According to the temperature change of the working environment, physical deformation occurs inside the switch, thus producing some special effects, a series of automatic control elements of conduction or disconnection action, called temperature control switch, also called temperature protector or temperature controller, referred to as temperature controller. Or through the temperature protector to the temperature controller, the temperature controller issued switch command, so as to control the operation of equipment to achieve the ideal temperature and energy saving effect.

Control methods are generally divided into two types; One is controlled by the temperature change of the cooled object, which is mostly controlled by steam pressure temperature controller; the other is controlled by the temperature difference of the cooled object, which is mostly controlled by electronic temperature controller. Thermostat is divided into:

Mechanical type is divided into: steam pressure thermostat, liquid expansion thermostat, gas adsorption thermostat, metal expansion thermostat.

Steam pressure thermostat is divided into: gas - filled, liquid - gas mixture and liquid - filled. Domestic air conditioning machinery is based on this kind of thermostat.

Electronic type is divided into: resistance thermostat and thermocouple thermostat.