Air handlers and furnaces aren't usually used side by side in Calgary. If you rely on a furnace, you most likely won’t need to think about an air handler.
Air handlers are frequently used with heat pumps and deliver airflow across your home. Some systems also have secondary heating and cooling parts to assist the heat pump.
A furnace works in a different way by blowing warm air into your vents, which send it around your house. Because furnaces use combustion chambers to create warmth, they don't need some of the pieces you'll spot in a standard air handler.