Viessmann Wind-induced flue disturbance

Boiler locks out frequently during windy conditions, especially with sidewall flue

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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

Flue terminal location in high wind zone, Inadequate terminal clearance, Negative pressure around building, Sensitive air pressure switch or sensor

How to Fix / Troubleshooting

Safety: Frequent lockouts indicate combustion instability. Do not bypass safety devices.

  • Observe pattern: Note if lockouts occur only during strong winds or specific wind directions.
  • Inspect terminal: Ensure the flue terminal is installed according to Viessmann clearances and not in a corner or recess that channels wind.
  • Temporary shielding: Do not obstruct the terminal, but discuss with a technician whether a manufacturer-approved terminal guard or deflector is appropriate.
  • Professional assessment: A Viessmann-trained installer should evaluate flue routing and may recommend relocation or modification within installation standards.
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Repair Difficulty

Professional Required 5/5

Required Part

Flue Terminal
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