Viessmann Vitodens 100-W fault 461

Burner in a fault state

Gas boiler

What it means

Flue gas damper fault.

Likely causes

  1. Flue gas damper fault
  2. Flue system leak causing flue gas recirculation
  3. Incorrect gas flow pressure
  4. Flue gas leakage
  5. Blocked flue system
  6. Simultaneous operation of boiler and air-extracting appliances
  7. Negative pressure created by extractor hoods, extractors, air conditioning units, or central vacuum cleaning systems
  8. Accumulation of condensate blocking flue system
  9. External causes sealing the flue system
  10. Inadequate supply of combustion air
  11. Building modifications affecting cable/pipework routing, cladding or partitions

Where to start

  1. Check flue gas damper
  2. Check the flue system for tightness (flue gas recirculation).
  3. Check gas flow pressure.

The full answer, free

  • 16 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 83), right under the answer

Safety: Isolate gas and power before you open the case. If you have been into the gas side, do a tightness test, and a combustion and flue check before you hand back. Gas Safe (UK) or RGI (Ireland) work only.

From the Viessmann manual for the Vitodens 100-W. Check the model on the data plate before you order parts.

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