Air handlers and furnaces aren't usually used side by side in Medina. If you have a furnace, you likely don't need to spend time thinking about an air handler.
Air handlers are frequently linked with heat pumps and deliver airflow throughout your residence. Some systems also offer secondary heating and cooling parts to assist the heat pump.
A furnace heats in a different way by sending warm air into your vents, which move it throughout your house. Because furnaces rely on combustion chambers to create hot air, they don't need some of the components you'll find in a normal air handler.