Bleeding radiators header

How to bleed
your radiators

Learn how to bleed your radiators
with these easy steps

Why bleed a radiator?

Trapped air stops warm water from circulating around your radiator, which can make the radiator cold at the top, but warm at the bottom. This can mean that your central heating system isn’t working efficiently and it can take longer to warm up your room.

To let this trapped air out, you need to bleed your radiator.

What you need

What you need:

  • A radiator key. If you don't have one, you can buy it from a DIY shop, or online retailer.
  • An old towel or rag to catch any water.

How to bleed your radiators


  • 1.

    Turn your central heating off and lay your old towel or rag below the valve.

  • 2.

    Use the radiator key to turn the valve at the top of the radiator until you hear a hissing sound and some water starts coming out.

  • 3.

    Retighten the valve once the hissing stops and only liquid comes out. Do this quickly to stop too much water from escaping.

  • 4.

    Check the pressure by looking at the gauge on your boiler. Bleeding your radiators can cause the pressure to drop, so if the pressure is too low, you’ll need to top it using the lever or tap on your boiler.

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