Gas fireplace. Simple setup, has one power pile, one thermocouple.. As far as I know, the thermocouple is strictly for keeping pilot lit. Power pile provides millivolt to let gas main valve open. Pilot will light when holding in knob, hold for one minute, let off knob, pilot goes out. So only possible problems are thermocoulple or gas valve, correct? Have replaced thermocouple (twice just to double check, even though I have never had a bad new thermocouple. This fireplace is brand new install, has never been fired. You know and I know that the only reason for the pilot not staying lit(other than bad thermocouple) is a defective gas valve,( there are no other limits connected to gas valve) The only reason I ask for any other ideas here, is because my supplier wants to know what is wrong with the gas valve before they will send me a new one. I install these things on a regular basis. Think I know when I have a bad gas valve. But I also learn knew things every day , so if there is anyone who thinks it may be something other than the thermocouple or gas valve, please let me know.