Now we need some experience, advice, educated guesses? I am very interested in this because open loop is probably the only way I'll ever get geo in my big house on a little town plot. The yard is way too small for any loop field, and 400 ft boreholes are way too costly to consider.
It's against local ordinance to dig a well in town, but it's not against ordinance to sink a
shallow well. There is
a good video on youtube of a guy doing it with PVC, very interesting. My neighbor bought the stuff to sink one in his garage. A steel well point, some sections of steel pipe, and a heavy sliding head to pound the whole thing down into the ground. Seams simple enough.
I'd like to sink a supply well on one side of the basement and a discharge well on the other side. It's not the 200 ft or whatever they say the minimum distance between the two should be, but I don't see why it wouldn't work at least a decent amount. It would be no different than a standing column well, especially if the supply well intake is deeper than the discharge. Either way I think that even in a less-than-optimal open loop system, COP would be much higher than an ASHP.