Abstract: A water heater includes a water tank having an inlet and an outlet, and a flue extending through the tank. A nozzle is positioned near a first end of the flue, arranged so as to emit a fuel stream into the flue, and a flame holder is located within the flue in a position to receive the fuel stream and to hold a flame entirely within the flue.

Abstract: A dentistry hand piece is provided wherein a rotation of a drive motor is converted into an oscillation of a receiving part for a dentistry tool. The conversion of the rotation into the oscillation takes place in an attachment head (3) of the hand piece. The longitudinal axis (51) of the receiving part (8, 8') for the tool in the attachment head (3) is arranged at an angle (preferably approximately at right-angles) to the longitudinal axis (53) of the neck area (1) of the hand piece adjoining the attachment head (3), and the plane of oscillation of the receiving part (8, 8') for the tool is substantially perpendicular to the longitudinal axis (51) of the receiving part (8, 8').