Glow Worm Boiler Not Firing Up No Fault Code

If your Glow-worm boiler isn't firing up, a fault code can help identify the problem. But what happens when the boiler won't start and there is no code on the display?

Start with simple external checks rather than removing the boiler casing or attempting to diagnose internal components.

Why isn't my Glow-worm boiler firing up?

A boiler needs the correct operating conditions before it can fire.

If yours has stopped starting, possible causes can include:

• an electrical supply problem

• heating controls not requesting heat

• low system pressure

• an interrupted gas supply

• an ignition problem

• an internal component fault

Not all of these problems will necessarily present themselves to you as an obvious fault code.

The first step is therefore to establish what the boiler is doing and work through the checks you can perform safely.

Check whether the boiler has power

Look at the boiler display or indicator lights.

If the display is completely blank, check whether there has been a power cut and whether other electrical equipment in your home is working.

You can also check accessible household electrical controls associated with the boiler, such as its fused spur or relevant circuit breaker.

Don't remove the boiler casing or investigate its internal electrical components yourself.

Check the thermostat and heating controls

A boiler won't normally fire for central heating unless the controls are requesting heat.

Check that:

• the heating is switched on

• the thermostat is set above the current room temperature

• the timer or heating schedule is active

• battery-powered controls have working batteries

If you use wireless controls, check their display for any obvious connection or power issue.

What if hot water works but the heating doesn't?

If your boiler still provides hot water, it is capable of firing in at least some circumstances.

Check the thermostat and heating programme first, because the issue may relate specifically to the central heating demand rather than the boiler being completely unable to operate.

Further diagnosis may be required if the controls appear to be working correctly.

Check the boiler pressure

Glow-worm advises checking system pressure when a boiler won't ignite.

For many of its systems, pressure below 1 bar can indicate that repressurisation is required, but you should follow the instructions for your particular boiler.

If the pressure is low and your model allows homeowner repressurisation, use the correct procedure in its user manual.

Don't repeatedly add water if the pressure continues to fall. Persistent pressure loss needs investigating.

Check whether you have a gas supply

If you have another gas appliance, check whether it is operating.

If you use a prepayment meter, make sure there is sufficient credit.

If other gas appliances aren't working either, the problem may involve the property's gas supply rather than the boiler alone.

Don't attempt to inspect or adjust gas valves or internal gas components yourself.

What if you smell gas?

Stop troubleshooting if you smell gas.

Don't attempt to locate or repair a suspected gas leak yourself. Follow the current gas emergency procedure and avoid anything that could create an ignition source.

A boiler failing to fire doesn't itself mean there is a gas leak, but the smell of gas should always be treated separately as a safety issue.

Could low pressure stop a Glow-worm boiler firing?

Yes. Glow-worm lists low system pressure as one possible reason a boiler may fail to ignite.

Check the pressure gauge or display and compare it with the guidance for your particular model.

If pressure is low, appropriate repressurisation may restore normal operation.

If the pressure keeps dropping afterwards, however, there may be an underlying leak or system problem that needs investigating.

Could a frozen condensate pipe stop the boiler firing?

It can during freezing weather.

Glow-worm explains that a frozen condensate pipe can prevent ignition, although affected boilers may also display a fault code.

If the problem starts during very cold weather and you have an accessible external condensate pipe, check for obvious freezing.

Glow-worm advises using warm, not boiling, water to thaw a frozen section before resetting the boiler according to its instructions.

Don't attempt this where the pipe cannot be reached safely.

Should you reset a Glow-worm boiler with no fault code?

Check the user instructions for your particular Glow-worm model before resetting it.

A reset can sometimes restore operation, but it shouldn't become a repeated workaround for a boiler that continually fails to fire.

If the boiler starts after a reset but the problem returns, the underlying cause still needs identifying.

Why isn't the boiler showing a fault code?

A blank fault-code display doesn't establish that nothing is wrong.

The issue may involve heating controls, the power supply or another part of the system, or further diagnosis may be required before the cause becomes clear.

Concentrate on the symptoms rather than trying to make a fault code appear.

Useful observations include whether the boiler has power, whether hot water works, whether the thermostat is requesting heat and what system pressure is displayed.

What if the boiler still won't fire?

If the basic external checks don't resolve the problem, arrange professional diagnosis.

Glow-worm identifies internal possibilities such as ignition-component and fan faults among reasons a boiler may fail to ignite. These aren't appropriate DIY repairs.

A Gas Safe registered engineer can inspect the boiler and determine why it isn't firing rather than replacing parts based only on the symptom.

Does a Glow-worm boiler that won't fire need replacing?

Not necessarily.

A failure to fire can have causes ranging from external controls or low pressure to an internal component fault. The symptom alone doesn't establish that the boiler has reached the end of its useful life.

Repair or replacement should be considered after the fault has been diagnosed.

Factors such as the boiler's condition, repair history, parts availability and the work required can then inform that decision.

What to do if your Glow-worm boiler won't fire

Start with the checks you can make without opening the boiler: power, heating controls, system pressure and gas availability.

During freezing weather, an accessible frozen condensate pipe may also be relevant.

If these checks don't identify the problem, or the boiler repeatedly fails to fire after a reset, arrange professional diagnosis. Internal ignition, fan and gas-related work should be left to a Gas Safe registered engineer.