Vaillant Boiler F24 Fault Code
The Vaillant fault code F22 emergency boiler repair.
The Vaillant Boiler Fault Code F24 Fault Code Common Q&A
Just below, we have a list of common questions relating to the F24 fault code on the Vaillant boiler.
- What does the Vaillant F24 fault code mean?
- Is the F24 fault code easy to fix?
- What pump faults could cause the F24 fault code on my Vaillant boiler?
- How do I know if my pump is seized?
- How do I fix a seized pump to clear the F24 fault code?
- Will I need a new pump if it’s seized?
- How would the speed setting generate a F24 fault code?
- My boiler is leaking, will that cause the F24 fault?
- What is leaking in my boiler?
- The pump isn’t making a noise, warm, or vibrating at all, is that causing the F24 error?
- If the PCB is the issue, should I replace it, or the entire boiler?
- If an airlock is the issue, how do you remove it to fix the F24 fault?
- How do I know when all the air is released?
- Should I bleed towel rails and radiators to fix the F24 fault?
- How can a heat exchanger in my Vaillant contribute to the F24 error?
- How can I fix a blocked or dirty heat exchanger?
- What else can cause a circulation fault?
- Can I clean out my central heating to reduce the risk of blockages that cause a F24 fault?
- Are there any ways to protect my heating system from circulation faults?
- What’s the difference between a Micro/Compact boiler filter, and other filters?
What does the Vaillant F24 fault code mean
The Vaillant boiler F24 fault code isn’t limited to just one error, although it focuses on lack, or no water circulation.
So, your engineer is going to have to run a diagnostic to figure out the problem.
The fault code will relate to one of the following problems:
- Faulty Pump
- Closed isolation valves
- Air lock in the boiler or heating system
- Heat exchanger blocked with debris
Is the F24 fault code easy to fix
If someone has recently attended to your boiler or heating system, they might have turned the isolation valves below the boiler to the off position.
If they have, that’s going to starve the heating system of the water it needs to operate.
This is where the simplicity of fixing the F24 fault ends.
If the isolation valves aren’t the problem, an engineer will need to run diagnostics and inspect parts to figure out the issue.
What pump faults could cause the F24 fault code on my Vaillant boiler
Anything that affects the pump’s ability to circulate water will contribute to the F24 fault code being displayed.
There’s a few problems that could cause the issue:
- Seized internal components
- Pump full of debris
- Incorrect speed setting
- No power
How do I know if my pump is seized
Anything that creates energy will give off some heat. But, a boiler pump certainly shouldn’t be hot to the touch.
If it is, it’s likely that an internal component is seized, and the motor is working overtime to compensate (and is eventually going to burn out).
If you can feel a small vibration (signalling the pump is working), but the pump is incredibly hot, it’s likely a seized internal component is the issue.
How do I fix a seized pump to clear the F24 fault code
A gentle tap on the pump can sometimes free internal components.
However, it’s advisable to have a heating engineer come and inspect the pump. There’s a good chance debris has blocked the pump, and it needs to be cleaned.
Will I need a new pump if it’s seized
If this problem has been occurring for a while, there’s a good chance the motor is on its last legs.
In this case, we’d consider replacing the pump, which will then likely outlast the boiler.
How would the speed setting generate a F24 fault code
Most pumps come with the ability to adjust speed settings.
For a larger property, you’ll want a high-speed setting (it’s a long way for water to travel), and vice-versa.
If you have a large property and the pump is on its lowest setting, this could be the issue.
My boiler is leaking, will that cause the F24 fault
Given this fault code relates to lack of water, if you see pooling below your boiler, this could be what’s causing the error to be displayed.
What is leaking in my boiler
The most common issue that causes the F24 code, and a boiler to leak too, is a leaking central heating pump.
If your pump is leaking, there’s a good chance it’s either:
- Worked itself loose
- Has blown it's seals
New components do tend to work themselves loose. So, if you have had a new boiler fitted, this could be the issue.
However, it’s more likely that the pump seals have blown. This happens if the seals deteriorate, or if they are put under excess pressure.
Excess pressure could have come from:
- A pressure setting that is too high
- A pump of dirt
The pump isn’t making a noise, warm, or vibrating at all, is that causing the F24 error
The pump works in line with the PCB (printed circuit board). If the PCB is not communicating with the pump correctly, it won’t work.
