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 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; 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); using or not the water condensation heat in the combustion products; fitted with electrically operated mechanical flue dampers that are positioned downstream of the heat exchanger and tested as an integral part of the water heater. appliances whether subject to the water mains pressure or open-circuit. This standard does not contain all the requirements necessary for: appliances fitted with a fan on the combustion circuit; appliances intended to be connected to a mechanical means of evacuating the combustion products; appliances which fulfill a dual role of space heating and heating water for domestic hot water use; appliances with a combustion products discharge safety device other than that for type B11BS appliances; This standard does not contain all the necessary requirements to make it applicable to appliances with a variable combustion air flow rate.