How to bleed radiators

Nobody wants cold radiators in the winter. And the good news is, you don’t need to be an expert to bleed a radiator. If you’ve noticed that one or two radiators in your home aren’t heating up properly and have cold spots, you may need to bleed them. Follow our step-by-step guide on how to bleed a radiator:

But first! Diagnose the problem before bleeding radiator

Before getting to grips with a radiator key and bleeding the radiator, it’s best to rule out any other potential issues first:

  • If your radiator is cold in places and is leaking water, then you should turn your heating off and contact us to arrange a repair.
  • If all the radiators in your house are cold you probably have a larger issue, so it’s best to contact a Gas Safe engineer to take a look at the problem.
  • Are your downstairs radiators heating up but your upstairs radiators aren’t? Your heating system may not be operating at a high enough pressure, so you’ll need to increase the pressure. Read our blog on increasing your boiler pressure.

Haven’t identified any of the above issues? Then proceed with bleeding the radiator.

Bleeding the radiator

  1. Turn off your heating. Allow time for the problem radiator to settle and cool before bleeding and releasing the trapped air
  2. Lay rags or a bowl underneath the radiator to catch any leaking water. Discoloured water can leak out once the bleed valve is opened!
  3. Find the bleed valve and a radiator key to fit. Radiator keys come in different sizes, depending on the size and shape of your valve. You’l find the small bleed valve at the top end of your radiator – it will have a small square end.
  4. Next, insert your radiator key into the bleed valve. Turn the screw anti-clockwise to open the valve. You should hear a hissing sound as air escapes from your radiator. This is the cold air escaping. After the hissing, sputtering discoloured water may escape.
  5. Wait for sputtering water to escape. Once the sputtering water has stopped, a stream of water should squirt through the valve. This indicates that all the trapped air has been released.
  6. Re-tighten the bleed valve by turning the radiator key clockwise; make sure you don’t over-tighten it.
  7. Check your boiler pressure. Bleeding radiators can cause your pressure to drop so it’s best to check your boiler pressure gauge. The dial on the gauge should be between 1 and 2 (in the green zone.)

How often should I bleed my radiators?

To maintain an efficient heating system, you should try bleeding your radiators once a year.

We hope this guide on how to bleed your radiators gets your home all nice and warm again! If you’re still having radiator problems after bleeding, then your boiler may require a repair. To book a boiler repair in Lincoln, call Glow on 01522 300744.