[..] the manufacturer has to provide the information on which system has to be installed on the ventilation units [..] so that it complies with requirements when it is put into service. The installer is responsible for ensuring that the product is put into service in accordance with the information provided by the manufacturer[..].
Disclaimer: Please note that the European Commission cannot provide a legally binding interpretation of the EU legislation, as this is the sole competence of the European Court of Justice. Any remarks from the European Commission services are without prejudice to the position the Commission might take should related cases arise in a procedure before the Court of Justice.