Heating Expert Advice: How To Bleed A Radiator 

Bleed your radiator to remove air pockets that prevent hot water from circulating around your central heating system.

Therefore, bleeding your radiator allows heat to flow around your home more efficiently, creating a warm atmosphere in your home. If heat is not spreading evenly throughout the radiator, you are wasting energy and money.

Radiators should be bled once a year, to maintain efficiency and provide peace of mind your system is working as it should.

You should bleed radiators if:


Radiators take longer than usual to heat up.


Heating system is making gurgling noises.


Cold spots at the TOP of your radiator.


Mold / Damp is present around your house.

6 simple steps on how to bleed a radiator. 

It should take no longer than 30-40 seconds to bleed a radiator.

Before beginning the bleeding process, you will need a bleed key, a bucket, and a towel.

Also, if you are bleeding more than one radiator, start on the ground floor with the radiator furthest away from the boiler. 

Step 1

Turn your heating on full and check all radiators in your property for cold spots.

Step 2

Once the heating is turned off and the radiators are cold, place a towel on the ground and grab a jug.

Hold the jug under the radiator bleed valve – located at the top of the radiator, it is a hole with a square inside. Next, simply insert the bleed key.

Step 3

Turn the bleed key anti-clockwise, unit air starts escaping. 

Once the water starts to escape, turn the key clockwise to retighten and close the valve. 

Step 4

Repeat the process on other radiators which need attention, making your way toward the boiler.

Step 5

Once all radiators have been bled, turn your heating back on full and check if the radiators are heating up.

Step 6

Finally, check boiler pressure as it may have dropped as radiators were bled.

Boiler pressure should be between 1 and 2.

Please Note: If bleeding your radiators does not improve efficiency, your heating system may need to be flushed or drained by a professional plumber.

If you still need help with your heating system, get in contact with Refresh NI. We are your local heating experts, providing plumbing and heating services across Northern Ireland for the last 20 years.