How to Bleed a Radiator Without a Key

21st October 2022

The way to bleed a radiator depends on the type you have and the tools available to you. Radiator keys are easy to misplace, but given the right alternatives and know-how, you can still bleed a radiator without one. If you have a radiator key, head over to our guide on How to Bleed a Radiator.

Bleeding radiators is fairly simple, and you won’t usually need a professional’s help. That said, if you are planning to bleed a radiator by yourself, it’s important to follow the right process and use the correct tools. This can help you complete the process smoothly and safely. Here, we’ll take a look at the different tools you can use for bleeding radiators, as well as how, and when, to do this.

When to Bleed Radiators

There are a few signs that will tell you a radiator needs bleeding:

• Your radiator features cold spots, despite some areas being warm.
• Patches of mould, damp or condensation have built up on your walls.
• You notice rattling or gurgling noises coming from the radiator.

If your radiator is exhibiting any of these signs, bleeding it may be necessary.

Radiator Is Cold at the Top

Turn your radiator on – is it cold at the top but warm at the bottom? If so, this is typically a sign that the radiator has air trapped in it. This happens when air bubbles in the radiator rise to the top, stopping the water from properly circulating around the heating system. Bleeding your radiators can help resolve this issue by releasing the trapped air inside.

If instead the radiator is cold at the bottom and warm at the top, it’s likely that something else is causing the problem. Find out more about why your radiator is cold at the bottom but warm at the top, and how to fix this.

Patches of Mould, Damp, or Condensation Build-Up

Damp patches, condensation, or mould on your walls can be a sign that the radiator is not working properly. Mould occurs when hot moisture in the air lands on a cold surface, resulting in condensation. Coincidentally, this can happen when an area is not heated effectively or, in other words, when a radiator doesn’t work. Bleeding your radiators may help release the trapped air that’s preventing your heating system from working properly.

Radiator Is Rattling or Gurgling

If you find that your radiator is making unusual sounds like rattling or gurgling, this could indicate there’s some trapped air. Bleeding your radiators will remove the trapped air and stop the unusual sounds.

Strange sounds coming from your radiator can also be a sign of something more serious. If the strange noises still persist even after bleeding your radiators, it’s best to get a professional in to help pinpoint the issue.

Alternative Tools for Bleeding Radiators

While it’s easier to bleed a radiator with a key, there are other tools you could use instead that work just as well. You may need to try an alternative tool if you don’t have a radiator key. Here are some common tools you could bleed your radiator with, depending on the model and type.

• Flathead screwdriver – a screwdriver with a flat-bladed end. You could use this tool to bleed the radiator if the bleed valve features a straight slot. Find out more in our guide to radiator valves.
• Allen key – also called a hex key, these tools are shaped like an L with a hexagonal head. This head fits onto compatible screws to be tightened or loosened. If the bleed valve has a hexagonal shape, depending on the size of the Allen key, you could use this tool to bleed the radiator.

When preparing to bleed your radiator, you’ll also need a bucket or other type of container to collect any water that spills out. Having an old cloth ready can also help prevent any major spills when bleeding your radiators.

How to Bleed a Radiator in 6 Steps

Learn how to bleed a radiator using the following simple steps:

1. Get the equipment ready – gather all the equipment you’ll need. This includes placing the bucket/container and cloth below the radiator’s bleed valve.
2. Turn off your central heating – this will prevent the risk of burning yourself as well as stopping excess water from spilling out during the process.
3. Open the radiator’s bleed valve – using the appropriate tool for your radiator valve, open the bleed valve to release the trapped air inside. To do this, ensure your tool is positioned correctly and keep a good grip on the valve before twisting anti-clockwise. As the valve opens, you should hear a hissing sound. This is the pressure releasing from the radiator and a sign the process is working.
4. Close the bleed valve – when you no longer hear a hissing sound and water starts to leak out of the plug, it’s time to close the valve. Turn the plug clockwise to tighten it. Be careful not to overtighten, as this could damage the radiator.
5. Wipe moisture off the radiator – wipe away any excess moisture from the radiator. This will help to prevent a build-up of rust.
6. Check your boiler pressure – bleeding your radiators can cause the boiler pressure to drop. Therefore, it’s essential to check the pressure once you’re finished with this process.

Find out what to do if your boiler pressure is low. If the boiler pressure is okay, switch your central heating back on to check whether bleeding the radiators has fixed the issue.

Why Do Radiators Need Bleeding?

Bleeding your radiators can help them work more efficiently. As an efficient radiator will need less energy to heat a home, this can also help to reduce your energy bills. While you might only think to bleed your radiators when an issue occurs, it’s recommended to bleed them every year. 

If you find you need to bleed your radiators more frequently than this, or bleeding your radiators hasn’t helped resolve your heating issue, call in a professional who can help to diagnose the problem.

Radiator Not Working After Bleeding?

If the radiator still isn’t working properly after bleeding, something else could be behind the issue. In situations like these, it’s best to seek the help of a qualified professional. Did you know that Hometree’s Boiler Cover offers 24/7 protection not just for radiators, but for your home’s entire central heating system? Boiler and central heating cover can prepare your home for an unexpected radiator issue or, a more serious problem, such as a boiler breakdown. We cover all types of boiler and central heating systems – no matter the age or model.