How to Bleed a Radiator

By Kim
Last updated 18th March 2021 - Reading time: 4 mins

If you want to learn how to bleed your radiators correctly, this guide will show you step-by-step and it also includes the tools and materials you'll need to do it.

How to bleed a radiator

What Tools Do I Need to Bleed a Radiator?

Below is a list of the tools that you will need to bleed a radiator:

  • Radiator key
  • Old rag

What Safety Equipment Do I Need to Bleed a Radiator?

There is not any specific safety equipment needed when it comes to bleeding a radiator. However, you should be aware of water and sludge potentially spitting out during the process, so be sure to protect your clothes, as necessary.

What Materials Do I Need to Bleed a Radiator?

You do not need any specific materials to complete a radiator bleed.

How to Prepare to Bleed a Radiator

To prepare for bleeding a radiator, ensure that your heating is turned off. You should also have an old rag on hand to catch any spraying or dripping water that may come out when you turn the radiator key.

How to Bleed a Radiator Yourself

Step 1

Run your hand over the radiator to check if it is cold at the top or bottom. If it is cold at the top, that means there is air trapped in the radiator and that it needs to be bled.

how to bleed a radiator step 1

Step 2

Begin by turning off your central heating.

how to bleed a radiator step 2

Step 3

Next, place an old rag underneath the valve to catch any water that may drip out during the bleeding process.

how to bleed a radiator step 3

Step 4

Use the radiator key and turn it anti-clockwise about a quarter of a turn until the air stops and the water runs smoothly out of the valve.

how to bleed a radiator step 4

Step 5

Then, turn the valve off again.

how to bleed a radiator step 5

Step 6

You can then turn your heating system back on, and the problem should be solved.

how to bleed a radiator step 6


Can you bleed a radiator without a key?

It may be possible to bleed a radiator without a key. If your bleed plug has a small slit in the middle, you could open it with a flathead screwdriver.

Can you bleed a radiator when the heating is on?

You can't bleed a radiator while the heating is on as it may be too hot to touch and you may find that hot water sprays out of the radiator.

When is the best time to bleed radiators?

It is recommended that you bleed radiators at the start of the heating season. This allows you to check that your heating system is fully functional without any trapped air before you come to use it.

How long do you bleed a radiator for?

This varies depending on the size of your radiator and the amount of air that is trapped inside. It usually takes around 20 to 30 seconds to bleed a radiator, but some larger radiators could take a full minute.

Does bleeding a radiator cause your boiler to lose pressure?

If you have recently bled your radiator, you may notice a small loss of pressure. This is because air is released when you bleed a radiator, which can lower your boiler system's pressure.

How to bleed a towel radiator?

A towel radiator can be bled in the same way as any other radiator. It should have a bleed valve which can be opened so that any trapped air can escape.


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