How do I bleed a radiator?

Have you switched your radiators on and found them to not be working as well as the should? Or are there cold spots that need removing? If so, you should think about bleeding your radiators. If you're not sure how to do this, you've come to the right place. Keep reading to find out the correct way to bleed a radiator.

How do I bleed a radiator?

Bleeding a radiator means releasing the air that is trapped inside, in order to keep your central heating system working as efficiently as possible. Here is how...

  • Find the problem

All radiators will need bleeding occasionally, but there are a few signs to look out for. Things such as cold spots or your radiators taking a long time to heat up indicate you should be bleeding them. 

  • Check out the radiators

If you have found a problem with your radiator, you should switch on your central heating system and take a close look at each of your radiators. Feel for any cold spots or inconsistencies in warmth, and see how long they take to turn on.

  • Turn off the heating

Turning off the heating reduces the mess and clean up when bleeding your radiators. If you leave it on you will end up with a lot of water on the floor surrounding your radiator.
  • Release the trapped air
For this step, you need a radiator key that can be purchased at any DIY shop or online, and a rag. You need to fit the key into the valve at the top of the radiator and use the rag to catch any drips. When you've done this, begin to slowly turn the key anti-clockwise to release any air trapped.

  • Shut the valve

Once all the air has been released, water will begin moving towards the hole you have opened. When you see this happening you should quickly close the valve, to reduce any mess and to stop the water going everywhere.
  • Check the pressure
Finally, you should check the pressure gauge on your boiler. If the pressure is reading too low, you need to top it up. Adjust the filling loop, using the instructions from your boiler manufacturer.

Your local gas engineer in Essex

We offer our gas and heating service across Harlow, Essex- also covering Bishops Stortford, Sawbridgeworth, Epping, Stansted, Great Dunmow, Hoddesdon and Ware. Need a team of gas engineers with years of experience, correct qualifications and competitive prices? Look no further than D.A Gas, Heating & Plumbing. To get in touch with our team today, give us a call on 07920 875189 / 01279 316304, fill out the handy contact form on our website, or send us an email at We hope this blog post has helped you see how to bleed your radiators!