Are Radiator Keys Universal?

Radiator Key

Radiator keys come in all shapes and sizes – but do you know what they’re for and what they look like? These tiny metal keys are usually supplied with a radiator upon purchase from the manufacturer, but can also be bought by themselves when you inevitably lose one, drop it down the back of the very radiator you need it for or move into a new home and find none have been supplied.

If you’re looking for info on where to buy radiator keys, there’s no one stockist for all – but they can be found in hardware stores and the DIY aisles of supermarkets, as well as bought direct from the manufacturer if it's something a little more specialist. They come for as little as £0.69, so aren’t a huge investment.

What are the different radiator bleed key sizes and types?

Radiators should be bled at least annually as part of routine maintenance in order to keep radiators working to their optimum performance. This is done simply by loosening a radiator’s bleed valve, which usually sits to the top corner to the appliance and allowing the excess air to escape.

Aside from annual maintenance, you may also need to bleed your radiators to resolve any issues. If the performance of radiators seem limited or they develop cold patches, this may be caused by trapped air; so bleeding them can fix the problem.

Although most radiator bleed valves are similar, they’re not all identical, so radiator bleed key sizes and shapes do vary. Most hardware stores offer several types of radiator bleed keys so unless you have a very specialist model of radiator fitted, you should be able to find a compatible key fairly easily.

There are 11 main different types of radiator keys, and each has a different purpose:

  • Radiator bleed key – to bleed trapped air from radiators
  • Four-way key – to turn drain cocks or valves on/off when draining some radiators
  • Three-legged key – to turn some kinds of drain valves on/off
  • Double-ended key – to fit and remove radiator valve tails
  • Hex or Allen key – to loosen, fix or remove radiator valve tails and plugs
  • Radiator spanner – to fit or remove valve tails
  • Universal key – to loosen, fit or remove valve tails, blanking plugs and bleed plugs, but sometimes with profiles to fit other parts and plugs too
  • Combination radiator wrench – to fit or remove valve tails, blanking plugs and bleed plugs
  • Stepped ratchet key – to fit or remove valve tails
  • Radiator tail socket – to fit or remove valve tails
  • Radiator valve spanner – to avoid bending pipework when radiator valves are being tightened or removed.

There are also multi-way keys with several profiles for different functions but because of all the variables at play with different shapes, sizes and types, there’s not yet any one tool to cover off every eventuality; presumably because there would have to be so many parts to the key!

So, are radiator keys universal, or are they manufacturer or model specific? Unfortunately, there’s no one-size-fits-all. Some appliances have different sizes and types of keys and valves, and some have fittings for universal keys, so what you require depends on exactly what radiators you have installed.

This said, although most hardware stores stock lots of different types of radiator key, it may be worth taking a photo or even cast of the relevant valve along with you when you buy so that you can ensure you purchase the right one.

Can you bleed a radiator without a key?

Of course, if your radiator has started to develop a fault and/or you have reason to believe it needs bleeding, you may wish to do so as soon as possible – but can’t find a key. But can you bleed a radiator without a key, or is it a must?

This depends on the bleed valve your radiator has. Some bleed valves can be opened with pliers, a spanner or an Allen key; but care must be taken to ensure that the valve isn’t damaged when opened with something that isn’t a key. Most bleed valves can be carefully opened without a key, but it’s definitely easiest to do so with a properly shaped bleed key. Take it easy, be gentle and always use a protective cloth – to safeguard the valve itself and to ensure any leaking fluid is mopped up quickly.

If you’re unsure of which radiator keys you need or if the new radiator you have your eye on will need specialist equipment, drop a line to the Great Rads team. There can’t be many people you can chat bleed valves and radiator keys with, but we’ve got you covered.


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