What is the primary purpose of an expansion tank in a water system?

The primary purpose of an expansion tank in a water system is to allow for thermal expansion. As water is heated, it expands, leading to an increase in pressure within the system. An expansion tank provides a buffer zone where this extra volume of water can go, preventing excessive pressure that could damage the system or cause leaks. By accommodating the expansion of water, the tank ensures that the pressure remains stable and within safe limits, contributing to the efficient operation and longevity of the entire water system.

While the storage of excess water, maintaining pressure, and filtering contaminants are important functions in water systems, they do not directly pertain to the main role of an expansion tank. The expansion tank specifically addresses the issues related to temperature changes and the resultant physical behavior of water, emphasizing its critical role in managing thermal expansion.