 When the temperature reaches a specific setpoint, the pressure in the diaphragm will trip a switch which typically shuts down the flow of outside air while the capillary bulb's temperature is at or below the setpoint.Mechanical freeze stats can have more than one set of contacts, and the contacts can be NO or NC.Disadvantages
Advantages

Digital freeze stats, also known as "electronic" or "solid state" freeze stats, use an electronic circuit, microprocessor, or microcontroller in place of the mechanical freeze stat's diaphragm and switch.