My Heat N Glo AT Grand nat gas fireplace has a Robertshaw 7000MVRB-5-LC gas valve. The fireplace is 10 years old. Pilot went out and will not stay relit. I checked thermocouple: has low resistance and generates around 20mv. The Thermopile generates around 465mv and has low resistance. The TP terminals on the gas valve (that the Thermopile connects to) show an open circuit (infinite resistance) with the Thermopile disconnected. I am assuming that I should be reading some nominal resistance there, but not an open circuit. Is that correct? Does anyone have the specs as I cannot find them anywhere online
If you do not have continuity between the outer legs where the thermostat connects then the operator solenoid is bad. The thermophile must pull 750 millivolts for the valve to operate properly.Sometimes if the thermophile is weak it will hold the pilot but when turned on it dies. If you have no continuity between the TP and the other leg going to the thermopile then the magnet in the valve is bad. NOTE: a thermal fuse is usually tied in between on most units for safety to kill the magnet. Look for an open fuse somewhere.
Thank you for the feedback. Sounds like both the valve and Thermopile need replacement. BTW, there is no thermostat on my system, so no thermal fuse - at least not that I see. But you have given me an idea to add one; I see the unconnected leads there so it should be fairly easy.