belated response Hey guys, I work at REHAU and came across this thread from last year. Truthfully, I really liked reading through it and you all bring up some very good points to consider when choosing between PEXa and HDPE. One question I have though, in response to Eric's post from 9-24-2010 - why don't you include the cost of the drilling? If all you really need is 0.81 tons of cooling (or any multiple of that), you could simply drill 160 ft loops instead of 200 ft loops. By not drilling the extra 40 ft, you are saving your customer those drilling costs. You start to break even around the $13/ft mark. Another positive is if you're close to the house, you could use a 210' loop and use the remaining 50 ft (in keeping with the above example) to run directly into the house with no fittings. Of course if you need to drill bigger boreholes, more grout is needed. But in the area I'm in (Northern VA, MD, PA), drillers are drilling 5" or 6" bores anyway. Installing two loops actually decreases the grout required. I'm not a driller, so my reasoning might not hold from your perspective, but I thought I'd add my 2 cents! - Chris P.S. I agree, do not buy the rehau weights. They are simply a carry-over from the geothermal program in Germany. I don't know if they sell any there or not (probably not).