Worcester Expansion Vessel 10L 87161425000 Expansion Vessel is a small chamber that is used to protect closed water heating systems from pressure surges. Expansion Vessel is filled with air that acts as a cushion against pressure surges within the system. Some engineers refer to it as Boiler Expansion Tank or boiler expansion vessel. Whenever you replace a faulty or damaged boiler part, it is essential that you use a Genuine and Original Boiler Spare Part. Heatingspares247.com is one of the UK's largest independent Boiler Parts & Heating Spares Stockist, serving the whole of UK mainland from their 3,000 sq ft. distribution centre. We specialise in the supply of Genuine & Original Boiler Spares. Services available are trade counter pick up, Next working day, next working day AM and Saturday delivery. We also operate same day express delivery service. Our Opening times are Monday to Saturday, 8AM to 5.30PM Heatingspares247.com is an Approved Boiler Spare Parts Stockist, and we guarantee to supply genuine spares from the boiler manufacturers.