What is the function of a thermal expansion valve (TEV) in an HVAC system?

A thermal expansion valve (TEV) plays a crucial role in an HVAC system by regulating the flow of refrigerant based on the cooling demand. This regulation is essential because it allows the system to adjust the amount of refrigerant that enters the evaporator coil, which responds to varying load conditions. When the demand for cooling is high, the TEV allows more refrigerant to flow into the evaporator, where it can absorb heat from the indoor environment. Conversely, when the demand decreases, the TEV restricts the flow of refrigerant, preventing excess refrigerant from entering the evaporator. This ensures optimum efficiency and performance of the system while maintaining comfortable indoor conditions.

In essence, the TEV effectively balances system performance and efficiency by controlling refrigerant flow based on the immediate cooling needs of the space being served. This dynamic adjustment helps achieve the desired thermal comfort without causing unnecessary energy consumption.