Britannica Sources used in this answer

How can a forced-air heating system also provide air conditioning?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

heating In a thermoelectric generating system a heat source—usually fueled by coal, oil, or gas—is used within a boiler to convert water to high-pressure steam. The steam expands and turns the blades of a turbine, which turns the armature of a generator, producing electric power. A condenser converts any remaining steam to water, and a pump returns the water to the boiler.

A forced-air heating system can be converted into a year-round air-conditioning system by integrating a cooling coil connected to refrigeration machinery, provided the existing ductwork is properly sized.1

In this setup, the system utilizes the same fans and ducts used for heating to circulate cooled air throughout the building. When operating in cooling mode, the system draws heat from the air as it passes over an evaporator coil containing a refrigerant. As the air cools, it loses its ability to hold moisture, which also serves to dehumidify the space. The refrigerant then carries the absorbed heat to a condenser coil, where it is released into the outside environment.12

Alternatively, some systems employ a heat pump, which is designed to both warm and cool air by reversing the flow of the refrigerant, passing air over either heated or cold coils as needed to reach the desired temperature.2