What is the valve at the top of my radiator for?
Each radiator, connected to a boiler or a heat pump, is equipped with a vent valve always located at the highest part of the heating body. This element is used to remove any air formed inside the heating system and the radiator itself. To see how to do this look at the guide how to vent a radiator at this link: https://www.irsap.com/en/support-en/irsap-consiglia-3/2096-how-to-vent-radiators