What are the different types of radiator dials and how do their roles differ? Here we explain the major differences and functions of each.
Every radiator comes with several of what is technically referred to as valves, often also referred to as radiator knobs or dials. Or, when you’re at a loss for something better, ‘that thing’.
There are, of course, many types of radiator valves, each of which works in its own way.
In this guide, we’ll explore the most common types of radiator valves and answer the most common questions, including how they work. Aside from turning the knob - we trust that you’ve figured out that part.
With this knowledge, you’ll better understand what each component of your radiator does and how to fine-tune them to reduce energy waste and save money.
Let’s dive in!
What is a Radiator Valve?
The purpose of a valve is to control how much fluid or air passes through a pipe or duct.
In the case of a radiator valve, it functions to control the flow of water/air through your heating system pipes connected to your radiator. Not, as the name could also suggest, how much radiator flows through.
Of course, exactly how any given radiator valve works and its specific purpose varies from valve to valve.
Therefore, we’ll need to look at each type separately to explain the ins and outs of particular radiator valves.
The most notable types of radiator valves include:
Lockshield valves.
Manual radiator valves.
Thermostatic radiator valves or TRVs.
Lockshield valves control how much water can enter your radiator to inevitably ensure a balance between air and water within the unit. It’s like a boring interpretation of the Avatar series, with fire and earth notably absent.
The purpose of manual radiator valves and TRVs is to control a radiator’s temperature.
Naturally, the former must be manually controlled, whereas TRVs have automatic elements.
That said, TRVs can still be adjusted, even more so in the case of smart thermostatic radiator valves.
Different Types of Radiator Valves and How They Work
The average radiator features a lock shield valve, a regular radiator valve (which can come in one of two forms) and a bleed valve.
The exact location of these valves can vary depending on the radiator model you have.
As for the regular radiator valve, this may be a manual radiator valve or a thermostatic radiator valve.
What’s more, some radiator valves feature intelligent connectivity, making them examples of ‘smart radiator valves’. Unlike other smart devices, there’s no risk of radiators taking over the world, since they’re anchored into place.
Without further ado, here are the different types of radiator valves and how they work:
Lockshield Valves
All radiators come with a lock shield valve. This type of valve is generally covered with a plastic cap. If you have a modern radiator, it should be present at the bottom. If you have an old-fashioned radiator, do a curtsy before you start looking for the lock shield valve.
However, for older radiators, it may be positioned at either the bottom or top. Regardless, the lock shield valve will usually be found opposite the regular radiator valve.
The lock shield valve serves the purpose of controlling how much water enters the radiator from your heating system’s pipework.
It helps to ensure that your radiators have an appropriate balance of water and air.
However, if your radiators are not balanced correctly, the lock shield valve can be adjusted to re-balance them. Unfortunately, there are no training wheels for radiators, so this is a manual process.
These valves can also be used on all your radiators to re-balance your entire heating system.
Ultimately, when lockshield valves are doing their job properly on an ongoing basis, they’ll help to keep your radiators balanced and ensure that they heat up at the same pace.
Is your radiator leaking? It may be a lockshield valve leaking.
Manual Radiator Valves
As mentioned, the regular radiator valve will likely be opposite the lockshield valve.
The purpose of this valve is to control the radiator’s temperature. Of the two types of regular radiator valves, the manual version is more commonplace.
Manual radiator valves (as the name suggests) must be adjusted manually. By carefully and gradually turning a manual valve counter-clockwise, you’ll be able to bring up the radiator temperature. It might be manual, but it’s an improvement over shovelling coal into your furnace.
On the other hand, turning the valve clockwise will lower the radiator’s temperature or turn it off completely if you go fully clockwise until it can turn no more.
Unlike a thermostatic radiator valve, manual valves do not feature dials or numbers.
Therefore, you’ll only have a general sense of how much you’ve adjusted the radiator’s temperature as you turn the valve, not a scientific one. In that way, it’s a little like talking to your drunken uncle over Christmas: you have to feel it out.
Thermostatic Radiator Valves (TRVs)
Thermostatic radiator valves or TRVs are self-regulating regular radiator valves.
While they ultimately serve the same purpose as manual radiator valves, they are automatic, offer far more efficiency and enable more precision if you do decide to handle them manually on occasion.
That is to say, while they are primarily automatic, TRVs can be manually adjusted too.
To identify a TRV, you will likely find it on the opposite side of the lockshield valve (as would be the case for the average manual radiator valve).
It has a cylindrical dial and generally features numbers 0 through 6 with the ability to adjust it and turn it to any of these settings.
