Last updated on October 15th, 2024
The Vaillant F22 fault code indicates low boiler pressure so it must be repressurised to fix it. The first thing you need to do is check the pressure gauge and if it’s low, repressurise it until it’s at 1 to 1.5 bar.
I have been repairing boilers for over a decade and this is how I fix a Vaillant boiler F22 fault code most of the time.
What Causes an F22 Fault?
An F22 fault is caused by low boiler pressure. Low pressure can be caused by bleeding a radiator or boiler part problems, but if the pressure keeps dropping it could be caused by a leak anywhere on the heating system.
The F22 fault code should disappear when the boiler is repressurised, and you should hear the pump start to circulate the water in the boiler.
Vaillant F22 Fault Reset
The first thing I would check on a Vaillant boiler that is not working, no matter what fault code is showing, is to check the pressure and reset the boiler.
Knowing how to reset a Vaillant boiler is the simplest way to get your boiler working again, as it might have just locked out.
To reset a Vaillant boiler, you must find the reset button. This is usually a flame with a line through it. You have to press the button to reset the boiler. Sometimes you have to hold it down for 3 seconds, but on some Vaillant boilers, it just needs to be pressed.
F22 Error Keeps Happening
If your boiler is constantly losing pressure, showing F22 and going to lockout, then you most likely have a leak on the boiler or central heating system which needs to be fixed.
If the boiler pressure is dropping straight away after repressurising, then you must have a serious leak or an open-ended pipe on the system. This must be found and fixed to get your boiler working again.
Other Causes of an F22 Fault
Other causes for the Vaillant boiler F22 fault code, if it’s not low water pressure, could be:
- Pressure sensor
- PCB
How to Repressurise
To repressurise a Vaillant boiler, you must find the filling loop. If it’s a built-in filling loop, it will have two grey handles under the boiler. Both handles must be turned to open and then closed when the pressure reaches 1 to 1.5 bar.
If it’s an external filling loop, it will probably be on two of the pipes under the boiler. It will most likely have two valves with black handles and a flexible hose connecting them together. You must open both valves to repressurise the boiler, then close them both when it is repressurised.
You should be able to hear the water filling the central heating system when both valves are open, if not, then the filling loop might have problems or the house’s mains water might be turned off.
Vaillant Pressure Gauge
The main Vaillant boiler pressure gauge is a digital pressure gauge on the screen on the front of the boiler. You have to press multiple buttons to find and read it.
Vaillant boilers have annoying manual pressure gauges which don’t have any numbers on them so most people don’t know if it’s on the correct pressure. It always looks like the pressure is low, even though it’s not.
Vaillant Boiler Guides
- Vaillant boiler no hot water
- Vaillant boiler leaking
- Vaillant F54 fault
- Vaillant F28 fault
- Vaillant F75 fault
- Vaillant F83 fault
- Vaillant F29 fault
Conclusion
The F22 Vaillant fault code is almost certainly caused by low boiler pressure. You must repressurise your boiler to fix the problem and clear the fault code.
Feel free to ask any questions in the comments below, and I’ll do my best to help. If you found this post helpful, please consider sharing it.
