Vaillant got an F75 code? It isn't a winning Wonka bar. Here's what F75 means, and how to fix.
- What Causes the Vaillant F75 Fault Code?
- Common Reasons Why This Error Code Appears
- Do I Need to Contact a Gas Safe Engineer to Fix the F75 Fault Code?
- Common Causes Of The Vaillant F75 Error Code
- How to Diagnose the Vaillant F75 Fault Code
- How to Fix the F75 Error
- How Much Does it Cost to Repair an F75 Error?
- How Can You Avoid the F75 Error?
- Do You Need A New Boiler?
Exploring the juice of the F75 fruit below, we'll go as deep for as long as you can hold your breath for.
But you aren't here because you like Googling boiler fault codes.
F75 dragged you here.
F75 isn't a good thing.
Here's what to do.
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Key takeaways:
F75 error code indicates a failure to detect pressure change in the boiler.
Common causes include a faulty pump, pressure sensor, or a blockage in the system.
Troubleshooting steps involve checking for leaks, ensuring the pump is working, and verifying system pressure.
When to Call a Professional: If the problem persists after troubleshooting, contact a gas safe engineer for further inspection and repair.
In many cases, upgrading your old boiler to a new, more efficient model is the best solution.
Get a new quote (finance available including 0% APR).
What Causes the Vaillant F75 Fault Code?
The F75 fault code on Vaillant boilers points to a problem with the boiler’s pressure sensor or pump. This issue occurs when the boiler cannot detect any pressure change during the pump’s operation. As a safety measure, the boiler will lock out until the problem is resolved. Pressure consistency is crucial for safe and efficient boiler operation.
The Vaillant F75 error/fault code is displayed on the following Vaillant boiler models:
Vaillant EcoPro
Common Reasons Why This Error Code Appears
Faulty or Blocked Pressure Sensor: The pressure sensor may be clogged with debris, dirt, or limescale over time, leading to inaccurate pressure readings. Alternatively, the sensor itself may be defective and need replacement.
Pump Malfunction or Blockage: If the pump is not functioning correctly due to blockages, wear and tear, or mechanical failure, it may not generate the required pressure increase during operation, causing the boiler to issue the F75 fault.
Airlocks in the System: Air trapped within the heating system can obstruct water flow, preventing proper pressure changes and triggering the F75 code. Bleeding the radiators may help alleviate this issue.
Low Water Pressure: A lack of sufficient water pressure in the system may prevent the boiler from detecting necessary pressure fluctuations. Check that the system pressure is within the recommended range (usually 1.0 to 1.5 bar).
Electrical Faults: Electrical issues such as loose or faulty wiring between the pump and pressure sensor can prevent the components from communicating properly, leading to the fault code.
Do I Need to Contact a Gas Safe Engineer to Fix the F75 Fault Code?
Yes, it is essential to contact a Gas Safe registered engineer to resolve the F75 fault code since it is typically associated with a faulty internal component. These qualified professionals are legally certified to work on gas boilers and will ensure that any repairs are carried out safely and in compliance with industry regulations.
Attempting to fix complex boiler issues without professional expertise can pose safety risks and may void your boiler warranty.
Common Causes Of The Vaillant F75 Error Code
Faulty Pressure Sensor Causing the Vaillant F75 Error Code
In the early days of the Vaillant EcoTec range, there were some key components that seemed to experience issues more often than others.
Image showing a standard pressure sensor
Unfortunately, one of these parts was the pressure sensor, which detects pressure changes.
Important note: This common fault was restricted to the early launch of the EcoTec, which ran from 2005 to 2010.
There has been a series of improvements made since then and the issue is not as frequent in newer models.
What else can cause a faulty pressure sensor?
If you have a newer EcoTec pro and don’t suspect it’s related to the manufacturing fault present in some older versions, there are other plausible causes for a faulty pressure sensor.
One of the main causes of a malfunctioning sensor is the build-up of debris on the sensor itself.
For instance, over time dirty boiler water containing the likes of rust, sludge and limescale deposits can leave their mark on your system.
It’s for this reason that Heatable offer a complete system cleanse using a pro flush when we install any new boiler.
We also offer extras, such as inhibitors, for those individuals who reside in hard water areas that are susceptible to limescale deposits.
Faulty Boiler Pump Causing the Vaillant F75 Error Code
In many modern boilers, including modern Vaillant boilers, a boiler pump by Grundfos is used.
Image showing a standard boiler pump
These are some of the most reputable boiler pumps available, renowned for being competitively priced and durable.
Sadly, old Vaillant boilers used to use a less reputable boiler pump, primarily one called Wilo, which over the years has lost favour, becoming known for failing prematurely and experiencing issues.
Therefore, if you have an older Vaillant EcoTec boiler that’s built with a Wilo pump that’s experiencing issues and causing the F75 fault code.
Is your Vaillant boiler experiencing some of the brand's most common fault codes? We have you covered in our F29 fault code and F62 fault code guides.
