My radiators aren't heating up?
What to do when your radiators stay cold or only heat halfway
If your radiators are staying cold – or only heating halfway – you're not alone. It’s a common issue, especially during colder months in Ireland. Whether it’s a single cold radiator or your whole central heating system isn’t performing as it should, there are a few things you can try before calling in the experts.
Together with our team of energy professionals, we’ve pulled together some of the most common causes and practical steps you can take to get your heating back on track.
Start with the basics. Head to the boiler – the heart of your heating system:
- Is it switched on?
- Is it making strange noises?
- Do you still have hot water?
- Are all radiators affected, or just a few?
If all your radiators are cold, or your boiler isn’t working correctly, it could point to a wider issue. In that case, it’s best to book a visit with one of our qualified Service Engineers. They’ll test your boiler and find the fault. All our engineers are RGI certified and fully insured, so you can trust you’re in safe hands.
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If just one or two radiators aren’t heating, the issue could be local. Check:
- Are the valves fully open?
- Are the thermostatic radiator valves (TRVs) stuck or seized?
Sometimes a simple turn of the valve is all it takes to restore heat. If that doesn’t work, trapped air may be the problem – especially if the radiator is cold at the top and warm at the bottom.
Air in your heating system is a common cause of uneven heat. Bleeding your radiators can help:
- Use a radiator key to turn the bleed valve slowly.
- When you hear a hissing sound, let the air escape.
- When water starts to drip out, tighten the valve.
This should restore full warmth. If you find yourself doing this often, it might be time for Power Flushing.
If bleeding radiators doesn't help – or if they’re hot at the top and cold at the bottom – sludge or limescale may be clogging your system.
A Power Flush removes debris from your central heating system and can help:
- Restore heat to cold radiators
- Improve system efficiency
- Reduce boiler noise
- Extend the life of your heating system
One of our Service Engineers will assess whether Power Flushing is suitable. If so, they’ll drain your system, flush it with specialist equipment and chemicals, and remove any blockages.
Speak to our HomeCare team on 01 611 01 45 to arrange a Power Flush.
Related issue: My radiators are leaking
If your radiators are heating but you're noticing damp patches, drips or rust, you may be dealing with a leak. For guidance on what to check and when to call in help, visit our page on My radiators are leaking.
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Power Flushing: have you noticed your radiators are giving out less heat than they once did? It’s a common complaint, and usually because sludge and scale has built up in your central heating system over time making them less efficient and less cost effective to run.
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