Southernbelle, on our geo system we have the fan that runs constant for filtering the air (they just recommended to run it that way and we have been, you don't have to)so it costs a little more to run it that way. We do have a dehumdifier that we had on our previous system that we had the installer hook up to our geo system. Works fine that way. (PS...I'm originally from Louisiana so I know all about those hot humid summers).
Ladia, what's your take on running the fans constant? I'm still learning here. d
It all depends on how much money you want pay for increased comfort. If money isn't object I would add whole house filter integrated to the AC ducting. The difference between recirculation and separate filter is that the filter draws certain percentage of air from outside trough a heat exchanger (to increase the economy) and keeps the house under small positive pressure to prevent dust from outside entering the house. It also have hypoallergenic filter that is not always easy to incorporate in the AC. The reason is relatively large pressure drop at the flow rates used to cool or heat the house. The filter flow rates are much smaller.
Fan coils for geo are usually two speed. High speed is used for AC and the low speed is used for circulation.
The efficiency of heat pump in general depends on the temperature differential between outside and inside of the house. The smaller is the differential the better is the efficiency and vice versa. In other words the greater are the temperature extremes and longer is their duration the more advantages is geothermal system. So in some climate such as NC, SC, VA or OR air heat pump would work quite efficiently but further south or north geo is the winner.
