The expansion vessel is vital for regulating the pressure in a heating system.

• Function: When the water heats up, it expands and its volume increases.
• Without the expansion vessel, this increase could cause a dangerous rise in the network pressure.
• The vessel has a membrane (diaphragm) that separates the air from the water.
• The air compresses and absorbs the overpressure, protecting pipes, valves, and devices.