What Does it Mean to Bleed a Radiator?

Updated on July 26, 2021

Your central heating system will generally run throughout your house. As such a big part of your home, it is important to know how to take care of it and make sure it is working efficiently. One of the easiest yet key parts of this maintenance is bleeding your radiators.

But what does this mean?

In short, bleeding a radiator is letting out or releasing the air that has become trapped in your radiator.

Why Should We Bleed Radiators?

The trapped air stops the water circulating around your radiator. The warm water is what provides your heat. If it cannot move around the radiator, the full radiator cannot heat up and provide the heat your room needs. Think of it as the air shrinking the size of your radiator. Bleeding your radiator will keep you warmer.

When there is an issue, homeowners tend to turn up the heating not realising that the radiators need bleeding. This increases energy bills and isn’t going to help. Bleeding your radiator will save you money.

Do All Radiators Need Bleeding?

If your radiator is plumbed into your central heating system, it will need bleeding. 

Electric radiators are filled with either oil or a thermodynamic fluid called glycol. They do not need bleeding.

If you have a combi-fuel radiator, such as designer radiators direct from suppliers, this will need bleeding too as, though it contains an electric element, the other part of it still uses the central heating system.

How Do I Know If My Radiator Needs Bleeding?

Your first sign may be that your room is cooler than usual. You turn up the heating, but it isn’t making a difference. The main test is to feel your radiator all over. A radiator that needs bleeding is usually cold at the top, but warm at the bottom.

Noisy radiators are also a sign that your radiator has trapped air. Banging, clanking, and gurgling are often a result of the water and the air doing battle inside the radiator.

How Do I Bleed My Radiator?

You will need a radiator key. These are readily available at DIY stores. 

Make sure you have old rags or a small bowl to hand to catch any water that is released with the air. This can be dirty and could mark your flooring.

Ensure your central heating is turned off and cooled down. 

  • Place the radiator key over the square shape in the centre of the valve.
  • Holding your rag under the valve, slowly turn the key anticlockwise.
  • You will hear a hissing sound as the air escapes. A little water may be released at the same time which you can catch with your rag.
  • As soon as the hissing stops, and only water emerges, quickly turn the key clockwise to prevent too much water escaping.

You can now turn on your central heating. You should also check the pressure gauge on your boiler. If it has dropped too low (the gauge hand is in the red), you will need to top it up via the filling loop on your boiler.

Your radiator should now be heating up evenly.

How Often Should I Bleed My Radiators?

You should bleed your radiators at least once a year even if they are working properly.

Many homeowners will bleed the radiator at the end of summer/beginning of autumn when they are turning their central heating back on for the colder months.

+ posts

Throughout the year, our writers feature fresh, in-depth, and relevant information for our audience of 40,000+ healthcare leaders and professionals. As a healthcare business publication, we cover and cherish our relationship with the entire health care industry including administrators, nurses, physicians, physical therapists, pharmacists, and more. We cover a broad spectrum from hospitals to medical offices to outpatient services to eye surgery centers to university settings. We focus on rehabilitation, nursing homes, home care, hospice as well as men’s health, women’s heath, and pediatrics.