If your radiator is making banging noises or it feels cold at the top despite the heating being on full pelt then it is very likely that you have air trapped in your radiator. The only way to get rid of this air is by bleeding the radiator. There are two different ways of doing this, the first way is to fit an aladdin self bleed radiator valve which will automatically vent the air from your system. You can find out more about those by clicking on this link if you have modern radiators or click on this link if you have older style radiators.
But if you prefer to manually bleed the radiator yourself, then the steps below will help you along the way, remember though if in doubt call in the experts.
1. Turn your heating off to stop any more air entering your system before you start to bleed your radiator.
2. Locate the bleed valve and protect the area underneath it as you may find that some water leaks out, a cloth or small bowl or plastic container should be sufficient.
3. Be aware that any water that escapes could be very hot so protect your hands too.
4. Use only your radiator bleed key for the next step, if you do not have one then they are easily purchased in the major chains DIY shops such as Wickes or Homebase.
5. Insert the key into the valve and turn it anti-clockwise, but carefully does it you shouldn’t net turn it very far, you should hear the air escaping quite quickly it tends to make a kind of hissing noise.
6. When the air stops and the water starts, this usually means that all of the air has been forced out of the radiator. Simply tighten the bleed valve, clean up any water making sure again that you protect yourself as the water can be VERY hot. Then turn your heating back on again.
If the problem doesn’t go away and air returns quickly to the radiator then you may have an underlying problem, so if in doubt call in a plumber who can identify the problem for you.