Worcester Bosch Expansion Vessel 7 Litre Greenstar CDI 8716122434

The Worcester Bosch 8716122434 is a 7 litre expansion vessel used across the Greenstar CDi range of gas boilers. It is a Worcester Bosch spare part that absorbs the volume increase of water as the system heats up, holding the sealed air charge that keeps system pressure stable. When the internal diaphragm or charge fails, the vessel stops cushioning expansion and the boiler loses pressure control.

• System pressure climbs quickly once the boiler fires and the heating circuit warms up
• Boiler pressure drops repeatedly and needs frequent topping up from the filling loop
• Water discharges from the pressure relief valve during normal operation
• Water or moisture appears at the vessel's air valve when the charge is checked
• The vessel feels heavy or full of water when disconnected, rather than hollow

• Check the appliance GC number and model against the compatibility list to confirm the vessel matches your boiler
• Confirm the previous numbers 8-715-407-296-0 and 87154072960 against the label on the existing vessel
• Check whether the connecting seal or washer on your model needs replacing at the same time
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.