F72 Vaillant Boiler Fault: Meaning, Symptoms, Actions, Costs, Causes, Prevention
The F72 Vaillant fault code indicates a discrepancy between the flow and return NTC thermistors, suggesting they are providing incorrect readings. This issue may cause the boiler to shut down automatically for safety reasons. To resolve this fault, you should contact a Gas Safe registered engineer to inspect and rectify the problem. Repair costs typically range from £100 to £300, depending on the specific cause and required parts. Common causes include defective thermistors, wiring issues, or incorrect installation. Regular annual maintenance can help prevent this fault by ensuring all components function correctly. Always ensure that any work beyond basic operations described in the user manual is performed by a Gas Safe registered engineer. The next section will explain the meaning of the F72 fault in more detail.
Meaning of the F72 Vaillant Boiler Fault
The F72 fault code on a Vaillant boiler signifies a permanent temperature difference between the flow and return NTC thermistors.
These thermistors monitor the temperature of water entering and leaving the boiler, ensuring efficient operation. When they provide inconsistent readings, the boiler’s system detects a fault, leading to automatic shutdown to prevent potential damage or safety hazards.
Is the F72 fault a serious issue?
Yes, the F72 fault is serious as it causes the boiler to shut down automatically to prevent potential damage or safety hazards. Prompt attention from a Gas Safe registered engineer is necessary to diagnose and resolve the issue.
Can I reset my boiler to fix the F72 fault?
Resetting the boiler is unlikely to resolve the F72 fault, as the issue stems from defective thermistors, wiring problems, or incorrect installation. A qualified engineer needs to inspect and address the underlying cause.
Does a new thermistor always trigger the F72 fault?
No, a new thermistor should not trigger the F72 fault if installed correctly. However, if the thermistors are fitted to the incorrect pipes during installation, the fault may occur.
The next section will describe the symptoms of the F72 fault in more detail.
Symptoms of the F72 Vaillant Boiler Fault
When your Vaillant boiler experiences the F72 fault, it may shut down automatically to prevent potential damage or safety hazards. The boiler’s display panel will show the F72 error code, indicating an issue with the temperature readings from the flow and return thermistors. You may notice inconsistent heating performance or a complete lack of heating and hot water. In some cases, the boiler may attempt to operate but will shut down shortly after detecting the fault.
How To Recognise the F72 Vaillant Boiler Fault on Different Types of Boilers
The manifestation of the F72 fault can vary depending on the type of Vaillant boiler installed.
Vaillant Combi Boilers
In Vaillant combi boilers, the F72 fault presents as an error code on the digital display panel. The boiler may cease to provide heating and hot water, and you might observe fluctuations in water temperature before the system shuts down.
Vaillant System Boilers
For Vaillant system boilers, the F72 error code appears on the LCD screen. The central heating system may become inactive, and the hot water cylinder might not receive heated water. You could experience uneven heating or a complete lack of hot water supply.
Older Non-Digital Boilers
Older Vaillant boilers without digital displays won’t show the F72 code directly. Instead, you may observe a series of flashing lights or notice that the boiler is unresponsive. The absence of consistent heating or hot water indicates a potential issue with the temperature sensors.
The next section will suggest actions to take in the event of the F72 Vaillant Boiler Fault.
What to Do When Your Vaillant Boiler Shows the F72 Boiler Fault
If your Vaillant boiler displays the F72 fault code, indicating a discrepancy between the flow and return NTC thermistors, it’s essential to take appropriate action to restore heating and hot water.
- Turn Off the Boiler: Switch off the boiler to prevent any further operation that could cause additional issues.
- Contact a Gas Safe Registered Engineer: Arrange for a qualified professional to inspect and rectify the problem, which may involve checking the thermistors, wiring, and installation. Attempting to fix this issue yourself can be dangerous and may void any existing warranties.
- Avoid Resetting the Boiler Repeatedly: While it might be tempting to reset the boiler, doing so without addressing the underlying issue won’t resolve the fault and could lead to further complications.
