Worcester Greenstar Boiler Expansion Vessel 7L 8716122434

Product Overview

The Worcester Greenstar Boiler Expansion Vessel (Part Number: 8716122434) is a 7-litre pressure management component designed for use within selected Worcester Bosch Greenstar heating systems.

Part number 8716122434 is identified as a 7-Litre Expansion Vessel.

The expansion vessel forms part of the boiler's sealed central heating circuit. It accommodates the expansion of heating water as its temperature increases, helping to maintain stable system pressure during normal operation.

ℹ️ Product Condition:

This product may be available in New or Refurbished condition. Please select the required option when ordering.

Technical Insight & Common Failure Symptoms

The expansion vessel is a pressure management component within a sealed heating system. It contains a flexible diaphragm that separates the heating water from a pressurised gas chamber.

As the heating water expands during operation, the vessel accommodates the increased water volume, helping to prevent excessive pressure increases.

Over time, expansion vessel performance may be affected by loss of pre-charge pressure, diaphragm deterioration or internal damage.

Possible symptoms that may require investigation of the expansion vessel or associated components include:

• Boiler pressure rising excessively when heating is operating

• System pressure dropping after the heating cools

• Frequent need to repressurise the heating system

• Water discharging from the pressure relief valve

• Significant pressure fluctuations between hot and cold operation

• Loss of expansion vessel pre-charge pressure

• Leakage or damage around the expansion vessel

These symptoms do not necessarily confirm a faulty expansion vessel, as similar issues may be caused by leaks, pressure relief valve faults, incorrect system filling pressure or other heating system components. Correct professional diagnosis should be carried out before replacement.

Safety Advice

Boiler expansion vessels and associated pressurised heating components should only be inspected, removed or installed by a suitably qualified and competent heating engineer.

Always isolate the appliance and allow the heating system to cool before carrying out any work. The system must be safely depressurised in accordance with the manufacturer's servicing instructions. The expansion vessel pre-charge pressure, system filling pressure and all relevant connections must be checked, and appropriate leakage and operational safety tests completed before the boiler is returned to service.