How to bleed a radiator

If your boiler is on, but your radiator is cold, you might need to kick start the system and bleed a radiator. Here is a step by step guide to bleeding a radiator…

Step 1

Find a bleed key – this is a radiator valve key that can be picked up from Screwfix, B&Q or any plumbing or DIY shop… a flat head screwdriver can also work

Place a dustsheet on the floor directly underneath the radiator, to catch any water or muck

Make sure all the radiators are off/cold before you start work

Step 2

Locate the radiator vent. This is normally on the top at the right, and it looks like the end of a bolt which sightly sticks out. It’s generally silver

Step 3

Open the vent slowly with the bleed key. You normally need to turn it to the right, very slowly, until you start to hear the air hiss and rush out, which should take around 30-60 seconds to bleed (the larger the radiator, the longer it’ll take to come out). Don’t open the vent fully, just turn it quarter-turn

Step 4

Keep the vent slightly open until water starts to come out – you’ll need a tea towel or cloth to catch the water – then close it nice and tightly

It’s worth noting – you will usually need to top up the pressure on your boiler once you’ve bled the radiator.

For more information on any of the steps, click here

Doing DIY around your home? Take a look at our DIY guides page here