What could be the reason of main burner going out intermittently. The pilot stays on. The voltage of the thermopile is 638mv when burner is off. The thermostat is a manual heat only. When I short out the thermostat at the valve the burner lights every time, then after time the burner goes out.(sometimes will go out in one minute or last over a hour) It happens if the blower is on or off. I have changed thermopile same thing, thermostat same thing. Check thermostat wiring ok. This stove was converted from LP to NG 2 years a go and a new valve was installed. Thanks for your help
Make sure that any operating device and the thermostat are made to be used with a thermopile/powerpile system. The contacts of all devices are special for that type system. Thermopile systems produce around 3/4 volts so any added resistance reduces the voltage to operate the gas valve. Make sure that all connections are done with clean wire and are tight. When the system was converted did the person or contractor convert/replace the pilot, gas burners or gas orfices and the gas regulator. It may be a good idea to check these items or have an HVAC contractor check them.