Vaillant Boiler F28 Fault – Error Code Guide

The Vaillant F28 error code is triggered after three failed ignition attempts and is most likely caused by a gas supply problem or if it occurs during cold weather, a frozen condensate pipe.

Since the problem may be to do with the gas supply, a professional must be called to deal with the issue.

The F28 error does not mean it’s time for a new boiler, but some parts may need replacing.

What Does a Vaillant F28 Error mean?

The F28 error code means that the boiler has failed to ignite, and is triggered after three failed ignition attempts.

Since the flame is what enables the boiler to heat water, the heating system cannot work without it. When the F28 code shows, your boiler will lockout.

This error code usually means:

  • There is not enough gas in the system
  • There is a fault with the ignition components
  • Or that the condensate pipe is frozen.

What Causes a Vaillant F28 Error?

The most common cause of the F28 error is a problem with the gas supply; either a lack of supply to your home or due to the gas valve in the boiler.

Less commonly, there is an error with the gas meter, such as a blockage.

Alternatively, the fault could lie with the spark electrode, which can become worn down with general use. If this is the case, it means that although there is a supply of gas, the boiler cannot produce a spark to ignite the flame.

If none of these appears to be the problem, the F28 code can also be triggered by a malfunctioning PCB.

Another common cause is cold weather; boilers have a condensate pipe which goes outside and expels waste liquid.

During a cold snap it can freeze, which causes a blockage and subsequently stops the boiler working, which commonly triggers an F28 error code.

You can usually identify when this is the problem because you will also be able to hear a gurgling sound coming from the heating system.

How to Fix a Vaillant F28 Error

With the exception of the condensate pipe freezing (which can be fixed by simply thawing the pipe), the F28 error code is triggered by an internal boiler issue.

This will need to be identified and resolved by a professional – or if the problem is a lack of gas supply to your home, this should be addressed with your gas provider. 

If the fault lies with the gas valve, gas regulator, spark electrode or PCB then this should be dealt with by a Gas Safe Engineer.

If the problem is the valve, it is more likely that it has become stuck rather than worn out, in which case it is safe to reuse after it has been unstuck.

However, if it has become worn out then it will need to be replaced, which will cost around £300 including parts and labour.

Both a faulty spark electrode and a faulty PCB can be easily and cheaply replaced.

Can you Fix a Vaillant F28 Error Yourself?

If the problem is a frozen condensate pipe, this is easy to fix for yourself – but once you’ve identified that this is the issue, it’s important not to attempt to use the boiler again until the problem has been fixed.

Condensate pipes are easy to identify because they are made out of plastic rather than metal, and they will come out of the wall directly above a drain. 

To thaw your condensate pipe you first need to locate the blockage (which will most likely be in a bend or joint), and either apply a hot water bottle or pour hot water directly over it. After thawing the pipe, you will probably need to reset the boiler to start it again.

If this is not the cause, then you will be unable to fix the F28 error. If the problem is your gas supply, then you will be able to identify this yourself by testing other gas power appliances in your home; however, if you do identify that this is the problem then it needs to be addressed by your gas provider. 

If the problem is the spark electrode or gas valve, then this absolutely must be dealt with by a Gas Safe Engineer.

Does an F28 Error Mean my Boiler is Broken?

No, it doesn’t. Most likely there is a gas supply problem a part such as a gas valve or spark electrode simply needs replacing – sometimes, it just means you need to pour hot water over a frozen pipe! That said, if your F28 was caused by a worn-out gas valve, then this probably means that your boiler is quite old and it might be time to start thinking about investing in a new one.

Is an F28 Error Dangerous?

It’s never wise to try and fix a boiler error without professional help, but since the F28 could be due to an issue with ignition or gas flow, it’s even more important that resolving the error is left to a professional – tampering with the boiler in this scenario could be very dangerous.

Do I Need to Reset my Vaillant Boiler After an F28?

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.

If your F28 code was caused b a frozen condensate pipe, then you will most likely need to reset the boiler after the pipe has been thawed to get it working again.

How Can I Prevent the F28 Error from Happening?

One action you can take to reduce the chances of the F28 error is to prevent your condensate pipe from freezing.

This can be done by setting the boiler at a higher flow temperature during the cold months, and by regularly checking the pipe during cold snaps to remove any ice before it blocks the pipe.

You can also insulate the pipe with foam wrapping to prevent it from freezing in the first place.

Other than that, you can ensure that your gas bills are paid to date and that your spark electrode is up to scratch whenever you have your boiler serviced.

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