How to Bleed a Radiator (Step-by-Step Guide for Tunbridge Wells, Crowborough & Surrounding Areas)
Are your radiators not getting as hot as usual? Are they only warming up towards the bottom or in certain areas? Or are they making odd noises as they heat up? If you live in Tunbridge Wells, Crowborough, Uckfield, Rotherfield, or Mark Cross, it might be time to give your radiators a bleed.
Despite the name, bleeding a radiator is a simple job. All it means is releasing any trapped air inside your radiator that’s stopping it from heating up properly. If left alone, this trapped air can make your radiators less efficient and, over time, promote corrosion in your central heating system.
Bleeding your radiators doesn’t mean there’s a major fault. It’s just a normal part of heating system maintenance, especially in older homes across East Sussex and West Kent. Doing it regularly can help keep your heating running efficiently and save money on energy bills.
Let’s walk you through how to bleed a radiator the right way.
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How to Know If Your Radiator Needs Bleeding
If you live locally in Tunbridge Wells or Crowborough, these are the signs we look for when helping homeowners with heating issues:
Radiator is cold at the top but warm at the bottom
Gurgling or bubbling noises from the radiator
Condensation or damp patches around or above the radiator
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What You’ll Need
A radiator bleed key or flat-head screwdriver (depending on the valve)
A cloth or small container to catch drips
You can find a radiator bleed key at most DIY shops or online for a few pounds.
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Step-by-Step: How to Bleed a Radiator
1. Check Your Boiler Type
If you have a sealed system or combi boiler, you’ll need to be able to repressurise the system afterwards. If not, the pressure may drop too low, and the boiler could stop working after bleeding.
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2. Turn On Your Boiler and Heat the Radiators
Let your heating system run so all your radiators warm up. This will help you identify which radiators have trapped air and need bleeding.
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3. Check Which Radiators Need Bleeding
Feel the top and bottom of each radiator. If the top is cold and the bottom is warm, there’s likely air trapped inside.
⚠️ Don’t bleed all your radiators unless needed. Bleeding a radiator with no trapped air can cause a pressure drop and possibly stop your heating system.
➡️ Start with the radiator furthest from the boiler. In multi-storey homes, begin downstairs first.
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4. Turn Off the Heating and Let Radiators Cool
Before bleeding, always let the system cool completely. Bleeding while hot risks injury from hot water or steam.
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5. Locate the Bleed Valve
It’s usually found at the top of the radiator, either left or right. It will have a square slot for a bleed key or a slit for a screwdriver.
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6. Place a Cloth or Container Under the Valve
You’ll catch any escaping water here and prevent drips on your flooring.
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7. Use the Bleed Key to Release Air
Insert the key or screwdriver and turn anti-clockwise slowly. You’ll hear a hissing sound — that’s the air escaping. Once water starts to dribble out in a steady stream, close the valve by turning it clockwise.
✅ Wipe away any moisture to avoid rust around the valve.
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8. Check Your Boiler Pressure
After bleeding radiators, check that the boiler pressure is between 1.0 and 1.5 bar.
If it’s dropped too low, you’ll need to repressurise the system using the filling loop, or call a Gas Safe engineer — like one of our team at Absolute Plumbing & Heating, serving Uckfield, Mark Cross, and beyond.
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9. Turn the Heating Back On
Now it’s time for a heat test. Turn the system on again and check that the radiators are warming evenly from top to bottom.
If the cold spots are gone — job done! You’ve successfully bled your radiator.
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Still Have Cold Radiators?
Bleeding your radiators should only need doing once or twice a year. If cold spots keep coming back or you have multiple radiators with poor performance, there may be a bigger issue.
Possible Problems:
Leaks in pipework or joints (check around radiators and under the boiler)
Sludge build-up — causing blockages at the bottom of the radiator
Low boiler pressure after bleeding too often
A need for system flushing or power flushing
If your radiator is cold at the bottom, it’s likely a sludge issue. Over time, debris builds up inside pipes and radiators — especially in older properties across Rotherfield and Crowborough. This restricts hot water flow.
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When to Call an Engineer
If you’re unsure how to repressurise your boiler, or your radiators continue to underperform, it’s best to get a professional involved.
At Absolute Plumbing & Heating, we’ve helped hundreds of homeowners across Tunbridge Wells, Uckfield, and Mark Cross with radiator and boiler issues. Whether it’s a simple bleed, a leak repair, or a full power flush, we’ve got you covered.
📞 Call 07852 130 372
Or visit our boiler repair page to request a local engineer.
