Vaillant F29 Fault Code - Flame Failure
The Vaillant fault code F29 boiler flame failure Q & A or require an engineer for an emergency boiler repair.
The Vaillant Boiler Fault Code F29 Error Common Q&A
Just below, we have a list of common questions relating to the F27 fault code on the Vaillant boiler.
- What does the Vaillant F29 fault code mean?
- I can smell gas; will that cause the F29 fault code to be displayed?
- My gas is off, now what?
- Why does my boiler lockout and show the F29 fault?
- Can I just reset my boiler to fix the problem?
- My boiler clicks or ticks a few times, then shows the F29 fault, what is the cause?
- How do I know if the gas supply to the boiler is too low?
- Can pipework cause an issue with gas supply?
- Will a pre-paid gas meter cause a F29 fault to be displayed?
- The F29 code is displayed mainly in the winter, what could be the issue?
- How can my flue cause a F29 fault code to be displayed?
- The flame in the boiler keeps going out when its windy, how can I fix this?
- Will the burner need to be replaced if it has debris in it?
- How much does it cost to fit a new boiler burner?
- It doesn’t look like there is any spark or flame, what’s the problem?
- How much does it cost to fit a new electrode and ignition lead?
What does the Vaillant F29 fault code mean
The F29 fault code will be displayed on a Vaillant boiler when one of the following is causing an issue:
- The inlet gas pressure to your boiler is too low
- There is a problem with the flue
- The gas valve has not been correctly adjusted, or is faulty
- There is debris in the burner
- The ignition lead or electrode has a fault
These faults in your Vaillant boiler lead to one thing; flame failure during operation.
I can smell gas; will that cause the F29 fault code to be displayed
First, turn off your gas. Call a Gas Safe engineer or the gas emergency board.
Gas is not a force to be messed with.
My gas is off, now what
A Gas Safe engineer will run a tightness test.
This allows them to see if there’s a leak, and how bad it is. They’ll then figure out what’s causing the leak before fixing it.
Why does my boiler lockout and show the F29 fault
Most ignition or gas related faults (not just the F29) will lockout the boiler in the same way.
A boiler lockout is a fail-safe so that the boiler isn’t operating in conditions that:
- Are unsafe for people in the property
- ill cause damage to internal parts
For example, if the flue is the issue (which is designed to vent dangerous gases from the property), the boiler recognises the fault, and locks out to protect you from these gases.
But, another example is a burner that is clogged with debris.
This could cause the burner to fail completely long-term (rather than just be inspected and cleaned) and therefore, locking out in this case is to protect the boiler’s parts.
Can I just reset my boiler to fix the problem
Boilers are designed to cease operation and lockout for a reason; safety.
Essentially, it’s your boiler telling you it needs to be fixed. Therefore, you shouldn’t reset the boiler until the problem has been fixed.
A Gas Safe engineer will diagnose the fault, fix it, and reset your boiler for you.
My boiler clicks or ticks a few times, then shows the F29 fault, what is the cause
The clicking or ticking you can hear is likely to be the boiler trying to ignite. Modern boilers will attempt to ignite 3 times before a problem is recognised and the boiler locks out.
So, the fact that your boiler is ticking, doesn’t narrow down the potential fault.
Although it does suggest that the boiler is attempting to fire up, which helps to narrow down the potential problem.
How do I know if the gas supply to the boiler is too low
A Gas Safe engineer will need to diagnose the issue with the gas supply.
First, they’ll check that the gas valve is adjusted correctly. If the appliance has been worked on recently, or the gas valve replaced, it may be that this adjustment is not allowing enough gas to the boiler.
If the gas valve is adjusted correctly, they’ll check to see it’s not faulty.
If it is, boiler manufacturers stock gas valves for all their boilers, so the valve can simply be replaced.
Can pipework cause an issue with gas supply
Debris in pipework can lead to a small blockage.
As pipework for gas is small (22mm-28mm on domestic properties, bigger for commercial), even the smallest amount of debris can cause an inadequate supply of gas, and a boiler to lockout.
Will a pre-paid gas meter cause a F29 fault to be displayed
First, let’s assume you have credit on your meter. If you have, the boiler may need to be reset if you ran it to the point where all credit and emergency credit was used.
