F.29 / F29 — Vaillant ecoTEC exclusive 832/838

What it means: The flame went out while the boiler was running, and the restart attempts that followed also failed.

Typical causes

  • Gas supply interrupted briefly
  • Ignition transformer failing to spark
  • Poor earthing of the boiler

When to treat it as unsafe

Treat as unsafe if a gas escape is suspected or the gas supply fault is not found; follow your Gas Safe procedure and the gas emergency notice on this page.

NwadFix is decision support. The engineer confirms every safety decision.

NwadFix is not affiliated with or endorsed by Vaillant. Manufacturer and model names are used only to identify the appliances an entry refers to.

Last reviewed: 13 October 2026 by a Gas Safe Engineer

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