How smart radiator valves work

Smart radiator valves let you control the temperature in individual rooms when your central heating is on. They can be programmed and controlled remotely through your smartphone.

Manufacturers promise big savings on your heating bills, and, if used well, smart radiator valves can help you save energy. 

You’ll sometimes see smart radiator valves called smart radiator thermostats. Note that these are not the same as smart thermostats (which are a related product). Smart radiator valves, aka smart radiator thermostats, work locally on each radiator, while a smart thermostat controls your overall heating system and determines whether your boiler is on or off. 

If you pair your smart radiator valves with a smart thermostat, you can set up a heating schedule that runs completely by itself.

This guide breaks down everything you need to know so you can decide if smart radiator valves would be right for your home.

Smart radiator valve reviews – find the ones that aced our testing.

How do smart radiator valves work?

Manual radiator valves 

Before we get to smart controls, you need to know how basic valves work. The most basic type of radiator valve is a manual radiator valve. Manual valves have no way of sensing and reacting to the temperature in the room. They work similarly to a tap, and control the amount of water running through the radiator.

An ordinary, manual radiator valve allows you to adjust the temperature of each individual room in your home by controlling the flow of water from your boiler to your radiator. If you turn your radiator valve up, a higher volume of hot water will enter your radiator when your central heating turns on. This will warm the room to a higher temperature.

Once you feel that the room is warm enough, you will need to manually turn the radiator valve back down, or you will be wasting energy and money on heat that you don’t need. It would be easy to manually overheat.  

Thermostatic radiator valves (TRVs)

The next step up from this is a thermostatic radiator valve (or TRV for short). These work in a similar way, but have a sensor that can detect the air temperature in the room. 

As with manual radiator valves, you can use TRVs to control the heat output of individual radiators. When the surrounding air reaches a certain temperature, they limit the flow of hot water to that radiator. That means you don’t have to remember to keep manually adjusting them and your rooms won't overheat. 

A TRV could help you save money compared to a manual radiator valve, as you won’t have to remember to turn the valve down once your ideal heating level is achieved: the TRV will stop the water going to the radiator once the ideal temp has been achieved. They're particularly useful in rooms prone to overheating, such as small box rooms or those with a lot of natural light. They're also useful in rooms you want to keep cooler than your man living space - bedrooms, for example. 

Whether they're manual or not, you shouldn't use temperature limiting valves in the room where your main boiler thermostat is, as your TRVs and thermostat will compete with each other.  

They're not recommended in bathrooms either, as the humidity will interfere with its perception of the air temperature. 

Smart radiator valves

The function of a smart radiator valve (or SRV for short) is exactly the same as a TRV, but with these four key advantages: 

• You can control a SRV remotely through a smartphone app;
• You can set up a precise heating schedule for your SRVs through a smartphone app - you might want bedrooms to stay cool during the day and then warm up in the evening, for example;
• You can set the exact temperature of SRVs in degrees celsius rather than a 1-6 scale;
• Energy-saving smart features such as open window detection can help you reduce energy wastage. 

Installing and connecting smart radiator valves

You can install an SRV without needing the help of a professional if the radiator already has a TRV. If you're replacing manual valves with TRVs or SRVs you will likely need a plumber to set them up.

If replacing TRVs with SRVs, in most cases you simply:

1. Remove the old TRV from your radiator 
2. Attach the correct adapter (your SRV may come with adaptors for common radiator designs)
3. Put the batteries into your new SRV
4. Attach the SRV to your radiator.

You will also need to set up the manufacturer’s internet bridge or gateway.

This is a connecting device which plugs into your broadband modem and allows your smart appliances (in this case, your SRVs) to be controlled by your smartphone app. 

If you already have a smart thermostat, you've more than likely got the manufacturer's connecting device already. If you're just starting out with smart heating, most manufacturers sell starter packs that include a connecting device, smart thermostat and/or smart radiator valves.

Most smart radiator valves will not work with another manufacturer's smart thermostat and connecting device, so make sure everything you buy is compatible. 

How we test smart radiator valves – learn how we sort the best from the worst.

Different smart home heating setups 

Below are a few heating setups. We show you what you can and can't do with them.

Thermostat and manual radiator valves

This is the most basic heating set up. You set your thermostat to turn the boiler on and off (the radiators can’t emit heat unless the boiler is on). 

Your boiler heats water, which is sent to your radiators. The radiator valves allow hot water into the radiator. Turning the valve adjusts the level of water flowing through the radiator, and how much heat is given out. 

As we said before, you will need to turn the valve (of each individual radiator) down once your ideal temperature has been reached because the manual radiator valve won't know when to stop sending water to the radiator. 

Note that changing the setting of a radiator valve won’t turn the boiler itself on or off. If you want to turn your boiler off, you would need to do that on the thermostat or the boiler itself. 

