How to Bleed a Radiator

Regularly bleeding your radiators helps keep your home's heating system work efficiently, so it's a good idea that you know how to do it...

1. Diagnose the problem

Common signs you need to bleed your radiators include cold spots across the radiator or your radiators taking a long time to heat up. these problems are caused by trapped air, which is released when you bleed the radiator.

2. Check every radiator

If you have found a problem with one radiator, it is a good idea to check the others so you can get them all sorted at the same time. Switch your heating on and wait for your radiators to reach full heat. When they are hot, check for the common signs in step 1. Be careful when feeling the radiators, as they will now be very hot.

3. Turn the heating off

This is a very important step, as it saves you having a lot of water to clean up after you have opened the valve. 

4. Release the trapped air

Take your radiator key and fit it into the valve found at the top of the radiator. Use a rag or small towel to protect your hands from the hot air and to catch any water drips. Turn the key to release the hot air trapped inside. You will be able to hear the air hissing as it escapes.

If you don't already have a radiator key, they can be brought for a small amount from any DIY shop or online.

5. Close the valve

When you can no longer hear the air escaping, you need to turn the key to close the valve. After all the air has escaped, water will begin escaping too, so you want to avoid this by closing the valve quickly. 

6. Check your boiler pressure

After you have bled all the necessary radiators, you need to check your boiler pressure as this can sometimes have an effect on it. If the pressure is too low, you will need to fill it up. This isn't too complicated if you follow the official instructions from your boiler manufacturer. However, if you aren't sure, feel free to get in touch and we can sort this for you.

7. Test them out

Your radiators should be free from all cold spots now and your home should feel warmer, so give them a test run to make sure they are working as they should.

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We offer a range of home heating services across Harwich and Dovercourt, including boiler repairs, servicing and installation, amongst other gas services. Our gas engineers are on the Gas Safe register, so you are guaranteed to receive safe and efficient work from a team with all the correct qualifications. For any gas work across Harwich and Dovercourt- why look anywhere else? 

To get in touch with our team today, give us a call on  01255 714007 / 07544 395677, fill out the handy contact form on our website, or send us an email at We hope to hear from you soon!