Abstract: According to the invention it is suggested that, in a heating boiler with a vibrating grate (3), a supply pipe (6) from which fuel material in particle form, in particular pellets, is supplied to the grate, is mechanically connected to the grate (3) and arranged to freely support the grate, which is thereby freely suspended in the combustion chamber without contact with the bottom and walls of the combustion chamber. A vibrating means (19) is also mechanically connected to the supply pipe (6) and arranged to produce a rectilinear movement and to function as drive source to feed the fuel particles to the grate via the supply pipe (6). The vibrating means gives the fuel particles a toss movement obliquely upwards and forwards in the supply pipe and on the grate whereby the fuel particles move onto the grate and towards the end of the grate opposite the supply pipe (6).