Steps To Clean And Replace A Gas Furnace's Thermocouple

If the pilot light that is connected to your home's gas furnace won't stay lit, the thermocouple that runs to it may need to be cleaned or replaced. A thermocouple is a sensor that keeps the pilot light lit when the thermostat to your unit is adjusted to a temperature that is higher than the air inside of your home. Learn how to clean and replace one by completing the directions below.

Materials Needed

  • sandpaper or emery cloth
  • water
  • soft cloths
  • screwdriver
  • new thermocouple

Clean The Thermocouple's Surface

Turn the gas furnace's thermostat off. Look for a long, metal rod that is attached to two, thin flexible wires. The opposite end of each wire will be connected to the pilot light's enclosure. The metal rod and wires are known as the thermocouple. Inspect the metal portion of the thermocouple for corrosion. Corrosion will be white in color and will have a chalky texture. Move a piece of sandpaper or an emery cloth back and forth several times over any portion of the thermocouple that has hardened residue on its surface. Once finished, wipe the sanded areas with a damp cloth.

Use a clean cloth to dry the metal. Relight the pilot light and turn up the thermostat. If the light does not go out, removing the corrosion from the thermocouple solved the initial problem with the gas furnace. If the light still goes out, replace the thermocouple by completing the steps described in the next section.

Replace The Thermocouple

Again, turn the furnace's thermostat off. Unhook the wire ends that are connected to the pilot light's enclosure by grasping them and gently pulling them loose. Loosen and remove the screws that are holding the metal rod in place. Purchase a replacement thermocouple that is the same size as the original one. Line up the new part's metal section in the proper spot and insert and tighten the screws. Connect the wire ends to the pilot light's enclosure.

Relight the pilot light and adjust the thermostat. The pilot light will stay on and warm air will blow out of the vents that your furnace is connected to until your home's interior is warm. In the future, prevent large problems with the thermocouple by inspecting it at random times and removing corrosion as soon as it is noticed. As a result, this vital part may last for years and assist with keeping your gas furnace in operating order. If you need more assistance, companies like Kohl Heating & Air Conditioning may be able to help.