Electric actuator is a kind of two type drive device connected to the output terminal of the controller has two type, such as room temperature controller and humidity controller or remote control system for floor heating, a new actuator control terminal equipment and heat flow.Electric actuators are widely used in floor and ceiling radiation heating and refrigeration system, air conditioning system, radiator heating system, temperature control and other needs or system needs the on-off control of fluid. The electric heater should be matched with the regulating valve.The electric heater is divided into normally open type (Open Normally) and normally closed (Closed Normally). Normally open type is refers to the power in the case, the actuator control valve is in the open state, power off. On the contrary, it is normally closed. In the heating system, we must use the normally open type. If the use of normally closed, in the case of unexpected power outages, the valve is closed, if the water in the pipeline due to temperature drop and freeze, product expansion will damage the pipeline system. In an air conditioning system, a normally closed actuator is usually used.Electric actuator is working through the temperature of thermal expansion and contraction of the. On the normally open type electric heater, when the working voltage is switched on, the temperature of the actuator will be heated, after the end of the static time, it will execute the closing process. When the voltage is interrupted, the temperature is gradually cooled, and after the end of the rest time, the actuator will be opened. On the normally closed actuator is the opposite. By the working principle of the electric actuator can be seen, because the electric actuator is slow to open slowly, will not produce water hammer phenomenon, will greatly extend the service life of the valve.