Air handlers and furnaces aren't typically installed side by side in Roanoke. If you use a furnace, you likely shouldn’t need to spend time thinking about an air handler.
Air handlers are usually paired with heat pumps and control airflow across your home. Some systems also provide extra heating and cooling components to assist the heat pump.
A furnace runs differently by blowing hot air into your vents, which circulate it across your home. Because furnaces rely on combustion chambers to make hot air, they don't need some of the pieces you'll spot in a regular air handler.