Safety groups of this type are used to protect pressurised water heaters according to the requirements of DIN 4753-1, EN 806-2 and DIN EN 1488. They are compact appliances which incorporate all the necessary safety devices such as check valve, shut-off valve, test point, diaphragm type safety valve and pressure reducing valve in one unit. The safety valve protects the downstream cylinder, pressure vessel etc. by automatically opening when excess pressure occurs. The check valve prevents back pressure, backflow and back syphonage of water from the hot water unit. In addition, a balanced seat pressure reducing valve is fitted on the inlet to control the supply pressure to that required for the system.