How to bleed a radiator

First, turn on your heating system and wait for your radiators to achieve their maximum heat. This will allow you to detect any cold areas and, as a result, determine which radiators require bleeding.

Run your fingers carefully along the top of each radiator, and if you see any cold spots, this indicates that the radiator needs to be bled. Then, as you walk through the house, make a note of which radiators require bleeding.

It is critical to switch off the heating and allow the radiators to cool. This is so it can prevent the hot water in the radiators from burning you when you begin to bleed the radiators.

If you need to bleed more than one radiator, always begin with the one on the ground level farthest away from the boiler.

The bleed valve is normally located on the top and side of your radiator. The bleed valve is the little metal square or screw located within the nut.

Place your container or cloth beneath the bleed valve. This will collect any drips and protect your floor from discoloured water.

Insert your radiator bleed key into the bleed valve until they are locked together. Keep your cloth next to the valve and under the little drain hole, ready to collect any drips.

To open the valve, slowly turn the key anti-clockwise. This allows the air to escape, and you should hear a hissing sound. Continue twisting the valve until it is a quarter to a half-way open. To avoid water leaving too rapidly, do not fully release the valve.

You will have drained all the trapped air from the radiator when the hissing sounds and air stop – and water begins to pour out. Close the valve by turning the key clockwise. To avoid causing damage to the valve, do not seal it too firmly.

If you have a pressured central heating system, you may have noticed that the pressure gauge on your boiler has fallen since you last bled your radiators. If this is the case, you will need to fill up the boiler pressure before turning on the heating.