Learn how to fix Ariston Boiler Error 108 with our easy step-by-step DIY guide. Restore low pressure, reset your boiler, and avoid costly repairs quickly and safely.
Owning an Ariston boiler means enjoying efficient heating, modern technology, and reliable performance. But like all heating systems, even the best can experience occasional issues. One of the most common problems that Ariston boiler owners encounter is Error 108.
This guide will help you understand what this error means, why it happens, and how to fix it safely and effectively.
Facing Ariston Boiler Error 108? Here’s What It Means
Error 108 on an Ariston boiler is a clear warning that the system’s water pressure is too low. This is a safety feature built into all modern boilers to protect the system from damage. Low pressure can affect both heating and hot water performance, and if left unresolved, it may trigger further faults.
The error is straightforward: your boiler’s display will show 108 or sometimes FILL 108, often accompanied by a flashing indicator. It’s designed to be clear and actionable, giving you immediate insight into the root problem.
Why Your Ariston Boiler Pressure is Too Low
Low boiler pressure can happen for several reasons:
Natural water loss: Over time, water in the system may evaporate or escape through small leaks.
Leaks in the system: Pipes, radiators, gaskets, or the expansion vessel can develop leaks that gradually reduce pressure.
Air in the system: Trapped air in radiators can interfere with pressure balance.
Faulty components: Filling taps, pressure relief valves, or sensors may malfunction.
Your pressure gauge is the key diagnostic tool here. Most domestic Ariston boilers operate safely between 1 and 2 bars. If the needle falls below 1 bar, the boiler recognizes a low-pressure condition and triggers Error 108.
Step-by-Step Guide: How to Repressurise an Ariston Boiler
Repressurising is often a simple, effective DIY solution. Follow these steps carefully:
- Locate the filling loop: This is usually a flexible silver hose under the boiler. Your Ariston manual will show the exact location for your model.
- Open the filling tap: Turn the valve counterclockwise slowly. You should hear water entering the system.
- Monitor the pressure gauge: Aim for a reading between 1.0 and 1.5 bars. Avoid exceeding 2 bars to prevent triggering the safety valve.
- Close the valve: Once the correct pressure is reached, close the tap completely. Leaving it open can cause overpressure and potential flooding.
- Check for a system reset: Some Ariston boilers will automatically reset after pressure correction, while others may require you to press the reset button.
Important: If the filling tap appears stuck or water doesn’t flow, check that the water supply is active. A faulty tap may need replacement, and you should avoid forcing it.
Troubleshooting When Your Boiler Won’t Fill
Sometimes repressurising isn’t enough. If your boiler does not take in water even after opening the filling loop:
- Ensure that the water pump is activated. Opening a radiator tap may help prime the system.
- Inspect the filling loop valves for blockages or damage. A malfunctioning valve may prevent proper filling.
- Check for leaks or obstructions in pipes that could be preventing water from circulating.
If these steps don’t resolve the issue, it may be time to contact a professional. Persistent low pressure or repeated Error 108 can indicate a more serious underlying problem.
Checking for Leaks: A Hidden Cause of Error 108
Leaks are a common yet sometimes hidden cause of low pressure. Examine your system carefully:
- Pipes and joints: Look for damp patches or dripping water.
- Radiators: Check for corrosion, loose bleed valves, or leaking seals.
- Expansion tank and gaskets: A broken membrane in the expansion vessel can cause pressure drops.
- Boiler heat exchanger: Any internal leak will require a qualified technician to repair.
Even small leaks can cause the boiler to display Error 108, so early detection is critical.
How to Reset Your Ariston Boiler After Fixing Error 108
Once pressure is restored and leaks are addressed:
- Press the reset button on your Ariston boiler.
- Monitor the display for any recurring error codes.
- Check that the pressure gauge remains stable between 1 and 2 bars.
If the boiler fails to reset or the pressure drops again immediately, further investigation by a Gas Safe engineer may be required.
Preventative Maintenance Tips to Avoid Error 108
Preventing low pressure issues will keep your system running smoothly:
- Check the pressure regularly: Monthly checks help you catch drops early.
- Bleed radiators: Removing trapped air prevents pressure imbalances.
- Annual servicing: Professional maintenance keeps sensors, valves, and the expansion vessel in top condition.
- Keep your manual handy: Your Ariston boiler manual is invaluable for troubleshooting and model-specific instructions.
Routine maintenance not only prevents Error 108 but also extends the life of your boiler.
Integrating Smart Thermostats to Enhance Boiler Efficiency
While addressing Error 108 by repressurising your Ariston boiler is crucial, integrating a smart thermostat can further optimise your heating system’s performance. Smart thermostats offer precise control over your home’s temperature, leading to improved energy efficiency and potentially reducing the frequency of pressure-related issues.
Why Consider a Smart Thermostat?
- Energy Efficiency: Smart thermostats learn your schedule and adjust heating accordingly, ensuring energy isn’t wasted when you’re not home.
- Remote Control: Control your heating from anywhere using a smartphone app, providing convenience and flexibility.
- Integration with Smart Home Systems: Many smart thermostats are compatible with platforms like Amazon Alexa, Google Assistant, and Home Assistant, allowing for voice control and automation.
For a detailed guide on choosing the best smart thermostats for your combi boiler, check out the complete UK buyer’s guide to smart thermostats for combi boilers. This guide covers compatibility, features, and user reviews to help you make the right choice.
Frequently Asked Questions About Ariston Error 108
Q: What does Ariston error 108 mean?
A: It indicates that the boiler pressure is too low, usually below 1 bar.
Q: Can I fix Ariston error 108 myself?
A: Yes, most low-pressure issues can be resolved by repressurising the system.
Q: Where is the filling loop on an Ariston combi boiler?
A: Typically under the boiler, consisting of a flexible hose with valves. Your boiler manual provides exact locations.
Q: Why does my Ariston boiler pressure keep dropping after topping up?
A: This could indicate leaks, faulty valves, or a damaged expansion vessel.
Q: How do I clear the 108 fault on an Ariston boiler?
A: Repressurise the system and reset the boiler. Persistent faults may require professional attention.
When to Call a Professional for Ariston Boiler Error 108
While many low-pressure issues are DIY-friendly, certain conditions require expert intervention:
- Leaks in the heat exchanger or internal boiler components.
- Filling loop or valves that cannot be safely repaired.
- Pressure drops that persist despite multiple manual top-ups.
Hiring a Gas Safe engineer ensures safety and prevents further damage. The cost varies depending on the issue but investing in professional service can prevent expensive repairs down the line.
Conclusion
Ariston boiler error 108 is a common, manageable problem. By understanding the cause, carefully checking the system, and following the proper steps to repressurise and reset, most users can restore their boiler’s performance safely. Regular maintenance, vigilance, and prompt attention to warnings ensure your boiler continues to deliver reliable heating and hot water.
With clear guidance, the right tools, and knowledge from your Ariston manual, even complex issues like Error 108 can be tackled efficiently, keeping your home warm and your system safe.
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