Air will accumulate within your central heating circuit over time. As a result, cold spots occur and the panels become less efficient at dissipating heat. As a result, one of the simplest things you can do to increase operational efficiency and make your home more comfortable is to flush radiators throughout your home.
This straightforward procedure is best described in the video below, hosted by Craig Phillips. Do you remember him? Big Brother 1's all-around wonderful egg? Anyway, it's only around 3 minutes long, so give it a look; there are also some simple instructions underneath.
Radiator Bleeding Procedure
What you'll require:
First, turn on the heat and warm up the radiators throughout your home. This will increase the pressure in the radiators.
Go around each radiator and make a note of the ones that have cold spots, which are usually near the top of the panel. Here is where the air has gathered.
Turn off the heat and, once the radiators have cooled slightly, begin the bleeding procedure. Some valves have a slot in them that will accept a flathead screwdriver if you don't have a bleed key.
To evacuate the surplus air, use the radiator bleed key, preferably a brass one. Turn the square bleed screw or screwdriver anti-clockwise slowly. You can hear the air hissing as it escapes. Any droplets of water should be collected with rags or a sponge. When all of the air has been expelled, you will get a jet of water rather than a drip. Close and tighten the valve immediately.
Bleed radiators one at a time till finished.
Restart the central heating system and check for chilly spots once more. Repeat the procedure as needed.
If no air escapes despite this procedure, the pressure in the boiler may be too low to force the air out. To top up the pressure, follow the process, which is normally available on the front panel of the boiler.
Also, if the operation is effective, the boiler pressure may have dropped and may need to be replenished.
That's all there is to it.