It has a 0.5 inch hex, plus the usual two slot and square ends..
Similarly, you may ask, what size is a radiator key?
Old radiators are obviously imperial and use clock key sizes. A lot of the older ones are key size 12 which is approx 4.8mm, the size was simply rounded up when they went metric. If you have an older key (even metric) they usually fit but for some reason newer ones do not (also take account of a little wear).
Also Know, what size are radiator tails? Manual and thermostatic radiator valves. The tappings in a radiator are usually a standard 1/2 inch BSP female thread (see BSPT link at bottom of page for more info on plumbing thread sizes). Some radiator valves use a large union nut and tail, and others use a 15mm compression connection to the tail.
In this manner, what is a radiator hex key?
An Allen (sometimes called hexagon or hex) radiator key is for fitting and removing standard 1/2 inch radiator valves. It is also known as a half-inch section key. This key is normally made from high tensile steel and is usually galvanised or zinc-coated for protection against corrosion.
Does one radiator key fit all?
No key will do every job A universal key, like this one, may do jobs on radiator valve tails and plugs, but it might not adjust bleed valves.
Related Question Answers
Can I bleed a radiator without a key?
If you do not have a Radiator Key, it is sometimes still possible to bleed the radiator. Take a look at the end of the square shaft and check if it has a slot cut into the end of it. If so, you can use a screwdriver to carefully turn the shaft and open the valve, instead of using a Radiator Key.Are there different types of radiator keys?
Double-ended keys, Allen or hex keys, radiator spanners, universal keys, stepped ratchet keys, combination wrench/keys and tail sockets are used to remove and fit valve tails. Valve tails on most modern radiators have a fixed external hexagon (six-sided) or square (four-sided) nut built into them.Which radiator should I bleed first?
If your home has 2 floors you should begin bleeding the downstairs radiators first. It's also advisable to start with the radiator which is furthest away from the boiler. Once you've bled all the downstairs radiators you move on to the upstairs, again beginning with the radiator which is furthest from the boiler.What does radiator key look like?
It looks like a round hole with a square inside. When you insert the radiator key into the bleed valve, you will feel them lock together. Carefully turn the valve anti-clockwise – as the air begins to escape you'll hear a hissing sound.Do I need a radiator key?
Although a screwdriver can be used for some modern radiators, most radiators require a radiator key to bleed. If you don't have a radiator key, you can pick one up from most DIY stores. Ensure you have a cloth below the radiator valve to catch any water.How do you bleed an old radiator?
Method 1 Bleeding a Radiator in Your Home - Diagnose your radiator.
- Find a radiator key.
- Turn off your heat.
- Open your radiator's valves.
- Catch drips from the valve.
- Wait for water to squirt out of the bleed valve.
- Repeat this process on all the radiators in your house.
- Check your boiler's pressure level.
What is a radiator spanner used for?
A radiator valve spanner helps avoid bending pipework when the union nut of a manual, thermostatic or lockshield radiator valve valve is undone or tightened. It is also known as a radiator valve wrench and a radiator valve lever. Valve spanners can be made of plastic, like the one here, or zinc-coated steel.How do I measure for a new radiator?
The old radiator measure 675mm in width - from where the valve tail go into the actual radiator. The opening between the two valves on the pipes is 737mm (this would be between the thread on the valve bodies).Should TRV be on flow or return?
The vast majority of new TRV's are bidirectional and can be fitted to either the flow or return, but it is always good practice to fit them to the flow side. If a non bidirectional TRV is fitted on the return side it will create a vibrating sound as the water tries to flow though it.Can you fit TRV on towel radiator?
Can a trv be fitted to a towel rail. A TRV can be fitted to any radiator, however it is normal practice that 1 radiator on the system (usually in the bathroom) has 2 manual valves instead of a TRV and a manual valve.Do I need straight or angled valves?
Straight valves should be used when the inlets are at the bottom of the towel rail and the pipes are protruding from the floor. Angled valves will be needed if the water needs to be diverted at a 90-degree angle. This is often the case when pipes and valve inlets are situated at the side of the radiator.Are radiator valves universal?
With a large variety of radiators currently available on the market in varying shapes, styles and sizes, not every valve is universally suitable to all radiators.What side of radiator is thermostatic valve?
Many modern homes will have TRVs – Thermostatic Radiator Valves – attached to most of the radiators on the opposite side from the lockshield valves. A TRV should always be fitted to the inlet on the radiator and the LSV to the outlet.Are all radiator valves the same size?
While the overall size of each radiator valve can be dependant on the aesthetics and type (thermostatic valves are usually longer), we're going to talk about fitting sizes here. 15mm valves are the only size you're likely to encounter, since 15mm copper pipes are the most common.Should water come out when bleeding a radiator?
Loosen the bleed screw Just one quarter to a half turn is enough - never open the valve fully or water will pour out once the air is released. You should hear a hissing sound as the air escapes.Can you bleed a radiator with a screwdriver?
Depending on the type of bleed valves on your radiators, you'll either need a radiator key or a flathead screwdriver. Most radiators are bled using a radiator key but if you're not sure, find a bleed valve. On some newer radiators, the bleed valve has a straight groove for a flathead screwdriver.What happens if you don't bleed radiators?
Because air doesn't conduct heat as well as water, you might notice these air pockets as cold patches on your radiators. If you don't bleed your radiators, the problem will worsen. Eventually, your central heating won't get to the correct temperature, even with it turned right up.How do you drain a radiator without a key?
You will first need to check to see if your radiator has a slotted bleed screw. If this is the case, then your screwdriver should work as a perfect substitute for a key. Insert the head of the screwdriver into the slot and turn counter clockwise to bleed the radiator properly.What happens if I bleed my radiators with the heating on?
You can't bleed a radiator when the heating is on, as it may be too hot to touch. You could also get hot water spraying out of the radiator. Use your radiator key to turn the valve at the top of the radiator. Bleeding your radiators can cause the pressure to drop. 
