Tools required :- Radiator bleed key and an old towel or cloth.

If you find that the top half of a radiator is not as hot as the bottom, the cause is most likely to be trapped air in the heating system. This can be easily remedied by bleeding the air from the radiator.

First of all, turn off the central heating system, you will need a radiator air bleeding key, which are available at  DIY stores such as B & Q, Focus, etc and an old towel or absorbent cloth. Locate the air bleed valve at the top end of the radiator and hold the towel / cloth just beneath it.

Radiator air bleed key

Radiator air bleed key

Radiator air bleed valve

Radiator air bleed valve

SAFETY POINT – Any water that comes out of the bleed valve may be very hot, so take care to avoid being scalded.

Using the key turn the valve anticlockwise just enough to release the trapped air ( a low hiss can usually be heard ) when water starts to dribble out of the valve close it tightly and wipe away any drips or runs of water from the radiator.

Switch the heating system on and check the radiator. If the radiator still feels cooler at the top repeat the procedure.

Dave's DIY Tips recommends B&Q for all your tools and materials

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  1. Sonja Philips says

    A big thank you for sharing this information on how to bleed a radiator.

    I was going to call some to have a look at my radiators, however I’ve fixed them myself now!

  2. Gary says

    During the summer months, run your central heating for a short time each week to circulate the water and keep the pump impeller free.

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