How to Bleed a Radiator without a Key?

how to bleed a radiator without a key


Bleeding a radiator is one of the most straightforward DIY projects you can do for your central heating. If your heating system is turned on, but one of your radiators feels chilly or won’t heat up, the air is most likely trapped in the top of the radiator, and bleeding out the air might fix your issue.

But what if you’ve misplaced your radiator key and don’t have the proper instrument to bleed your radiator? While radiator keys are widely accessible in many DIY shops, and most are the same size, this is inconvenient if you need to fix your heating right away!

Fortunately, another approach will work on many radiators that need bleeding. Continue reading this guide on how to bleed a radiator without a key.

What Exactly Is a Radiator Bleed?

What Exactly Is a Radiator Bleed

Bleeding a radiator involves releasing trapped air within your heating system. Allowing this air to escape will allow you to heat your house more efficiently and save money on your energy costs. If you hear pipes banging or radiators gurgling, this is typically an indication that your radiator needs to be bled.

The Fundamentals of Radiator Bleeding

The Fundamentals of Radiator Bleeding

A simple test may inform you whether one of your radiators needs to be bled. Before touching the radiator, please turn on the heat and allow it to warm up. It will be heated since it is near to the water intake. Now, run your hand along with the radiator to the top.

If it becomes progressively colder as you do this, the air in the pipes prevents the hot water from flowing. This air is released by opening the bleed plug.

It’s a basic notion, yet many people overlook it. Consequently, your heating cost will be higher, and your home will be colder.

What to Do If You’ve Misplaced Your Radiator Key

What to Do If You've Misplaced Your Radiator Key

Bleed plugs come in a variety of forms. Some are in the form of square nuts, and the key is just a socket that fits over the nut and is attached to a handle.

If you happen to lose this sort of key, grab your socket wrench set and choose the socket that fits over the plug. This plug style may also be turned using a spanner or pliers.

Some plugs resemble security screw heads, with a hexagonal opening and a square or hexagonal nut. The nut prohibits you from replacing the lost key with a hex wrench or screwdriver, but you can generally slip the jaws of a set of needle-nose pliers into the orifice to hold the nut and spin the plug.

Bleed plugs with hexagonal sockets are another option. This sort of radiator key is essentially an Allen key. If you lose your key, replace it with an Allen key of the same size.

There are no Allen keys in the house? A flathead screwdriver may frequently use in place of an Allen key. Wrap duct tape around the head is slightly smaller than the socket.

Various Ways for Bleeding Radiators

Various Ways for Bleeding Radiators

If you don’t have a radiator key, don’t worry; you could have something else in your toolkit to aid you with rad bleeding. It is crucial to understand since being able to bleed your radiators may assist in remedying the issue of a cold radiator.

A flat head screwdriver is the most often used alternative to a radiator key. Most new radiators made in the past 5 – 10 years include a tiny depression that allows a flat head screwdriver to be put into the bleed plug.

Using a receptacle or a towel to collect any drips, insert the screwdriver end and gradually spin anti-clockwise. As air is caught in your radiators, it hisses when it exits.

Not many radiators, especially older convector radiators, will allow you to use a flathead screwdriver. In this case, bleed the radiator using an Allen key, a small wrench, or pliers.

However, exercise caution while utilizing any of these tools since you may cause permanent damage to the bleed plug. Even if you open the bleed valve and let the air escape, you may find it difficult to seal it again.

If you don’t have a radiator bleed key and your radiator doesn’t allow you to use a flathead screwdriver, think about if this problem can wait until you can acquire a bleed key.

It will assist you in clearing the problem without causing harm to your radiator. It may be worth the somewhat longer wait rather than settling for a quick, heavy-handed remedy.

Is It True That All Radiator Bleed Keys Are the Same?

Radiators installed in the last 30 to 35 years will be of a standardized metric size, and you can purchase a radiator key that will fit all radiators in your home.

They usually have one flat end for you to grip between your thumb and fingers and one square end to slot over the bleed valve.

Some properties with extremely ancient central heating systems may have radiators with imperial radiator bleed plugs that current radiator keys would not fit. Older radiators may still be bled using imperial clock keys (keys traditionally associated with winding up clocks).

A clock key size 12 (4.8mm) will most likely be sufficient for an old radiator, but it’s recommended to obtain keys in sizes 8 – 12 to be safe.


A boiler, generally located in the basement, provides hot water to radiators in a home. Hot water must circulate fully through each radiator or Energy efficient electric radiator to provide effective heating, which it cannot accomplish if air enters the system.

The air tends to congregate near the top of the radiator, forming a barrier. As a result, each radiator includes a bleed plug, which is often situated on the side near or at the top. A bleed plug is usually a unique form that requires a radiator key to spin. Don’t be concerned if you misplaced your key.

A variety of tools may fill in and complete the job. If you read the above article on bleed a radiator without a key, you already know the solution.

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