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

The main purpose of an expansion tank in a heating system is to accommodate the expansion of water as it heats and to maintain system pressure. As water heats up, it expands, and this increase in volume needs to be managed to prevent excessive pressure from building up within the system. The expansion tank provides a designated space for this expanding water to go, helping to maintain a safe and consistent pressure throughout the heating system.

By accommodating the thermal expansion, the expansion tank protects other components of the system from potential damage caused by overpressure, such as bursting pipes or failure of fittings. This function is critical for the safe and efficient operation of closed-loop heating systems.

While other options mention relevance to pressure management and water collection, they do not specifically address the primary function of managing water expansion caused by heating.