Caleffi Solar Expansion Tanks for Hydronic Solar Heating Systems
Modern solar heating systems can reach temperatures of up to 385°F during inactivity. The result is the vaporization of the solar liquid and extreme temperatures in the solar circuit, up to the solar station. This damages parts of the system, including pumps, connection joints and the diaphragm in the expansion tank. Furthermore, in the event of prolonged heat absorption, for example in the summer, when on vacation or if the electricity is out, the pressure of the solar systen can increase to the point of activating the safety relief valve. In order to support the highest possible inactivity temperatures, the special heat-resistant diaphragm in the Caleffi expansion tanks can withstand temperatures up to 210°F.
The diaphragm pressure expansion tank ensures that the system pressure does not exceed or drop below the limits established in the system design. The diaphragm divides the space inside the tank occupied by the pre-charged gas and the solar fluid. When the volume of the solar fluid expands because of the heat, the diaphragm stretches into the gas chamber. As a result, the space available for the solar fluid increases and the pressure inside the system remains constant at the designed value. When the volume of the solar fluid decreases because of cooling, the diaphragm returns to the correct initial pre-charged pressure.