A cleaning device includes at least: a holder, a lance having a fluid distribution device, a drive unit for a translational motion of the lance in the holder, and a fluid conducting system having a feed, a return, and flow paths starting from the feed to the return and to the fluid distribution device. At least one actuating means (or actuator) is provided in order to connect the feed to the return or to the fluid distribution device as needed. Furthermore, a method involves cleaning heating surfaces of a convection section of a thermal power plant that includes spaced heat exchanger pipes using such a cleaning device.