You should set the TRV to a suitable setting per the manufacturer’s instructions - assuming you’ve read them. If not, this would be the time.
Mostly, this will be setting 3 (which would set your radiator to a temperature of about 20 °C). However, always verify with the manufacturer’s instructions.
Room temperature is not just about comfort, but can also come down to health and safety (since a room too cold or too hot can prove a health hazard).
For more information on the ideal room temperature, check out our guide on this topic.
Smart Radiator Valves
Some thermostatic radiator valves have Wi-Fi connectivity and smart abilities, making them ‘smart radiators’. That term is in quotation marks because while our radiators may seem smart, they’ve never been able to do our taxes right.
To ensure your smart TRV can work as intended, you’d need to also purchase a smart thermostat that is compatible with smart TRVs. This way, you’d be able to control all radiator TRVs remotely via an app.
While TRVs without smart technology can improve the energy efficiency of your heating, smart TRVs can enhance their efficiency even more.
Of course, control, and convenience are other key benefits of smart radiator valves. Now, you can change the channel on the TV and the temperature without getting up. What a time to be alive.
Turning down your boiler flow temperature could also save you up to 8% on your heating bill too, check our new guide on whether to turn the radiators off in unused rooms for another quick and free energy-saving hack.
Bleed Valves
Radiator bleed valves come in the form of small metal squares inside a round nut.
They are usually located toward the top of your radiator. The purpose of a bleed valve is simply to release air from your radiator. The valve ensures that you don’t have to break the radiator to do so.
Naturally, opening the bleed valve is a key part of bleeding air from radiators. It is recommended that you bleed your radiators at least once a year. It doesn’t hurt them, whatever you call it.
You can undertake this work DIY, but only if you are sure of what is involved. Otherwise, hire a professional.
There are, of course, various other necessary steps to bleeding radiators than opening and closing the bleed valve.
Do radiator covers block heat? Check our guide and more energy-saving tips.
Angled Radiator Valves
We can also categorize a radiator valve based on its positioning, with the options being angled and horizontal.
Starting with angled radiator valves, this option is more common than the horizontal alternative.
Angled valves feature a 90° bend in the valve body where the radiators meet the rest of your central heating pipework.
Straight Radiator Valves
Some households feature radiators with straight radiator valves, however, they are not too common in the UK. It’s more a continental type of thing, like sunshine and winning World Cups.
These radiator valves connect a radiator to the rest of the pipework without the need for a bend.
Straight radiator valves make the most sense for homes in which the radiator inlets and pipework align. On second thought, we sure hope the pipework aligns everywhere, otherwise, things get messy.
More specifically, this may happen if they align through the radiator, where the radiator features inlets toward the bottom.
Corner Radiator Valves
Corner radiator valves resemble angled valves.
One difference, however, is that they don’t stick from the bottom of the radiator to the same extent.
Also, they have to be installed facing inward, making them trickier to adjust. This is a plus if you’ve got kids who keep dialling up the radiator instead of wearing a jumper.
If you have limited space, you may prefer a corner radiator valve, assuming it’s a suitable match in other regards.
H-Block Radiator Valves
These H-shaped radiator valves are installed in the middle of the radiator rather than at the side.
Along with generally being easier to fit and replace, H-block radiator valves can save space since they’re installed at the centre of the radiator and do not add width to the overall unit.
Sizing Radiator Valves For Your Home
Regardless of the type of radiator valve you need, sizing is important.
Sizing radiator valves does not relate to the physical size of the valve, but rather the width of the connections and size of pipework as measured in millimetres (mms). A poorly fitting valve also lets through a certain amount of water, but not in the way it was designed to.
The majority of UK households feature 15 mm pipes. However, pipe sizes can range from 8 mm up to as much as 28 mm.
It’s worth noting that various connectors and adapters exist to help fit a valve correctly.
Either way, though, it’s significant that you know what size radiator valve you’d need prior to making any purchases. If in doubt, hire a professional.
A heating engineer can, if you’d like, buy the right valve for you and perform the installation.
Get a free, no-obligation boiler quote today
Do you think it’s time for a boiler replacement? Or just curious to see how much one would cost?
Use our free boiler quote tool, and we could be fitting your new boiler tomorrow.
Why choose Heatable?
Gas Safe installation within 24 hours.
Thousands of happy customers – an average score of 4.9 on Trustpilot (that’s better than the market leader).
Price match guarantee – if you find a cheaper quote, we will match (must be like for like).
Multiple payment options – interest free available.
10 year guarantee.
Fixed price guarantee – no hidden costs.
Save your quote until later.
Heat Happy.
