This European Standard applies to oil-fired heating boilers, which are declared by the manufacturer to be condensing boilers up to a nominal heat output of 1 000 kW supplied as a unit with an atomizing oil burner which meets the requirements of EN 267. NOTE This European Standard defines three classes of oil fired boilers with efficiency requirements higher than those given for low temperature boilers in the Boiler Efficiency Directive (BED) 94/42/EEC. This European Standard completes/modifies EN 303-1, EN 303-2 and EN 304 and specifies supplementary requirements for condensing boilers.