Common Glow-worm Boiler Problems and Repairs

As the cold weather sets in, we become more reliant on our boilers and the last thing any of us wants is for our heating system to stop working. In most cases, you’ll need to get in touch with a Gas Safe registered engineer to diagnose problems and carry out boiler repairs when something goes wrong with your Glow-worm boiler. However, there might be some simple checks you can do to identify a problem with your Glow-worm boiler before you contact an engineer, but this will depend on the type of issue or fault that you encounter. 

We’ve put together this guide on the most common Glow-worm problems and repairs to help understand what is wrong and what you need to do next.

1. Reduction in boiler pressure

When your Glow-worm boiler’s pressure gets too low, it should display a fault code to alert you that your boiler needs attention. The most common cause of pressure loss is a leak or a faulty component.

What to do next: If the boiler pressure has been decreasing gradually, you may need to just re-pressurise your boiler. You can do this yourself as long as it is safe to do and you feel confident to do it. You should also check your heating system and radiators to see if you can spot a leak. Some leaks aren’t as obvious as others, so you might not be able to find anything at first. If you do find a leak, turn off the water supply and get in touch with a Gas Safe registered engineer. 

2. Condensate pipe is frozen

This is a very common problem that tends to occur during spells of cold weather because the pipe usually runs outside into a drain. A frozen condensate pipe can stop your boiler from working, and a fault code should appear on your Glow-worm boiler when the condensate pipe freezes. 

What to do next: You can try and thaw the condensate pipe yourself if you are happy to do so by either pouring some warm water over the frozen pipe or using a cloth or towel soaked in warm water. Don’t be tempted to use hot or boiling water to thaw it, though. If you feel unsure about attempting to do this yourself, simply call a qualified engineer to do it for you. 

3. Intermittent heating or hot water

Potential causes of intermittent heating or hot water include thermostat issues, broken airlocks and diaphragms, valve failure or low water levels. 

What to do next: The first thing you can do is check to see if the boiler pressure is too low. Also, make sure the thermostat is set correctly to enable your heating to switch on. If you don’t find any problems with the pressure or thermostat on your Glow-worm boiler, you’ll need to call a Gas Safe registered engineer to take a look. 

4. Problem with the PCB

There are many different fault codes that could appear on your Glow-worm boiler to tell you that there is a problem with the PCB (printed circuit board). If the PCB is faulty, your boiler won’t be able to work as it should. 

What to do next: You’ll need to contact a qualified engineer. The engineer will first test the connections and sequence to see if the problem can be rectified and to get your boiler working again. If they find that the PCB is broken, your engineer will have to replace it with a new one. But be warned, a replacement PCB can be an expensive repair. 

5. Flame detection fault

If your Glow-worm boiler is telling you that there is a flame detection fault, it could be caused by a defective gas valve, blocked condensate pipe or a faulty PCB. It’s usually the F16 error code that appears on your boiler when there’s a flame detection fault.

What to do next: As there are many potential causes of a flame detection fault, this kind of Glow-worm boiler problem will need to be diagnosed by a Gas Safe registered engineer.