Bleeding a radiator is an easy and cheap fix for combatting cold and patchy radiators. It's something anyone can do in their own home without the need for a heating or plumbing engineer.

For guidance, please see our step by step instructional video below:


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Why do I need to bleed my radiators?

Radiators become less effective the more gas there is trapped within them. Bleeding your radiators will release the trapped air allowing the hot water to circulate freely.

Enabling you to heat your home more effectively and efficiently, bleeding your radiators regularly is an important part of maintaining your central heating system.


What do I need to bleed my radiators?


  • A radiator key – these can be found in all good DIY stores
  • A dry cloth
  • A cold central heating system


How do I bleed my radiators?


  • Before you do anything you’ll need to ensure that your central heating and hot water are switched off at the boiler. This will enable you to handle your radiators safely.
  • Locate the valve at the top or side of your radiator.
  • Position your cloth beneath the valve, ready to catch any water that’s likely to escape.
  • Insert your radiator key into the square groove of the valve and slowly turn it anti-clockwise.
  • After a few seconds you should hear a hissing noise, which is the sound of air escaping from your radiator.
  • Once the air has escaped, it will usually be followed by water. When a small amount of water starts to drip, close the valve by turning your radiator key clockwise.

For further help, please see our step by step video guide below:


How do I know if bleeding my radiators has worked?


Once you’ve closed your radiator valves, it’s safe to turn your central heating and hot water back on. If you’ve been successful your radiators should start to heat up within a few minutes.

You can also check the pressure gauge on your boiler and check that it reads between 1-1.5 bar.


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Can I use automatic radiator valves to bleed my radiators?


Depending on what type of radiators you have in your home, it may be possible to bleed them automatically using an auto vent. These handy devices are attached to your radiator valves and let out air gradually over time. Helping to keep your radiators working efficiently, with an auto vent you won’t need to bleed them manually.

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