Best smart thermostats 2024: Which? Best Buys and expert buying advice

Smart thermostats offer greater flexibility than other heating controls, allowing you to remotely control your home's temperature and heating schedule. 

They also have a wide range of features, so you'll need to decide which ones you need the most. 

Keep reading for our expert buying advice, or go to straight our smart thermostat reviews to compare all those we've reviewed and find the right one for your home.

Why buy a smart thermostat?

Like a normal thermostat, a smart thermostat allows you to schedule your heating, with the aim of saving you money on your heating bills and reducing your boiler's environmental impact.

With a thermostat that is smart, you also can control your heating remotely using an app on your smartphone or via a website. For example, you could turn your heating on when you're travelling back from a weekend away. Or, if you go away and then realise you've left your heating on, you could turn it off using your phone. 

Like a smart meter, most smart thermostats can show you how much you're using your heating, letting you keep a closer eye on your energy bills. 

Some smart thermostats also monitor how you heat your home and learn your routine, allowing you a more hands-off approach to scheduling your heating. 

There are several brands of smart heating thermostat on the market and each works in a slightly different way. Take a look at our smart thermostat reviews to see which ones are accurate and have user-friendly apps. 

The smart thermostat features to look out for

Knowing what the common features are and deciding which ones are must-haves for you can really help to narrow down your search for the best.

Our smart thermostat reviews reveal which features the different models have. 

Hot water control

Some smart thermostats can be used to control your hot water, as well as your central heating. Being able to use an app makes turning on the hot water much more convenient. If you've switched it off because you've had a weekend away, for instance, and fancy a hot shower when you get back, simply use your smartphone to turn it on again before you get home. 

Not all smart thermostats with hot water control include it as standard, though, and some cost more to include this function.

If you have a combination boiler, which provides hot water instantly when you turn on the hot tap or the shower, then you won't need a smart thermostat that does this.

App and website controls

Many smart thermostats can only be controlled by an app and don't have a standard website that can be accessed from a laptop or desktop computer. 

If you want a smart thermostat that can be controlled from a website rather than an app, you'll have a much smaller pool of models available to you. 

Multi-room control or zonal heating

Some smart thermostats let you set different temperatures in different parts of your home from the same smartphone app. This could be useful if you have a larger property and only parts of it are in use at a time. 

For example, if you have a dedicated office room, you can heat it during work hours and then turn the heating off in that room after you clock off.

Or, if you usually watch TV in the living room in the evening, you can keep your living room cosy, but turn the heating down or off in any rooms you're not using. 

To use this feature, you'll need a thermostat that supports zonal heating and you will have to buy either an extra thermostat or another connected device such as a smart radiator valve. With two thermostats you could have different settings upstairs and downstairs. With smart radiator valves, you can control each room's temperature and schedule individually. 

It's best to speak to a heating engineer before setting this up to ensure you're actually going to be making efficiencies. 

The ability to learn your routine

Some smart thermostats are able to learn your routine and preferred temperatures, and program themselves accordingly. 

This saves you the trouble of having to program a schedule yourself, potentially offering savings without you having to do much extra work. 

Learning functions can also be turned off. So, if you don't like the schedule that the smart thermostat has come up with, you can switch back to manual control and program it yourself.

The ability to modulate your boiler

Some thermostats are able to communicate with your boiler using a common language. Different boilers have different languages (known technically as communication protocols), though the most common is called OpenTherm. 

When thermostats are able to communicate with boilers using a shared language, they can control boilers more efficiently. Rather than using basic on/off controls, the thermostat is able to coordinate with the boiler to vary outputs according to heating need.

So rather than firing your boiler in spurts, your boiler will work less hard when a smaller effort is needed. This is called modulation.

Not all thermostats can modulate, and you'll need a boiler-thermostat pair that can speak a common language. 

Motion sensors and GPS tracking

The purpose of both of these features is to detect when you enter and leave your home and adjust your heat settings accordingly, turning the heating down when you've left, and pre-heating your home when you're on your way back.

Some smart thermostats use it slightly differently. For example, the Hive's geolocation feature alerts you when you’ve left the heating on and you’re away from home, or when you’re coming back and the temperature’s set lower than you’d like. But it won’t adjust the settings automatically.

This feature is most useful if you're in and out of your home at irregular times, as otherwise you can simply rely on the schedule.

Weather-responsive functionality

Smart thermostats with a weather-responsive function can adjust the internal temperature according to the forecast and the temperature outside. 

