Which plumbing component is fitting to a vented indirect hot water system to accommodate the increase in volume when heated?

In a vented indirect hot water system, as water is heated, it expands, which increases its volume. To effectively accommodate this increase in volume, an expansion tank is utilized. An expansion tank is designed to absorb the additional water expanding from heating, thereby keeping the system pressure within safe limits and preventing potential damage to the plumbing system.

The expansion tank is specifically designed for this purpose, ensuring that excess pressure caused by thermal expansion does not lead to leaks or ruptures in the piping. It functions by providing a cushion of air that compresses when the water expands, allowing for a smooth and safe operation of the hot water system.

The other components mentioned, while important in plumbing systems, do not serve the specific function of managing water expansion due to heating.