Continue reading
%20(1).PNG)
The F29 error code on Vaillant boilers relates to a "loss of flame" during operation. Put simply, your boiler was working and a flame was present, but it was lost.
This isn't to be confused with a "flame detection" issue, where the boiler fails to ignite.
F29 isn't a generic code, it's specific to Vaillant.
If you have a different model or brand, here are the fault codes that might be displayed if you are having a similar issue:
When there's an issue with your boiler, a fault code is displayed and it will lock out. This doesn't necessarily mean your boiler needs to be replaced.
A Gas Safe engineer needs to find and fix the problem before resetting your boiler to clear the F29 fault code.
(Source)
So, we know your boiler worked (with a strong flame), but the flame has suddenly been lost. Now, we need to figure out what’s caused that to happen.
Fixing boilers isn’t easy, which is why there aren’t many reliable specialists. This is simply because fault codes aren’t specific. It gives a Gas Safe engineer an indication of what might be wrong, but in reality, there’s a lot of fault finding (and time) involved.
For example, the F29 error code on Vaillant boilers could point to one or more of the following:
Below, we’ll get into each of these in detail. Remember, you shouldn’t work on a gas boiler yourself. Gas Safe repair engineers are the only people qualified to work on gas combi, heat-only and system boilers.
The printed circuit board (PCB) on your boiler is one of the most critical components. It receives and sends signals to all other boiler components.
A faulty PCB may result in your boiler having various faults (rather than just one). Generic faults are the likes of:
If your boiler display is showing the F29 fault code linked to a PCB issue, it's likely you'll also have some specific faults such as:
The fixes for your Gas Safe engineer here are to check the connections and earth continuity (repair if possible).
If the PCB can't be repaired, expect a replacement to be in the region of £500-£600.
For a boiler that's old and out of warranty, that's not a wise investment. Especially considering that you can get a new one from our list of the most reliable boiler brands, with a 5+ year warranty from £2,300.
Get a free boiler quote here (no obligation to buy and no contact details needed). You can then compare that directly with your PCB’s repair cost.
Above, we mentioned the flame sensor. Whilst your boiler might not be receiving the correct flame signal, it might not be the PCB's fault.
Over time, your flame sensor can develop hairline cracks thanks to getting hot. It could also have a weak earth or worn probe, both of which will contribute to a weak signal.
Whether your PCB or flame sensor is to blame, if a flame isn't detected, your Vaillant boiler will lock out and display the F29 error code until the issue is fixed.
To check the flame sensor, your Gas Safe engineer will:
If the flame sensor is pinpointed as the issue and can't be fixed, you'll need a replacement.
Boiler model dependent, you could be looking at a replacement cost of £150-£225.
If your burner isn't working correctly it's likely you'll have issues such as:
If the F29 fault code seems to appear and disappear at random, there's a good chance the burner is to blame.
Most likely culprit? Carbon build-up over time is partially blocking the burner, so it's not working to its full potential.
The fix? Your Gas Safe engineer will remove the burner and clean off as much debris as they can. If easily accessible, they'll also clear the injector port.
If this doesn't fix the issue, you've guessed it; you probably need a new burner.
Burners vary in cost considerably. With diagnostic, cleaning and then a replacement, you should expect to pay somewhere in the region of £400-£500.
Similar to a PCB replacement, a sizable repair bill like this on an old boiler makes little sense.
Especially considering you can get an Ideal Logic Plus fairly cheaply. That comes with a standard 7-year warranty, 10-years on the heat exchanger (another expensive component).
Check new boiler prices here using our 60 second clickable tool.
Next, your boiler engineer will need to look at the gas supply.
Pressure into your meter, out of your meter and into your boiler needs to be stable. Fluctuations will cause the sensor to send a signal to the PCB (unstable or insufficient gas supply) and your boiler will lockout.
This could happen due to a faulty regulator, issue at the mains or even a gas valve fault.
Most commonly, this is a gas valve fault. Sometimes they stick and sometimes, they fail altogether.
So, how do you fix it? A repair engineer needs to check inlet and working gas pressure, as well as external gas pressure to determine if this is a regulator fault (repair if possible).
If they find external gas pressure is to blame, you'll need to call your utility supplier.
The most common fault with a gas valve is usually it's sticking (not opening or closing in full). If your boiler engineer can't free it, a replacement will be needed.
Expect a replacement gas valve to cost £300-£400.
A condensate blockage can cause an array of fault codes to be displayed. It’s uncommon that it will cause the F29 error code to be displayed, but not unheard of.
Blockages in the condensate (small white pipe on the exterior of your property) are common in cold conditions. If it’s routed incorrectly, waste isn’t able to flow out of it fast enough and can freeze, causing a blockage.
How do you fix it? Pour warm water on it until the pipe is completely thawed. Once thawed, you’ll be able to reset your boiler to clear the F29 fault code.
You can reset your boiler, but without fixing the problem it will lock out again.
The F29 fault relates to flame loss which is potentially a gas supply, ignition component, a blockage, PCB or sensor issue.
Yes, flame loss on a boiler is a common problem. The most common issues causing the F29 code to be displayed are due to old and tired boiler components (gas valve, flame sensor, PCB) that need to be replaced.
Call a Gas Safe engineer. They can fault-find components such as the gas valve, PCB, flame sensor as well as the gas supply.
Once they’ve found and fixed the issue, they’ll be able to reset your boiler to clear the F29 error code.
Only Gas Safe engineers are qualified to work on gas boilers. They’ll need to systematically test the: printed circuit board, flame sensor, gas supply, gas pressure, gas valve. They’ll also need to check the condensate pipe for blockage (frozen).
No, because your boiler is locked out. However, you should get a Gas Safe engineer to inspect it before resetting it.
And that’s it for this fault finding guide…
Tired of your old and unreliable boiler? Get boiler quotes using our quick and easy online form.
Try our free quote tool. You'll have your personalised quote in under a minute.
.svg){kind=icon}
.PNG)
.png)
%20(2).PNG)