Abstract: A device for generating pressure waves of high amplitude, in particular for boiler cleaning, has a pressure-resistant container (21, 40) with a combustion chamber (121) inserted therein, which can be filled with a flowable burn-off material via supply lines. The pressure-resistant container has a discharge opening (306) for the directional discharge of gas pressure generated by ignition of the combustible material. A piston (70) closes the discharge opening, can release it for directional discharge and can be pushed back into the initial position by a spring device.