Vaillant boilers are renowned for their reliability, but like any complex system, they can encounter issues. Understanding fault codes is crucial for effective maintenance and timely repairs.
Fault codes serve as a diagnostic tool, alerting you to specific issues within your boiler system. By decoding these numerical signals, you can pinpoint problems accurately and take appropriate action. Whether you're a homeowner or a heating professional, this comprehensive overview will equip you with the insights needed to address Vaillant boiler faults promptly and effectively.
Common Vaillant Fault Codes
Vaillant F22 Boiler Fault
The F22 fault code indicates insufficient water pressure within the boiler system. This issue can arise from:
- Gradual pressure loss over time
- Leaks in the system
- Recent bleeding of radiators
This problem occurs mostly in the EcoTEC Plus and EcoTEC Pro models. As most modern boilers are equipped with sensors that constantly measure the pressure of the water in the system, in Vaillant's boilers, there may be a red light showing on the display screen which confirms that the boiler is not operating correctly.
How to fix a F22 Fault?
If you notice your boiler pressure dropping below the ideal range of 1 to 1.5 bar, you can repressurise the system using the filling loop, but be sure to check visible pipework for leaks and contact us immediately if the pressure drops again rapidly as this could indicate a problem requiring professional attention.
However, not only does this not fix the problem but it can dilute the chemicals that are protecting the system which can be more damaging. You'll need a professional Gas Safe registered engineer to check the F22 error code because if your boiler continues to operate while this code is showing, then your boiler could be functioning with a deficit of water in the system, which could lead to the complete damage of your boiler.
Vaillant F27 & F28 Boiler Faults
These codes either refer to the boiler's flame not working correctly; the PCB not working the gas valve not working correctly (F27) or the boiler having a frozen condensate pipe meaning that the condensate waste cannot run into the drain and is trapped in the boiler, meaning that the boiler cannot function (F28).
How to fix a F27 or F28 Fault?
You may have to simply wait for the condensate to defrost to fix this fault. If the pipe runs outside, then you could pour hot water over the pipe to defrost it, or place a bucket under the boiler and disconnect the plastic waste pipe on the far right of the boiler, before draining the condensate into the bucket. If this does not work, then you will have to call a professionally qualified Gas engineer to inspect the boiler and its internal components.
Vaillant F29 Boiler Fault
When your Vaillant boiler displays the F29 error code, it indicates a flame failure issue. While this could be due to simple causes like an empty gas meter, local gas works, or supply interruption, we strongly recommend having a Gas Safe registered engineer inspect the problem as it relates to gas safety. Please contact our team for prompt, professional assistance with your F29 fault.
How to fix an F29 Boiler Fault?
If it turns out that there is no problem with the gas supply to your boiler, then your professional gas engineer will test the gas valve operation and adjustment settings, check the condition of the ignition leads and check the condition and operation of the ignition unit are all running smoothly.
Vaillant F75 Boiler Fault
It is particularly common in the EcoTEC Plus range of Vaillant boilers. If the F75 code is flashing in your display, the fault is most likely to do with the boiler’s sensor not registering the fact that the pump has started running, thereby failing to register a change in pressure.
This commonly happens in some of Vaillant's older models that are equipped with a Wilo pump instead of a newer, improved Grundfos pump. A build-up of sludge can block the pressure sensors in older Vaillant boilers.
How to fix a F75 Boiler Fault?
You can do a quick manual check of the pump on your Vaillant boiler by simply turning on the heating or hot water. If you hear a low humming sound when the boiler starts working, this is the sound of the pump circulating the water through the pipework, which means both your pump and boiler are working just fine.
However, if there is no sound after you have turned on the boiler, then this indicates that your pump is faulty. If your pump is no longer working, then you will need to call a gas engineer to come and replace the pump or sensor of your boiler.
Vaillant F23 Fault
When your Vaillant boiler displays an F23 error code, it indicates a concerning temperature difference between the flow and return pipes. This common issue often stems from trapped air in your system, potential blockages in your pipework or radiators, or problems with your circulation pump.
How to fix a F23 Boiler Fault?
While you can try bleeding your radiators to release trapped air and check for cold spots that might indicate blockages, we recommend professional inspection to ensure your system's safety and efficiency.
Vaillant F76 Error - Overheating Fault
The F76 error code, which signals dangerous overheating in your boiler, requires immediate attention. This serious fault typically occurs due to blockages in the heat exchanger, circulation problems, or faulty temperature sensors (thermistors). While you should immediately turn off your boiler if you see this code, it's crucial to have a Gas Safe registered engineer perform a thorough inspection.
How to fix a F26 boiler fault?
At Boiler Boys London, we'll comprehensively check your system's pressure, assess the heat exchanger condition, test all sensors, and ensure your heating system is operating safely and efficiently. Contact us right away if you're experiencing either of these fault codes for expert diagnosis and repair.
