The electric valve is an accessory found in central heating systems and is what allows the movement of gas. Its function is the same as a simple valve, except that in this case it uses a motor that receives an electronic command for when to open and when to close. It is diode which means it has 2 ports, one for gas intake and one for exhaust. When the inlet is closed the flow is stopped, while when it is open the flow in the inlet is the same as the flow in the outlet.