But not for the reason or application you might think...lol I live in SE Texas, just south of Houston. It is hot as balls here in the summer. (Which accounts for three of our seasons here) My neighborhood is on a "community well" type water system, and the well is in the back of the neighborhood, about 1/2 mile away. My water comes out of the tap noticeably cool. I am also on a .99 acre lot, so I have plenty of room to play with, and I'm outside the city limits, so there's also no one to tell me I can't. My theory is that if I could get my hands on a trencher and create a more or less closed circulatory system underground that I could bleed off enough heat from the water to actually cool my home. And if not cool it completely, at least take significant load off of the A/C, and therefor, the light bill. Also, I would like to eventually go solar and this would eliminate a very demanding system, removing a big hurdle toward that end. What I need to be able to figure out is what kind of transfer I would get with different materials for the piping so I can determine how many linear feet of field I would need for a given material. Also, depth would be a consideration, but my plan there would be to just go as deep as the machine would dig and go from there. Also, would the dirt be the best primary contact material to the piping as far as heat transfer out of the pipe is concerned, or is there some sort intermediate material that I could backfill the trench with first that would help facilitate the transfer from the pipe into the ground. There is also the consideration of how fast the earth itself can wick the heat away from the area. It won't do me any good to saturate the ground with heat energy as it would cause my contraption to cool very well for a short time, but then peter out as the ground warmed up. I don't know if this will even work or not. I have to believe that as cold as the water is coming from my tap, even on the hottest of days, that if I could get enough water back underground for a long enough period of time, that I could relocate enough heat directly into the ground to actually cool my home. Any useful input would be very welcome! ie:pipe material suggestions, or alternatives to water as a transfer liquid, etc. Thanks for entertaining my "pipe dream"! "I don't think outside the box. I simply refuse to acknowledge existence of said box." "Boxes? We don't need no stinking boxes!"