Expansion Vessels / Pressure Vessels

An expansion vessel is used to protect closed central heating systems from becoming overloaded by excessive pressure. It is a small tank or container that is divided in to two.

It provides a cushion against any shocks caused by small influxes of air that lead to increased air pressure in the system. This can also occur when the water hammer absorbs too much pressure as a result of thermal expansion.

Expansion vessels are most commonly used to remove the need for a continuous pump in a pumped central heating system. The user can configure a low and high pressure level on the pump settings. When the water pressure reaches the lowest setting, the pump will engage and fill the vessel to the high pressure point. When it reaches this point the pump still stop.

Once this cycle has been completed, the expansion vessel will maintain the stored water at high pressure levels, ensuring a better and more consistent water flow. If the pressure in the vessel drops to the lower point, the pump will kick in and the cycle begins again.

An expansion or pressure vessel can be used in the home for the supply of drinking water. When used with a boiler, an expansion vessel can help maintain water pressure to ensure showers reach full power on demand.

All tanks and containers supplied by Pump Sales Direct are manufactured to comply with UK water regulations when used in this application. Pump Sales Direct supply expansion vessels for Europe’s leading manufacturers, including Airfix, Flexcon, Gitral, Grundfos, Heatwave, PressureWave, Reflex, Varem and ZILMET.