Abstract: A water boiler which has a tank with a cylindrical circumferential wall, a cover and a convexly outwardly curved bottom, and at least one heat exchanger is in the tank, the heat exchanger being formed by at least one pipe coil of spiral or meandering development, the turns of which lie in a plane parallel to or in the direction of the axis of the tank, and the circumferential wall has at least one connection socket which is closed by a plate with the forward and return runs of the heat exchanger extending in sealed fashion through said plate.

Abstract: A heat storage unit is disclosed having a vertically cylindrical container accommodating a latent-heat storage medium and a conduit introducing a heat carrier liquid not miscible with the medium at the bottom of the container. The conduit has an exit nozzle which is located outside the axial center of the cylinder and nearly perpendicular to the radius of the cylinder so that the heat carrier liquid enters the cylinder at the bottom in a direction to cause the heat storage melt to be set into a rotary motion.

Abstract: A heat storage unit is disclosed having a vertically cylindrical container accommodating a latent-heat storage medium and a conduit introducing a heat carrier liquid not miscible with the medium at the bottom of the container. The conduit has an exit nozzle which is located outside the axial center of the cylinder and nearly perpendicular to the radius of the cylinder so that the heat carrier liquid enters the cylinder at the bottom in a direction to cause the heat storage melt to be set into a rotary motion.