This standard specifies safety requirements for the design, the installation and verification of water- based heating systems with a maximum operating temperature of up to 110 °C and not exceeding a nominal heat output of 35 kW.This part of the standard is applicable to hydraulic circuits of either open or sealed water-based heating systems and for the production of hot water for the hygienic services, provided with heat generators, as stoves and fireplaces, burning solid fuels (pellets, chips, nor pulverized solid fuels). The systems could be automatic or automatic-manual, with a forced or a natural circulation of the water , singles or combained with other heat generators.