Glow-Worm Boiler F.29 Fault Code

The Glow-Worm fault code F.29 relates to flame loss during operation and here we have Q & A or require an engineer for an emergency boiler repair.

The Glow-Worm Boiler Fault Code F.29 Error Common Q & A

Just below, we have a list of common questions relating to the F.29 fault code on the Glow-Worm Boiler.

What does the F.29 fault code mean on my Glow-Worm boiler?
Is there a DIY fix for the F.29 fault code?
Is my boiler dangerous?
Why is my boiler losing its flame?
What causes low gas pressure?
How will my boiler engineer know if the gas valve is adjusted correctly?
My boiler engineer thinks the gas valve is faulty, how do they know?
How will my engineer know if I need a new gas valve on my boiler?
What would cause the electrode/ignition lead to become faulty?
What could be the cause of a leak in my boiler?
How can I stop limescale build-up in the future?
My boiler engineer thinks there is a problem with the PCB, does that sound right?
What does the F.29 fault code mean on my Glow-Worm boiler?

What does the F.29 fault code mean on my Glow-Worm boiler

Your boiler’s printed circuit board (PCB) gives and receives signals to all electronic parts. When it recognises a problem, it displays a fault code. Alongside this, it may stop working. This is called a lock out and is designed to isolate the boiler from being dangerous, as well as protecting important boiler components from further damage.

The F.29 fault code on Glow-Worm boilers is displayed when there’s an instance of flame loss during operation. This isn’t the same as an ignition failure. In this case, the boiler has managed to ignite, but the flame isn’t able to stay lit.

Is there a DIY fix for the F.29 fault code

Gas appliances can only be worked on by those with Gas Safe accreditation. Unlike some more simple faults (such as low boiler pressure), you shouldn’t attempt to fix this problem, unless you are qualified with Gas Safe.

Is my boiler dangerous

In its locked-out state, a boiler shouldn’t be dangerous. So, it’s important to not reset your boiler to try and trick the appliance into thinking you’ve fixed the issue.

Your Gas Safe engineer will find and fix the problem. Once they’ve done so, they’ll reset the appliance on your behalf.

Why is my boiler losing its flame

This fault code isn’t specific; there could be a handful of different problems with your boiler.

This includes:

Low gas pressure
Incorrect adjustment of the gas valve
Faulty gas valve
Faulty electrode or ignition lead
Dirt or carbon build-up in the burner

What causes low gas pressure

Your boiler requires a certain amount of gas pressure to operate. If this pressure drops even slightly, the boiler will lock out as a safety precaution.

In winter, we find the biggest cause of boiler’s losing gas pressure, is due to a gas meter that’s not protected from the elements.

Each meter has a regulator, that helps control the flow of gas. If this isn’t protected, it’s likely to freeze. As weather warms up, it will thaw. It’s wise to get a heating engineer to protect the meter, by boxing it in and lagging any part of the meter that they can.

In other instances, it’s likely the gas main isn’t up to standard; it’s not big enough to provide enough gas to the boiler. If you’ve upgraded your boiler to a more powerful one, it’s likely you’ll also need to upgrade the gas main to cope with the extra demand.

How will my boiler engineer know if the gas valve is adjusted correctly

If your boiler keeps losing its flame, the gas valve could be to blame. Your boiler engineer will be able to check the operation of the valve and adjust it to suit your boiler. If you’ve had a new gas valve fitted, or had it adjusted recently, it could’ve been done incorrectly.

Your boiler engineer will be able to test the gas pressure at the meter and the boiler, and then adjust to suit the burner on your appliance.

My boiler engineer thinks the gas valve is faulty, how do they know

Incorrect adjustment is a possibility, but a faulty gas valve is a more probable cause of the F.29 fault code being displayed.

The gas valve on your boiler is a mechanical component, so it will wear over time, and eventually break. In some instances, the gas valve can be salvaged. It’s likely it’s sticking, so when the PCB calls for gas to be let into the burner, it’s not able to get into the right position.

In some instances, the gas valve can be repaired. Your boiler engineer will try to free the valve. If it’s operation is smooth, and the rest of the valve isn’t showing signs of excessive wear, the valve can be reused.

How will my engineer know if I need a new gas valve on my boiler

Sometimes, the valve won’t be salvageable. If it continues to stick, or the wiring/connections have been burnt out due to water damage, it’s likely that your boiler repair company is going to suggest a replacement.

Replacement gas valves can be fitted for £250-300, depending on the model of boiler that you own.

What would cause the electrode/ignition lead to become faulty

Besides old-age, moisture is a big killer of electrical components. If you’ve noticed moisture around or beneath your boiler, there’s a good chance there’s a component leaking. Typically, it’s going to be the heat exchanger or pump.

If this is the case, you’ll need to get your boiler repair company to find and fix the leak before they deal with the electrode and ignition lead. If they don’t, it’s likely the same thing is going to happen again. And, a leak is likely to cause damage to other electrical components, such as the PCB.

What could be the cause of a leak in my boiler

Get your boiler repair company to check the pump first. Pumps on boilers are prone to the seals leaking. Service kits can be purchased to recondition the pump, if overall, it’s in good condition.

If you need a new pump, it’s likely to cost around £250 to install. This will include labour, as well as a quality pump from a brand like Grundfos.

The heat exchanger is a different story. If this is leaking, it’s probably due to a small crack. These cracks usually occur due to limescale build-up. And, it’s rare your boiler repair engineer will repair it. Instead, a new heat exchanger will be needed. Typically, that’s going to cost somewhere in the region of £400-500.

How can I stop limescale build-up in the future

The best way to stop limescale building up on the heat exchanger, is to fit a limescale reducer. These are small filters that connect to the heating pipes. As heating water flows through the pipe, the filter catches any small particles of limescale, rather than them getting lodged in the boiler.

My boiler engineer thinks there is a problem with the PCB, does that sound right

The PCB controls all the electrical components in your boiler. It even powers the display, that shows fault codes. So, if the PCB is faulty, it could be giving suggestions of a problem that doesn’t even exist.

If your boiler engineer thinks your PCB is faulty, they can test the wiring and connections to/from it. This is going to help determine whether the boiler’s PCB is getting power.

PCBs can be extremely complicated to fix, and that leads to a huge expensive. Typically, a boiler repair engineer will usually install a new one. The cost to replace a PCB on a Glow-Worm boiler will sit in the region of £400-500 including parts and labour.

Of course, if there are other problems (such as a leaking pump, and broken flame sensor), it’s going to cost more. Before spending £500+ on boiler repairs, it makes sense to get an estimate of the repair costs and comparing that to installing a new boiler.

Other Glow Worm boiler issues

For more boiler issues regarding the Glow Worm then please visit the Glow Worm Boiler Problems And Cures page.

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