How to Bleed a Radiator

If your radiators aren't heating up properly or are chilly at the top and warm at the bottom, they may need bleeding. This will allow hot water to circulate through your heating  system once more. Bleeding radiators once in a while will keep them running efficiently. That means not just a warmer home, but also lower energy bills!

Although it may appear intimidating, bleeding your radiator is a quick and easy job that you can do yourself. To help you, Frank Key has created a video and step-by-step guide on how to bleed a radiator.

What is it to Bleed a Radiator?

Bleeding a radiator is essential for removing any excess or trapped air from the heating system. When air builds up within the system, it obstructs the flow of hot water, limiting its reach to only halfway within the radiator. This failure leads to cold areas in your house or you wondering why a room feels a bit cold.

Bleeding a radiator lets the trapped air out and instantly improves the efficiency of your heating system and makes your home a little cosier.

How to bleed a radiator - Step by step

Step 1: Make sure your central heating and hot water are turned off at the boiler and the radiator has cooled down. If you attempt to bleed your radiators while they are still warm, you risk spraying boiling water everywhere.

Step 2: Using a radiator key, you can now release the trapped air. Insert your radiator bleed key and turn it anti-clockwise to slightly open the radiator bleed valve without removing it (a hissing sound will be heard).

Step 3: Water will begin to come up through the hole once the air is gone, quickly turn the key clockwise to re-tighten the valve.

Step 4: Turn on your heating system and touch the top of the radiators to see if they are heating up properly.

Step 5: Check the pressure gauge on the front of your boiler after you've bled your radiators. The boiler pressure should be between 1.0 and 1.5 bars. If it's less, you'll need to top up your boiler pressure. 


What tools do I need to bleed a radiator?

The only tools you need are a radiator bleed key and it is advised that you use a towel or a jug to catch any excess water.

How do I bleed a radiator without a key?

To bleed a radiator without a key, use a flathead screwdriver. Insert the flat head into the bleed valve's notches and turn anticlockwise to open the valve and clockwise to close it.

How do I know if my radiator needs bleeding?

An easy way to tell if your heating system needs bleeding is if your radiators have cold patches at the top but are warm at the bottom.  Other typical signs include the radiator taking longer than usual to heat up or making grumbling noises.

Do you bleed radiators hot or cold?

Always make sure your boiler is turned off and the radiators are cool before attempting to bleed them. When turned on, the hot water in the radiator has the risk of scalding you.

How long does it take to bleed a radiator?

Bleeding a radiator is a quick procedure - roughly 30 seconds, depending on the size of the radiator and how much air is trapped inside.