Air handlers and furnaces aren't typically installed side by side in Oakville. If you have a furnace, you most likely shouldn’t need to spend time thinking about an air handler.
Air handlers are often linked with heat pumps and control airflow throughout your residence. Some units also provide backup heating and cooling pieces to support the heat pump.
A furnace heats in a different way by sending hot air into your vents, which send it around your house. Because furnaces use combustion chambers to make warmth, they don't need some of the components you'll find in a regular air handler.