I have an old millivolt gas furnace that's stopped working. The pilot stays lit fine and the thermopile generates about 360 millivolts, and there's no problem at the thermostat (checked voltage and shorting past it), but the main valve no longer opens. I'm looking for help identifying what model it actually is (so I can search for information specific to it) or ideas on what might be wrong. Here are a couple pictures of the valve:

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Since this question was asked 1 year ago, I have to assume you have solved the problem. If you have not I will give some ideas. first the 360 millivolts you show should have been 750 to 800 millivolts since this is a pilot generator. You can test the rest of the system by temporarily replacing the generator with a 1.5 volt standard flashlight battery. The condition of the wiring is also suspect; loose connections, old oxidized control contacts, an old thermostat, are all potential problems. I would recommend replacing all the wiring and controls and the pilot generator. As for the gas valve it is probably a "general controls" valve but any 800 millivolt gas valve can be used as a replacement. I recommend you call a heating expert. For the battery test above only connect the battery for a second or two just to see if the gas valve works.

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