Abstract: There is disclosed a boiler system in which ash-bearing fuels are fired in horizontal suspension and in which provision is made for the removal of the ash without shutting down or reducing the output of the system. The system comprises an upper water and steam drum and at least one lower water drum. A furnace cavity is located substantially between the upper drum and the lower drum, with the cavity being defined by a pair of side walls, a front wall, a rear wall, a ceiling and a floor. Means in the form of openings in the floor of the furnace cavity are located near the rear wall of the furnace cavity for permitting ash to be removed from the boiler system without requiring the shutting down or the reduction of the output of the boiler system.