What is the actuator of thermostat?
It is a thermoelement, which contains wax (paraffin).
What is wax (paraffin)?
It is produced in oil refining process and is basically same as the wax of candle. The wax further refined to be in a narrow melting temperature range is used for thermoelements.
What is the mechanism of thermostat operation?
Wax is enclosed in metal case. As temperature rises, it melts and expands its volume. The piston lifts to the extent of the volume expansion. [Detailed explanation]
What are the applications of thermoelement?
They range from the thermostat, etc. for automobile application to thermoshower (hot water & cold water mixing device), control valve for floor heating system, thermocontrol ventilators, wind direction control device, etc. for housing application.
What is thermistor?
Thermistor is the resistor which sensitively changes the coefficient of resistance in accordance with temperature change. NTC thermistor, which has the negative coefficient of temperature, is the semiconductor ceramics made from the metallic oxide burned at high temperature. On the other hand, PTC thermistor has the positive coefficient of resistance.
What is temperature sensing actuator?
It is the device which actuates itself, sensing temperature. Typical are thermoelement and shape-memory alloy, which has coil-shape and the restoring power to the original shape memorized with heat.