I have an old steel plate franklin stove with the little slots on the bottom to let air in. It has a grate that sits about 2-3 inches about the bottom, the bottom has a 3 inch shelf all the way around the outer perimeter and inside that a recess that drops down another 2 inches. When I look at the new stoves it seems like they did away with grates. Should I try just burning on the bottom of the stove? Or is that airspace needed because of the way my stove takes in air?