This standard specifies the requirements for the thermal insulation, corrosion protection and manufacturing for unvented (closed) storage water heaters for drinking water with a capacity of up to 1000 l, to be connected to water supply systems having an allowable operating pressure between 0,05 MPa and 1,0 MPa (0,5 bar and 10 bar). They shall be fitted with control- and safety devices which shall be dimensioned so that the allowable operating temperature of the stored drinking water does not exceed 100 °C. It is only applicable to water heaters and water heating installations for drinking water where the formation of an air- or steam cushion of more than 2 % of the content, maximum 10 l, can be safely avoided. If the heating medium has temperatures over 110 °C, the Directive 97/23/EG (Pressure Equipment Directive) applies, which has to be considered then. This standard contains specifications which are not covered by the title and scope of DIN EN 12897 "Water supply - Specification for indirectly heated unvented (closed) storage water heaters" and which can be regulated on national level.