Skip to the content
Trustpilot logo 0800 61 22 302

 BLACK FRIDAY - WE'LL PAY YOUR WINTER GAS BILLS. MORE INFO

How to bleed a radiator - quick & easy steps

In this guide, we’ll explain how to bleed your radiator in 7 quick & easy steps. Bleeding your radiators will help increase the efficiency of your central heating, lower your energy bills and help make your home get warm quicker.

What does bleeding a radiator mean?

If your radiator isn't as warm as usual and you've noticed cold patches at the top, then you'll likely have air trapped within the radiator – this is a common issue for un-vented heating systems. To fix the issue, you'll have to bleed the radiator, this is a simple process to do with our friendly step by step guide - we'll even show you how to manage if you don't have a radiator key.

Our step by step guide to bleed a radiator

Bleeding radiator to ombat cold patches at the top

How to bleed a radiator

Before you get started, you’ll need a radiator bleed key and a spare hand towel or mug to catch any drips. 

  1. Turn your heating off – if you don’t, you’ll be at risk of scalding yourself and getting hot water on the floor.

  2. Get the towel/mug ready – when you bleed a radiator, some discoloured water will come out and will need to be caught before falling on your carpet/floor.

  3. Open the radiator bleed valve – using your radiator bleed key, insert it into your bleed valve, this is often found at the side of a radiator and looks like a round hole with a square inside. When you insert the key, you’ll feel them lock together, turn the valve anti-clockwise – you’ll hear a hissing noise which is the hot air escaping, so be careful.

  4. Bleed your radiator – a quarter-turn of the valve will be enough; don’t turn it too far or else water will come rushing out. Hold the radiator valve open until the air stops coming out and water starts to drip out - this means you’ve successfully bled a radiator.

  5. Seal the valve – turn the radiator bleed valve clockwise to tighten, making sure not to overtighten. Repeat the above processes on all the radiators that need bleeding.

  6. Check the pressure on your boiler – once you’ve bled your radiators, check your boiler’s pressure gauge to see if your system needs to be re-pressurised. If it’s between 1.0 - 1.5 bars then you’re all done. 

  7. Adjust boiler pressure - if your boiler pressure is too low then you need to manually increase the boiler pressure, this could be with a central filling loop that’s connected to your boiler. Find out what make and model your boiler is, then go to the manufacturers' website, they'll have a walkthrough explaining how to increase pressure for your exact boiler. 

How to bleed a radiator without a key

Some modern radiators are equipped with valves that are designed to be turned with a simple flathead screwdriver. So, if you don’t have a radiator key handy then a flathead screwdriver could do the trick.

Before you get started, you’ll need a spare hand towel or mug to catch any drips. 

  1. Turn your heating off – if you don’t, you’ll be at risk of scalding yourself and getting hot water on the floor.

  2. Get the towel/mug ready – when you bleed a radiator, some discoloured water will come out and will need to be caught before falling on your carpet/floor.

  3. Open the radiator bleed valve – using your flathead screwdriver insert it into your bleed valve, this is often found at the side of a radiator. When you insert the key, you’ll feel them lock together, turn the valve anti-clockwise – you’ll hear a hissing noise which is the hot air escaping, so be careful.

  4. Bleed your radiator – a quarter-turn of the valve will be enough; don’t turn it too far or else water will come rushing out. Hold the radiator valve open until the air stops coming out and water starts to drip out - this means you’ve successfully bled a radiator.

  5. Seal the valve – turn the radiator bleed valve clockwise to tighten, making sure not to overtighten. Repeat the above processes on all the radiators that need bleeding.

  6. Check the pressure on your boiler – once you’ve bled your radiators, check your boiler’s pressure gauge to see if your system needs to be re-pressurised. If it’s between 1.0 - 1.5 bars then you’re all done. 

  7. Adjust boiler pressure - if your boiler pressure is too low then you need to manually increase the boiler pressure, this could be with a central filling loop that’s connected to your boiler. Find out what make and model your boiler is, then go to the manufacturers' website, they'll have a walkthrough explaining how to increase pressure for your exact boiler. 

Still got cold patches? Get in touch now

If you notice more and more cold patches in your radiators, get in touch with us at 0800 61 22 302 or book a repair with us and we'll send out one of our Gas Safe engineers to fix any issue.