Worcester Bosch Expansion Vessel 18L DHW

The Worcester Bosch Expansion Vessel 18L DHW is a domestic hot water expansion vessel used in Worcester Bosch Greenstore combi SOFT Start appliances. It absorbs the expansion of heated domestic hot water within the sealed system, helping to keep pressure stable and protect components from excessive strain. It is identified by the supplied product name Expansion_vessel 18L DHW.

• Pressure rises sharply when the appliance heats domestic hot water and drops again once it cools
• The pressure relief valve discharges during normal heating cycles
• Visible corrosion, pitting or water staining on the vessel body
• Loss of charge pressure at the vessel's air side when checked with a gauge
• Frequent topping up of system pressure to keep the appliance running

• Confirm the appliance model and that it is a Greenstore Combi SOFT Start unit
• Check whether the fault is the vessel itself or the charging valve and connection
• Verify the existing vessel's stated capacity matches 18 litres
• Confirm access and space for removal and refitting before ordering