The manner in which you correctly remove and position the ash in the firebox.
Remove ash and coals every week and scrape firebox clean. Never operate the furnace with a fire in it with the door open, except for brief periods while loading wood or removing ash. Always remove ash into a covered, non-combustible container. Clean ash from all firebox surfaces, especially the rear plate and side plates.DO NOT ALLOW ASH TO BUILD UP ON THE STEEL SURFACES.