F28 Glow-worm Boiler Fault

How To Fix F28 Glow-Worm Boiler Fault Code Repair

Last updated on June 10th, 2024

The F28 Glow-worm boiler fault code, and all Glow-worm boiler fault codes, show on the screen on the boiler when there is a problem and your boiler locks out.

Glow-worm uses them to show you what might be wrong with the boiler not firing up.

Having fault codes on the screen is a great way to help diagnose your boiler problems.

I have been carrying out boiler repairs for over a decade and having fault codes on the screen when I arrive is very welcome.

Not all boilers use fault codes, so having them is a huge bonus.

What Does F28 Mean on a Glow-worm Boiler?

Here is what the Glow-worm Compact manual (PDF) says about their F.28 Glow-worm fault code:

F28 Glow-worm boiler fault meaning
F.28 Glow-worm boiler fault meaning

The most likely cause of an F28 fault code on a Glow-worm boiler is the boiler has been locked out due to a gas supply fault.

An F28 Glow-worm fault code could also mean that a part on the boiler is broken and needs to be replaced, but most of the time in my experience it is a gas supply issue.

Having no gas can be checked quite easily without having to open up the boiler.

How to Fix F28 Fault on a Glow-worm Boiler

To fix the F28 fault code on your Glow-worm boiler, the first thing I would do is check:

  1. The gas is turned on at the gas meter.
  2. If you have a prepayment gas meter, then make sure you are in credit, as this is quite a common situation I come across.
  3. If you have other gas appliances, like a gas hob or gas fire, then check to see if these are working to find out if you have a gas supply problem. If they don’t work, then you might have to contact your gas supplier.

Other Causes of an F28 Fault Code

A gas supply problem is the most common cause of a Glow-worm boiler f28 fault code, but here are some other potential causes –

  • Faulty gas valve – Might need a new one.
  • Worn-out spark electrodes – Might need to be replaced.
  • Faulty PCB (printed circuit board) – The PCB is the brain of the boiler and might need to be replaced.
  • Frozen condensate pipe – If it’s freezing outside, then having a frozen condensate pipe is possible. You can pour hot water on it to melt the frozen condensate and reset the boiler. 

Glow-worm F28 Fault Boiler Reset

The first thing I would do on a Glow-worm boiler that is not working, no matter what fault code is showing, is to check the pressure and reset the boiler.

Knowing how to reset a Glow-worm boiler is the simplest way to get your boiler working again, as it might have just locked out.

To reset a Glow-worm boiler, you must find the reset button. This is usually a flame with a line through it.

You have to press the button to reset the boiler. Sometimes you have to hold it down for 3 seconds, but on some Glow-worm boilers, it just needs to be pressed.

If your Glow-worm F28 won’t reset then you have a problem that needs to be fixed before it will reset.

Glow-worm Boiler Guides


A Glow-worm F28 error on your boiler can sometimes be easily fixed without opening the boiler.

Make sure to verify you are getting gas by checking the gas meter ECV and that you have credit if you use a pre-payment gas meter.

Feel free to ask me any questions in the comment section below and I’ll try my best to help.

Please share this post if you found it helpful.


How do you clear the fault code on a Glow-worm boiler?

To clear the fault code on a Glow-worm boiler, you must reset the boiler. If the fault code appears after resetting the boiler, you will need to find and repair the problem causing your Glow-worm boiler to lock out and show a fault code.

Why is my Glow-worm boiler not turning on?

If your Glow-worm boiler is not turning on at all (nothing on the display), then you probably have an electric supply issue.
You should check the fused spur switch that should be next to the boiler. Make sure it is switched on and the 3 amp fuse is good. It could also be that the fuse at the main board (consumer unit) has tripped, so you should check there also.

What do I do if I have no gas supply?

If you have no gas supply after making sure it’s turned on at the gas meter then you need to call your gas supplier (eg British Gas). There could be a problem with your account or a gas supply issue to your house that they are not aware of.
Any gas supply issues from the street up to the gas meter are the gas suppliers’ responsibility and won’t cost you a penny to fix.


  • Steven Reid

    I am a full-time plumber and Gas Safe registered engineer. I incorporated Housewarm Ltd. in 2011 to provide heating and plumbing services to homes in Newcastle upon Tyne, England. I now blog about what I've learned over the years to help DIYers and plumbers.

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