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

The purpose of an expansion tank in a hydronic system is fundamentally linked to managing thermal expansion of the water as it heats. When water is heated, it expands, which can lead to increased pressure within the system. The expansion tank serves as a cushion or reservoir that allows this expanded water to flow into it, thus preventing excessive pressure buildup in the main system. This is crucial for maintaining structural integrity and operational efficiency.

In systems without an expansion tank, the increased pressure can lead to potential leaks, failure of components, or even catastrophic system failures. By properly accommodating the thermal expansion through the expansion tank, the system can operate safely and effectively, ensuring both longevity and reliability. This role is critically important in maintaining the balance within the hydronic system, especially in closed-loop configurations where pressure fluctuations can cause significant problems.