Bimetallic thermal switches basically fall into two broad categories: 1) creep action devices with slow make/slow break switching action; and 2) snap action devices with quick make/quick break switching action.
Creep action devices are excellent in either a temperature control application or as a high limit control. They have a narrow temperature differential between the opening and closing temperatures and generally have more rapid cycling characteristics than snap action devices.
Snap action devices are most often used for temperature limiting applications as their fairly wide differential between opening and closing temperature provides slower cycling characteristics. We have been able to control the amount of differential in many of our snap action controls, that enables them to be used for temperature control applications, especially in dual voltage applications.