We have a six-year-old system with a nine-well, 1" HDPE, vertical closed loop feeding a non-pressurized flow center and two 3-ton Bosch heat pumps (each serving one floor of our house). On a recent call to diagnose a lack of heat, the current HVAC contractor (not the installing firm, which has since closed) determined that the two heat pumps were unable to function simultaneously due to insufficient water flow. This week they attached a flush cart to the ground loop, and concluded that it was obstructed. They reported that the supply side of the flush cart pegged the pressure gauge, and the return side started at 3 psi then increased to 5 psi only after hours of flushing in both directions, with intermittent dead-heading of the pump. They recommended abandoning the entire system, and offered to replace it with air-source heat pumps. The driller who installed the ground loop is unresponsive, and designed it badly in the first place: there is no manifold - the nine vertical segments are connected in series, forming one long continuous loop (about 5000 feet of hose in total), preventing us from isolating the wells for testing. It's possible the ground loop has been leaking. We have repeatedly had to add water to the flow-center reservoir. Some of the water loss was due to a dripping valve on one of the heat pumps, but that may not account for the amount of water loss experienced (multiple gallons). * Does that flush-cart test seem to indicate an obstruction (perhaps infiltration due to a leak)? * If so, are there other ways to clear the obstruction? * If it can't be cleared, can the existing ground loop be salvaged in whole or part - is it feasible to uncover the well-heads and horizontal runs for individual testing and/or replacement? * Any other suggestions?