Vaillant Boiler F22 Fault – Error Code Guide

A Vaillant F22 error code is triggered by low water pressure, and can happen gradually over the life of the boiler or suddenly as a result of a faulty part or leak in your system.

At its simplest, you will be able to resolve this error yourself, but if the problem is caused by faulty parts or leakage then a professional needs to be called.

Depending on the cause of the problem, you may need to replace parts or invest in a new boiler.

What Does a Vaillant F22 Error Mean?

The F22 error code means that the water pressure in the boiler is too low, and it needs to be raised for the boiler to work properly.

Your boiler needs a particular balance between water and air to ensure it can respond properly when hot water is needed, and low water pressure means that there is not enough water in the heating system.

When this happens, the boiler won’t ignite, and your heating system will stop functioning. 

A Vaillant boiler requires the water pressure to be around 1.5 on the pressure gauge. If it drops to 0.3 or below then this is when the F22 error code will be displayed.

An F22 error triggers a lockout, which means your central heating and hot water won’t work until the error is fixed.

What Causes a Vaillant F22 Error?

There are a few things that can cause an F22 boiler error, the simplest of which is just that the boiler has naturally lost pressure over time.

This is to be expected and happens gradually over the life of the boiler.

Other causes of the F22 error can be more problematic. 

One possibility is that a component within the boiler itself has gone wrong – this is usually the pump, pump lead, or pressure sensor. 

If there is a sudden drop in water pressure, then there may be a leak somewhere in your heating system.

Pipes lose strength over time and, especially at joints, sealants lose efficacy and allow water through, causing the drop in water pressure.

It is also possible that the leak lies within the boiler system, originating on old or worn/damaged internal components.

How to Fix A Vaillant F22 Error

If the problem is that your boiler has simply lost pressure over time, then the boiler just needs to be repressurised.

To do this yourself, you can follow these instructions:

  • Amongst the pipework beneath your boiler, you will find its filling loop; a silver flexi-pipe with two taps attached.
  • Open one key fully open. Turn the other key slightly and you will start to hear water running back into the boiler.
  • Keep an eye on the pressure gauge with the bar measurement whilst you turn the tap. Once the pressure is back to 1.5 bars, turn off both taps.
  • If you turn off the taps too late the water pressure will be too high.

However, if there is a sudden drop in pressure or you keep having to repressurise the boiler, then it is likely the problem is caused by a leak in the system. This should be identified and fixed by a professional.

It’s also possible that there’s a leak within the boiler system itself rather than in the wider heating system; this can be caused by corrosion or simple age.

The part the leak is coming from will need to be identified and replaced in order to fix the problem, or in some cases the whole boiler.

In some cases, repairing a boiler leak can be quick and cheap; however, it depends on the severity of the problem and which component is faulty – some parts are very expensive to replace and, particularly if the boiler is old, hard to source.

If replacing the faulty component is expensive or if the fault is down to age and wear and tear, In this case, it may be more cost-effective to get a whole new boiler rather than replace expensive parts.

This is especially true when a boiler is past its prime, as faults are likely to become more and more frequent.

Can You Fix A Vaillant F22 Error Yourself?

If your boiler simply needs repressurising, you can quite easily do this yourself.

Equally, in some cases, if you follow the line of your pipes around your property, you may be able to spot signs of leakage yourself and pinpoint the location yourself.

Leaks are particularly likely around the joints and seals of your pipes as these are the areas where pipes lose strength over time.

However, as much as you can help out by spotting the leak for yourself, that’s as far as you should take it – fixing a leak is a task that should be left to the professionals, especially if it has sprung behind plaster or near electrics.

If the cause of the error is that there is a leak within your boiler, then you can remove the cover of the boiler yourself and see if you can see any obvious signs of water – however, you won’t be able to identify which component is causing the leak or repair the problem yourself.

When it comes to anything concerning the inner workings of the boiler, it is always best to leave it in the hands of a Gas Safe Engineer.

Does an F22 Error Mean My Boiler is Broken?

No, an F22 is not a fatal error; low water pressure won’t cause any damage to your boiler.

Is it safe to use the boiler with an F22 error code showing?

An F22 error is not dangerous; it simply means that not enough water can be circulated around your heating system, and therefore your central heating and hot water won’t work. However, the fault will need to be repaired before you try to use the boiler again.

Do I Need to Reset my Vaillant Boiler After an F22?

You can reset your boiler after an error code is displayed, but if you don’t first fix the problem the boiler will simply show the error code again and lockout. After the error has been addressed, you should reset your boiler to start it up again.

Can I Prevent the F22 Error From Happening?

It’s impossible to completely prevent boiler errors from taking place, but what you can do is ensure your boiler is regularly serviced and in good working order, and regularly check your pipes for signs of wear.

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