Vaillant F22 Fault Code: What it is & How to fix it

Vaillant boiler broken, displaying the F22 fault code? Find out what it means and what it might cost to repair.

Like all boiler brands, Vaillant's are capable of breakdown.

And like all good boiler brands, Vaillant's at least let you in on why they aren't happy. Opposed to the silent treatment.

These fault codes inform homeowners what the problem is - or at least spit out something you're able to Google.

While some faults can be fixed DIY, others must be solved by a professional.

But what about Vaillant’s F22 fault code in particular?

Boiler old, unreliable and costing a fortune in repairs? Simply answer these questions, get your fixed price and you could get a new one installed as quick as tomorrow.

What Does the F22 Code Mean?

Low water pressure can trigger an F22 Vaillant error code or it may be caused by a system leak or faulty part.

It’s important that your boiler has the right balance of water and air. This makes sure your boiler can provide hot water correctly when required.

Low water pressure occurs when your heating system doesn’t have enough water to meet its needs. If this occurs, your boiler will fail to ignite, triggering an F22 and your boiler to shut off.

The correct water pressure for Vaillant boilers is 1.5 bars. You can find your water pressure on the pressure gauge. If water pressure falls to 0.3 or less, an F22 fault will occur.

Causes of Low Water Pressure

As mentioned, there are different potential causes for low water pressure.

Here are the common reasons for a boiler having low water pressure:

General ageing - For starters, a boiler could suffer from low water pressure simply because it has slowly seen a reduction in water pressure over time without any apparent cause explaining the gradual reduction.
Component error - If a component like the pressure sensor or pump lead has experienced an error, this could lead to low water pressure.
Leak - A common reason for a sudden drop in water pressure is a boiler leak. If a boiler is topped up but the water pressure drops relatively soon after, it’s most likely because there’s a boiler leak.

Can I Fix an F22 Fault DIY?

Whether or not an F22 fault can be fixed DIY depends on the actual cause of the issue and the type of fix required.

However, it may be difficult to know what the issue is for sure. Thankfully topping up your boiler should either solve the issue or tell you that another issue is at hand if your water pressure were to go down again in the weeks after.

Topping Up Boiler - Yes

Hopefully topping up your boiler will suffice, in which case, you fix the problem by yourself.

Here’s how you can repressurise your boiler:

Ensure your boiler is off and cooled. Of course, it should be if an F22 fault has occurred.
Find the filling loop and ensure both ends are attached.
Open both valves to allow water to enter your heating system. Watch the pressure gauge carefully.
Close both valves once the pressure gauge lands on 1.5 bars.
If the filling loop isn’t built-in, it’s time to remove it.
Turn on your boiler and check the pressure is still good.

You may be interested in Gas Engineer Allen Hart explaining the most common boiler problems and how you can resolve them in the video below:

Fixing a Leak - No

Unfortunately, you can’t repair a boiler leak by yourself. This must be fixed by a qualified professional.

Replacing a Boiler Component - No

Should a boiler component need to be replaced then you’ll also need to hire a professional.

However, if you believe your boiler is beyond economical repair, it’s probably best to simply replace your boiler entirely.

Cost of Hiring a Heating Engineer to Fix an F22

The average cost of hiring a Gas Safe Register engineer is £30 to £60 per hour although this depends on factors like your location in the UK.

This is because the labour price of heating engineers varies from region to region.

Here is the cost of specific fixes:

Topping up a boiler - £30 to £60.
Repairing a leak - £60 to £120.
Replacing a boiler component - £150 to 400.
Replace an entire boiler - £1,800 to £3,800 *

*It may be best to replace your boiler entirely particularly if it is old and a boiler component needs to be replaced.

Either way, though, if you have an old boiler, you may decide it's time to get a new one installed. Of course, this is expensive, which is why it’s good to know that it’s possible to purchase a boiler and have it installed on finance.

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:

Will my Warranty Cover Repairs or Replacement Work for an F22 Fault?

Your boiler warranty will only cover fixes that relate to a defect caused by how the boiler was manufactured.

In other words, if the fault is caused for any other reason such as boiler misuse, it will not count.

Furthermore, even if a manufacturing error is at play, it’s important to confirm that your boiler warranty is currently active.

The length of boiler warranties for Vaillant boilers can vary quite a bit. Moreover, specific terms and conditions also cover these warranties.

As some examples, a domestic Vaillant boiler warranty comes with the following Ts & Cs:

Your boiler must be serviced once a year by a Gas Safe engineer.
It must have been installed and commissioned within half a year of despatch, again by a Gas Safe Register engineer.

So, unfortunately, it’s unlikely that your boiler warranty will cover a repair or replacement job, if either is required for your Vaillant boiler.

This includes in relation to fixing an F22 fault.

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