This European Standard is applicable to boilers used for central heating in accordance with prEN 303-1:2016 up to a nominal heat output of 1 000 kW and EN 303-4 up to a nominal heat output of 70 kW with forced draught burners in accordance with EN 267 that are designed for operating with liquid fuels. The performance requirements of this standard apply to type testing to heating boilers (standard, low temperature and condensing boilers) which are tested on a test rig in accordance with the test code given in prEN 304:2016. This standard applies also to room sealed boilers as defined in EN 15035 regarding efficiency and emissions. This standard can also be used as the basis for evaluation of boiler-/burner units.