A Gas Safe engineer can run checks to see the pressure at the meter and the boiler. If the difference is high (i.e. with the lower pressure being at the boiler), it’s likely pipework is causing the issue.
If the pressure is low at the meter, it’s either the meter at fault, or the supply from the mains.
Obviously, the mains gas pressure (i.e. gas pressure to the meter, rather than coming from the meter) is a utility provider issue.
They’ll advise if this is the case, and you’ll need to contact your mains gas supplier.
The F29 code is displayed mainly in the winter, what could be the issue
If the gas engineer has checked the meter and found no faults, did they check it on a freezing cold day?
Some gas meters are located outside. And, the regulators on the meter are known to freeze. If the problem mainly occurs in the winter, the unit needs to be insulated.
How can my flue cause a F29 fault code to be displayed
Poor installation, or debris in a flue can cause an F29 fault to be displayed.
Your boiler needs to vent gases out through the flue to work correctly. If a blockage occurs, the boiler will recognise that the pressure/temperature internally, is not correct for optimal operation.
It will lockout (causing a flame failure), and display the F29 fault code.
A similar thing occurs with the condensate pipe (the small white pipe that you might have noticed dripping).
The difference here is that the condensate will expel condensed waste gases in the form of a liquid.
It’s rare that the condensate pipe gets blocked with debris, but in winter months they are prone to freezing.
This creates the blockage, and the boiler to lockout in the same way as it would if it recognised a flue blockage.
An engineer can thaw out the pipe, run other checks to ensure there are no other faults, and reset the boiler.
The flame in the boiler keeps going out when its windy, how can I fix this
It’s very rare that wind alone will cause flame fault on a boiler. However, on occasion, this is the case and caused by an incorrect flue installation.
Generally, the wind isn’t physically blowing out the flame.
When a boiler recognises an imbalance of flue gas pressure, it will lockout.
A slight gust of wind can change the pressure in the flue and causes the lockout.
Alternatively, the fan (that helps expel the gases to the flue) is at fault.
A typical example would be deteriorating bearings. The fan is working below its desired speed and even the slightest draught will be able to enter the flue, change the pressure in the flue, and cause the boiler to lockout.
A similar thing can happen if the fan is set to a speed that’s too low.
Have you had a new fan fitted, or has someone altered the speed (possibly to reduce the noise of the fan)?
The lack of draught being created by the fan could be the culprit.
Will the burner need to be replaced if it has debris in it
Debris in the burner can cause a F29 fault, but a faulty burner can also cause the same problem.
An engineer will need to check whether the lockout causing the fault code to appear is due to a faulty, or dirty burner.
A dirty burner can be cleaned. Once inspected (assuming there is no excessive wear or damage), it will be operational again.
If the burner is faulty, or shows excessive signs of wear or damage, replacing it is the only option.
How much does it cost to fit a new boiler burner
The cost of fitting a new burner in your boiler will vary, depending on which model boiler you have.
Expect to pay somewhere in the region of £300-£400, including parts and labour.
It doesn’t look like there is any spark or flame, what’s the problem
Assuming all other parts are working correctly, and the ability to create a spark is the issue, the problem could lie with the electrode or ignition lead.
These can fail for several reasons. If your boiler is old, there’s a good chance they have simply deteriorated over time.
However, any small leak inside the boiler can cause electrical components to fail.
When boiler parts get hot, they’ll condense the water and it will find its way to almost every single boiler part; including the electrics.
How much does it cost to fit a new electrode and ignition lead
If it’s just the electrode and ignition lead that need replacing, that’s good news. You should expect to pay around £100 for them to be fitted.
But, if your engineer has noticed a small leak which has led to the failure, this needs to be addressed quickly.
Many times, when electrodes or ignition leads fail due to moisture, the PCB (the boiler’s circuit board) isn’t going to be too far behind. These units are usually a little more protected, given how important and expensive they are.
The leak needs to be found and fixed quickly. Having a new PCB fitted is no £100 job.
You should expect to pay somewhere closer to £400.
Other Vaillant Fault Codes And Error
If your looking for the list of error codes relating to the Vaillant boiler then please read the article Vaillant Boiler Fault Codes And Cures