Why are bleeding radiators important?

Bleeding your radiators is one of the simplest ways to cut your heating bills, and it costs nothing but a few minutes of your time. 

Trapped air stops radiators from filling completely with hot water, so they heat unevenly and take longer to warm a room. That means your boiler runs for longer to reach the same temperature, using more gas than it needs to. 

If your radiators are cold at the top but warm at the bottom, or you can hear gurgling, they need bleeding. Doing this before the cold weather sets in helps your system run efficiently all winter, saving you money and keeping your home warmer.

Here, we set out four important points to remember when bleeding your radiators at home:

Turn the heating off first

Always switch your heating off and let the radiators cool before bleeding them. Have a radiator key and a cloth ready to catch any drips, and open the bleed valve slowly. Close it once the air has escaped and water starts coming out – you don’t need to drain the radiator.

Check the boiler pressure afterwards

On a sealed heating system, bleeding radiators can lower the pressure, so check your boiler’s gauge afterwards. If it has dropped below the recommended range, follow the manufacturer’s instructions for topping it up before switching the heating back on.

Bleeding isn’t a fix for every cold radiator

Where the cold patch appears matters. A radiator that is warm at the bottom but cold at the top often has trapped air. If it is warm at the top but cold at the bottom, sludge or debris could be restricting circulation, and bleeding alone is unlikely to solve it.

Check before the first cold spell

Give your heating a trial run before you need it every day, and check which radiators are warming up properly. Bleed any radiators showing signs of trapped air, then check again once the heating is back on to make sure the cold patches are gone.