Ariston 108 Fault

Ariston 108 Fault

The Ariston error code 108 signifies a significant drop in water pressure within the boiler system, indicating that the system pressure is much lower than the required operational level. This is a more severe manifestation of low water pressure issues, potentially indicating substantial leaks or a major fault within the system’s pressure maintenance mechanisms.

Causes of Error Code 108

  1. Significant Leaks: Large leaks in the heating system’s pipework, radiators, or boiler components can cause a rapid loss of water, leading to a drastic drop in pressure.
  2. Faulty Pressure Relief Valve: If the pressure relief valve is malfunctioning and releasing too much water, it could lead to significant pressure loss.
  3. Issues with the Filling Loop: Problems with the filling loop, including incorrect setup or failure, can prevent the system from maintaining the correct pressure.
  4. Recently Performed Maintenance or Repairs: If the heating system was recently serviced or repaired, and the system was not properly repressurized afterward, it could result in low pressure.

Troubleshooting and Resolving Error Code 108

  1. Locate and Repair Leaks: Inspect the system for visible signs of leaks. Check all accessible pipework, radiators, and boiler components. Any leaks found should be repaired promptly.
  2. Repressurize the Boiler System: Use the boiler’s filling loop to carefully repressurize the system to the recommended level, typically between 1 and 1.5 bar. The process for this can usually be found in the boiler’s user manual.
  3. Inspect the Pressure Relief Valve: Ensure the pressure relief valve is functioning correctly and not releasing water unnecessarily. If faulty, it may need replacement.
  4. Check the Filling Loop: Make sure the filling loop is correctly configured and operational. If there are issues with the filling loop, they will need to be addressed to maintain system pressure.
  5. Reset the Boiler: After addressing the potential causes and repressurizing the system, reset the boiler to see if the error clears and normal operation resumes.
  6. Seek Professional Assistance: Given the potential complexity of the issues indicated by error code 108, especially if leaks are not easily identifiable or if system components need replacement, consulting a professional is advisable. A qualified heating engineer can provide a comprehensive inspection, accurately diagnose the underlying cause, and perform necessary repairs.


The Ariston error code 108 highlights a critical issue with water pressure that requires immediate attention to ensure efficient and safe boiler operation. While homeowners can perform basic checks and attempt to repressurize the system, identifying and resolving the root cause of significant pressure loss often necessitates professional intervention. Regular maintenance and timely repairs can help prevent such issues, ensuring your heating system remains reliable and operational.