High Limit Switches
A High Temperature Limit Switch is used on hot water pressure washers to prevent excessive water temperature. The switch is a bi-metallic, non-adjustable thermostat. When the bi-metallic sensor expands and bends, it breaks an electrical circuit when the water reaches a pre-set temperature. When the switch cools, the metal contracts and the circuit is again completed. The sensor consists of two strips of metal bonded together. The strips expand at different rates when the temperature increases. The differing expansion rate of the two metals allows the sensor to bend. Normally the bi-metallic sensor will touch another contact. The control circuit runs through this connection. As the temperature rises, the bi-metallic sensor bends away from the contact and the circuit is broken, cutting power to the fuel solenoid.