Safety Disclaimer
Always adhere to the guidelines provided in your boiler’s user manual. Any maintenance or repairs beyond basic operational instructions should be performed exclusively by a Gas Safe registered engineer to ensure safety and compliance with regulations.
How to reset my Vaillant boiler after an F72 fault?
Locate the reset button on your boiler’s control panel and press it for a few seconds. The boiler will attempt to restart, but if the F72 fault persists, it indicates an underlying issue that requires professional attention. A Gas Safe engineer should inspect the thermistors, wiring, and overall installation to resolve the problem.
Should I turn off my boiler if it shows the F72 error?
Yes, turning off the boiler prevents further operation that could worsen the issue. If the temperature sensors are providing incorrect readings, the boiler may attempt to function inefficiently, leading to further malfunctions. Switching it off and calling a Gas Safe engineer is the safest course of action.
Where can I find a Gas Safe engineer to fix an F72 fault?
You can find a certified engineer by contacting a Gas Safe Engineer through our website. We are Vaillant-approved service providers and we specialise in diagnosing and repairing manufacturer-specific faults, ensuring a correct and safe fix.
How to check if my boiler has a gas or water leak after an F72 error?
The F72 fault relates to incorrect temperature readings rather than gas or water leaks. However, if you notice a gas smell or suspect a leak, turn off the gas supply at the meter and call the emergency gas helpline. For water leaks, inspect the area around the boiler for visible drips or damp patches and contact an engineer if you find any issues.
Should I replace my boiler if it keeps showing the F72 fault?
If the F72 fault persists after replacing the thermistors or addressing wiring faults, an engineer should assess whether deeper issues exist, such as internal corrosion or a failing PCB. If your boiler is old and experiencing multiple faults, replacing it with a more efficient model may be the best long-term solution.
Cost to Repair F72 Vaillant Boiler Fault
The cost to repair the F72 Vaillant boiler fault depends on whether the issue is caused by a faulty thermistor, wiring issue, or incorrect installation.
If a Gas Safe engineer can recalibrate or reposition the thermistors, the cost typically ranges between £100 and £200, including call-out and labour. If the thermistors require replacement, the parts cost £20 to £50 each, with total repair costs falling between £150 and £300.
If additional issues exist, such as faulty wiring or a failing PCB, repair costs may exceed £400. Always contact a Gas Safe engineer to ensure repairs are done safely and correctly.
The 3 Major Causes of the F72 Vaillant Boiler Fault
The F72 fault occurs when the flow and return NTC thermistors provide inconsistent temperature readings. The three main causes are faulty thermistors, incorrect sensor placement, and wiring issues.
1. Faulty Thermistors
Thermistors measure water temperature and relay data to the boiler’s control board. Over time, thermistors can degrade, leading to inaccurate temperature readings. If one or both thermistors fail, the boiler detects an imbalance, triggering the F72 fault.
2. Incorrect Sensor Placement
If the flow and return thermistors are installed on the wrong pipes, they will provide inaccurate temperature readings. This issue often arises after a boiler service or component replacement. An incorrectly placed thermistor can cause the boiler to misinterpret temperature differences, leading to shutdowns.
3. Wiring Issues
Loose, corroded, or damaged wiring between the thermistors and the PCB can cause communication errors. If the boiler does not receive consistent temperature data, it assumes a fault has occurred and shuts down to prevent damage. Electrical issues should always be diagnosed and repaired by a qualified engineer.
Preventing Future F72 Vaillant Boiler Faults
Regular boiler maintenance reduces the risk of an F72 fault by ensuring the thermistors and wiring remain in good condition. An annual boiler service allows an engineer to check for early signs of sensor failure and ensure the components are correctly positioned.
A boiler cover contract provides routine maintenance, priority call-outs, and discounted repairs, reducing the likelihood of unexpected failures. Ensuring that repairs and replacements use manufacturer-approved parts also helps maintain system accuracy.
Disclaimer
Any work beyond basic operation described in the user manual should only be performed by a Gas Safe registered engineer. Opening the boiler casing, replacing thermistors, or adjusting internal wiring without certification is dangerous and may invalidate your boiler warranty. Always seek professional assistance when diagnosing or repairing boiler faults.