What is the role of the refrigerant in an HVAC system?

The role of the refrigerant in an HVAC system is fundamentally to transfer heat. This is achieved through a cyclical process of evaporation and condensation. In the cooling mode, the refrigerant absorbs heat from inside the building as it evaporates in the evaporator coil, effectively lowering the indoor temperature. It then travels to the outdoor unit where it releases that absorbed heat into the outside air as it condenses back into a liquid state. This heat exchange process is vital for cooling and maintaining comfortable indoor environments.

In contrast to this key role, regulating airflow is primarily managed by fans and ductwork rather than the refrigerant itself. Providing insulation is not a function of the refrigerant; instead, insulation in the home’s structure helps to maintain temperature by reducing heat transfer. Generating electricity is also unrelated to the function of the refrigerant, as the HVAC system relies on electrical components and inputs from the electrical grid rather than the refrigerant for power. Hence, the refrigerant's primary purpose is indeed to transfer heat within the system.