In a stratification cylinder, particular use is made of the natural tendency of water to stratify into temperature layers. The cylinder is charged from the top down (stratified). This is made possible by the special design of the stratification cylinder and the use of a heat exchanger. It means that DHW with the required temperature is available to be drawn in the upper section of the cylinder after only a short heat-up time. In addition, this process allows relatively hot water to be drawn from the top of the cylinder, even if most of the energy has already been discharged from the cylinder as a whole.