How to Clean a Gas Fired Furnace

Shut off the main gas valve and turn off the power at your home's main's service panel. Most utility companies also install a unit disconnect switch that should be turned off before cleaning begins.

Pull out the metal drawer that houses the burner tubes if you have a gas fired furnace with this feature. Remove the screws if your furnace has removable burner tubes. Older model furnaces may require that the pilot assembly needs to be completely removed to access the burner tubes. A brass fitting called a spud connects the burners to the manifold in this type of furnace. Free the burner from the retaining bracket and give it a gentle twist forward to remove it from the spud. Pull out the burner.

Dip the burner tubes into a bucket filled with water. Allow the burners to soak for 15 minute and completely dry. Use a brush with stiff bristles to clean the burner tubes. Use a soft-bristled brush to clean the burner ports. If any of the tubes are cracked or corroded, it is better to replace them than to clean them.

Loosen the spuds with a ratchet wrench and remove spud. Inspect the spuds for signs of dirt or wear and tear. Use the soft-bristled brush to clean the spuds. Use a toothpick or a piece of wire to insert into the spud opening to clear the inside. Make sure you don't chip the opening. Replace the spud inside the furnace and gently tighten it onto the manifold.

Disconnect the pilot gas line and thermocouple from the control housing. Be sure to hold each line very steady to avoid damage. Unscrew the pilot bracket from where it is mounted near the burner tube. Remove the bracket and then remove the gas line and thermocouple from the bracket. Unscrew the pilot nozzle from the bracket.

Brush dirt from the pilot nozzle with a toothbrush. Use another toothpick or piece of wire to dislodge any deposits that built up inside the nozzle. Reassemble and the pilot assembly and then reinstall in the burner. Turn the gas and power back on and relight the pilot light.