Hell, I have an ITT gas valve on an older Osborn fireplace insert. Sometimes when I switch the flame on, the pilot goes out. I checked the millivolts on the thermocouple, and it puts out above 200 mv, but when I switch the gas on, it drops to about 70, and the pilot dies. Is it the thermocouple or the gas valve or?

Thanks!

The value on the thermopile should be closer to 750. I would almost guarantee that the thermopile needs to be replaced. At least, that is the best place to start. When the gas valve kicks in, the millivolt will drop, and since your reading is so low already, it is shutting down the pilot.

Thanks a million. That is sort of what I thought might be happening. Appreciate it!

Don