Why should I bleed the radiators?

If your radiator is cold at the top and hot at the bottom it means there is air trapped inside. You will need to release that air to make the radiator work. The air doesn’t conduct heat like water so the top of the radiator will feel cold.

Most radiators have a standard sized key, take this along with a cloth to the radiator if you don’t have a key you can buy one here.  

How do I bleed a radiator?

Place the cloth behind the radiator to protect the wall put the key  on the bleed point give it a gentle turn anti clockwise until you hear air coming out. Stop turning as soon as you hear the hiss of the air leaving the key on the bleed point.  When water starts coming out turn the key clockwise to reseal the bleed point.  Remember the bleed point only needs to be turned until it is just tightened up.   Its only made of brass so turning it hard will snap it off in the radiator causing more trouble.

There are also kits available that collect any water that spills from the radiator when you bleed it. They are available here.

Remember to check the pressure on the boiler when you are finished bleeding radiators if you have a sealed central heating system.

Summary

If the radiator is hot at the bottom cold at the top the most likely problem is air stuck.

Using a bleed key gently open the bleed nipple.

Protect the wall and the floor using blue roll.

When water starts to come out close the bleed nipple.

Check the boiler to make sure it doesn’t need to have the pressure topped up.