5 Signs of a cracked heat exchanger

How does a heat exchanger work

A furnace heat exchanger works by literally exchanging (or transferring) the heat created in the combustion chamber to the exterior of the unit, where it is then blown through the ductwork throughout the house. When your furnace calls for heat it begins the combustion process and starts to heat up the metal walls. While the fan is circulating air throughout your homes ductwork the air passes by the metal walls of the heat exchanger. In that process heat is transferred from those metal walls to the air you breathe in your home.