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Last updated: 3rd May, 2024


F22 Vaillant Fault Code

F22 Vaillant Fault Code

Key takeaways

  • The Vaillant F22 error code indicates low water pressure in the boiler.
  • It is usually caused by insufficient water in the system due to leaks.
  • Professional assistance from a Gas Safe registered engineer is recommended for fixing this error.

Boiler error codes are crucial indicators for identifying and diagnosing issues within heating systems. They serve as the first point of reference for troubleshooting.

When homeowners encounter the F22 error code on their Vaillant boiler, it signifies low water pressure within their heating system. This issue is typically a result of not enough water in the system, which is often caused by leaks. 

For a boiler to function correctly, maintaining the correct water pressure is essential. Low pressure hinders the boiler's ability to circulate hot water through the heating system, leading to inadequate heating and potentially the boiler ceasing operations as a safety precaution.

Identifying an F22 fault is relatively straightforward, as the Vaillant boilers are designed to display this error code when the system's water pressure falls below the operational threshold. 

The presence of this error code halts the boiler's operation to prevent damage to the system and to signal the need for maintenance. While some may consider troubleshooting the problem themselves, seeking the assistance of a Gas Safe registered engineer is often recommended to ensure safety and proper resolution of the issue.

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What Is a Boiler Error Code?

A boiler error code, such as the Vaillant F22, acts as a critical diagnostic tool for identifying issues within your boiler. These codes are displayed on the boiler’s control panel when the system's internal sensors detect operational anomalies.

This specific alert system helps homeowners and service technicians quickly pinpoint problems, facilitating faster and more accurate troubleshooting and repairs.

Importance of Understanding Error Codes for Boiler Maintenance

Understanding these error codes is essential for maintaining the health and efficiency of your boiler. The F22 boiler fault, for instance, immediately informs you that there's a problem related to water pressure, allowing for prompt action to mitigate any damage. Familiarity with such codes can save time and money on maintenance and prevent small issues from escalating into major, costly repairs.

  • F22: indicative of low water pressure.

  • F28: suggests ignition failure.

  • F75: marks a pump water shortage.

What Does the Vaillant F22 Fault Code Mean?

The Vaillant F22 fault code specifically indicates that the boiler has detected low water pressure. This condition can prevent the boiler from operating safely and efficiently.

It is a common issue that can occur due to various reasons such as leaks in the system, recent maintenance work, or natural pressure losses over time.

Possible Reasons Why This Error Code Appears

A number of issues could lead to the occurrence of the F22 fault:

  • Low water pressure, inherently indicating that the amount of water within the system is not sufficient for the boiler to function correctly.

  • Leaks in pipework or radiators may go unnoticed, slowly draining the system of water and thus reducing pressure over time.

  • Problems with the pressure sensor itself could misrepresent the actual pressure, causing the boiler to present the F22 error incorrectly.

In essence, if the heating system reports an F22 fault code, it's recommended to inspect for leaks and verify the pressure reading to determine the correct course of action.

Signs of the Vaillant boiler f22 fault code

Recognising the signs of a Vaillant F22 error code is pivotal to addressing it promptly. The code is specific to Vaillant boilers and is indicative of water pressure troubles within the heating system.

List and Explain Common Signs and Symptoms That Indicate This Specific Error

  • Persistent Low Water Pressure: The central heating system's pressure gauge often illustrates pressures below the 1.5 bar norm, revealing insufficient water within the system.

  • Leak Indicators: Unexplained damp spots or leaks around the boiler, pipework, radiators or radiator valves can signal issues leading to pressure drops.

  • Boiler Lockout: If the boiler ceases to function and displaces the F22 code, it's a direct signal of the fault, often concomitant with a boiler 'lockout'.

  • Cold Radiators: Despite the heating being on, one might find the radiators remain cold, attributing to inadequate water pressure.

  • Flashing Numbers: Occasionally, the boiler display might flash numbers such as 0.3, which couples with the F22 code to highlight water pressure anomalies.

Can I Fix This Boiler Error Code Myself?

  • Pressure Adjustment: If the issue is merely low pressure, homeowners can often re-pressurise the system themselves following the manufacturer's guidelines.

  • Leak Inspection: Conducting a preliminary visual inspection for leaks around the boiler, pipework, and radiators might reveal something fixable without professional help.

  • Professional Assessment: For persistent or complex issues, particularly when self-troubleshooting doesn't resolve the F22 code, professional intervention is recommended.

Do I Need to Contact a Gas Safe Engineer to Fix This Error Code?

In some instances, remedying the F22 error code may be straightforward; however, professional intervention is highly recommended for safety and compliance.

Advice on When It's Necessary to Call a Professional

Calling a Gas Safe registered engineer is crucial when:

  • The boiler's water pressure doesn't stabilise after repressurising the system.

  • There are signs of water leaks within the heating system.

  • The homeowner is not comfortable performing any boiler repairs or troubleshooting.

In cases where the boiler continues to display the F22 error even after checking and adjusting the pressure, it could be indicative of a more complex issue. Given the potential for intricate technical complications, enlisting a qualified engineer is not only about rectifying an error code, but also about ensuring the long-term reliability and safety of the heating system.

All of iHeat’s engineers are fully qualified and Gas Safe, ensuring a swift and safe installation.

Explanation of What a Gas Safe Engineer Is and Why Their Expertise Is Important

A Gas Safe engineer has:

  • The necessary certification to work legally on gas appliances.

  • Access to advanced diagnostic tools not typically available to homeowners.

Their role is not merely confined to addressing the immediate F22 fault; they meticulously inspect the boiler to diagnose underlying issues that could pose risks. Moreover, incorrect handling of boiler repairs can result in voiding the warranty, highlighting the importance of their specialised expertise.

