The pump in a pressure washer depends on the inflow of cool tap water to avoid overheating. Inflow to the pump only occurs if the pressure washer is spraying out fluid. If, for an extended period, the device is pumping but not spraying, then the pump will overheat and destroy itself. To avoid this possibility, our bimetal disc senses the temperature of the fluid inside the pump. If the temperature exceeds a set point, the disc will open an exhaust port and hot fluid will exit the pump. When this occurs new tap water will then flow into the pump. The new tap water is cold and will thus cool the pump. When the pump temperature gets back to the normal range, the bimetal will sense this and close the exhaust port.
