Barry Irby
4000 LF for $4000 is amazing. I would have thought the pipe alone was close to that. Are you using high density PE?

I have not checked lately, but I would have expected it to be double or triple that. And the equipment cost would be about the same as an Air to Air HP, so I would think the ground source unit would cost more than the A to A unit by about the cost of the loop. In a mild climate it would take a LONG time to recoup the cost of the loop.

It is not a simple comparison but worthy of being careful about. For example, Many people would not have room for a 4000 LF loop or would not want to suffer the disruption to there landscape.