The Working Principle of Heat Controller

The Working Principle of Heat ControllerA heat controller is a device that automatically maintains temperature within a preset limit. There are various types of heat controllers. However, their working principle can be easily described using the example of a heat regulator in a regular flatiron.A bimetal plate with an insulator finger at the end is attached to the bottom of a flatiron. It is in thermal contact with a heater element. The electric contact of a heat controller consists of two flexible plates. A rod goes through an opening in the plate. The bottom end of the rod rests against the plate, while the top end is connected to a limb. The limb is used for adjusting the necessary temperature.If the limb is turned clockwise, the rod is screwed into the stationary nut attached to the cramp. It presses against the plate. As the result the left end of the plate goes down together with the other end. There is still electric contact between the plates. However, the distance between the rod and the left end of the plate decreases.On the contrary, if the limb is turned counterclockwise, the rod will be unscrewed and the left end of the plate will go up lifting the whole plate.As the result the distance between the rod and the left end of the plate will increase.As the bimetal plate heats up, it bends. The rod attached to one end raises and reaches the plate. It lifts the plate and breaks the electric contact. At this moment the flatiron turns off automatically. If you set a smaller distance, the contact will be released at a lower temperature.As the bimetal plate cools down it becomes straight and the rod goes down. It moves away from the plate and the contact closes again. The flatiron turns on automatically. The indicator light shows, if the heat controller is working. If you adjust it to a lower temperature, the light will turn on less often.