atag boiler problems

Atag boilers, known for their technical advancements, can encounter issues that require specific attention. A case in point is a 60 kW Atag boiler, circa 2004, experiencing issues with heating and displaying error codes.

Problem Diagnosis

  1. BL85 Error Code:
    • Symptoms: Lack of heat in radiators, error code BL85 displayed, the return pipe remains cold.
    • Potential Causes: Faulty pump, inlet filter blockage, or pressure sensor issues.
    • Solutions:
      • Check and clean the inlet filter.
      • Inspect the pump for proper operation. Consider replacing it if faulty.
      • Evaluate the pressure sensor for blockages or malfunction.
      • Ensure the pressure in the system is around 1.5 to 1.7 bars.
      • Investigate possible internal blockages in circulation pipes.
  2. Water Leak Impact:
    • Concern: A detected water leak in the heating system could contribute to the issue.
    • Solution: Repair the leak immediately to maintain system pressure and integrity. This could indirectly affect the boiler’s functionality.
  3. Professional Intervention:
    • Given the complexity and potential safety hazards, professional diagnosis and repair are recommended. It’s crucial to engage with a heating engineer who is familiar with Atag boilers.

Considering Alternatives

  1. Boiler Replacement: If the boiler is deemed unreliable, consider replacing it with a new model. When choosing a replacement, factor in the existing system layout (like low loss headers) and opt for a model known for reliability and serviceability.
  2. Finding a Qualified Technician: Explore options for technicians outside the immediate area (Bristol or Swansea), as local experts might be limited. Prioritize finding a service provider with specific experience in Atag boilers.

Additional Considerations

  • Service History: The boiler’s past service and reliability history can inform the decision to repair or replace.
  • Manufacturer Support: Direct contact with Atag may provide additional support or insight into the specific problem.
  • User Knowledge: Understanding how the boiler and its control system operate can be crucial for proper maintenance and troubleshooting.
  • Budgetary Constraints: Weigh the cost of ongoing repairs against the investment in a new boiler.


Atag boilers, while sophisticated, can present challenges that require specific knowledge for troubleshooting. For persistent problems like the BL85 error, a combination of expert diagnosis and potential component replacement is advisable. If issues continue, considering a new boiler might be a more cost-effective and reliable solution. Regular maintenance and a clear understanding of the system are key to long-term boiler health.

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