This European Standard defines the specifications and test methods for the construction, safety, rational use of energy and fitness for purpose, environment and classification and marking of gas-fired storage water heaters for domestic hot water uses, hereafter called "appliance". This European Standard applies to appliances: - of types B11, B11BS, C11, C12, C13, C21, C31,, C32, C33, C42, C43, C51,C52, C53, C62, C63, C72, C73, C81 connected to an individual flue duct, C82 and C83 according to CEN/TR 1749; - fitted with atmospheric burners; - using one or more combustible gases corresponding to the three gas families and the pressures indicated in EN 437; - of nominal heat input not exceeding 150 kW (net calorific value); - fitted with electrically operated mechanical flue dampers that are positioned downstream of the heat exchanger.