How To Bleed A Radiator : A Step by Step Guide

The term ‘bleeding a radiator’ refers to the action of letting out any air that is trapped inside the unit. If you do not bleed your radiators, the trapped air or gas inside them will stop them from working properly and the fuel efficiency of your home will suffer.

Bleeding your radiators is an easy task that you can do yourself and it will make a real difference to your home.

By following this step by step guide, you will be able to bleed your radiators with confidence.

Turn on your heating

Your radiators should all be turned on and you may need to adjust the thermostat and radiator temperatures so that each individual one comes on.

Identify the radiators that need bleeding

You can do this once you have waited for your radiators to heat up. Systematically go around your house and feel each radiator to see it they are warming up. Do this with care.

If you feel cool spots in the radiator, it may mean it has air trapped inside and therefore needs bleeding. This typically happens in the highest radiator in a home.

Bleed your radiators

Make sure you have turned OFF your central heating in order to do this. A radiator key is normally required, although with some modern models you might be able to bleed them with a flat blade screwdriver.

At one end of each radiator there is a valve. You simply attached your radiator key to the centre of the valve (or fit the screwdriver into the valve’s groove). Make sure you hold the key with a cloth.

Slowly begin to turn the key anti-clockwise. You will hear a hissing noise if gas is escaping. Keep turning the key until no more gas escapes and liquid begins to come out. You then turn the valve the opposite way so that you close it quickly.

Pressure checking


The final step is to check the pressure of your system by having a look at your boiler gauge. If the pressure is shown to be too low, you can top up by using the filling loop, which is the tap or lever on your boiler.

When you have finished bleeding your radiators and have checked the pressure of your boiler, you might want to switch on your central heating and see if all the radiators are now performing correctly.

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