Thermostat and thermostatic radiator valves

Again, you manually set the thermostat to turn the boiler on and off depending on the temperature it is set to compared to the temperature it is detecting. You can then set the desired temperature of each room using the thermostatic radiator valves. In the diagram below:

• Bedroom 1 is set to 5 (approximately 25-30°C)
• Office to 3 (approximately 15-20°C)
• Bedroom 2 to 0 (radiator off).

You would only have to go to each room to manually set this up the first time around. Thereafter, the TRVs would work by themselves to maintain this temperature.

In this scenario, the valves and thermostat can’t communicate, because neither is smart. 

What you can do:

• use the thermostat to turn the boiler on and off
• control the temperature of individual rooms with TRVs.

What you can't do:

• control the TRVs remotely from, say, your phone
• turn the boiler on or off by changing the setting of a radiator valve
• easily create zoned heating for different times of the day.

Smart thermostat and thermostatic radiator valves

As shown by the dotted line in the diagram below, you can use your smartphone to communicate wirelessly with your smart thermostat via a compatible connecting device.

This means you can remotely set the thermostat temperature, and it will turn the boiler on and off to maintain the temperature of the room it's placed in. Find out more about smart thermostats.

You can also set up heating schedules within the app to change the thermostat temperature throughout the day. In the diagram above, the thermostat is located in the living room. So you could set it to a lower temperature when you’re active during the day and a warmer temperature in the evening when you’re  sitting down in front of the TV.

You can set the temperature in each of the other rooms individually  using the thermostatic radiator valves. However, as seen on the diagram, the valves can't communicate with the smart thermostat or your smartphone. So, if you want to change their settings, you would need to do this manually. If you wanted to heat your rooms to different temperatures at different parts of the day, you would need to do this manually.

What you can do:

• control your smart thermostat remotely with your smartphone
• use the smart thermostat to remotely turn your boiler on and off
• program heating schedules for the room your thermostat lives in with your smartphone.

What you cannot do:

• control the thermostatic radiator valves remotely. Only the temperature of the room with your thermostat would be controllable remotely
• turn the boiler on or off by changing the setting of a radiator valve. You would still need to do this either at the thermostat on the wall or via your phone.
• easily create heating schedules for different times of the day.

Smart thermostat with smart radiator valves

As shown by the dotted line in the diagram below, you can use your smartphone to communicate wirelessly with your smart thermostat and also the smart radiator valves, via a compatible connecting device.

This means you can remotely set the smart thermostat and smart radiator valve temperatures. You can even set the exact temperature for each room with smart radiator valves, instead of the 'rough' temperature as you do with TRVs

All the smart radiator valves can communicate with the smart thermostat, meaning you can turn the boiler on and off by changing the settings of any of the connected heating devices. The home setups above, this gives you the most complete control of your heating.

You can easily set up heating schedules. For example, the heating can be turned off in all the rooms but the office during the day, and then be turned on low in the bedrooms and higher in the living room during the evening. 

This allows you to only have heating on when you need it, and in the rooms you need it – potentially saving money on heating bills. Whether it definitely will save you money or not depends on how effectively you use the heating system, though. 

What you can do:

• control your smart thermostat and SRV settings remotely with your smartphone
• turn the boiler on or off remotely with the smart thermostat or by changing the setting of a smart radiator valve
• program heating schedules with your smartphone
• easily create zoned heating so that different rooms are set to different temperatures for different times of the day.

What you can't do:

• In theory you can control every aspect of your home heating, but this setup is the most complex. It can be tricky to use to its full potential if you are not tech savvy.

Smart thermostat reviews – find a top thermostat to start your journey to smart home heating.

Are smart radiator valves worth it?

Ultimately, this will depend on what you want smart heating for. Smart radiator valves offer high levels of control, but that doesn't suit everyone and isn’t the right way for everyone to save money.

Smart radiator valve pros

• You set the temperature in degrees Celsius You might find this easier to use and more intuitive than the 0-5 scale on TRVs.
• You can change the settings remotely If you tend to keep your heating schedule consistent, then you don't need to adjust your TRVs. However, if your heating needs change and you find that you need a particular room to be warmer on certain days, you could save energy by turning the valve down when you're not there. In that scenario, it would be necessary to adjust your TRVs manually.
• You can see how much you're heating Many smart heating apps allow you to monitor your energy use, making it easier to see where you could be saving money.
• You can create zoned heating If you want smart heating where you can control the temperature and whether the heating is on or off in each room, smart radiator valves allow you to do this.

