Anyone have any experience installing/working with an earth cooling tube system? Ive have researched over and over and wanted to know what the opinion was on them. Basically you run 9 paralell plastic drainage tubing buried like a standard ground source heat pump setup, but you duct furnace air though the closed loop passage and it feed to the return of the furnace. Any moisture that condenses to the insides of the cooling tube is drained by putting a slope towards the build. From my research I have found that this system should work well for my ground temp(49F), but the main concern that arrises is bacteria and mold growth problem. But I believe that is easily combated by use of HEPA furnace filter and UV light filtration. This is one of the sites I did come across outlining the process http://www.mb-soft.com/solar/intake.html . It also shows a very good design pipe layout that utilizes a large ground area. I would love some feedback on this subject, pros and cons.