NOVELTY - The latent-heat accumulator (1) comprises a container (2) with a first latent-heat storage material having a first melting temperature and a crystallization seed material having a second melting temperature of 45-55 degrees C for initiating a crystallization of the first latent-heat storage material, where the first latent-heat storage material indirectly contacts with the crystallization seed material and the first melting temperature is greater than the second melting temperature. The container is made of corrosion-resistant steel or steel with corrosion-resistant coating.    USE - Latent-heat accumulator useful in a water heater (claimed).    ADVANTAGE - The latent-heat accumulator can be simply and economically manufactured with high efficiency and high storage capacity.    DETAILED DESCRIPTION - The latent-heat accumulator (1) comprises a container (2) with a first latent-heat storage material having a first melting temperature and a crystallization seed material having a second melting temperature of 45-55 degrees C for initiating a crystallization of the first latent-heat storage material, where the first latent-heat storage material indirectly contacts with the crystallization seed material and the first melting temperature is greater than the second melting temperature. The container is made of corrosion-resistant steel or steel with corrosion-resistant coating. The crystallization seed material is a second latent-heat storage material, and is partially incorporated into the first latent-heat storage material as a related material accumulation without intermixing with the first latent-heat storage material. The first latent-heat storage material to the crystallization seed material is present in a ratio of 100:1 in the container related to the mass. INDEPENDENT CLAIMS are included for:    (1) a water heater; and    (2) a method for manufacturing a latent-heat accumulator.    DESCRIPTION OF DRAWING(S) - The diagram shows a sectional view of a water heater with a latent-heat accumulator.    Latent-heat accumulator (1)    Container (2)    Salt hydrate (4)    Drinking water heat exchanger (8)    Water. (10)