The Caleffi anti-freeze valve causes the medium to slowly flow out of the system when its temperature reaches an average of 3 °C. This prevents the formation of ice in the system, which protects pipelines and equipment from damage. The valve must be installed in a vertical position with the bleed facing downward in such a way as to allow the medium to flow out freely. Valves should be installed outside the building at the location of the lowest temperatures when the heat pump is turned off. The installation site should be away from elements that could interfere with the valve (heat source).