Thermal Circulators are used for sous vide food cooking, which is the prolonged cooking of food in sealed packages in a water bath and at lower temperatures than is usually used for cooking.
A thermal immersion circulator comprises a circulator pump (a mechanism to move the fluid), a heating element immersed in the fluid, an accurate temperature probe and control circuitry, which compares the measured temperature with the desired value and supplies power to the heater as required to stabilise the temperature.