This European Standard specifies the requirements and test methods for the construction, the safety and the rational energy usage for heating boilers (standard-heating boilers) and low temperature boilers fired by liquid fuels from steel and cast iron with burners according to the relevant burner standards (for atomising oil burners, see. EN 267) up to a nominal heat output of 10 MW. 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 manufacturer's instructions Boilers in accordance with this European 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 up to 110 °C and the maximum safety temperature limiter of 120 °C. The maximum allowable operating pressure is 10 bar. 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. For these boilers there are further requirements. For gas-fired central heating boilers equipped with a forced draught burner of nominal heat out put not exceeding 1000 kW, see prEN 303-7. For shell boilers with a nominal heat output exceeding 10 MW and a maximum safety temperature limiter exceeding 120 °C, see EN 12953 series. NOTE Definitions for heating boiler and low temperature boiler see Council Directive 92/42/EEC.