Radiator cold at the top, warm at the bottom
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Most likely cause & what to check
A radiator cold at the top has trapped air inside — the easiest radiator fix there is.
Turn the heating on and wait until the system reaches temperature.
Insert the bleed key and turn anti-clockwise by a quarter turn — you'll hear hissing air.
Once water trickles steadily, close the valve firmly but don't overtighten.
After bleeding, check boiler pressure and repressurise to 1–1.5 bar if needed.
🛠 Tools & materials you may need
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Get a vetted local engineer to handle it — no hassle, Gas Safe registered.
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