Abstract: The invention provides a stove for burning a charge of fuel by primary air directed either above or underneath through the firebed. A firebed support is defined by an array of alternating fixed and movable bars, the movable bars having a length greater than their width when viewed endwise and being rotatable between a vertical attitude in which they permit upward passage of air and downward passage of ash through said support and a horizontal attitude in which they permit build up of a layer of ash at the base of the firebed. An air distribution chamber has an inlet for primary air, a first outlet from which primary air passes to a space above the firebed and a second outlet from which primary air passes to a space below the firebed. An air diversion flap is movable between positions in which air is selectively directed through the first and through the second outlet.