How to bleed a radiator

If you’re radiators aren’t heating up properly or have cold spots they may need bleeding.

Don’t panic this is a simple fix and can be done by yourself. Bleeding your radiators will not only keep your house warmer but it will make sure your heating is running efficiently and save you money in the long run.

Why would you need to bleed a radiator?

Radiators need bleeding when they have air trapped inside them. This trapped air stops warm water circulating around your radiator. That can make the radiator cold at the top, but warm at the bottom.

It means your central heating system isn’t working efficiently and it can take longer to warm up your room. It can also cost you money, as your bills will be higher.

You might also need to let out trapped air if you have noisy radiators which are making banging, clanking or gurgling noises.

It’s recommended that you bleed your radiators once a year, even if they are working properly.

What if the entire radiator is cold?

If your entire radiator is cold we would recommend calling out a heating engineer as it is a sign there could be trapped air or a blockage somewhere in your pipes. If not sorted quickly it could cost you more money in the long term.

Bleeding your radiators

  1. Turn your heating on.
  2. Identify which radiators (if any) have cold spots.
  3. Turn off your heating, do not bleed your radiators until they are cold to touch. If you bleed them whilst your heating is on you may burn yourself!
  4. Place a cloth or towel under the valve to catch any water that may be released.
  5. Use a radiator key to turn the valve at the top of the radiator. Turn the key clockwise, you should hear a hissing sound (this is the trapped air escaping).
  6. Once the hissing has stopped use your radiator key to re-tighten the valve. Do this quickly to stop the water escaping.
  7. Turn your heating back on.
  8. Check the pressure by looking at the gauge on your boiler. Bleeding your radiators can cause the pressure to drop. If the pressure is too low, you’ll need to top it up. Use the lever or tap on your boiler, known as the filling loop. if the boiler pressure is below 1 bar it is too low; normal pressure is between 1 and 2 bars.
  9. Check your radiators. if the problem was trapped air the heat should now be spreading evenly throughout your radiators.

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