How does Boyle’s law relate to sizing expansion tanks in domestic hot water systems?

Boyle’s law states that, at constant temperature, the volume of a gas is inversely proportional to the pressure. In a domestic hot water system, as water is heated, its volume increases, which can lead to increased pressure. To accommodate this expansion, an expansion tank is required to absorb the increased volume and prevent excessive pressure buildup. Proper sizing of the expansion tank is critical to ensure that it can handle the maximum expected pressure and volume increase, thereby preventing damage to the system and ensuring safe operation.