Most homes do not use an air handler. Why? because an air handler is only needed in one of two situations:
1) You heat your home with something else other than a furnace.
2) You live in an area where heating is not needed.
Typical residential heating and air conditioning systems use a furnace, evaporator coil and air conditioner setup to provide comfort for a home. The air conditioner pumps cold refrigerant into the evaporator coil, and the fan motor in the furnace pulls air from the home and circulates it through the coil (or heat exchanger for heating).
When a furnace is not used (radiant heating, geothermal, etc.) an air handler provides the coil from the evaporator coil, and the fan motor from the furnace. The air handler is only used in the summer for an air conditioner only installation, and it’s used year round if you’re heating with a heat pump.
Variable speed fan motors offer quiet operation, higher efficiency and greater comfort. They also work better for indoor air quality solutions as air is moved through the IAQ products more often. A UV lamp keeps the coil clean of mold and bacteria that can hurt efficiency.