Air handlers and furnaces aren't often used in the same home in Ravenna. If you have a furnace, you most likely shouldn’t need to think about an air handler.
Air handlers are usually linked with heat pumps and control airflow around your house. Some units also offer backup heating and cooling pieces to help the heat pump.
A furnace runs in a different way by blowing warm air into your vents, which move it across your home. As furnaces rely on combustion chambers to make hot air, they don't use some of the parts you'll see in a regular air handler.