person using a flathead screwdriver to bleed a radiator

If your radiators feel cold at the top or aren’t getting warm at all, they could need bleeding. Only, now that you’ve come to do the task, you might discover you can’t find the radiator bleeding key. Luckily, there are a few alternative tools you can use to get your radiators up to full heat again. 

How to bleed radiators without a key

Below, you can find some radiator bleeding key substitutes that should do the task at hand just as well. However, before we reveal what these are, there are some tools that shouldn’t be used for this job.

For example, you should avoid using pliers. Many people think that these will be a good option as they can easily grip the screw that will open the valve to release the air. However, no matter how careful you are, pliers can damage the screw, which could make it difficult to close the valve again or to bleed the radiators next time you come to do this job.

You should also avoid using a cross head screwdriver. These will likely scratch and damage the valve, so these shouldn’t be used either.

Now that we’ve revealed the tools to avoid, what can be used to bleed your radiator?

A flathead screwdriver

If you look at the bleed plug that’s currently in the radiator and it has a small slit in the middle, you could use a flathead screwdriver to open it. Not every radiator will have a slotted screw, so you may not be able to use this type of tool, however, it’s worth having a look.

Insert the screwdriver so it fits neatly in the screw and open the valve by turning the screwdriver to your left (anticlockwise). You’ll begin to hear a hissing noise - this is just the air escaping from the radiator. Ensure that you have a towel on the floor and a bucket to catch any water that might leak out.

No matter which method you choose, you should follow our guide to bleeding radiators carefully to avoid any accidents and ensure you’re staying safe.

Are there different types of radiator keys?

If you think that you’ve lost your radiator key permanently, you may want to purchase another one instead of always using a screwdriver. However, you may not have realised that there are over 10 types of radiator keys that all do different things. There is only one type of bleed key for modern radiator, but there is also a four-way key, used for turning drains or valves on and off, a double-ended key, used for installing or removing valve tails, and a universal key that can be used on blanking plugs.

Some keys can be used for multiple jobs, for example the bleed key, radiator spanner, allen key and the combination radiator wrench can all be used to bleed radiators, as well as being good for other things. A heating installer will generally have all of these things, but they aren’t devices that are likely to be in your home.

Are radiator keys all the same size?

Radiator keys for modern radiators will generally be a standardised size, so you needn’t worry about buying a radiator key that won’t fit.

However, older radiators adhere to the imperial scale that was used in the UK before the switch to the metric system. Therefore, if your radiator is around 30 years old, you may find that newer radiator keys don’t fit. These imperial radiators use the same scale as clock keys. Keys that are used to wind up clocks work on a number scale from 000 to 16. A clock key between size eight to 12 should work on your older radiator if you wish to bleed it. Many clock keys come with multiple sizes in one pack so you should be able to find one that’s the right size.

It’s important to be aware that new radiators are much more efficient and could save you both money and energy at home, so if your radiators still use the imperial system, you may wish to swap them for a newer model.

Where to buy a radiator key

Radiator keys can be purchased from your nearest DIY and hardware store, local plumbers merchants and national retailers such as Screwfix.

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