The Trane air handler directs air from inside the home across a heat exchanger and through air-conditioner coils before a system of ducts distributes it back into the house. Depending on which system is working at the time the unit heats or cools the air in the process.
Manufacturers build the furnace heat exchanger into the air handler. In systems that burn gas or propane, the heat exchanger is a chamber in which combustion takes place. It allows the fuel to burn without introducing by-products into the home. The heat exchanger eliminates the by-products by means of the flue while transferring the heat the furnace produces from the metal firebox to the air.
When the system is cooling, the air passes through the air conditioner coils. When warm, moist air passes through the coils, the cooling causes moisture to condense on the metal, and the process reduces the air temperature and relative humidity in the home.
While most air coolers use a single wall of metal surrounding the air handler, Trane indicates it uses a double-wall process, similar to insulating a refrigerator. This process reduces the chances contaminating the air in the home with fine particles of fiberglass insulation and reduces moisture condensation on the cabinet that causes corrosion of the air handler.