How to bleed a radiator

14 April 2022 – 1 Minute Read

If you’re having problems with your central heating, and your radiators aren’t warming your home evenly, it could be caused by air bubbles trapped in your system. If so, it could mean you need to bleed your problem radiator to force the air out. Find out how to make sure your central heating works before the cold sets in with our step by step guide to bleeding your radiators.

You can do this process when you notice there’s a problem, but it’s also a good idea to check this every autumn when you turn your heating back on ahead of winter.

Check for cold pockets in your radiators

Turn you heating system on and wait for you radiators to get fully heated. Carefully check each one to see where there are cold patches, where the radiator isn’t heating up.

Turn off your central heating

When you’ve identified the radiators with issues, turn off the heating. Make sure your radiators have cooled completely, so you can handle them properly before you set about bleeding them.

Prepare your tools

You’ll need to have your radiator key (or buy a new one from any hardware store), a dry cloth or towel and a bowl.

Locate the radiator valve

Put the bowl under the valve ready to catch any drips. Insert the key into the valve at the top or the radiator and hold the cloth underneath.

Release the gas

Slowly twist the key anti-clockwise, no more than one and a half turns, until you hear a hissing noise. This is the gas escaping the system.

Close the valve

When the hissing noise stops, and all the gas has escaped the radiator, liquid will come out of the valve. Be prepared with the cloth and the bowl to catch the water. At this point, the valve will need to be closed quickly. Turn the key back clockwise until the valve is closed. Repeat on all radiators with an issue.

Turn the heating back on

Now, run another hot test to make sure the process has worked: put the radiators back on, when they are all heated carefully check again for cold spots and make sure none of the valves are leaking. If you still spot any problems, you may have to bleed the radiator again.

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