The role of gas water heater solenoid valve

Gas water heater valve dual protection, that pressure is started, the water film by water pressure, push the left, turn the machine power, but also to a spring cover, top to the left. (This is another source of air control switch), it is the mechanical action, if the water film, there had been the dregs, the scale, if the water film back in place, and you do not use heater valves, it would leak, accidents.