A device used to control heating and cooling systems to maintain a certain temperature within certain ranges. The thermostat can keep the temperature low or high depending on the desired level. Once the engine reaches its ideal temperature, the thermostat begins to let the hot coolant pass to the radiator, where it is again cooled, usually designed so that the regulating valve begins to open around the degrees to reach its maximum opening. This thermostat has a 45ºF opening and 25ºF closing.