If you own a Vaillant boiler, you may sometimes see strange fault codes on the screen. One of the most common is the F22 fault code. This generally indicates that there is not sufficient water pressure in the boiler or heating system.
If this occurs, the boiler won’t work until you repair it. The good news is that the Vaillant F22 error code is generally simple to repair. In this guide, we explain what the F22 error code means, the common causes, and the best ways to fix an F22 fault.
What Does the F22 Fault Code Mean?
The F22 fault on the Vaillant boiler occurs when water pressure is low. The Vaillant boiler fault code indicates that the boiler is malfunctioning due to the lack of water. The boiler pressure should be around 1.5 bars when cold.
After the pressure gauge drops below a safe point, the boiler indicates the F22 code. It is a protective boiler code. It turns off the boiler to avoid damage. The F22 boiler fault is therefore not always a serious issue, but it needs to be repaired.
Common Causes of the Vaillant F22 Fault Code
There are many causes of the F22 fault in a Vaillant boiler. The most common reason is a tiny leak in the pipes or radiators.
Leaks reduce the pressure in the boiler over time. The second problem is air that is trapped in the radiators, which blocks water from flowing through.
Sometimes the system leaks pressure on its own. Improper pressure sensor, water pressure sensor, or pump in the boiler can also cause the F22 error. As soon as you understand the cause of the issue, you will be able to decide how to fix the F22.
Check the Pressure Gauge
When you see the F22 error code, your first step should be checking the pressure in your boiler. Look at the pressure gauge on the front of the unit. If it is below 1 bar, the boiler error is due to low water pressure.
The code indicates the system does not have enough water to function. For a regular boiler to work, pressure should be at about 1.5. If the gauge is broken, an experienced heating engineer may need to test it.
Causes of Low Water Pressure
Here are the common reasons for a boiler having low water pressure:
- General ageing: A boiler can slowly lose pressure over time without a clear reason. The gradual pressure drop happens naturally with an older boiler.
- Component error: If a part like the pressure sensor or pump develops a fault, this can reduce water pressure.
- Leak: A sudden loss of pressure often means a boiler leak. If pressure falls soon after topping up, a leak is the likely cause.
Repressurize Your Boiler: Quick Fix
The most common way to fix the Vaillant F22 is to repressurise your boiler. Find the filling loop under the boiler. It looks like a silver flexible pipe with small valves. Open the valve slowly and let water enter the system.
Keep watching the pressure gauge until it shows around 1.5 bar. Close the valve and reset the boiler. This usually clears the F22 Vaillant fault code. If pressure keeps falling, there may be a boiler fault such as a hidden leak.
On some models, like the Vaillant boiler F22 no valve visible outside, the filling mechanism is built inside the boiler casing. In that case, you should call a Gas Safe heating engineer to guide you or repressurize safely.
Bleeding Radiators to Remove Trapped Air
If repressurizing alone does not solve the Vaillant F22 error, trapped air may be the cause of the F22. Radiators that feel cold at the top usually have air inside. Use a radiator key to release air. Open the small valve until air escapes, then close it once water flows.
Do this on all radiators in your central heating system. After bleeding, check the boiler pressure again. You may need to add more water with the filling loop. This simple step can often get your boiler working again.
Check for Leaks Around the Boiler
Leaks are a major cause of the Vaillant F22. Look carefully for damp patches, dripping pipes, or wet areas around the boiler. Even small leaks can trigger the F22 fault. Pay close attention to radiator valves, joints, and connections.
If you find a leak, call a Gas Safe heating engineer for boiler repair. Fixing leaks not only clears the Vaillant boiler F22 error code but also prevents long-term damage to your boiler. Ignoring leaks will eventually force you into a costly boiler replacement or new boiler installation.
Faulty Pressure Sensor or Pump Issues
Sometimes the causes of the Vaillant F22 fault are faulty parts. A broken pressure sensor or water pressure sensor may wrongly tell the system there is low pressure. A failing pump may also stop water circulation inside the boiler or central heating system.
