Article 5
1. Boilers must comply with the following useful efficiency requirements: - at rated output, i.e. operating at rated output Pn expressed in kW, at an average boiler-water temperature of 70 oC, and - a part load, i.e. operating at 30 % part load, at an average boiler-water temperature which varies according to the type of the boiler. The useful efficiency requirements to be complied with are set out in the following table: Type of boiler Range of power output Efficiency at rated output Efficiency at partload kW Average boiler-water temperature (in oC) Efficiency requirement expressed (in %) Average boiler-water temperature (in oC) Efficiency requirement expressed (in %) Standard boilers 4 to 400 70 & {Ì8}; 84 + 2 logPn & {Ì8}; 50 & {Ì8}; 80 + 3 logPn Lowtemperature boilers (*) 4 to 400 70 & {Ì8}; 87,5 + 1,5 logPn 40 & {Ì8}; 87,5 + 1,5 logPn Gas condensing boilers 4 to 400 70 & {Ì8}; 91 + 1 logPn 30 (**) & {Ì8}; 97 + 1 logPn (*) Including condensing boilers using liquid fuels. (**) Temperature of boiler water-supply. 2. The harmonized standards relating to the requirements of this Directive drawn up under mandate from the Commission in accordance with Directive 83/189/EEC and 88/182/EEC (14) shall determine, inter alia, the verification methods valid for production and measurements. Appropriate tolerances must be incorporated in the efficiency levels.