Vaillant Boiler Support, Fault Codes & Manuals

Vaillant Boilers: Frequently Asked Questions

1. What does the Vaillant F22 fault code mean?

The F22 code is the most common Vaillant error and indicates low water pressure. Your boiler needs a specific amount of water to operate safely. Check the digital display or the circular gauge; if it is below 1.0 bar, you need to use the external filling loop to top it up to 1.5 bar. If this happens frequently, you likely have a small leak that requires a professional inspection.

2. Why is my Vaillant boiler showing an F75 error?

The F75 code is a "classic" Vaillant fault, usually found on ecoTEC models. It means the boiler is struggling to detect a pressure change when the pump starts. This is often caused by a blocked pressure sensor or a failing pump. While bleeding your radiators can sometimes clear airlocks, a persistent F75 usually requires a Gas Safe engineer to replace the sensor or pump.

3. How do I reset my Vaillant ecoTEC boiler?

To reset a modern Vaillant boiler, look for the button with a flame symbol with a cross through it. Press and hold this button for about 3 to 5 seconds. You should hear the boiler attempt to reignite. If the fault code reappears immediately, it means a safety component is preventing ignition and you should not attempt further resets.

4. What causes the F28 or F29 ignition faults?

These codes mean your boiler tried to light but failed (F28) or the flame went out during operation (F29). Common causes include a frozen condensate pipe in winter, a lack of gas supply (check your meter credit), or dirty ignition electrodes. Because this involves the gas supply and combustion, these faults must be diagnosed by a qualified specialist.

5. Why is my Vaillant boiler making a loud humming or vibrating noise?

Loud noises are often a sign of "kettling" or a pump struggle. If it sounds like a vibrating drone, it could be a fan issue or debris caught in the pump. If it sounds like a whistling kettle, it is likely a build-up of limescale on the heat exchanger. A professional service or Powerflush can usually restore the quiet, smooth operation Vaillant is known for.

6. How long is the lifespan of a Vaillant ecoTEC boiler?

With annual servicing, a Vaillant boiler is an incredibly robust piece of German engineering that should last 12 to 15 years. To keep your 7, 10, or 12-year warranty valid, you must have a Gas Safe service every 12 months. This allows us to catch minor wear and tear before it leads to a total system breakdown.