shading, night ventilation, good infiltration control, ... before the earth tubes??

Gary
www.BuildItSolar.com


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## Dahc

momanto said:


> What Kind Of Roof Does Your Mobile Home Have? Surely Not Tin.
> 
> Down Here Sometimes Folks Build A Pole Barn Over Their Mobile Home.
> 
> Some Fast Growing Trees Around It Would Help Too.
> 
> From - Low Tech, Low Budget Mom


This is what my dad is suggesting... Even offering to pay for it at present and allow lax payments over the course of a year or two. He would actually pay for it and forget it but I'm not willing to go that route. Yes, the roof is some sort of metal, most likely painted aluminum. It doesn't seem as strong as tin and doesn't have anything like a roof coat on it. It's silver rather than white.

I'll have to figure up the cost of both and go the cheaper route.


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## Dahc

SolarGary said:


> Hi,
> 
> Here are some more ideas yet on efficient cooling:......


Hi Gary, thanks for posting these links. There is too much info here to go over in a day but I'm workin' on it.


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## caballoviejo

The most cost efficient savings on cooling a single wide would be had by stopping air infiltration, blockling radiant heat from the sun, better insulating the house, and limiting or venting heat and vapor production in the home.


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## Dahc

This is what I've come up with at this point. We will put the pole barn type structure over the house like Momanto suggested but with a little twist.

I had no choice on the position of the mobil home and because of that, in the hottest part of the day the sun shines on a long wall and the end bedroom. That's way to much surface area that's being used to heat up the thing, so on that end and side, the pole barn roof will extend out 12'. I'll make those extensions into a walled porch/family room type thing with straw bale walls. This will provide superior protection from the sunlight that hits those two sides and enable me to do the work myself.

My wife and I have always wanted to build our own straw bale home but due to some serious circumstances with my health, had to settle for this trailer. We kind of thought that that dream was history but fortunately, I see this can be done in a way in which I can pull this mobil home right out from under the roof structure at a later date, rent it out to pay off the mortgage, and fill in the rest with straw bales. It will be hard but it will be fun.

The geothermal cooling idea is great but I have come to believe it is a little premature considering the exposure to sunlight that the home gets. I don't think it would cool the house well enough when the house is actually a huge solar heater at this point. First things first. Maybe I can do the geothermal thing the year after next, God willing.


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## SolarGary

Dahc said:


> This is what I've come up with at this point. We will put the pole barn type structure over the house like Momanto suggested but with a little twist.
> 
> I had no choice on the position of the mobil home and because of that, in the hottest part of the day the sun shines on a long wall and the end bedroom. That's way to much surface area that's being used to heat up the thing, so on that end and side, the pole barn roof will extend out 12'. I'll make those extensions into a walled porch/family room type thing with straw bale walls. This will provide superior protection from the sunlight that hits those two sides and enable me to do the work myself.
> ...


Hi,

Here is a similar concept from MEN -- seems like a pretty nice concept to me:
http://www.motherearthnews.com/library/1984_January_February/A_Thermal_Envelope_Trailer

Its more for heating than cooling, but might supply some good ideas.

Gary
www.BuildItSolar.com


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## ET1 SS

I just installed PEX tubing underneath our subflooring. I had to buy 1000' soil of it. I used 600'. So I have about 400' left over.

I had the thought of installing this left-over tubing into the trench for the leech-line, about 4 to 5 feet deep, as a loop. then later circulating water through this buried loop for cooling. Maybe running this cooled-water through a radiator in our house.


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## highlands

I did this in 2001. Even a foot down is enough. The trick is put a layer of insulation, e.g., blue board, right above the pipes. 4" of blueboard = 4' of soil insulation. Extend the blue board out 2' to either side (2" thick) and lay another 2' wide piece 2" thick over the seam. Works great for those of us who can't go down deep (ledge - this is Vermont).

I put in 70' x 4 pipes wide x 4" diameter pipes (drainage). The last 10' of each pipe is perfed with the perfs on the bottom. The whole thing slopes 3' down over the 70' of distance.

I actually use it for the opposite purpose. We are in northern Vermont and our winters routinely get to -45Â°F for extended periods. By drawing in fresh air through the pipes in the winter I get a 70Â°F temperature boost on the air. This saves me on heating and gives me fresh air. Works great. We've had it in for five years now.

Put a screen on both ends of the pipe to keep out pests.


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## Loumeister

Is anyone concerned about pulling in mold or other stuff by moving large amounts of air through buried line? What about using water or some other liquid and then moving it past a heat exchanger ? The liquid would be a better heat transfer agent, but the heat exchanger may be a bit pricey....

