Vaillant Boiler f22 Error – How To Fix

Vaillant Boiler f22 Error – How To Fix

How to Fix Vaillant Boiler F22 Error: A Step-by-Step Guide

Encountering the F22 error code on your Vaillant boiler can be concerning, but it's a common issue that often has a straightforward solution.

The F22 error typically indicates that there is low water pressure in the boiler.

Here鈥檚 a comprehensive guide to help you understand and fix the F22 error, ensuring your boiler returns to optimal performance.

Understanding the Vaillant Boiler F22 Error

The F22 error code appears when the boiler detects low water pressure, which is essential for the efficient operation of the system.

Insufficient pressure can prevent the boiler from functioning correctly and can even cause damage over time if not addressed.

Common Causes of F22 Error

  1. Low Water Pressure: The most frequent cause of the F22 error is simply low water pressure in the system.
  2. Leaks in the System: Leaks in pipes, radiators, or the boiler itself can cause a pressure drop.
  3. Faulty Pressure Sensor: Sometimes, the pressure sensor might be malfunctioning, giving false readings.
  4. Air in the System: Air trapped in the system can also lead to pressure issues.

How to Fix the Vaillant Boiler F22 Error

1. Check the Pressure Gauge

First, locate the pressure gauge on your Vaillant boiler. The needle should be in the green zone, typically between 1 and 1.5 bar. If it鈥檚 below this range, you need to increase the system pressure.

2. Repressurise the System

If you are confident enough and have done it before you can go ahead and repressurise the boiler, but if you have little idea then please follow the steps to repressurise your Vailliant Boiler

  1. Turn Off the Boiler: Ensure the boiler is switched off and has cooled down before starting any work.
  2. Locate the Filling Loop: The filling loop is usually a silver, flexible hose found beneath the boiler, connecting it to the main water supply.
  3. Open the Valves: Slowly open the valves on the filling loop. You should hear water entering the system.
  4. Monitor the Pressure Gauge: Keep an eye on the pressure gauge and stop when it reaches 1.5 bar.
  5. Close the Valves: Once the desired pressure is reached, close the valves securely to prevent any leaks.

3. Check for Leaks

Inspect your boiler and the entire heating system for any signs of leaks. Focus on joints, radiators, and pipes. If you identify any leaks, they need to be repaired to maintain the correct pressure.

4. Bleed the Radiators

Air trapped in the radiators can affect the pressure. Here鈥檚 how to bleed your radiators:

  1. Turn Off the Heating: Make sure your heating system is off and the radiators are cool.
  2. Use a Radiator Key: Insert the radiator key into the bleed valve at the top of the radiator and turn it anti-clockwise.
  3. Release Air: You will hear a hissing sound as the air escapes. Once the water starts to come out, close the valve promptly.

5. Check the Pressure Sensor

If the problem persists after repressurising and bleeding the radiators, the pressure sensor might be faulty. In this case, it鈥檚 best to consult a professional to check and possibly replace the sensor.

6. Consult a Professional

If you have tried all the above steps and the F22 error still appears, it鈥檚 time to call a qualified heating engineer. They can diagnose and fix more complex issues, ensuring your boiler operates safely and efficiently.

Preventive Measures

To avoid encountering the F22 error in the future, consider the following preventive measures:

  • Annual Service: Have your boiler serviced annually by a qualified engineer.
  • Regular Pressure Checks: Periodically check the pressure gauge and repressurise if necessary.
  • Inspect for Leaks: Regularly inspect your heating system for any signs of leaks.


The Vaillant boiler F22 error is a common issue related to low water pressure that can usually be resolved with some basic steps.

By understanding the causes and following this guide, you can quickly fix the error and ensure your boiler runs smoothly.

Regular maintenance and attention to pressure levels will help prevent future issues, keeping your home warm and your boiler in good condition.

If you continue to experience problems or are uncertain about any steps, always consult a professional to avoid further damage to your boiler system.