Thermal expansion tanks are designed for pressure control in a potable water system. The building's water heater or water heating system typically creates thermally expanded water.
A properly sized thermal expansion tank will accommodate this additional volume of water created through expansion during the heating cycle, and control the system pressure increases, keeping pressures from reaching critical safety relief limits.
Hydro-pneumatic tanks are vessels that store water for a well system or pressure boosting station.
Properly sized, these tanks provide drawdown water used to supply water for small demand loads, keeping the pumps off until needed. Additionally, these tanks can be applied to reduce harmful surge and water hammer pressure spikes.