How to Bleed your Radiators

What does it mean to bleed a radiator

Bleeding a radiator is an issue commonly found in un-vented heating systems. It is a process where you let out trapped air from the radiator. Trapped air in radiators can prevent the entire radiator from properly heating up and can create cold spots.

When to bleed radiators

Some indicators that your radiators need bleeding are:

  • You can sometimes hear a banging or clucking sound coming from the radiator as it begins to warm up.

  • The radiator remains cold long after it has been turned on.

  • The top of the radiator is cold whereas the bottom part is warm.

If you notice any of the above, that means there is air trapped in the radiator, preventing effective air circulation for heating and it is time to bleed your radiators.

How do you bleed a radiator

Here are step-by-step instructions on how you can bleed a radiator. Before you begin, you will need a radiator bleed key to open the radiator vent valve.

  1. Turn your central heating on to the maximum temperature and wait for the radiators to heat up.

  2. Test all the radiators in your house for cold spots. These are the ones that will need bleeding.

  3. Turn off the central heating. It is important to turn off the central heating before you bleed your radiators

  4. Make sure you have a cloth or tray to catch any water from the radiator.

  5. To start bleeding, use the radiator bleed key and insert it into the bleed valve. This is often found on the side on the top of the radiator. When inserted, you will feel the bleed valve and key lock together. Turn the key in an anti-clockwise direction carefully and you will hear a hissing sound from the air escaping. Make sure you keep a distance as the air escaping can be hot.

  6. Continue this till the hissing sound stops and water drips from the radiator. Once the water starts dripping, close the valve by turning the key in the clockwise direction. The time taken for a radiator to bleed can vary depending on the size of the radiator and the amount of air trapped inside. Some radiators can take about 20 to 30 seconds whereas larger ones can take up to a full minute.

  7. Repeat this for all affected radiators, by starting with the one closest to the boiler. Once you have bled all your radiators, turn on the heating again to make sure that the bleeding has been successful. If not, you might have to bleed some radiators a second time.

  8. Once you have bled all the radiators, make sure to check your boiler pressure to ensure that it is at a recommended level — usually between 1.0 and 1.5 bar for houses. This is because when you bleed your radiators by releasing air, the overall pressure of the heating system falls. When this happens, the system is unable to generate heat to the upper levels of the house.

Please see the link below for a basic guide to bleeding your radiators: