How to bleed a radiator
Radiator cold at the top and hot at the bottom? It probably needs bleeding — a 10-minute job.
1. Turn the heating off
Let the radiators cool. Bleeding a hot radiator can spray scalding water.
2. Open the bleed valve
Use a radiator key on the valve at the top corner. Hold a cloth underneath and turn a quarter-turn anticlockwise. You'll hear air hiss.
3. Close it when water appears
As soon as water drips steadily, close the valve. Don't over-tighten.
4. Check the boiler pressure
Bleeding drops pressure. On most combi boilers it should sit around 1–1.5 bar when cold — check your boiler manual and top up if needed.