This European standard applies to gas-fired central heating boilers, which are declared by the manufacturer to be " condensing boilers" : - of types B (excluding appliances without a fan) and C, - using one or more gases corresponding to the three gas families, and - for which the nominal heat input is less than or equal to 70 kW. This European standard only covers type testing. This European standard completes or modifies the standards EN 297, prEN 483 and EN 625, hereafter called " boiler standards" . It specifies supplementary requirements for condensing boilers.