In matters of gas safety and compliance, the significance of a Gas Safe engineer's qualifications can't be overstated. They are the gatekeepers to safe and efficient boiler operation, and their seal of approval is your peace of mind.

How Much Does Fixing the vaillant boiler f22 fault code Cost?

Discovering the F22 error code on a Vaillant boiler can be worrying, but understanding the potential repair costs can put a homeowner’s mind at ease.

General Cost Range for Fixing This Error

The cost range to fix the F22 error code typically varies. Most homeowners may expect to pay between £50 to £200 for boiler repairs connected to this issue. This estimate largely depends on whether it's a simple pressure issue or a problem requiring more extensive repairs. It is generally cost-effective to address this problem as early as possible to avoid more significant boiler damage.

Factors That Might Affect the Cost

Several factors can influence the overall cost, including:

  • The extent of the issue: A system merely needing a pressure reset will cost significantly less than one with a damaged water pressure sensor.

  • Labour rates: Costs may vary depending on the engineer’s experience and regional rates.

  • Warranty: If the boiler is still under warranty, the repair might be covered, although there may be a service fee.

  • Safety considerations: Complying with safety standards may require additional checks or parts, impacting the cost.

  • Part replacements: Should specific components be faulty, the price of these parts could affect the total expense.

These variables highlight the importance of understanding the intricacies of the F22 error and consulting with a professional for an accurate quotation.

Do I Need a New Boiler?

Encountering the F22 error code on a Vaillant boiler indicates low water pressure, which can often be resolved without the need for a complete boiler replacement. However, several factors should be assessed to determine whether repair will suffice or if a new boiler is warranted.

Criteria to Decide Whether a Repair Is Sufficient or If a New Boiler Is Required

  • Age of the Boiler: If the boiler is still within its expected lifespan, usually 10-15 years, and the history of repairs is minimal, it's more likely that a repair may be sufficient.

  • Frequency of Breakdowns: Frequent breakdowns can be a sign that the boiler is on its last legs. In such cases, replacement rather than repair might be more cost-effective.

  • Repair Costs vs. Replacement: When the cost of repair approaches a significant fraction of the price of a new boiler, it could be more prudent to invest in a new, more efficient system.

Information on the Lifespan of Boilers and When Replacement Is Typically Recommended

Boilers have an average lifespan of around 10 to 15 years. However, Vaillant ecoTEC boilers, known for their efficiency and reliability, might last longer if they are well-maintained. As boilers age, they lose efficiency, which can drive up energy costs.

Trustpilot reviews often reflect satisfaction with Vaillant boilers' longevity, which may influence the decision to repair over replace. However, if the boiler is nearing the end of its efficient lifespan, replacement is typically recommended.

New Boiler Costs

Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.

Boiler costs can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer. 

Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.

Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type.

Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).

Installation Type

Price (inc VAT)

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System to combi conversion


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New boiler install


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Back boiler to a combi


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System to system


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The F22 fault code on a Vaillant boiler signifies a low water pressure problem, typically stemming from insufficient water within the system or a leak. They should address this promptly to prevent further issues, such as damage to the heat exchanger. The initial course of action involves checking for visible leaks and repressurising the boiler if necessary.

Common causes for the F22 code:

  • Leaks in the heating system

  • Malfunctioning pressure gauge

  • Insufficient water supply

To resolve the F22 error:

  1. Inspect the system for signs of leaks and repair if detected.

  2. If no leaks are found, repressurise the system according to the manufacturer's instructions.

  3. Monitor the pressure gauge to ensure it maintains the correct pressure level.

It is strongly recommended to seek professional assistance if the problem persists, as they may indicate more complex issues requiring expert attention.

Safety should never be compromised, and a qualified engineer will ensure the system operates efficiently and securely. Regular maintenance can prevent the recurrence of such faults and extend the life of the boiler.

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Frequently Asked Questions

How do I fix my Baxi boiler E133 error?

To rectify an E133 error on a Baxi boiler, first check the gas supply to make sure it is on and that there are no issues with supply pressure. Then, reset the boiler according to the user manual. Persistent problems may require professional service to inspect the ignition system or flame detection sensors.

What does 133 mean on a Baxi boiler?

The E133 code on a Baxi boiler indicates that the boiler has experienced an interruption in gas supply, a failure in the ignition process, or the flame has not been detected after several attempts. This is a safety feature to prevent gas from accumulating without being ignited.

How do I clear the error code on my Baxi boiler?

To clear the E133 error code, you can try resetting the boiler using the reset button or turning it off and on again using the main power switch. If the code persists, it may indicate a more serious issue that requires attention from a qualified technician.

How do you ignite a Baxi boiler?

To ignite a Baxi boiler, ensure the gas supply is on. Then, follow the startup procedure outlined in the boiler's user manual, which typically includes setting the thermostat to a desired temperature and using the boiler's control panel to initiate ignition.

Why is my Baxi boiler not igniting?

If a Baxi boiler fails to ignite, it could be due to a problem with the gas supply, such as valves not being open or low pressure. It might also be an issue with the ignition system itself, including faulty spark electrodes or problems with the flame sensor.

How do I get the flame back on my boiler?

Reigniting the flame in a boiler involves checking gas supply valves, ensuring good pressure, and following the boiler's ignition procedure. If these steps do not work, the flame sensor or other components may need cleaning or replacement.

How do you fix a flame failure on a Baxi boiler?

Fixing a flame failure on a Baxi boiler may require cleaning or repositioning the flame sensor to ensure it can properly detect the flame. If these actions don't resolve the issue, it's best to consult a professional engineer who can pinpoint and repair the cause of the flame failure.

Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.