We have a brand new 4 Ton GeoStar Sycamore and a new closed loop system. My installer has set the auxiliary heat to kick in when the outside air drops to 30 degrees. What does the outside air temperature have to do with when the auxiliary heat should kick on? Shouldn't the ground temperature in the loop or the efficiency of the heat exchange (however that is measured) be the determinant as to if we need auxiliary heat? It feels backwards and arbitrary. Does anyone have advice, please?