203
Ariston Flue Draft / Airflow Instability

Furnace intermittently shows error 203, especially in windy conditions.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Improper flue termination, Excessive flue length, Wind affecting pressure switch, Partially blocked flue

How to Fix / Troubleshooting

Safety: Flue issues can lead to unsafe combustion. If you suspect flue damage, stop using the furnace and call a professional.

  • Check outdoor terminal: Inspect the Ariston concentric flue terminal for correct orientation and clearance from walls, corners, and windows as per installation manual. Remove any obstructions.
  • Look for signs of condensation leakage: Stains or water marks around the flue joints may indicate internal blockage or poor slope. This can disturb airflow and trigger 203.
  • Secure flue joints: Ensure all visible flue joints are properly locked and supported. Loose joints can cause pressure fluctuations.
  • Monitor pattern: If the error only occurs in strong wind, a flue terminal deflector or re-routing may be required. This must be designed and installed by an Ariston-qualified installer to maintain certification.
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Repair Difficulty

Professional Required 5/5

Required Part

Flue Kit (Concentric Flue Pipe)
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