In the main, new Vaillant boilers are fairly reliable. However, owners of the older ecoTEC range have been known to experience a few problems with the fault code F75.
But what is the Vaillant F75 error code and how do you fix it?
This guide will explain everything you need to know.
Vaillant is a German boiler manufacturer – so you would expect their boilers to have first-rate engineering. However, that has not always proven to be the case.
In Vaillant’s defence, they weren’t actually to blame for the defects. Like most boiler manufacturers, Vaillant source mechanical parts from third-party manufacturers.
The early models were fitted with a pump and a pressure sensor that were not as reliable as they should be. Subsequently, EcoTEC models made between 2000-2010 often experience an F75 fault code.
Since the first-generation EcoTEC range was developed, the boilers have undergone three major overhauls. The newer models are much more durable and reliable.
The EcoTEC Plus and Eco Pro 28 appear to be the boilers that are most likely to experience the F75 error code.
What is the Vaillant F75 Fault Code?
The Vaillant F75 error code is caused by one of two reasons;
- A faulty pump or
- A clogged pressure sensor.
When you receive one of these messages it is recommended you contact a Gas Safe Engineer to resolve the issue.
According to Vaillant’s official EcoTEC boiler manual, the explanation for the F75 fault code reads:
The error message is basically saying is that the boiler is not detecting any pressure and is unable to circulate water around the pipes or through the central heating system.
The cause of the fault is either because the pump is not working or the pressure sensor is clogged in debris and is unable to detect any change in pressure even though the pump is working.
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F75 error – Pump Fault Causes
When Vaillant originally launched the EcoTEC range, the pumps were manufactured by a company called Wilo. Unfortunately, these pumps were prone to leaking and splitting. The reputation of Wilo has since deteriorated.
Since 2005, Vaillant began fitted pumps made by the Danish manufacturer, Grandos. The company has a strong reputation in the industry and deliver high-quality products. British boilermakers, Glow Worm use them as well.
Subsequently, most EcoTEC boilers don’t have as many problems with the pump, certainly problems that are regarded as out-of-the-ordinary. If you have an EcoTEC 20 or EcoTEC Pro that was made pre-2005, and keep getting the F75 error message, it’s probably a problem with the Wilo pump.
How to Detect A F75 Default Code Pump Defect
- Reset the boiler. You do this by pressing the lockout button – the one with a symbol of a flame on it.
- Wait for a few moments then run a hot water tap. This will fire the boiler.
- When a boiler is fired, the heating pumps kicks in and sends the water to the tap.
- If the pump is broken and non-operational, you won’t hear or feel anything. In this situation, you will need to install a new pump. It is recommended that you call a Gas Safe Registered engineer to install a replacement pump for you.
- If the pump is working you will hear a humming sound and the boiler will softly vibrate. Bear in mind that the pump will run for a couple of seconds, then fall silent for about 20 seconds, then rumble again. If you can hear the pump at work, the F75 fault code is due to a fault with the pressure sensor.
F75 Error – Pressure Sensor Fault
Mechanical equipment in boilers tends to collect carbon deposits and limescale. The debris gathers on the pressure sensor and the build-up can get so thick the sensor is unable to detect changes in pump pressure.
If you hear the pump working whilst the boiler is in operation, but you are not getting any hot running water or heat through to your radiators, change the pressure sensor.
There are two ways of repairing a pressure; clean the existing component or fit a new one. Either option will require a qualified engineer.
Believe it or not, the most cost-effective option is to buy a new pressure sensor. They are not very expensive – between £30-£85. It actually costs more in labour costs to clean a water pressure sensor.
Costs of Repairing a Vaillant F75 Fault
The cost of repairing the pump or pressure sensor for a Vaillant EcoTEC boiler will depend on the make of the replacement part and the ease of the job. Some boilers can be harder to reach and repair than others.
The prices below cover the cost of pumps and pressure sensors. Installation costs should be negotiated with a Gas Safe Engineer but will typically be around £130-£150.
|DIFF||Typ505 ex comfort||£44.48|
Vaillant EcoTEC Pro 28 Review
Despite the problems of past Vaillant boilers, it should be noted that the latest-generation are much more reliable. They will, of course, still experience defects like any other boiler but owners of models post-2010 shouldn’t have as many F75 faults.
The Vaillant EcoTEC Pro comes in three power outputs; 24KwH, 28KwH and 30KwH. The Vaillant EcoTEC Pro is arguably the most popular as it is best suited to flats and average-sized three-bedroom household with one bathroom.
With measurements of 720mmx440x338mm, the unit is compact enough to fit neatly into an airing cupboard or under the stairs. Alternatively, you should be able to store it in a kitchen cupboard. If you don’t have much space, the Vaillant EcoFit Pure 825 is slightly smaller.
The Vaillant EcoTEC Pro 28 has an ErP energy efficiency rating A and a Sedbuk rating of 89.3%. The flow rate is 11.1 l/min which is plenty for a shower and will also run a bath.
These boilers are also shipped with a 5-year warranty which is a testament that the manufacturer is confident their new range of EcoTEC boilers is reliable.
If you are experiencing problems with an old Vaillant boiler and interested in finding a replacement boiler, take advantage of our free service. We can help find quotes for replacement boilers together with installers in your area. Our service is free of charge and there is no obligation to purchase.