What is the role of an expansion valve in an HVAC system?

The role of an expansion valve in an HVAC system is to reduce the pressure of the refrigerant before it enters the evaporator. This process is crucial because it allows the refrigerant to expand and cool as it absorbs heat from the indoor air.

When the refrigerant arrives at the expansion valve, it is in a high-pressure liquid state. As it passes through the valve, the pressure drop occurs, and the refrigerant becomes a low-pressure mixture of gas and liquid. This transition enables the refrigerant to effectively absorb heat in the evaporator, promoting efficient cooling of the indoor environment.

Understanding the correct function of the expansion valve is vital for ensuring that the HVAC system operates efficiently. The other functions listed, such as increasing refrigerant pressure, regulating airflow, or distributing refrigerant to multiple zones, are not tasks assigned to the expansion valve. Instead, those functions are handled by different components within the HVAC system, such as compressors or dampers. Thus, recognizing the specific role of the expansion valve helps in troubleshooting and maintaining HVAC systems effectively.