Homemade geothermal cooling

Discussion in 'Alternative Energy' started by Dahc, May 11, 2006.

  1. Dahc

    Dahc Don't Tase me, bro!?!

    Messages:
    1,358
    Joined:
    Feb 13, 2006
    Location:
    GA
    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.
     
  2. MELOC

    MELOC Master Of My Domain

    Messages:
    7,220
    Joined:
    Sep 26, 2005
    Location:
    Pennsylvania
    it sounds like you have one of those electric trailer furnaces.
     

  3. WisJim

    WisJim Well-Known Member Supporter

    Messages:
    2,180
    Joined:
    Jan 13, 2004
    Location:
    WI
    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.
     
  4. 12vman

    12vman Offgridkindaguy

    Messages:
    793
    Joined:
    Feb 16, 2004
    Location:
    Out in the Boonies.. In Ohio
  5. Dahc

    Dahc Don't Tase me, bro!?!

    Messages:
    1,358
    Joined:
    Feb 13, 2006
    Location:
    GA
    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.
     
  6. 12vman

    12vman Offgridkindaguy

    Messages:
    793
    Joined:
    Feb 16, 2004
    Location:
    Out in the Boonies.. In Ohio
    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.
     
  7. Jim-mi

    Jim-mi Well-Known Member

    Messages:
    7,883
    Joined:
    May 14, 2002
    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.
     
  8. 12vman

    12vman Offgridkindaguy

    Messages:
    793
    Joined:
    Feb 16, 2004
    Location:
    Out in the Boonies.. In Ohio
    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..
     
  9. Dahc

    Dahc Don't Tase me, bro!?!

    Messages:
    1,358
    Joined:
    Feb 13, 2006
    Location:
    GA
    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.
     
  10. tamilee

    tamilee Well-Known Member

    Messages:
    1,202
    Joined:
    Apr 12, 2005
    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
     
  11. 12vman

    12vman Offgridkindaguy

    Messages:
    793
    Joined:
    Feb 16, 2004
    Location:
    Out in the Boonies.. In Ohio
    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..
     
  12. 12vman

    12vman Offgridkindaguy

    Messages:
    793
    Joined:
    Feb 16, 2004
    Location:
    Out in the Boonies.. In Ohio
  13. Dahc

    Dahc Don't Tase me, bro!?!

    Messages:
    1,358
    Joined:
    Feb 13, 2006
    Location:
    GA
    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?
     
  14. chrisl

    chrisl Well-Known Member

    Messages:
    105
    Joined:
    Jan 20, 2006
    Location:
    NW Missouri
    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
     
  15. 12vman

    12vman Offgridkindaguy

    Messages:
    793
    Joined:
    Feb 16, 2004
    Location:
    Out in the Boonies.. In Ohio
    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
     
  16. Dahc

    Dahc Don't Tase me, bro!?!

    Messages:
    1,358
    Joined:
    Feb 13, 2006
    Location:
    GA
    Thanks. I've been a member there for about 3 years...lol. Mucho bueno info there.
     
  17. momanto

    momanto SW FLORIDA HAPPYLAND

    Messages:
    440
    Joined:
    Jan 14, 2005
    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
     
  18. SolarGary

    SolarGary Well-Known Member

    Messages:
    1,495
    Joined:
    Sep 7, 2005
    Location:
    Montana
    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
     
  19. Dahc

    Dahc Don't Tase me, bro!?!

    Messages:
    1,358
    Joined:
    Feb 13, 2006
    Location:
    GA
    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.
     
  20. Dahc

    Dahc Don't Tase me, bro!?!

    Messages:
    1,358
    Joined:
    Feb 13, 2006
    Location:
    GA
    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.