Air handlers and furnaces aren't typically used together in Calgary. If you use a furnace, you likely won’t need to consider an air handler.
Air handlers are often linked with heat pumps and manage airflow throughout your residence. Some models also offer secondary heating and cooling components to support the heat pump.
A furnace works differently by blowing warm air into your vents, which move it across your home. Since furnaces depend on combustion chambers to make hot air, they don't need some of the pieces you'll find in a regular air handler.