F.24 / F24 — Vaillant ecoTEC exclusive 832/838
What it means: The boiler suspects a water shortage because the temperature is rising faster than expected.
Typical causes
- Pump seized
- Pump output is low
- Air trapped in the boiler
- System pressure is too low
When to treat it as unsafe
Treat as unsafe if there is any sign of overheating, or if the boiler fired with poor water circulation.
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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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