Boilers, radiators, valves, pumps and other system components are manufactured industrially, their data for system design determined in a standardized manner in type tests. Each distribution system in a building, by contrast, must be tailored to the conditions in the building and calculated individually to meet user requirements. Inappropriate hydraulic circuits are often chosen, increasing the energy effort. This standard specifies the fundamentals for the design of hydraulic distribution systems to forecome this error. It imparts, to the planning engineer, erector or user of a heating or air-conditioning or other hydraulically supplied system the basics o