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How to bleed your radiators

Bleeding your radiators removes pockets of air that are trapped in your central heating system and help your radiator to run efficiently and effectively.

Step 1 - Turn your heating on

Switch your heating on so that all of the radiators in your home start to warm up. You'll need to wait until your radiators are fully heated before moving on to the next stage of the process.

Step 2 - Identify the radiators which need bleeding

Check each radiator in your home to check that all parts of the radiator are radiating heat. Be careful not to burn your hands as you check the radiators. If a radiator has cool spots along the top of the panel, you'll need to bleed the radiator to remove the air pocket that is inside.

Step 3 - Prepare

Before you start to bleed a radiator, make sure your central heating system is switched off. You'll need the radiators to be cool enough to handle.

Some modern radiators can be bled with a screwdriver. However, for most types of radiator you'll need to use a radiator key. Radiator keys can be purchased cheaply from any homeware or DIY shop.

Step 4 - Bleed the radiators

  • Attach the radiator key into the square section in the centre of the radiator valve
  • Use a cloth or strong tissue paper to hold the radiator key
  • Have another cloth under the radiator valve to catch any drips
  • Turn the radiator key slowly in an anti-clockwise direction
  • If air is escaping you'll hear a hissing sound
  • Once the air has escaped, liquid will start to leak from the valve
  • Close the valve quickly by turning the radiator key

Step 5 - Check the pressure of your heating system

Once you've bled the radiators, check the pressure gauge on your boiler. If the pressure is too low you'll need to repressurise the boiler.

Watch our video guide to learn how to repressurise your boiler

If the system pressure is adequate, you can switch your heating on and check your radiators again to ensure that there are no remaining cold spots on the panels.

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