heat pump: coil placement with gas furnace
Looking for some advice on placement of a heat pump coil with an existing gas furnace:
Option 1: Standard placement above upflow furnace, gas burner runs during heat pump defrost cycle. Problem: high pressure at compressor, possible early failure
Option 2: Standard placement above upflow furnace, gas burner does *not* run during defrost cycle (blower only). Problem: cold air from registers during defrost
Option 3: Evap coil placement in cold air return plenum, before furnace. Problem: air flow can blow coil condensation through furnace, leading to corrosion of internal components.