HVAC - EPA Certification Practice Exam 2026 – Comprehensive All-in-One Guide to Exam Success!

The expansion valve in an HVAC system serves a critical role in regulating the flow of refrigerant and reducing its pressure as it enters the evaporator. When refrigerant moves through the expansion valve, its pressure is significantly decreased. This pressure drop is essential because it allows the refrigerant to expand and absorb heat from the indoor air as it moves into the evaporator coil, facilitating the refrigeration cycle.

The ability of the expansion valve to control the flow of refrigerant is vital for maintaining the efficiency of the HVAC system. By adjusting the refrigerant flow based on the load demands of the space being cooled, it ensures optimal heat exchange can occur. This regulation helps maintain comfort levels in indoor environments and prevents the evaporator from becoming flooded with excess refrigerant or starving for refrigerant, both of which can lead to inefficiency and potential system damage.

The other options do not accurately describe the function of the expansion valve. The valve does not increase refrigerant pressure nor is it primarily intended to filter impurities or maintain a constant temperature. Instead, its primary function is focused on pressure reduction and flow regulation, making it a key component in the overall performance of the HVAC system.