This European Standard defines procedures for determining the standard thermal output of the heating appliances fed with water or steam at temperatures below 120°C, supplied by a remote heat source. This European Standard specifies the laboratory arrangements and testing methods to be adopted, the admissible tolerances, the criteria for selecting the samples to be tested and for verifying the conformity of the current production with the samples tested at the initial test. This European Standard also defines the additional common data that the manufacturer shall provide to the trade in order to ensure the correct application of the products. This European Standard does not apply to independent heating appliances.