A water heater includes a tank and a jacket surrounding the tank. During operation, the measuring tube executes, at least at times andor at least in part, bending oscillations about an imaginary bending oscillation axis, which imaginarily connects the two coupling zones with one another. A latch circuit in the backup area latches the low level but not the high level of the mask signal. In a preferred embodiment, the ultraviolet emitting device emits light that includes short wavelength ultraviolet light, causing the formation of ozone in the area of the shoe, thereby killing pathogens that are not easily killed with ultraviolet light alone. The number of successful responses received from the second network element are accumulated and the results are reported back to the source of the connectivity test command. The sensors are disposed on the object, distributed in the circumferential direction, and the antenna array has a directional characteristic for transmission andor reception which is stationary with respect to a coordinate system not rotating with the object and which includes only a subregion of the object.