dont know shits about it but our heat pump is a ground system. id rather have a ground system than a roof system. eaiser to work on. my return air is down stairs. (2 story) the girls hit the ac and the down stairs is like a meat locker where i sleep! The instal was simple just a few k$ for a pump out side and a cold copper pipe to the existing furnace/ heater.. i say a few, its not cheep! i wish i knew more and id make their money instead of paying for it. put a security cam on it..