vaillant ecotec pro 28 problems

Vaillant Ecotec Pro 28 boilers are well-regarded for their efficiency and reliability. However, like any complex machinery, they can sometimes encounter issues. A common problem reported by users involves inconsistent hot water supply, despite regular servicing and part replacements. This article delves into this issue, offering insights and potential solutions.

Problem: Inconsistent Hot Water Supply in Vaillant Ecotec Pro 28 Boiler


  • Hot water starts off at the expected temperature but quickly drops off, becoming cold.
  • Central heating functions without issues.
  • Repeated service visits and replacements (including heat exchanger, sensors, and pump) have not resolved the problem.
  • The boiler modulates down after initial heating but fails to reheat the water to the desired temperature.

Possible Causes and Solutions

  1. Faulty Pump: Initially suspected and replaced, but the problem persisted.
    • Solution: While the pump was a plausible cause, its replacement alone was insufficient. Further diagnosis is necessary.
  2. Diverter Valve Issue: The problem’s recurrence suggests a possible issue with the diverter valve, which directs water flow between heating and hot water.
    • Solution: Have a heating engineer check and potentially replace or repair the diverter valve.
  3. Blocked Canoe Filter or Hose: Partial blockage in internal components could hinder water flow and heating efficiency.
    • Solution: Check and clean or replace the internal hose and canoe filter.
  4. Primary Heat Exchanger Fault: Suggested by a service engineer but questioned due to the efficient central heating performance.
    • Solution: Seek a second opinion or confirmation from another qualified engineer before agreeing to significant work like a power flush or heat exchanger replacement.

Additional Considerations

  1. Power Flush Necessity: British Gas suggested a power flush, but its relevance to resolving the specific hot water issue is questionable.
    • Solution: Consider an independent engineer’s assessment before committing to a power flush, especially if central heating is unaffected.
  2. Service Contract Terms: Review the terms and conditions of your home care contract for clarity on service requirements.
  3. Independent Assessment: Given the repeated unsuccessful attempts by British Gas, an independent heating engineer’s diagnosis might offer a fresh perspective.
  4. Customer Rights and Warranties: Familiarize yourself with your rights as a consumer and any warranties applicable to your boiler and its components.


The Vaillant Ecotec Pro 28 boiler’s hot water issues, despite multiple service interventions, suggest a complex problem that might not be related to the parts already replaced. A detailed examination by an experienced heating engineer, potentially exploring the diverter valve, internal hoses, and canoe filter, could provide a more accurate diagnosis.

Homeowners should carefully consider the necessity and validity of suggested services like power flushes, particularly if they do not align with the symptoms experienced. Engaging with independent professionals can offer unbiased opinions and potentially more cost-effective solutions. Regular maintenance and a thorough understanding of service contracts and warranties can further aid in efficiently resolving such boiler issues.

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