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Bleeding radiators! It's super-easy when you know how

Heating Advice

Release trapped air and get maximum heat by bleeding your radiators. Follow our steps to bleed them safely and successfully.

As water travels around your heating system, some air can creep in over time, leaving it trapped in your radiators. The trapped air can block the water from parts of the radiators leading to some radiators in the property taking a while to heat up or staying cold at the top.

When do I need to bleed my radiators?

Before you try to bleed any radiators, you need to establish where the issue is. Switch on your heating and carefully feel each radiator. Those with trapped air may take a while to heat up or have cold patches across the radiator, especially at the top. To bleed the radiators, you’ll need to get a radiator key, which you should be able to buy from any DIY shop.

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How do I bleed my radiators?

Once your radiators have cooled down, you can bleed them. Hold the radiator key with a rag or cloth, and place one underneath the valve to catch any water which drips out. Slowly open the valve by turning the key anti-clockwise – you should hear the trapped air begin to escape. Once the sound of the air escaping stops, water will start to dribble out. At this point you need to close the valve quickly before the pressure drops too low. Make sure that the valve is closed tightly to stop more pressure from leaking out.

If the pressure drops too low, you’ll need to top it back up using the filling loop to repressurise your boiler.

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