How to bleed a radiator

Air may build inside a radiator over time.

A radiator with air inside will be relatively cold at the top whilst hot at the bottom.  What is happening is that the hot water of the central heating  is heating the bottom of the radiator whilst the top one remains cold because there is trapped air in the top of the radiator instead of water.


Bleeding a radiator is a very simple task and tenants are expected to carry out this type of maintenance tasks.

To bleed a radiator you will need a radiator bleeding key, which can be purchased in any DIY shop or at most supermarkets.  You may also need a piece of clothing to collect any water dripping that may occur when bleeding the radiator.

Once you have confirmed that your radiator needs bleeding ,please follow the following steps:

1. Switch off the central heating system
2. Slowly,open the bleeding valve at the top of the radiator (anti-clockwise).
3. Initially you may get a low hissing noise as air escapes from the radiator. Keep the valve open.
4. Eventually the water will start coming out, first in drips, then continuously.
5. Wait until the water comes out continuously, with no air mixture, and then close the bleeding valve (clock-wise)
6. Switch on the central heating system

Please refer to the following video, which explain very well the steps above-mentioned.

Depending on the age of the central heating system, you may need to bleed some radiators fairly regularly.

If you have any queries about this repair please simply leave your comment below.

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