Vaillant F72 Fault Code: Causes and How to Fix It
If you own a Vaillant Ecotec Pro or Ecotec Plus boiler, you may have encountered the Vaillant boiler F72 fault code. This error can disrupt your hot water and central heating, leaving your home cold and uncomfortable. In this guide, we’ll explain what the F72 fault code means, its common causes, and a step-by-step approach to fixing it.
Table of contents
What Does the Vaillant F72 Fault Code Mean?
The F72 error code indicates a problem with the flow or return NTC thermistors in your boiler. Thermistors are temperature sensors that monitor the water in the boiler’s system. If they give inaccurate readings, the boiler cannot correctly regulate water temperature, often leading to a lockout.
Key points:
- The fault affects the flow or return pipes.
- It may be caused by defective thermistors, faulty wiring, or installation errors.
- When triggered, the boiler may mistakenly think the water is too hot, preventing proper heating.
Common Causes of the Vaillant F72 Fault Code
There are three main causes of an F72 fault:
1. Broken or Faulty Thermistors
Thermistors measure water temperature by changing resistance in response to heat. Over time, these parts can wear out or fail, causing inconsistent readings and triggering the F72 fault.
2.Internal Wiring Issues
Faulty or loose wiring between the PCB (printed circuit board) and the thermistors can prevent accurate communication. Vibrations or aging can damage wires, leading to the F72 error.
3.Installation Errors
In rare cases, the flow and return thermistors may have been connected to the wrong pipes during installation. If testing wasn’t completed correctly, the boiler may show an F72 fault from the start.
Other factors can include limescale buildup, which can degrade components and cause inaccurate temperature readings.
How to Fix the Vaillant F72 Fault Code: Step-by-Step
Time needed: 5 minutes
Fixing an F72 fault typically requires a qualified Gas Safe engineer. Attempting DIY repairs can be dangerous and may damage your boiler. Here’s what professionals do:
- Diagnose the Issue
The engineer will test the flow and return pipe temperatures using a manual thermometer to verify if the thermistors are accurate.
- Check the Wiring
All wiring between the PCB and the thermistors is inspected for looseness, damage, or corrosion. Faulty wiring is replaced.
- Replace Faulty Thermistors
If the thermistors provide incorrect readings, they will be replaced to restore proper water temperature monitoring.
- Correct Installation Errors
If the thermistors were connected to the wrong pipes, they will be correctly installed and tested to ensure proper function.
- Treat Limescale Buildup (if needed)
Limescale can be removed, and a professional may install a magnetic filter or scale decreaser to prevent future problems.
- Reset the Boiler
After repairs, the boiler will be reset by the engineer to clear the fault code and resume normal operation.
Can You Fix the Vaillant F72 Fault Code Yourself?
No. Diagnosing and repairing electrical faults in a boiler is dangerous without Gas Safe certification. Only a registered engineer should handle this problem to prevent injury, boiler damage, or voiding your warranty.
Preventing Future F72 Faults
- Schedule annual servicing for your Vaillant boiler.
- Treat your system with limescale inhibitors and install a magnetic filter.
- Replace worn parts promptly to prevent more costly breakdowns.
Conclusion
The Vaillant F72 fault code can be frustrating, but understanding its causes and solutions makes it easier to handle. This error usually points to issues with the flow or return thermistors, wiring faults, or installation errors. While it may be tempting to try fixing it yourself, only a Gas Safe registered engineer should diagnose and repair the problem to ensure safety and prevent further damage.
With proper maintenance, regular servicing, and timely replacement of worn components, you can prevent F72 faults and keep your Vaillant boiler running efficiently, ensuring reliable heating and hot water all year round.
Frequently Asked Questions
Topping up your boiler pressure is a simple fix and can be carried out without a heating engineer. First of all identify what sort of filling system you have and then follow the instructions, or watch our technical trainer show you how its done.
A boiler can indeed lose pressure without a visible leak. Common reasons include issues like a faulty expansion vessel. This vessel is essential in maintaining system pressure; if it malfunctions, pressure may drop even if there is no leak. Another reason for pressure loss is trapped air in the system.
The F74 fault code on your Vaillant boiler signals that your boiler’s water pressure sensor is detecting readings outside its normal range. This isn’t as scary as it might sound – it’s actually your boiler’s way of letting you know there could be an issue with the pressure monitoring system.
