What is the function of an expansion tank in a heating system?

The function of an expansion tank in a heating system is to absorb excess pressure and accommodate thermal expansion. As water is heated, it expands. If there is no way to accommodate this expansion, the increased pressure can lead to potential damage to the system, such as ruptured pipes or safety valve releases. The expansion tank provides a space for this expanded water to go, effectively managing pressure levels within the system.

In many systems, the expansion tank is partially filled with air, which compresses as water expands, cushioning the increase in volume and maintaining an even pressure. This function is critical for the safe and efficient operation of heating systems, especially in closed-loop systems. By controlling pressure fluctuations, the expansion tank helps ensure the longevity and reliability of the system components.