Air handlers and furnaces aren't often found in the same system. If you have a furnace you likely don't need to consider an air handler. Air handlers are usually paired with heat pumps and help manage airflow throughout your home. Some models also have secondary heating and cooling components to assist the heat pump. A furnace operates differently. Instead of an air handler, furnaces have blowers that send warm air into your vents, which supply it across your home. Since furnaces have combustion chambers and make heat, they don't have some of the parts you'll find in a normal air handler.