What is the principal function of an expansion tank in a hot water system?

An expansion tank serves a critical role in a hot water system by accommodating the changes in water volume that occur when the water is heated. As water heats up, it expands, leading to an increase in pressure within the closed system. The expansion tank provides a space for this expanded water to go, effectively preventing excessive pressure build-up which could lead to system failures or leaks.

By allowing volume changes in the water, the expansion tank helps to maintain consistent pressure levels within the system. This not only protects the integrity of the pipes and fixtures but also ensures the efficient operation of the hot water system. This function of managing pressure and accommodating thermal expansion is essential for the longevity and reliability of the system.