Abstract: A water heater comprises an inner container (1) and an outer container (2). An upper part of the inner container (1) is connected with an insulating water inlet pipe (3) which communicates with a cavity of the inner container (1); the outer container (2) is provided to encase the inner container (1) and it is axially movable relative to the inner container (1); two different heating electrodes (4) are connected with one end of the inner container (1) and one end of the outer container (2) respectively; water outlet holes (5) are provided on the inner container (1) and the outer container (2). As a result, the insulating water inlet pipe forms a hot water supply circuit in a sandwiched layer between the inner and the outer containers. By adjusting the spaces between the inner and the outer containers to regulate electrical current, water temperature control is achieved.

Abstract: A water heater comprises an inner sleeve (1) and an outer sleeve (2). The upper part of the inner sleeve (1) is connected with an insulating water inlet pipe (3) leading to the inner chamber of the inner sleeve (1). The outer sleeve (2) surrounds the periphery of the inner sleeve (1) and can move axially relative to the inner sleeve (1). One end part of the inner sleeve (1) and one end part of the outer sleeve (2) are respectively connected with different heating electrodes (4). The inner sleeve (1) and the outer sleeve (2) are respectively provided with water outlet holes (5) so that a hot water supply loop is formed in the interlayer between the inner and outer sleeves. The clearance between the inner and outer sleeves is adjusted for regulating current so as to control water temperature. The water heater has a simple structure, small volume, light weight and low production cost, and can regulate the water temperature quickly in an energy-saving mode.