If the communication between the PCB and pump is fine, and the pump hasn’t failed completely, there could be a wiring issue.
A quick diagnostic with an electrical tester can determine whether it’s the entire pump, or just the wiring.
If the PCB is the issue, should I replace it, or the entire boiler
Unfortunately, besides basic wiring issues, this is likely to mean a whole PCB replacement. A typical PCB (parts and labour) can cost over £500.
Unless your boiler is almost new (and therefore, under warranty), we wouldn’t advise spending this kind of money on a boiler that is deteriorating.
Instead, it makes much more sense to install a new boiler.
If an airlock is the issue, how do you remove it to fix the F24 fault
We’d head straight for the boiler pump. Most boiler pumps will have a bleed screw on them.
You’ll need to close the gate valves to stop the water flow to the pump.
Slowly open the bleed screw to allow any air build-up to be released. You’ll hear the air hissing out of the pump.
Don’t forget to open the gate valves when you’re done, otherwise you’ll have no water to the boiler, and the F24 will continue to be displayed.
How do I know when all the air is released
When bleeding anything (radiators, towel rails and a pump) you’ll know when all the air has escaped.
The hissing noise will be replaced with a slight drip of water (unless you’ve opened the bleed screw too much, in which case, it will be flowing).
Should I bleed towel rails and radiators to fix the F24 fault
If there’s an airlock in the system, you want to get rid of it completely; and that includes from towel rails and radiators.
You can bleed towel rails and radiators using a bleed key.
Remember, like the pump, you’ll want to watch and listen for when the hissing noise of air being released, turns to a dribble of water.
How can a heat exchanger in my Vaillant contribute to the F24 error
Water passes through the heat exchanger that’s located in the boiler. Unfortunately, this water will have heating sludge and limescale in it.
This can attach itself or get stuck to the heat exchanger, and cause the flow of water to be limited.
How can I fix a blocked or dirty heat exchanger
It’s not advisable to start taking apart a boiler. Especially when we are talking about expensive parts like heat exchangers.
Get a qualified expert to do the job for you.
They’ll be able to inspect the heat exchanger and decide whether it’s worth cleaning, or if it needs replacing altogether.
What else can cause a circulation fault
Any blockage in a central heating system will reduce water circulation.
This could be something as small as a piece of grit in a rad valve, or copper pipe that has huge internal limescale build up.
Can I clean out my central heating to reduce the risk of blockages that cause a F24 fault
Yes. For older systems, we’d recommend a hot-flush.
After getting the heating up to temperature, the system is flushed through using central heating cleaner.
Newer systems will take a powerflush.
Essentially, this is a flush at a higher pressure.
The reason you’ll want to avoid this on older heating systems is simply since old pipes, soldered fittings and radiator valves are much more prone to leaking than new ones.
The additional pressure could spring a leak.
Are there any ways to protect my heating system from circulation faults
There are 3 common ways any qualified heating engineer will be able to protect your system.
First, they’ll dose your heating system with central heating inhibitor. This helps to break down iron oxide and limescale in the central heating system.
That stops it getting stuck to the inside of radiators, pipes, and radiator valves, as well as making its way to the boiler heat exchanger and pump.
Next, you’ll need to determine if you’re in a hard water area (high mineral content, and bad for heating systems).
If you are, your engineer will be able to fit a small device called a scale reducer. This will catch the limescale that’s circulating around the heating (which will have been broken down by the inhibitor).
Finally, you’ll want to fit a magnetic system filter. If you’ve searched these before, you’ll know the best boiler filters are Fernox (such as their TF1) and MagnaClean (such as their Professional 2).
This will catch central heating sludge.
What’s the difference between a Micro/Compact boiler filter, and other filters
Boiler filter manufacturers make small and large filters.
For example, Fernox do a TF1 Compact, and MagnaClean do a Micro.
These are small filters, with smaller bodies.
That means, the capacity of central heating sludge they’ll catch is smaller. So, they are only suitable for small properties, or new heating systems where there’s likely to be little or no sludge build up.
If in doubt, buy a larger filter (such as the Pro 2/TF1). If a small filter fills up, excess heating sludge will remain in your heating system and cause damage, or another F24 fault.
And, don’t forget to get the filter cleaned out with your annual boiler service!
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