ErP is made up of two separate directives.
EcoDesign ensures that products meet the performance and emissions standards at the point of manufacture. Any product that does not meet these requirements will not get a CE mark, and can't be legally sold in the EU. This applies to heating products with an output equal to or less than 400kW and tanks with a storage volume equal to or less than 2,000 litres.
Energy Labelling works in conjunction with EcoDesign, it requires all energy-related products to clearly display their efficiency grade, ranging from A+++ to G. Energy labels help customers identify and choose products which save energy.
Installers are required to provide an overall energy efficiency label for newly installed package of products. For this they have to calculate the efficiency figure based on certain components of the system - boiler, controls, solar thermal etc - which they write on a package label when they have completed the installation.