When air gets trapped in a radiator, the top stays cold while the bottom is warm. Letting the air out, called bleeding the radiator, helps it heat the room properly again.
You will need
- A radiator key (from a hardware shop) or a flat screwdriver, depending on the valve
- An old cloth or towel
Step by step
- Turn the heating off and wait until the radiators are cool.
- Hold the cloth under the bleed valve at the top corner of the radiator.
- Turn the key slowly anticlockwise, about a quarter turn. You will hear a hiss as the air escapes.
- When water starts to come out, close the valve again.
- Check the pressure gauge on your boiler. If it has dropped below the level in your boiler manual, top it up as the manual explains, or ask your heating engineer.
If a radiator still stays cold, or you have to bleed it every few weeks, there may be a bigger problem in the system. Book a heating engineer to take a look.