Heat Exchanger: A device used to transfer heat from one fluid to another without direct contact of the fluids. Heat exchangers usually maximize the transfer of heat by maximizing the contact surface area between fluids, as when the warmer fluid is passed through a series of coils or thin plates. A furnace’s heat exchanger is a set of tubes or coils that are looped repeatedly through the air flow inside your furnace for the purpose of heating air. Simply put, the furnace heat exchanger is the part of your furnace that actually heats the air.
