🕑 10 minutes read

For homeowners and landlords, the F28 Glow-worm boiler fault code can be as mysterious as inconvenient. The chilly realisation of a heating system down, especially in colder seasons, prompts an immediate need for understanding and rectification.

Like other boiler brands, Glow-worm boilers have built-in fault codes to indicate issues to homeowners. You can find out what these codes mean and how to fix them in the Glow-worm manual. Fault codes are helpful for heating engineers, too.

Now, let's explore the F28 fault code specifically. If your boiler is old and expensive to fix, answer these questions for a fixed price on a new installation, possibly as soon as tomorrow.

This complete guide serves as your troubleshooting compass through the maze of Glow-worm F28 fault code, empowering you with the knowledge to address the issue directly or to seek prompt, professional assistance from Serviceteam.

[A Homeowner's Guide to Swift Solutions]

Before we roll up our sleeves and get into the nitty-gritty of repairs, we must understand the culprit we're dealing with

What Is the F28 Glow-worm Boiler Fault Code?


The F28 fault with Glow-worm boilers usually indicates an ignition fault in the boiler. This can happen for different reasons, like no gas or a broken part like the gas valve.

Understanding the Root Causes of F28 on Boiler

To fix any problem, it's crucial to know what's actually wrong. When the error code flashes, it's your boiler's way of telling you it is struggling to ignite or there's something awry in the ignition sequence. The usual suspects for the F28 fault include:

Gas Pressure

If you've got a new boiler and it's not working right, it might be because of your gas pressure. This could happen if your gas supply isn't strong enough for your new boiler, especially if it's more powerful than your old one. You might need to upgrade your gas supply to fix this.

Sometimes, even older boilers can have problems with air pockets in the gas supply. Another possibility is that the regulator on your gas meter has frozen, but this usually only happens when it's freezing outside, not usually in the summer.

If a frozen pipe caused the F28 error, fixing it should solve the problem. But if it doesn't, you'll need to call a heating engineer.
Flue Blockage

Sometimes, an F28 fault can happen if there's a blockage in the flue, which is the pipe that lets out exhaust gases. This blockage can occur in the flue or even in the condensate pipe.

Flues can also get blocked over time from wear and tear. So, finding out why you're getting an F28 fault can be challenging, you should, therefore, contact a boiler professional for a thorough boiler repair.

Gas Valve Issues

An inaccurate temperature sensor or a problem with the gas supply can often lead to gas valve issues. The valve may not be at fault here, but wiring problems or voltage defects may affect the communication lines between it and the PCB.

In addition, if your gas valve is not set correctly, the burner won't get enough gas.
PCB Woes

The PCB serves as the brain of your boiler, orchestrating the complex sequence of combustion events. If there's an F28 code, the issue could lie with the PCB not sending the right signal at the right time.

Faulty Electrode or Ignition Leads

Sometimes, the issue might be with your boiler's electrical components. Over time, these parts can wear out or become affected by moisture and vibrations, leading to problems with ignition.

Faulty Spark Generator

A faulty spark generator is another electrical issue that could trigger an F28 fault. This part is responsible for creating sparks to ignite the gas in the burner. If it's not working properly, the boiler won't ignite, but it's usually a straightforward fix by replacing the faulty component.

Glo-Worm 0020020763 boiler igniter

Glow-worm 0020020763 igniter

Burner Debris

Debris, like carbon buildup, can also block the burner and prevent ignition. Even a small amount of debris can cause a blockage in the tiny burner jet, resulting in the Glow-worm boiler F28 error.

Sensor Malfunctions

Boiler sensors play a crucial role in safety and efficiency. An F28 problem might hint at a temperature sensor fault, which isn't providing the accurate readings required for ignition, or worse, a case of sensor wiring gone astray.

Wiring Mismanagement

The maze of wiring in any heating system can rival that of a complex circuit board. If wires aren't connected properly or have sustained damage, communications between crucial components like the gas valve and PCB can break down, leading to an F28 error.

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How To Fix F28 On Glow-worm Boiler?

F28 Glow-Worm boiler fault code

F28 Glow-worm boiler fault on the PCB

Check the Gas Supply

Ensure that your gas supply is running smoothly. Check other gas appliances to see if they are functioning; if they're down too, then the issue might be with your gas supply company, not your boiler.

Reset the Boiler

Sometimes, a clean slate can set things right. Turn off your boiler, wait a couple of minutes, then switch it back on. This can reset your system and clear some minor errors.

Inspect the Wiring

Carefully examine the wiring. Look for any signs of damage, such as exposed wiring or charring. Reconnect any loose connections, ensuring a snug fit.

Can I DIY For the F28 Boiler Fault?

Fixing an F28 fault usually requires professional help, except if a frozen condensate pipe is an issue. In that case, you can try these steps:

  • Pour hot (not boiling) water over the frozen pipe with a watering can.
  • Place a heated cloth or a hot water bottle in the pipe's frozen section.

Frozen condensate pipe during winter

Be careful while doing this, and watch out for dripping water from the melting ice.

So, it's clear that some of the fixes are technical and require professional intervention, but there are a few DIY steps that might just save the day before you dial the service number.

Don't Ignore the Glow-worm F28!!!

Ignoring the F28 error isn't just about comfort—it's about safety and efficiency.

Running your boiler with unresolved faults can lead to increased gas consumption and, in the worst cases, safety hazards.

Address the issue promptly, and you'll not only restore warmth but also ensure the long-term health of your boiler.

Here are the key points of the Glow-worm guarantee:

  1. Your boiler needs to be installed and checked by a Gas Safe Register engineer within six months of getting it.
  2. Get your boiler serviced every year by a Gas Safe Register engineer, following Glow-worm's instructions.
  3. Register your guarantee within 30 days of installation. If you don't, your guarantee will only last for one year instead of the longer period you were offered. For example, if you were given a five-year guarantee but don't register it, you'll only have a one-year guarantee.

Seeking Professional Help From Serviceteam


Serviceteam heating engineers are dedicated professionals with extensive experience and expertise in handling various heating issues. Whether it's boiler repairs, installation, or maintenance, our engineers are committed to delivering top-notch service and ensuring your heating system operates efficiently and effectively.

When DIY attempts to lead to further confusion, Serviceteam's team of qualified heating engineers is a call away.

Serviceteam is a Vaillant-accredited boiler installer.

Our professionals are adept at handling Glow-worm boilers and can swiftly diagnose the F28 error's root cause, providing expert resolutions.

  • Gas Valve Replacement
    If the issue lies with your gas valve, it might be best to replace it, as repairing a faulty gas valve is seldom an option.
  • PCB Repair or Replacement
    A defective PCB might be fixable, but when the board fails, a replacement is often the only long-term solution. Our engineers can efficiently provide and install a replacement PCB.
  • Comprehensive Sensor Solutions
    Serviceteam's experts understand the intricacies of each sensor within your boiler. They can calibrate, repair, or replace the sensors to ensure precise readings.
  • End-to-End Wiring Service
    Our team can identify issues within the wiring system, using top-of-the-line diagnostic tools to spot the most elusive problems and offering comprehensive rewiring services.
  • New Boiler Installation
    Don't fret about installing a new boiler! With Serviceteam, you're in good hands. Our Gas Safe registered engineers are qualified professionals who handle the boiler installation with expertise and ensure it's done right.

Final Word on F28 Faults

Understanding the F28 fault code means knowing when to tackle it yourself and when to call in the pros.

Check out our blog section on boiler error codes to learn about the error codes displayed on your home boiler.

Remember, Serviceteam stands ready to lend its expertise, ensuring your boiler is back in business without a hiccup.


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