These issues cannot be solved by homeowners. You will need a Gas Safe engineer to diagnose and fix an F22 fault safely. Attempting to replace parts without training risks serious boiler issues.
Reset the Boiler After Fixes
After you fix an F22 fault, the code on your Vaillant boiler may not clear immediately. You might need to reset the boiler. Most modern Vaillant boilers have a reset button on the panel.
On some, you may see the Vaillant boiler F22 red reset button, which you hold for a few seconds before releasing.
The boiler will restart and should clear the F22 Vaillant fault. If the boiler will stop again or the F22 code returns, contact a Gas Safe engineer.
Model-Specific Tips – EcoTEC Plus and EcoTEC Pro 28
Different models handle the F22 boiler fault slightly differently.
Vaillant ecoTEC Plus F22 fault: It appears when the boiler pressure is less than 0.8 bar. To fix it, slowly fill the filling loop until the pressure gauge is 1.5 bar. If the error remains, reset the boiler and bleed radiators.
Vaillant boiler ecoTEC Pro 28 F22 error: On this model, the Vaillant boiler F22 filling loop is often located beneath the boiler. Turn both small taps slowly to increase pressure.
The Vaillant ecoTEC Pro 28 F22 fault code How to fix usually involves repressurising, checking for leaks, and then pressing the reset button.
If you cannot see an external filling loop, you may have a Vaillant boiler F22 with no valve case, where the filling mechanism is integrated internally.
By following these model-specific steps, you can fix the Vaillant F22 faster and avoid repeated errors.
Replace Your Old Boiler for Free under ECO4 Grants
If you are a homeowner or private tenant, you may qualify for help under the ECO4 scheme. This government-backed grant allows some households to replace their old boiler for free.
If your current boiler is operating on electricity only, you can potentially switch to a better system.
If you had a gas meter installed prior to April 2022, install a new electric or gas boiler. This can save you a fortune on heating costs, enhance your central heating system, and slash your bills. Always ensure you can qualify, as rules do vary based on your circumstance.
When to Call a Heating Engineer
Not all boiler malfunctions can be solved at home. If you’re repeatedly receiving boiler fault codes or noticing the F22 Vaillant fault code over and over, you should call in a professional.
A professional heating engineer will be able to diagnose hidden leaks, faulty parts, or worn-out valves.
Only Gas Safe registered engineers are qualified to legally repair a gas boiler. Attempting to repair complex boiler issues yourself could lead to more issues. Sometimes, when issues arise again and again, perhaps it’s time to install a new boiler.
Preventing Future Boiler Issues
To avoid repeat boiler fault codes, have an annual boiler service. A pro will check the pressure relief valve, the expansion vessel, and other components that cause the boiler pressure to remain constant.
Check your pressure gauge too. Bleed radiators of air every year. These measures ensure that you maintain your boiler safe, efficient, and less likely to display the F22 boiler fault again.
Conclusion
The Vaillant boiler shows an F22 fault code when the water pressure is low. You can normally fix the fault code by topping the water up, bleeding radiators, or checking for leaks.
If you get a repeated F22 fault code, you will need to call out a Gas Safe boiler heating engineer to fix the boiler properly.
Routine maintenance will prevent the F22 fault code and maintain your heating system in good working order. Repairing the root cause of the Vaillant F22 enables you to simply repair your boiler and enjoy safe hot water and heat throughout the year.
Frequently Asked Questions
Vaillant F22 is the low pressure error code on your boiler. It normally activates when the pressure gauge is less than 1 bar.
You are usually able to correct the F22 fault by filling pressure in your boiler with the filling loop until the pressure gauge reads approximately 1.5 bar.
A pressure drop may be caused by small leaks, air in radiators, or faulty parts like the pressure sensor or pump.
Yes, once you fix the pressure problem, you can safely reset the boiler. If the error returns, call a Gas Safe engineer.
Not always. Most F22 errors are minor. But repeat offenders may point to leaks, faulty components, or in the worst-case scenario the need for a replacement boiler.
