An expansion tank is a crucial component in heating, cooling, and plumbing systems that helps manage the pressure caused by the expansion and contraction of water or other fluids when they are heated or cooled. It is a safety device used primarily in closed-loop systems, including residential and commercial hydronic heating systems, hot water systems, chilled water systems, and even certain industrial applications. The primary purpose of an expansion tank is to absorb excess pressure resulting from the thermal expansion of fluids, ensuring that the system operates efficiently, safely, and without causing damage to pipes, pumps, or other components.

As the fluid in a heating or cooling system is heated, it expands. In a closed system, the volume of the fluid cannot increase, so the pressure inside the system rises. This increase in pressure can lead to a variety of problems, such as damaging pipes, causing leaks, or overloading pressure relief valves. Expansion tanks prevent these issues by providing a cushion of air or gas that absorbs the excess pressure, ensuring the system maintains stable operation.