Minnesota Special Engineer Boiler License Practice Exam

In a hot water system, the expansion tank is primarily designed to accommodate changes in water volume and temperature due to thermal expansion. When water is heated, it expands, increasing its volume. If there is no room for this added volume, pressure in the system can rise to dangerous levels. The expansion tank provides a cushion for this increased volume, allowing the water to expand into the tank instead of increasing the system pressure. Temperature increases also influence the amount of water that the system can accommodate, as higher temperatures lead to more expansion. Thus, the focus of the expansion tank is on managing the changes in water volume resulting from temperature variations in the system.