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Repair Advice for Common Glow-worm Boiler Problems


Glow-worm are known for their efficiency and reliability but like any appliance they can sometimes encounter problems. In this article we will discuss some of the most common issues that homeowners may experience with their Glow-worm boilers and provide information on how to troubleshoot and repair them. Whether you are a homeowner looking to solve a problem on your own or a professional plumber seeking additional knowledge this article will provide valuable insights and guidance.

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Faults with PCB/electronics


The Printed Circuit Board (PCB) is a vital component of your glow-worm boiler as it controls and monitors various functions of the system. A problem with the PCB can cause a range of issues such as:

  • Boiler not turning on or off
  • Boiler not heating up properly
  • Boiler not responding to thermostat changes
  • Boiler displaying error codes or strange messages on the display screen

If you suspect that there is a problem with the PCB in your glow-worm boiler it is important to address it as soon as possible. Ignoring the issue can lead to more serious problems and potentially costly repairs down the line.

Troubleshooting a PCB problem

If you are experiencing any of the issues listed above you can try the following troubleshooting steps to determine if the PCB is the cause:

  • Ensure that the boiler is receiving power
  • Check the fuse and circuit breaker
  • Ensure that the thermostat is working properly
  • Check for any loose or damaged wires

If you have tried these steps and are still experiencing problems with your boiler it is likely that the PCB is the cause and will need to be repaired or replaced by a professional.

No or intermittent hot water and heating


If you are experiencing intermittent issues with your Glow-worm boiler's ability to provide hot water or heating there could be a few possible causes:

  • A faulty thermostat: The thermostat regulates the temperature of your boiler and controls when it should turn on and off, if it is not working properly it could result in intermittent heating or hot water. You can try adjusting the thermostat to see if this resolves the issue or consider replacing it if the problem persists.
  • A damaged diaphragm: The diaphragm is a small rubber part that helps to control the flow of water through the boiler, if it is damaged it can cause issues with the boiler's ability to produce hot water or heating. You may need to replace the diaphragm to resolve this issue.
  • A blocked pump: The pump helps to circulate hot water throughout your home, if it becomes blocked it can cause intermittent hot water or heating issues. You can try flushing the pump to see if this resolves the issue or consider having a professional check and clean it if the problem persists.

If you are unable to identify the cause of your intermittent heating or hot water issues it is recommended to seek the help of a professional, they will be able to diagnose the problem and suggest the appropriate repair solution.

Error 108/F22 (Low Pressure)


One common issue with glow-worm boilers is low pressure which can be indicated by error codes 108 or F22. This can lead to a lack of hot water or heating in your home. There are a few potential causes for low pressure including a leak in the system, a faulty pressure relief valve or a problem with the expansion vessel. Here are some steps you can take to troubleshoot and repair low pressure in your glow-worm boiler:

Step 1: Check for visible leaks

The first thing you should do is look for any visible signs of a leak. Check all the pipes, fittings, and seals in your heating system for any cracks or damage. If you find a leak you'll need to repair it before you can restore the pressure in your boiler. You may need to call a professional plumber to help with this task.

Step 2: Check the pressure relief valve

If you don't see any visible leaks the next thing to check is the pressure relief valve. This valve is designed to release excess pressure from the system and it can fail if it becomes clogged or damaged. To test the valve lift the lever to release any built-up pressure. If the pressure doesn't return to normal you'll need to replace the valve.

Step 3: Check the expansion vessel

The expansion vessel is a crucial component of your heating system that helps to maintain the correct pressure. If the expansion vessel is damaged or not functioning properly it can cause low pressure in your boiler. To check the expansion vessel you'll need to locate it (it's usually located near the boiler) and inspect it for any visible damage. If the expansion vessel is damaged you'll need to replace it.

Step 4: Refill the pressure

If you've checked for leaks tested the pressure relief valve and checked the expansion vessel and everything looks normal the next step is to refill the pressure in your boiler. To do this, you'll need to locate the filling loop (a small valve located near the boiler) and use a pressure gauge to add water until the pressure is at the correct level (usually between 1 and 1.5 bar).

When to call a professional

If you're unable to troubleshoot and repair the low pressure issue on your own it's best to call a professional. A qualified technician will have the expertise and tools to properly diagnose and fix the problem, ensuring that your boiler is running safely and efficiently.

Error F16 (Flame detection fault)


A flame detection fault is a common problem with glow-worm boilers. This error occurs when the boiler is unable to detect the flame in the burner causing it to shut down and display a fault code on the control panel. This can be caused by a variety of issues including a faulty ignition electrode or a dirty flame sensor.

Troubleshooting a flame detection fault

If you are experiencing a flame detection fault, you can try the following steps to troubleshoot the issue:

  • Check the ignition electrode for any visible damage or obstruction
  • Clean the flame sensor using a soft cloth or cotton swab
  • Ensure that the gas supply is turned on and the gas valve is open

If these steps do not resolve the issue, it is best to call a professional to diagnose and repair the problem.

Frozen (blocked) condensate pipe


A frozen condensate pipe is a common problem that can occur in a glow-worm boiler. The condensate pipe is responsible for carrying away excess water produced during the heating process. If the pipe becomes frozen it can cause the boiler to stop working or function poorly.

There are a few ways to thaw a frozen condensate pipe:

  1. Use hot water: Slowly pour hot water over the frozen area of the pipe. Be careful not to use water that is too hot as it can damage the pipe.
  2. Use a hair dryer: Aim the hair dryer at the frozen area of the pipe and move it back and forth until the ice has melted.
  3. Use a heating pad: Wrap a heating pad around the frozen area of the pipe and leave it on for a few hours until the ice has melted.

If you are unable to thaw the frozen pipe or if the pipe continues to freeze despite your efforts, it is best to call a professional heating engineer. A frozen condensate pipe can be a sign of a more serious issue with your boiler and a professional will be able to assess the problem and make any necessary repairs.

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