How Do You Clean a Furnace?

To clean a furnace, vacuum off the burners, and then get the debris off other important components, including the blower, flame sensor, surface igniters and pilot. Change the furnace filter to keep your furnace operating at its peak for another year.

  1. Open up the furnace

    Go to your circuit panel, and find the switch that sends power to your furnace; it is likely to be a double switch because of the necessary power. Turn this switch to the "off" position to avoid electrocution. Go to the furnace, and lift the combustion chamber door up before pulling it out. Take off the burner cover if your furnace has one.

  2. Check to see if you can do this yourself

    Turn the power back on to the furnace, and turn up the thermostat to bring the burners on. Look at the flames to see if they are blue and evenly sized. Call a professional if any of the flames are yellow, because that indicates dirt in the burner, which a licensed pro must fix.

  3. Clean the burners

    Turn the power to the furnace off again, and turn the valve from the gas line one quarter to the right to switch off the gas. Attach 18 to 20 inches of 1/2-inch drain line to the hose on your vacuum to reach the back side of the burners, and vacuum up any dust.

  4. Remove and clean the blower

    Pull the blower out, using screwdrivers to remove the cover (if there is one) and a socket wrench to take out the bolts holding the blower in place. Use a small brush and vacuum cleaner to clean the blades on the blower. Clean it evenly to keep it in balance.

  5. Clean the pilot and the flame sensor

    Blow through a drinking straw to get dust off the pilot. Pull the flame sensor down gently from its bracket. Use a fine emery cloth or fine-grit sandpaper to clean the surface gently, and return the sensor to its bracket.

  6. Clean surface igniters, and change the filter

    Take out the old furnace filter gently, so as not to release a lot of dust and debris, and slide the new one into place. Blow through a drinking straw to get the dust off the surface igniter. Do not touch the igniter because it is extremely fragile.

  7. Put everything back together

    Put the blower back into place, and put the covers back on the furnace. Turn the gas back on to the furnace by turning the valve one-quarter to the left, and turn the circuit switch that sends electricity to the furnace back to the "on" position.