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