Loumeister


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## ET1 SS

Loumeister said:


> Is anyone concerned about pulling in mold or other stuff by moving large amounts of air through buried line? What about using water or some other liquid and then moving it past a heat exchanger ? The liquid would be a better heat transfer agent, but the heat exchanger may be a bit pricey....
> 
> Loumeister


A heat exchanger designed for transfering heat between liquid and air, is also called a junk-yard car radiator, worth $40.


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## jnap31

All around my grandpas farm there are abandoned mine shafts where they took out clay for bricks sometimes they cave in and trees fall over. Well there is one place I remember from when i was little where animals had dug into one and their were two holes bout the size of a ground hog hole they were constantly blowing 55 to 60 degree air out I dont know the physics behind it but it was neat and even when their was snow all around you could always see that spot cause their was no snow there. Grandpa said it would be a good place to build a house and have free heat in the winter and airconditioning in the summer Problem is it was in a really steep holler. So how big an underground chamber/cavern would you need to make the same effect? perhaps if you had a big underground storm/root cellar you could have a pipe from to your house? would you only get the effect if it was completely sealed off everywhere but where the pipe is?


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## airwolftruker

Dahc said:


> This is what my dad is suggesting... Even offering to pay for it at present and allow lax payments over the course of a year or two. He would actually pay for it and forget it but I'm not willing to go that route. Yes, the roof is some sort of metal, most likely painted aluminum. It doesn't seem as strong as tin and doesn't have anything like a roof coat on it. It's silver rather than white.
> 
> I'll have to figure up the cost of both and go the cheaper route.


Those metal roofs are very inefficient. The cool air system seems very cool but i would suggest maybe a different approach. Pvc plastic or plastic in general doesn't transfer heat or cold as well as metal. Your problem seems to be cooling in the summer.
i have a friend that sunk a very long coil into his water well. He is on city water so it wasn't
being used. Then he ran the piping underground to the house to a semi trailer evaporator
coil ( looks like a big radiator) with a big fan to blow thru the coils.
My freind is a very skilled titewad.
He says the water coils at the house are 63Â° all year long
im pretty sure you can find a geo thermal forced air system. Or get something to retro fit your hvac system....good luck


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## airwolftruker

Dahc said:


> This is what my dad is suggesting... Even offering to pay for it at present and allow lax payments over the course of a year or two. He would actually pay for it and forget it but I'm not willing to go that route. Yes, the roof is some sort of metal, most likely painted aluminum. It doesn't seem as strong as tin and doesn't have anything like a roof coat on it. It's silver rather than white.
> 
> I'll have to figure up the cost of both and go the cheaper route.


Those metal roofs are very inefficient. The cool air system seems very cool but i would suggest maybe a different approach. Pvc plastic or plastic in general doesn't transfer heat or cold as well as metal. Your problem seems to be cooling in the summer.
i have a friend that sunk a very long coil into his water well. He is on city water so it wasn't
being used. Then he ran the piping underground to the house to a semi trailer evaporator
coil ( looks like a big radiator) with a big fan to blow thru the coils.
My freind is a very skilled titewad.
He says the water coils at the house are 63Â° all year long
im pretty sure you can find a geo thermal forced air system. Or get something to retro fit your hvac system....good luck
Oh ya, you could save some doe, by painting your roof white or a lite color
At the big box store look for a metal roof coating called "snoseal" its great!


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## fishhead

We just had 96 degrees and my house didn't get above 83 because of all the shade trees around my house.

My first thoughts are more insulation, a white roof over the trailer with an air space between it and the real roof, vines for shading the sides.

I've been told that it's critical to keep the ground moistened around the earth tubes in order to transfer the cold of the earth to the tube.

When I build I'm definitely going to use earth tubes for cooling and dehumidifying but I'm also going to super insulate with a heat exchanger built into my air exchange.


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## motdaugrnds

Dahc, I'm in a similar situation as you in that we live in a 65' x 12' trailer that is like a furnace in the summer time.

I'm saving money to dig a large hole, be it a root cellar for veggies or a storm cellar or a basement...haven't decided yet. However, it will be "under" the ground's freeze zone; and during hot summers, this is where we will be spending a lot of time.


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## Belfrybat

Wow! A six year old thread resurrected! How do you even find a six year old thread? 

I would imagine that the technology had advanced quite a bit over what was available when this thread was started, and perhaps some of the difficulties of mold that were prevalent in such a system back then have been resolved.


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## meddac

How deep and big is the pond? I have conventional geothermal in a pond and it's the bomb. The pond is the most efficient at exchanging heat/cold just like a car radiator. I'd be focusing on it if it's at least 8 feet deep.


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## shawnlee

Is this working out still...any problems...…..


This threads all end the same.


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