Abstract: A device for cleaning a combustion device such as a boiler coincidentally with operation of the boiler. The apparatus comprises a means for rotation of a lance and rotatable cleaning head attached to the lance. The lance also moves in a linear direction and out of a combustion chamber. The invention requires the presence of the linear and rotational driving mechanism exterior to the boiler to allow operation of the device while the combustion chamber is at high temperature. During operation, a high pressure water jet is expelled from the nozzles of the rotatable cleaning apparatus at greater than 10,000 psi. A microprocessor controls the system to allow a repeatable, consistent, and tailored cleaning of the internal components of a combustion device.