How to Bleed Central Heating Radiators

What You'll Need
Appropriate radiator bleeding key

Bleeding central heating radiators needs to be done occasionally, for them to work correctly. Bleeding a radiator will get rid of any pockets of air in the system, which will prevent them from heating up correctly. When water enters a central heating system, air will as well to a degree. When more air builds up in the system than it can handle, the radiators on the system will stop working as effectively. The more air that is allowed to build up in the system, the less efficient the heaters will be. Eventually, they will stop working altogether. Bleeding a radiator is an extremely easy job, and a problem that can be fixed in a matter of a few minutes in the majority of cases. This will make your central heating more efficient almost immediately.

Step 1 – Check the Radiator

Determine whether the radiator needs bleeding. Also, make sure you have an appropriate radiator bleed key that fits the radiators in your central heating system. If you do not, purchase one from your local hardware store. Check all of the radiators in your home, to determine the efficiency of the system. If the top of a radiator is considerably cooler than the bottom, and the system is switched on, then the system needs to be bled. Likewise, if the radiator is cooler all over than it should be, then it will also need to be bled and have any air removed from the system. Switch the central heating system off before continuing, as this can lead to more air getting into the system.

Step 2 – Bleed Each Radiator

Provided you have the right bleed key to fit the radiators in your home, attach it to the bleed valve you will find on the radiator. The bleed valve will be on the side or on the back of the unit. The valves require the special key, allowing you to open and close them, bleeding excess air out of the system. Fit the key into the valve and slowly turn it counterclockwise. If it is working as intended, you should hear a hiss, as air escapes from the pressurized interior of the heating system. Eventually, once the air has been purged from the system, a little water should trickle out of the valve. Turn the key clockwise to close the valve. At this point, the radiator is purged of air, and should start working as intended.

Step 3 – Turn the Central Heating Back On

Turn the central heating back on again, and leave the radiators to warm up. After about half an hour, the radiators should be hot again. Also, make sure that the temperature dials on the radiators are turned up to a satisfactory level. When the heating is on again, go around the house and check each radiator, to confirm that they are evenly hot. If any of the radiators are still cool at the top or all over, try bleeding them again. If this still does not work, then there may be another problem effecting the system.