worcester greenstar diverter valve problems

The Worcester Greenstar range, including models like the 28CDi RSF combi, is known for its efficiency and reliability. However, diverter valve issues can sometimes arise, affecting the boiler’s ability to provide consistent hot water. Understanding these problems and their solutions is essential for effective maintenance and repair.

Problem: Insufficient Hot Water and Diverter Valve Issues

A common issue faced with the Worcester 28CDi RSF combi boiler involves the replacement of the diverter valve diaphragm, leading to problems with water flow and heating.

Symptoms and Potential Causes

  • Insufficient Water Flow: The boiler requires a higher flow rate (6-7L/min) than specified (2.5-3L/min) to operate correctly.
  • Faulty Diverter Valve Diaphragm Installation: Incorrect installation of the diaphragm could lead to malfunctioning of the valve, requiring a greater load to operate effectively.


  1. Check Diaphragm Installation: Ensure the diverter valve diaphragm is installed correctly. The spring on the diaphragm should be inside the larger spring. If installed the wrong way, it might need a greater load to lift, leading to flow issues.
  2. Air Lock in Diaphragm Housing: Air trapped in the diaphragm housing might prevent the hydraulic effect, leading to flow problems. Check for any air lock and bleed if necessary.
  3. Replace the Diverter Valve: If the problem persists, consider replacing the entire diverter valve. This is particularly advisable if the diaphragm has been fitted incorrectly or if there are other faults in the valve mechanism.
  4. Flow Adjuster on the Diverter Valve: Adjust the flow adjuster on the diverter valve. This can sometimes resolve issues with insufficient flow rate.

Additional Considerations

  1. Check for Leaks: After replacement or adjustment of the valve, check for leaks as improper installation can result in significant leakage.
  2. Professional Assistance: For accurate diagnosis and repair, consulting a professional technician, preferably one experienced with Worcester boilers, is recommended.
  3. Cost-Benefit Analysis: Weigh the cost of replacing the valve against the cost of repairing it. Often, replacing the valve is more cost-effective considering the time and effort involved in repairs.
  4. Compliance with Regulations: Ensure that any adjustments or replacements comply with building regulations, particularly in specific installations like caravans.


Diverter valve issues in the Worcester 28CDi RSF combi boiler can lead to problems with hot water supply and heating efficiency. Properly diagnosing the issue, whether it’s a faulty installation or a malfunctioning component, and implementing the appropriate solution, is crucial. Regular maintenance checks and prompt attention to any signs of malfunction can help in preventing long-term issues. Consulting with a professional for complex problems is advisable for ensuring the longevity and efficiency of the boiler.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *