Regular heating and cooling of water can cause a build-up of trapped air in your radiator, making them less energy efficient and effective at heating your home. They should be checked on a regularly and bled if necessary. Try our simple guide to bleeding your radiator.

What you will need

  • Radiator key
  • Bowl
  • Cloth


1. Check your radiators

Does your radiator feel cold at the top and warm at the bottom? If so, air might be trapped and it may need bleeding.

2. Turn off the central heating

Before you start make sure you switch the heating off at the main controls and wait for the system to cool down. This will prevent injury to yourself. Do not attempt to bleed a radiator if the water is still hot.

3. Locate the bleed valve

Find the bleed valve on the affected radiator – it’s usually a small handle on one side.

4. Shield the area

Bleeding radiators can be a messy job, especially if yours is badly affected. Place some old sheets under the valve to catch any water, and it’s also a good idea to wrap your hand in some cloth – any water spraying from the valve could be very hot. Also place a bowl under the valve in case water leaks out.

5. Turn off the valve

Turn the bleed valve anticlockwise using the bleed key. If you can’t find yours they can be easily picked up at a local DIY store. Upon turning the valve, there’ll be a slight hissing sound which is air being released. The goal here is to see water dribbling from the valve – when this occurs we know then that all of the air has escaped from the radiator.

6. Re-tighten the valve

When all the air is released, carefully re-tighten the bleed valve. You can now also turn the heating back on. Check on the radiator a couple of hours later to make sure it’s heating evenly, and that no water is escaping from the valve.