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Vaillant F29 Fault Code: Causes & How To Fix

Vaillant boiler F29 error code – what it is & how to fix it

Vaillant is one of Europe’s top boiler and heating appliance brands, creating some of the best boilers sold in the UK. Sometimes, however, your Vaillant boiler may sometimes have something wrong with it, causing an error code to appear on the boiler’s display, much like the Vaillant F29 fault code.


When you see an F29 fault code, this means that there is a flame failure in your boiler, usually caused by a lack of or fault with your gas supply.

If you see this, the best thing to do is call a Gas Safe registered engineer out to your property to come and fix it, as they will likely have the knowledge and experience to do so.

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How to fix the Vaillant F29 fault code

When you see any error code, including the Vaillant F29 error code, you will want to deal with it as soon as possible to get your boiler back up and running. With some error codes, you are able to fix them yourself if they don’t require too much work or experience, but most of the time, the best thing to do is call a professional Gas Safe engineer to come and sort it.


When your boiler does have an issue and a fault code appears on the boiler’s display, your boiler will likely perform an emergency shutdown to prevent any further damage to the boiler and to keep the household safe. This boiler lockout will also mean no hot water for your home, so getting your boiler’s flame back to normal is important.

Whenever your boiler issues are sorted and you wish to get it back up and running, you’ll have to reset your boiler, allowing all of the components to begin working again and hot water to return household.

What a Vaillant F29 fault code means

As previously mentioned, if you were to see an F29 fault code on your Vaillant boiler, it will likely mean a flame failure. Without a working boiler flame, your boiler won’t be able to produce hot water or steam properly, meaning getting a shower or turning on your radiator will be a difficult task.

There are a number of reasons why your boiler flame has failed and the F29 fault code has appeared, so here we will go through them with you and tell you what they mean and what you can do.

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F29 fault code causes

Frozen condensate pipe

A frozen condensate pipe can be quite a common issue with a condensing boiler, especially during the Winter. Condensate pipes are a component of your central heating system designed to get rid of acidic waste water that isn’t wanted in your system.

frozen condensate pipe

When experiencing low temperatures, water that flows through the pipe can collect in areas, such as the joints and exits, and get frozen, where a blockage occurs. Once this happens, the waste liquid cannot be as easily disposed of and can cause issues internally for your boiler.

To melt the ice and unblock the condensate pipe, you can warm up water in a kettle so that it is warm/hot but not boiling, so it doesn’t damage the pipe. Once this is warm, pour the water over the pipe to slowly unblock it and allow the wastewater to flow through it once again.

Alternatively, you can pour warm water into a water bottle and place it next to the pipe to slowly thaw it out. This can be done if you’re not that confident in pouring warm water over the condensate pipe without damaging it. Make sure to reset your boiler when this is all done to allow your boiler components to start functioning properly again.

Gas supply or gas valve problem

When a boiler flame failure occurs, a common reason is that something is wrong with the gas supply. Problems with the gas valve, such as a gas leak, can be the main reason for this as it means the gas pressure is too low, not allowing your boiler to work.

engineer checking gas valve

Over longer periods of time, the inlet gas pressure of your boiler can drop due to a clogged boiler burner. This can lead to an ignition error for your flame, causing a boiler lockout. To fix a faulty gas valve, you will likely need to call a heating engineer out to your property to come and find the cause of the low gas pressure and repair it.

Regular boiler service can go a long way for your boiler’s health and will usually mean that a lot of the complications your boiler faces can be dealt with before getting worse.

Lead problems/Ignition electrode

Ignition leads are a crucial part of your boiler if you are wanting it to fire up and if it isn’t, it could mean there is a problem with it. An internal leak can cause quite a lot of harm to electrical components in your boiler, such as your ignition lead. Any damage to these parts will mean your boiler flame won’t ignite and you will be without a functioning heating system.

If you find your ignition lead is damaged, you should call a Gas-Safe engineer out to come and service your boiler, so they can replace any of the parts that are necessary for your boiler to fire up again. Doing this yourself isn’t recommended as you could further damage the boiler or cause harm to yourself.

Faulty flue

When your boiler is in operation, it will need to dispose of harmful gases that can be produced, which is done so through the flue pipe. A boiler flue will usually be seen coming out the side of your home, allowing these harmful gases to be transported outside of your household.

boiler flue

When a flue pipe is poorly installed, it can cause blockages in the pipes meaning the flue gases cannot flow freely through it. This can end up blocking your boiler flame and completely stop ignition, causing the F29 fault.

To get this issue resolved, you should get a boiler engineer to come to your household and make sure your flue is installed correctly this time. To further prevent blockages for your flue, you can get your engineer to install a flue guard, giving it extra protection and more peace of mind for you.

Other common Vaillant fault codes

Vaillant boiler service cost

boiler service

Getting your Vaillant boiler serviced regularly can help prevent a lot of these issues as well as similar problems, especially with Vaillant fault codes. You will be able to get a Gas-Safe engineer to come and examine your boiler, repairing or replacing parts that require it.

The fee for Vaillant boiler service is usually between £80-£125, with quite a few factors changing the price such as the type of boiler, the model it is and how old your boiler is. Although this might seem like quite a lot, it is very likely that this will cost less in the long term as you can stay on top of your boiler issues and won’t have constant boiler breakdowns that need fixing.

Vaillant boilers at a fixed price

If your Vaillant boiler is giving you constant issues and breaking down all of the time, it may be for a new boiler. Getting a boiler replacement can actually end up being more financially beneficial as you won’t have to keep paying for new parts and repairs, especially for people with older Vaillant boilers.

Learn more about new boiler quotes online for a replacement boiler by Vaillant.

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