scope:

Applies to heating boilers with burners using fans up to a nominal heat output of 1000 kW. They are operated, either with negative pressure (natural draught boiler) or with positive pressure (pressurized boiler) in the combustion chamber, in accordance with the boiler manufacturers instructions. This document specifies the necessary terminology, the requirements on the materials and testing of them, and marking requirements for heating boilers. Particular requirements for boilers which can be used with open vented systems are contained in prEN 303-4. The requirements of this standard apply to heating boilers which are tested on a authorized test rig.