How does a vernatherm valve work?

A vernatherm valve is a thermal control device commonly used in automotive cooling systems. It operates based on a wax-filled element that expands when heated and contracts as it cools. As the engine temperature rises, the wax expands, pushing a rod that opens the valve, allowing coolant to flow to the radiator and facilitating temperature regulation. When the engine cools down, the wax contracts, closing the valve and restricting coolant flow, thus maintaining optimal engine operating temperatures.