Smart radiator valve cons

• Price Smart radiator valves typically cost between £35 and £80 each, about five times more than a traditional TRV. That cost adds up if you want smart valves on multiple radiators.
• You need a compatible smart thermostat if you want to get everything that a smart radiator valve has to offer, as this will allow your valves to communicate with the boiler to turn it on and off. ou're locked into a brand if you want to expand: Most smart radiator valves aren’t compatible with smart thermostats and connecting devices from other brands. This means you'll have to buy into one brand's ecosystem. If you already have a smart thermostat and are looking to buy SRVs, the will probably have to be from the same manufacturer that made your thermostat.

Smart radiator valves are great if you want complete control and transparency over how much you're using your heating. 

If you have a regular schedule, you may well benefit from being able to program a heating schedule. 

Conversely, if you go away on holiday – or just a night out – you can easily turn the heating off to save money, then turn it back on when you're on your way back so you're greeted to a nice warm home.

You need to be tech-savvy to control them correctly. When making changes remotely there is the potential to make mistakes in the settings and you would not realise until you came home.

They’re not for people who don’t own smartphones or don’t like using one, as not all are compatible with desktop. 

Small spaces, such as a one-bed flat or bedsit, tend to only have one or two radiators. So buying smart radiator valves for such homes won't be of much benefit.

While tinkering with your heating settings can result in energy savings, don't neglect other actions that could be more useful, such as lowering your boiler flow temperature.

Which smart radiator valve brands offer the best software and security support?

Software and security support are important considerations when buying a smart radiator valve, since this will dictate how long the brand aims to continue updating the device with new features and security patches, to guard against emerging threats.

We reached out to the biggest brands to find out more about support policies, and some are far better than others.

• Salus stood out last year, when it said it offers security updates for a minimum of 12 years from launch. However, this year it didn't respond.
• Drayton promised a minimum of five years of update support from launch when we asked last year, but didn't confirm that policy with us this year.
• Honeywell stated in 2022 it will offer at least two years support from launch, but didn't respond this year.
• Energenie said it offers two years of support for its smart thermostats. 

Other brands, including Tado, Netatmo, and Eve did not provide us with specific information on update support periods.

While you may not be at immediate risk if you're using a device that's unsupported, it's obviously desirable to buy and use a device that you know will receive update support for a decent period of time. For more information, read our guide to smart devices and security.

Do smart radiator valves save you money?

Yes, but probably not as much as manufacturers claim. 

Firstly, most estimates on savings that can be made with smart home heating assume that, before you started using smart heating, you left your heating set to maintain a constant temperature during the day. So if you already turn your heating off when you leave home, or don't have it on for long periods of the day, you're unlikely to save as much as the manufacturers claim. 

The more wasteful you already are with heat, the more you can save by making a change. 

Secondly, with more power to control your heating comes greater responsibility to get it right. Whether you actually save money will depend on how you use it. 

And, if your home is poorly insulated, you'll make greater savings on your energy bills by improving your home insulation first. Smart heating can then shave off a little bit more

Wi-fi and smart radiator valves: what's the difference?

Wi-fi (or wireless) radiator valves and smart radiator valves are not the same thing.

• Wi-fi radiator valves cannot communicate with a smart thermostat (so they cannot turn your boiler on and off).
• They can let you change their temperature remotely using a smartphone app.

Essentially, a wi-fi radiator valve is just a traditional TRV that you can adjust remotely. 

This can be a good thing depending on what you're after. You don't need to purchase a smart thermostat or connecting device to start using a wi-fi radiator valve, meaning they're less of an upfront cost. If you want to dip your toes into the world of smart heating for the first time, wi-fi radiator valves could be an ideal first step.

However, you won't get the 'smarter' functions or complete heating control that's possible with a smart thermostat and smart radiator valve setup.

It's also worth noting here that you can use smart radiator valves without a smart thermostat, but this setup would have the same limitations of wi-fi radiator valves.

There are also valves which are Bluetooth-only. 

Nest vs other smart thermostats - is the extra cost worth it?

Smart radiator valves compatible with Alexa

• Drayton Wiser Smart Heating Radiator Thermostat
• Energenie MiHome Smart Radiator Valve Kit
• Honeywell Home Evohome Radiator Zone Kit
• Netatmo Smart Radiator Valve Starter Pack
• Salus Single Zone Smart Home Starter Pack
• Tado Smart Radiator Thermostat
• TP-Link Kasa Starter Kit
• Worcester Bosch Easycontrol Smart TRV

How to buy the best smart thermostat – what are the features to look out for?

Smart radiators valves without a hub

Most smart radiator valves require a hub, also known as a bridge, to communicate with your smart thermostat and your smartphone app. 

If you don’t want a hub, there are options out there (like wi-fi radiator valves), but be aware that this comes with less functionality. So you won’t be able to communicate with your thermostat to bring the boiler on and off.

Manufacturers such as Radbot have radiator valves that detect when a person is in a room and only heats it whilst they are in the room. It doesn’t use wi-fi or a smartphone app, so it's potentially a great solution if you're less tech savvy but still want a bit of automation to your home heating.