Air handlers and furnaces aren't often used together in Albany. If you use a furnace, you most likely won’t need to spend time thinking about an air handler.
Air handlers are frequently used with heat pumps and deliver airflow around your home. Some models also have backup heating and cooling pieces to support the heat pump.
A furnace heats in a different way by pushing heated air into your vents, which move it around your residence. Since furnaces use combustion chambers to make warmth, they don't need some of the pieces you'll see in a standard air handler.