The Vaillant EcoFit Pure and Sustain Expansion Vessel 0020237676 is a genuine Vaillant spare part with a Vaillant manufacturer's guarantee. An expansion vessel is a small but vital chamber found with sealed heating systems to manage any pressure changes caused by water expansion when heating. This component uses pre-charged air to maintain a constant stable pressure within the system via the use of a diaphragm or bladder. This separates the vessel into two sections of water and air allowing for when the water pressure increases, the air side compresses meaning there’s room for the expanded volume.

• Suitable for Vaillant Ecofit Pure and Sustain appliances