This document applies to electronic control equipment for heating systems with water as the heating medium and a supply water temperature up to 120 °C. This control equipment controls the distribution and/or the generation of heat in relation to the outside temperature and time and other reference variables. This document covers also controllers that contain an integrated optimum start or an optimum start-stop control function. Safety requirements on heating systems remain unaffected by this document. The dynamic behaviour of the valves and actuators are not covered in this document. A multi-distribution and/or multi-generation system needs a coordinated solution to prevent undesired interaction and is not part of this document. Table 1 shows the relative position of this document within the set of EPB standards in the context of the modular structure as set out in EN ISO 52000-1. NOTE 1 In CEN ISO/TR 52000-2 the same table can be found, with, for each module, the numbers of the relevant EPB standards and accompanying Technical Reports that are published or in preparation. NOTE 2 The modules represent EPB standards, although one EPB standard can cover more than one module and one module can be covered by more than one EPB standard, for instance a simplified and a detailed method, respectively.