How to Clean Soot From a Furnace Combustion Chamber

Shut down the furnace and allow it to cool completely before attempting to clean it. Wait until the outside is completely cool to the touch, then open the door and carefully feel inside. The interior combustion chamber of the furnace can remain hot for some time after the exterior has cooled.

Reach inside the furnace and carefully remove the oil filter. Clean the oil filter with a damp cloth. Discard and replace the filter if it is heavily soiled.

Brush the soot from the ceiling of the furnace with a stiff-bristled brush. Use a sweeping motion to knock the soot loose and send it to the floor of the combustion chamber. Use a back and forth motion with the brush to remove more soot. Continue until all soot has been removed from the ceiling, corners and sides of the furnace.

Plug in your shop vacuum and clean out the interior of the furnace. Continue to vacuum the entire combustion chamber until all soot is removed.

Use a damp cloth to wipe down the combustion chamber and remove any remaining soot. Never use solvents or chemicals, since they could combust or give off dangerous fumes the next time you use the furnace.