Worcester Bosch Tank Assembly Highflow CDI 8716118200

The Worcester Bosch 8716118200 is a tank assembly serving as the expansion vessel for the Greenstar Highflow CDi range of floor-standing combination boilers. It provides the sealed air cushion that absorbs the volume increase of water as the system heats, holding the sealed heating circuit at a stable pressure. The vessel is listed under the manufacturer's expansion vessels part group and is supplied as a complete tank assembly.

• System pressure drops repeatedly and needs topping up, with no visible leak on the pipework or radiators.
• The boiler locks out or shows a low-pressure fault shortly after the system has been filled and bled.
• Pressure climbs sharply once the boiler is running and hot, then falls again as it cools.
• Water discharges from the pressure relief valve during normal heating cycles.
• The vessel feels heavy or water is heard inside it when the connection is drained, indicating a failed internal diaphragm.

• Check the appliance GC number and model data badge against the compatibility list above before ordering, as the assembly is specific to the Highflow CDi ErP models.
• Confirm the part number on the existing component or in the appliance literature matches 8716118200 or the alternative number 2245009.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.