ÖNORM EN 303-1

This standard is applicable 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 (pressurised boiler) in the combustion chamber, in accordance with the boiler manufacturers instructions. This standard 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 an authorised test rig. Boilers in accordance with this standard are designed for the heating of central heating installations in which the heat carrier is water, and the maximum allowable operating temperature of which is restricted to 100 °C. The maximum allowable operating pressure is 8 bar. For boilers with a built-in or attached water heater (storage or continuous flow heater) this standard only applies to the parts of the water heater which are necessarily subject to the operating conditions of the heating boiler (heating part). This standard does not apply to gas boilers with atmospheric burners, boilers for solid fuels, oil or gas fired condensation boilers, boilers with oil vaporisation burners and low temperature boilers. For these boilers there are further requirements. NOTE: Low temperature boilers are those operating with a (water) variable temperature up to 40 °C or less, or those which cannot be set at a temperature higher than 55 °C.