HERZ heating top-up station consisting of RPZ back flow preventor, pressure reducer, manometer and filling unit with water meter. In order to achieve optimum filling water according to VDI 2035 and ÖNORM H 5195. The first filling cartridge, which contains a mixture of selected ion exchange resins and a pH stabiliser, largely demineralises the water and simultaneously alkalizes it to a pH value of between 8.2 and 8.7. Because corrosive ions such as chloride and sulphate are also removed, permanent corrosion protection is also provided without chemical inhibitors. Max. supply pressure: 6 bar. Max. temperature: 60°C.