The embedded bimetal is a snap action disc, which is actuated at two temperatures: a hot temperature, and a cold temperature.

The first movement (hot temperature for example) creates a fluid suction in a sealed cavity. This fluid is then expelled in a second movement (at cold temperature in this case).

Two different channels are used for suction and expulsion ; one channel is equipped with a duckbill valve, which ensures a one-way liquid flow.