I have a propane powered vent free fireplace in my garage. It doesn’t get plugged in anywhere and it doesn’t take batteries. I get how the peizo works to start it but how the hell does it turn the gas valve on and off by itself? When I go from pilot light to on there is a delay to when you actually hear the gas start flowing. Then it will also click and just shut itself off sometimes.
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There is a device called a thermopile located next to the pilot.
When you light the pilot, turning the knob allows gas to flow, and the piezo spark ignites it.
The thermopile, which consists of a stack of dissimilar metal, generates a small voltage from the heat of the flame (this is the principle of the thermocouple). By stacking, the small voltages add together to produce enough power to activate the gas valve.
That’s why these are quite safe; if the pilot goes out, the thermopile cools off, and the gas valve closes due to no power.
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