Technical Standards and Safety Authority (TSSA) G3 Practice Exam

What takes place at the heat exchanger in a forced air furnace?

1. Gas and air are mixed

2. Return air is heated

3. The combustion process takes place

4. The flue gases are stored

The correct answer is: The flue gases are stored

In a forced air furnace, the heat exchanger is a critical component where the transfer of heat occurs. Its primary function is to heat the return air that circulates through the furnace and into the living spaces of a building. As the system operates, air from the environment is drawn into the furnace, passes over the heated surfaces of the heat exchanger, and is warmed before being distributed through the ducts. The combustion process actually takes place in the combustion chamber, not in the heat exchanger itself. While flue gases are produced during combustion, they are vented out of the furnace and should not be stored. Thus, the right function of the heat exchanger is to facilitate heat transfer, which directly aligns with the option where return air is heated, making it an essential aspect of the heating process in forced air systems.