How to Bleed a Radiator

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Regular heating and cooling of water can cause a build-up of trapped air in your radiator, making them less energy efficient and effective at heating your home. They should be checked on a regularly and bled if necessary. Try our simple guide to bleeding your radiator.

Step 1

Check Radiator

Firstly you should check if your radiator requires bleeding. Turn on your central heating. When the radiator has been on for about 15 minutes, place your hand on the radiator. If it is cold at the top and hot at the bottom, it is likely to have trapped air and requires bleeding.

Step 2

Open Thermostatic Valve

Open the thermostatic valve to the highest setting, which is usually the fifth setting. This will allow the air to bleed from the radiator more efficiently.

Step 3

Locate Bleed Valve

Locate the bleed valve on the radiator; this is usually at the top of one end of the radiator.

Step 4

Prepare Floor Area

Place an absorbent cloth or rag directly under the valve to collect any water that spills during bleeding. You may also want to spread more out on the ground near the valve for added protection against water that may spurt out.

Step 5

Open Valve

Using your radiator bleed key, open the bleed valve by twisting it about a quarter of a turn anti-clockwise until you hear a hissing sound. This is the sound of air escaping from the radiator successfully. When the hissing stops and drops of water start spitting out, close the bleed valve tightly by turning the key in a clockwise direction.

Step 6

Close Valve & Check Radiator

Wipe away any excess water, some of which may be dirty. Ensure the radiator has been fully bled by checking it is hot all over. Congratulations, you have now successfully bled your radiator! You may need to repeat the above steps with other radiators in your home.