The Radiator Centre Bleed key nickel air vent on Vintage bare metal lacquer steel radiator

How to bleed a radiator: Simple Step Guide

Written by
Nick Duggan

If some of your radiators are not heating up evenly, or there is a gurgling sound coming from inside, it often means that air has become trapped in the system. This air needs to be released, something often referred to as bleeding. It requires minimal equipment and isn’t difficult to difficult to do

Check all radiators

If the central heating system is not running, switch it on to build up pressure and test the radiators. Take care not to burn yourself when touching hot radiators, but feel each one to identify where air has become trapped. A radiator is noticeably cooler towards the top when this happens. When you discover where the air is trapped, prepare to start bleeding the affected radiators (get an old towel ready!).

Bleed each radiator with a cool spot

Before you start, be sure that the heating is now switched off.

The valve that you need to open is located near the top end of a radiator. It has a squared off middle which fits inside a radiator key. If you don’t have a key, you can buy them from any DIY or hardware shop. Or contact us at The Radiator Centre and we will send you one. On a modern radiator you can use a flat-bladed screwdriver by placing the end into the groove in the centre of the valve.

Use a cloth to catch any drips and turn the key or screwdriver anticlockwise – do so slowly, a quarter turn should be enough. You will hear a hissing noise when the air is being released. Be ready to close the valve quickly as soon as the hissing stops and liquid starts to emerge through the valve.