This European Standard applies to heat generators according to EN 15036-1, which are connected to chimneys/ducts which discharge combustion products via a duct into open air. The data measured according to this European Standard will probably be different from the noise radiated from the end of the chimney. Readings from forced-draught burners complying with EN 267 or EN 676 are only applicable in practice if they have been taken in conjunction with a boiler. Noise emitted into chimneys/ducts by heat generators operating independently of indoor air can also be measured in accordance with this European Standard. Boilers supplied with combined air inlet and exhaust terminal configuration where ducts are within an external wall can be measured according to one of the test methods detailed in EN 15036-1. This European Standard describes the objective procedure for determining sound power levels LW, at the outlet of a heat generator that is emitting broad-band, narrow-band, or tonal continuous sound. This European Standard is applicable to boilers designed to be connected to a chimney or flue duct with a duct size greater than or equal to 0,06 m and whose mean flue gas flow at the microphone head is less than 5 m/s. This European Standard only applies for test purposes under laboratory conditions.