Worcester Bosch Expansion Vessel Type CP 335 87183100570

The expansion vessel type CP 335 is a sealed pressure vessel manufactured by Worcester Bosch for use in the Greensource air/water heat pump range. It accommodates the expansion of water as it heats within the sealed heating circuit, limiting the pressure rise across the system. This protects the appliance and connected components from excessive pressure during normal operation.

• System pressure rises sharply as the appliance heats up and falls again once it cools.
• The pressure relief valve discharges water during normal heating cycles.
• The pressure gauge fluctuates widely or reads inconsistently between hot and cold states.
• Water is present at the vessel's air valve, indicating a failed internal diaphragm.
• The system repeatedly loses pressure with no visible leak elsewhere in the circuit.

• Confirm the part number 87183100570 matches the vessel fitted to the appliance or the manufacturer's parts list.
• Check the appliance model against the Greensource units listed above.
• Inspect the existing vessel's connection size, mounting position and available clearance before ordering.