A step-by-step guide to bleeding a radiator

Follow our step-by-step guide to bleeding your radiators.

Cat sleeping on radiator

1. Carefully feel the radiator to see whether the top is cooler than the bottom – if it is, it needs bleeding.

2. Turn off the central heating.

3. Grab some old cloths, a bowl and a radiator key (you can get one at most DIY shops if you don’t have one). 

4. Place the bowl under the radiator to catch water and insert the radiator key into the square bleed screw at the top of the radiator. 

5. Have a cloth handy as you slowly turn the key anti-clockwise - you should start to hear a hissing sound as the air escapes.

6. Once the air has escaped, water will leak out. You can then retighten the bleed screw (don’t over-tighten it).

7. Sometimes water will spurt out, so don’t lean in close and use the cloth to catch any spray.

8. Repeat the process for any other radiators that need bleeding.

9. Turn the central heating back on and check the boiler pressure. If it’s too low you will need to boost it by using the filling loop – check your boiler’s instruction manual to find out how to do this.

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