Vaillant F22 fault code how to fix

Vaillant F22 fault code how to fix

Understanding & fixing the Vaillant Boiler F22 Fault Code: A Guide for Homeowners & heating engineers 

When your home suddenly loses hot water or central heating, it can be a significant inconvenience. Modern Vaillant boilers are designed to communicate issues through specific error codes, which can be incredibly helpful for homeowners trying to understand the severity of a problem. The Vaillant boiler F22 fault code is a common issue that many homeowners encounter. This comprehensive guide will explain the meaning behind this fault code, the steps you can take to address it. 

Vaillant F22 fault how to fix

Deciphering the Vaillant Boiler F22 Fault Code

The F22 error code on a Vaillant boiler indicates a problem with water pressure or flow rate through the boiler, AKA poor circulation — specifically, that the water pressure is too low for the boiler to operate. If you're seeing this code, it's likely that your boiler has entered a 'locked out' state, resulting in a lack of hot water and cold radiators. Note, sometimes it will also trigger and F75 fault for the same reason. 

You might also notice a figure, such as 0.3, flashing on your boiler's display panel. This number represents the current pressure level within your system, which typically should be around 1.5 bar, depending on your specific boiler model. To confirm this issue, you can also check the pressure gauge if your boiler is equipped with one.

Also, especially on the heat only Vaillant boilers, it can mean that there is a circulation issue, usually the pump, an airlock or the main heat exchanger is scaled.

Tip: if you do have a guage on your Vaillant boiler and it doesn't increase when you top the pressure up, give the guage a tap when adding water pressure, that should free the pressure gauge needle. 

Root Causes of Low Water Pressure or circulation issues 

Several factors can contribute to a loss of pressure in your boiler system. Common causes include leaks in the pipework, issues with the expansion vessel, or a faulty pressure release valve. If you've recently bled your radiators, this could also result in a temporary drop in pressure, However, it is  important to note, typically, the F22 fault arises just due to natural contraction & expansion in the heating system causing a certain amount of the water volume to be lost, thus, it needing to be refilled. Meaning, it's likely you do not have any issues at all and you just need top up your system. 

F22 fault leaking Vaillant boiler
that being said, if you're experiencing a rapid loss of pressure or find yourself frequently repressurising your boiler, this could signal a more serious underlying problem.
As mentioned above F22 can also be triggered by low water flow through the boiler, this is usually caused by. 
  • No water in the header tank/low water pressure.
  • Weak or seized pump. 
  • Restriction in the heat exchanger or heating system. 
  • Air locks in pipework

You would need a gas safe registered engineer to look into these issues. 

Repressurising Your Vaillant Boiler clearing the F22 fault code 

If you feel confident and safe in doing so, you may attempt to re-pressurise your boiler to clear the F22 fault code. This involves adjusting/opening the valves on the boiler's filling loop.

Here's a step-by-step guide:

  1. Confirm that the display shows an F22 code.
  2. Locate the two valves beneath the boiler.
  3. Turn the right valve 90 degrees, followed by a slow turn of the left valve.
  4. Monitor the pressure gauge on the display, ensuring the pressure rises to between 1.2 and 1.5 bar.
  5. Once the ideal pressure is reached, close both valves.
  6. If the F22 code persists, you may need to reset your boiler.
how to repressurise a vaillant boiler

If you do not have the 2 white valves underneath, you may have a traditional filling loop, here's a guide on You Tube. 

This process should be swift, and caution is advised to avoid over-pressurising the system, which can occur if the pressure exceeds 2.5 bar.

Tip: If you've inadvertently over-pressurised the system, you can release pressure by bleeding your radiators. Check the boiler pressure after each radiator is bled. If you're not comfortable performing this task, professional assistance is recommended.

Persistent F22 Fault Code

Should the F22 code reappear shortly after repressurising, it's time to consult a Gas Safe-registered engineer. They will thoroughly inspect your boiler for any damaged components and perform necessary repairs. 

Important: Never attempt repairs on your own. Unqualified interventions can lead to significant damage and increase the risk of carbon monoxide exposure. Always rely on trained professionals who adhere to HSE regulations.

Preventing the Vaillant Boiler F22 Error Code

While boiler issues can arise unexpectedly, regular maintenance is your best defense against faults. Annual servicing not only satisfies home insurance requirements but also maintains your manufacturer's guarantee. Moreover, a well-serviced boiler can operate up to 30% more efficiently.

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