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Updated: 4 Mar 2022

How we test smart radiator valves

Find out how we test smart radiator valves, from their accuracy to app security, and what it takes for one to be rated as a Best Buy
Sam Morris
person touching phone displaying 18 degrees to change smart radiator valve setting

Our independent lab tests go further than anyone, revealing how easy each smart radiator valve is to use, how well it functions, what features it offers and if the app keeps your data secure.

Find out more about what we look for in our tests, or head straight to our smart radiator valve reviews to see the best. 

Why our smart radiator valve tests are different

Other websites review smart radiator valves, but this is usually just one tester who has spent some time using the valve and will give their opinion on how it looks, how easy it is to install and how easy it is to control. Sometimes these sites may receive products free of charge from manufacturers to review.

Which? smart radiator valve tests go above and beyond this. We buy every radiator valve we review, and don't accept free samples when we put a product through our lab tests, so you know our opinion is honest and unbiased.

Our lab tests go above and beyond other reviewers, with scores based on measurements and ratings by our expert lab testers, ensuring there is no unconscious bias and ensuring when we say a valve functions well, there is the data to back it up.

Finally, we also carry out extensive privacy and security tests on smart radiator valves. If there are any vulnerabilities we'll find them and let you know - something other reviews won't.

Only a smart radiator valve that performs well in all these areas will become a Best Buy, meaning you can buy with confidence. A Don't Buy is a product to avoid - it may not keep your data secure, not work as expected, or overall be a pain to use. 

  • All smart radiator valves with a score of 80% or more are Best Buys
  • All smart radiator valves with a score of 45% or less are Don't Buys

How is the Which? score calculated

All our tests are used to create an overall score for each smart radiator valve. We survey consumers and Which? members regularly to understand what's important to you when buying a smart radiator valve. Based on this, we refine our evaluation so the overall score is representative of what consumers value in a smart radiator valve.

  • Ease of use (50%)
  • Radiator valve function (40%)
  • Features (10%)

How smart radiator valves work - our expert guide on getting the most out of a smart heating set up

Our key smart radiator valve testing criteria

Is it easy to use?

We assess how straightforward each smart radiator valve is to use. This includes:

  • Ease of installation - how useful are the instructions (if any) and how easy is it to install yourself
  • Ease of connecting to your wi-fi - do you need a specific connecting device (such as a hub or bridge) to connect the smart radiator valve and is it a complicated set up? Devices that have a long or complex setup are penalised
  • Ease of adjusting settings and programming schedules - how easy it is to find and change the radiator valves temperature through the app, how easy is it to program and change a heating schedule

How quick and accurate does the valve function?

A smart radiator valve should be precise and fast-responding, so your room stays at the temperature you expect.

We put each smart radiator valve into a temperature-controlled chamber to measure how accurately it detects the temperature of the room.

We also evaluate how long it takes to respond when the user changes the temperature in the app, and how long it takes to turn on and off after the temperature drops below / rises above the selected set temperature on the valve.

What features does it offer?

Some smart radiator valves come with features that are designed to boost the functionality of the valve, making your life easier. Some of the most common are:

  • Child Lock - to stop your kids playing with the settings you've selected
  • Frost Protection - to make sure your pipes don't freeze in cold weather
  • Open Window Detection - the valve detects when a window is opened and switches off the heating in the room to save energy
  • Boost mode - when needed, this raises the temperature on the valve for a set period of time, before returning to the previous setting.

Our reviews highlight the features of each smart radiator valve so you can make sure you're buying one that has the functionality you want.

Are there any security issues with the radiator valve?

Privacy and security are vital considerations for all smart devices. With a smart radiator valve you'll be controlling the device remotely over wi-fi or mobile data. 

Our thorough privacy and security tests put each valve and its app through their paces so you can be sure your data is protected. If one does have any vulnerabilities we will let you know.


The firmware (the software programmed into the hardware of the smart radiator valve) needs to be updated or maintained regularly, or else it could more vulnerable to hackers. 

We check that the valve and app can receive updates and whether the app automatically checks for and performs the latest available updates. 

Password Policy

We check whether the app and smart radiator valve have a strong password policy, forcing you to passwords that aren't easily cracked. Our guide explains more about setting a secure password.


We check what personal data is needed when you set up an account with the app, and what app permissions are requested (such as location, access to camera and calendar). 

We investigate the reasoning behind each app permission, checking it's really necessary to collect each piece of data. 


During daily use, data is being sent back and forth from your app and radiator valve. If this data is encrypted - where the information is converted into secret code - it means your data is safe-guarded against any snoopers.

We check that your personal data is encrypted and where this data is getting sent to. If we spot any personal data being sent unencrypted, we will alert both you and the manufacturer of the product and investigate further.

Man-in-the-middle attacks

Hackers may try to intercept data passing to or from your app or valve. This is particularly worrying if the data being sent is unencrypted personal data.

We run tests on every app and valve to make sure they are not susceptible to this kind of attack: if they are, we investigate further.


You may decide to change to a different brand of radiator valve, delete your account or need to reset it for some other reason. We check whether you can do all of this easily - as you should be able to. 

Our testing checks how easy it is to reset the valve to its factory settings and how easy it is to reset your account. And we check whether a future user of your smart radiator valve can see or access any of your data.

New forms of cyberthreat

The methods hackers use are constantly changing, so we'll update our tests to counter new threats.  

There’s no such thing as 'unbeatable' security when it comes to connected devices. But we check for the most common attack vectors, and alert manufacturers to any issues we find. 

The smart radiator valves that we recommend had no issues that worried us at time of testing.

What else do we check?

You should be able to install a smart radiator valve yourself, so long as the radiator already has a thermostatic radiator valve on it. 

We check that the instructions are clear, and that the most common connectors are supplied so that set up is nice and easy.

We measure the weight and dimensions of the valve so you can check if a product will easily fit in your home.

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