How To Change A Thermocouple In A Gas Fireplace Or Stove

How to Check and Replace Your Thermocouple in a Fireplace

If your fireplace's pilot light won’t stay lit, the thermocouple could be the culprit. This small but vital component senses the pilot flame and ensures the gas valve stays open. A faulty thermocouple can prevent your fireplace from functioning properly. Here’s how to check and replace it.

Tools You’ll Need:

• Multimeter
• Screwdriver (flathead or Phillips, depending on your fireplace)
• Wrench or pliers
• Replacement thermocouple (compatible with your model)

Step 1: Checking Your Thermocouple

1. Turn Off the Gas Supply: For safety, ensure the gas supply to your fireplace is off before starting.
2. Locate the Thermocouple: It’s usually attached near the pilot light assembly.
3. Detach the Thermocouple: Use a wrench to unscrew it from the gas valve and pilot assembly.
4. Test with a Multimeter: Set your multimeter to millivolts (mV).
   • Attach one lead to the thermocouple’s tip and the other to the connector end.
   • Heat the tip with a lighter. A functioning thermocouple should read at least 6-12 mV.
5. Evaluate the Results: If the reading is below 6 mV, your thermocouple is faulty and needs replacement.

Step 2: Replacing Your Thermocouple

1. Remove the Old Thermocouple: Unscrew it completely from the pilot assembly and gas valve. It typically screws into the gas valve. 
2. Install the New Thermocouple:
   • Secure the tip near the pilot flame.
   • Screw the connector end into the gas valve snugly, but avoid over-tightening.
3. Reconnect and Test: Turn the gas supply back on and relight the pilot.
   • Hold the control knob for 30 seconds to ensure the pilot stays lit.

If the pilot remains stable, your replacement was successful! If not, contact a technician for further assistance.