How to clean thermocouple on gas fireplace. Locate the gas valve its usually behind a grill on the front of the fireplace and find the copper thermocouple wire leading from it. Step 2 hold pilot open to heat thermocouple push in the control valve and light the pilot flame. Place the new thermocouple in the same place your old one sat and close up the fireplace to conduct a test.
Give the thermocouple about 15 minutes to heat up and then turn on the flame to make sure it all stays functioning. Turn the gas back on and relight the pilot light. Shut off the furnace gas to remove and clean the thermocouple if it is covered with soot.
Replacing a thermocouple or thermopile if cleaning didnt work. If cleaning the thermocouple didnt allow your pilot light to stay lit or cleaning the thermopile didnt allow the pilot light to generate enough electricity to open your gas valve and ignite the burner it might be time to replace one of them.