How to Diagnose the Vaillant F75 Fault Code
As mentioned already, the Vaillant models that seem to be prone to the F75 fault code error are the EcoTEC Plus and the EcoPro 28.
With that in mind, here are a few tips on how to diagnose the root of the problem with your particular boiler:
How to Diagnose a Faulty Boiler Pump
To determine if your boiler's pump is faulty and triggering the display of the F75 error, you can follow these simple steps:
Firstly, reset your boiler by pressing the reset button, this is easy to find as it has a flame icon embossed on it.
Allow your boiler time to restart, this should take a few minutes.
Next, run a nearby hot tap and allow the boiler to fire up and the heat pump to kick in.
Shortly, you should be able to hear the pump operating, which will provide an audible humming sound and gentle vibration.
If the pump is not functioning as normal you probably won't hear or feel anything, signalling that the pump is indeed broken and in need of repair.
However, if your pump is operating as normal but soon falls silent and you lose hot water, the F75 fault is more likely to be the result of a broken pressure sensor.
How to Diagnose a Faulty Pressure Sensor
If your boiler's pump sounded and felt like it was operating as normal, but you still lost hot water and were presented with the F75 error code, then the next most likely cause of the fault is an issue with the pressure sensor.
Pressure sensors in boilers are prone to collecting debris and dirt from the circulating water in your central heating system.
This debris can build up to the point where it will block the pressure sensor from detecting the necessary signals e.g. changes in pressure, resulting in your pump not being triggered and the boiler malfunctioning.
Logically, it may sound like the best option is to clean the pressure sensor and that should do the trick, however, it's usually advised that the part be completely replaced instead.
The usual reason for this is that it makes sense from a financial perspective. Since cleaning can be laborious, it can cost a substantial time in labour costs.
If the sensor itself is in complete disrepair, it may simply mean withholding the inevitable and wasting more money in the process.
Replacement pressure sensors are relatively cheap too.
How to Fix the F75 Error
Unfortunately, there is no DIY fix for the F75 error. If the pump is broken, it will need to be replaced with a new one by a registered Gas Safe engineer.
If the issue lies with a faulty pressure sensor e.g. one that is in need of a cleaning, this will also require the assistance of a Gas Safe engineer.
However, as mentioned, cleaning is rarely advised due to the high labour costs in comparison to the relatively cheap cost of replacing it with a new pressure sensor instead.
Is your Vaillant boiler experiencing some of the brand's most common fault codes? We have covered many Vaillant boiler error codes in the following guides:
How Much Does it Cost to Repair an F75 Error?
If your boiler is displaying the F75 and it is caused by either a faulty boiler pump or pressure sensor, it will need to be diagnosed and repaired by a registered Gas Safe engineer.
The costs will depend on factors, such as the Vaillant boiler model you have e.g. some boilers are more complex and take longer to repair, so naturally cost more to repair as the labour and time required will be greater.
How Much Does a New Boiler Pump Cost?
Excluding installation costs, a replacement boiler pump from a leading brand can cost between £250 and £350 on average.
How Much Does a New Pressure Sensor Cost?
A replacement pressure sensor can cost between £150 and £250 excluding labour costs.
How Can You Avoid the F75 Error?
It's always recommended that you have your boiler serviced annually, in fact, most boiler manufacturers outline that this is a condition of cover.
During the service, the Gas Safe engineer will look for any issues and carry out basic maintenance, including basic cleaning, which will help to avoid parts like the pressure sensor becoming blocked and malfunctioning.
In addition, a routine power flush is advised in order to keep your heating water free from dirt and sludge, a major culprit of blockages and corrosion in your boiler and central heating system.
Unfortunately, sometimes boilers just malfunction, this is especially true of old boilers that are no longer in their warranty period.
If this sounds like you, it may be time to replace your boiler before it starts to cost you more and more in repair costs.
Do You Need A New Boiler?
In some cases, replacing a boiler can make more financial sense than continuing to repair it. Here are the key factors to consider:
Age of the Boiler - If your boiler has surpassed its average lifespan (typically beyond 15 years) and is no longer covered by the manufacturer’s warranty, replacing it may be a more cost-effective option to avoid recurring repair expenses.
Repair Costs - When the cost of repairing the boiler exceeds 50% of the price of a new one, it’s usually more financially sensible to invest in a replacement rather than continuing with costly repairs.
Frequency of Breakdowns - If your boiler is breaking down more frequently, it’s often a sign of significant wear and tear and it is beyond economical repair. In such cases, replacing the boiler can help avoid mounting repair costs and the inconvenience of ongoing issues.
Energy Efficiency - Older boilers tend to be far less efficient than modern models, leading to higher running costs. Upgrading from a G-rated to an A-rated boiler could save you up to £385 per year in energy bills, making replacement a financially smart decision in the long run.
By carefully weighing these factors, you can determine whether replacing your boiler offers better value and peace of mind compared to continued repairs.
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