Air handlers and furnaces aren't usually used in the same home in Longmont. If you have a furnace, you probably won’t need to consider an air handler.
Air handlers are frequently paired with heat pumps and manage airflow across your home. Some units also provide backup heating and cooling pieces to assist the heat pump.
A furnace works in a different manner by blowing heated air into your vents, which send it across your house. As furnaces use combustion chambers to make heated air, they don't need some of the pieces you'll find in a standard air handler.