So if a cold snap is on the way or the sun is about to come out, the thermostat can raise or lower the temperature settings respectively to reflect the fact that the temperature is about to change.

Professional installation

Many smart thermostats require professional installation, which can add significantly to the cost. But some, such as the Netatmo thermostat, can be installed by a competent DIYer.

Check out our smart thermostat reviews to find out which smart thermostats have the features we've talked about here

Is it worth getting a smart thermostat?

This depends on the model you choose and also how you use it. 

In a 2021 survey of 315 Which? members, two thirds said they found their heating easier to schedule after installing a smart thermostat. So, if easy control is what you want, you're likely to get this by going 'smart' with your heating.   

Plus, if you don't already have a boiler controller installed (such as a 'dumb' thermostat or a boiler timer), then you could consider getting a smart thermostat to help you save money on your heating bills.

However, it's less clear how much you'll save if you already have a device to control and schedule your boiler. In the same 2021 survey,  three quarters of Which? members who own a smart thermostat don't know if they've saved money since getting one, or have spent around the same amount. 

Pros of a smart thermostat?

• You can control your heating remotely Through your smartphone, you can control your heating from anywhere in the world, offering greater control and flexibility than other boiler controls.
• You can see how much heating you're using Most let you view and monitor how much energy you're using, making it easier to see where you could save money.
• You can create multiple heating zones. Using multiple smart thermostats, or a smart thermostat with smart radiator valves, you can control the temperature on a room-by-room basis and make further energy savings. As we said before, speak to a heating engineer to ensure you're setting this up in a way that's genuinely useful. 
• It can learn your routine to automate your heating Some will learn your routine (such as when you're out of the house or when you go to bed) and can automatically adjust the temperature for you. This means after a week or so after installation, you could start saving on your bills and use less fossil fuels without having to think about your heating again.
• Voice control If you have Alexa, Apple HomeKit or Google Home and want to integrate your home heating into your smart home setup, get a smart thermostat that works with your device.

Cons of a smart thermostat? 

• Higher upfront costs Although they are coming down in price, smart thermostats generally cost more than non-smart heating controls. This goes up even more if you're also getting smart radiator valves. 
• Being locked into a brand Most smart thermostats are only compatible with that brand's other connected heating devices such as smart radiator valves. If you think you'll want to add smart radiator valves in the future, you'll most likely be locked into the smart thermostat brand that you buy. 
• Can take a bit of getting used to If you're less tech-savvy, or not a confident smartphone user, a smart thermostat will be a bit of a learning curve in order to get the most out it. You can make this easier by getting an engineer to install the thermostat and help set up the schedule for you, or going for one that can learn your routine.

Be aware that a smart thermostat doesn't solve underlying lifestyle choices or poor property insulation issues. While a learning thermostat can help, if you're likely to forget to use the app, or want your heating on full blast all the time, then you're unlikely to save money with a smart thermostat. Similarly, if you have a poorly insulated property, it is better to improve the energy efficiency of your home first.

How do smart radiator valves work? Read our expert guide to see if adding these to your heating system is the right call for you

Will a smart thermostat save you money?

In 2021, we asked Which? members what single factor would most encourage them to buy a smart thermostat. Of the 953 who responded, the top factor (cited by one in 10 respondents) was if it would save them money on their heating bill. 

Many smart thermostat manufacturers claim big savings on your energy use and heating bills after installation. However, to be able to make these claims, manufacturers make assumptions about how you’re currently heating your home. Our 2021 investigation into manufacturer claims found that Hive assumed an annual usage much higher than the average cited by Ofgem. And Tado° was basing its claims on an assumption that all rooms in the home were set to maintain a constant temperature of 20°C throughout the day, whereas government figures showed that the average UK home only had its thermostat set to 20°C for 7.5 to 8 hours a day.  

We took some of the top smart heating manufacturers to task in a 2021 Which? investigation over their savings claims, as we believe these claims should be representative for a typical UK home, not just the savings possible for the few heavy gas users. 

We'd still recommend a degree of caution regarding manufacturers' money-saving claims. Look at the statistics they're basing this on, if shown on their websites. Are they based on the assumption that you're using a large amount of gas each year, or that you have your heating on all the time? If so, and that doesn't reflect your usage, you may well save much less than claimed. 

Who will save more with a smart thermostat?

• Those who want to make a proactive lifestyle change A smart thermostat lets you see exactly how much you're spending, and some even suggest where you can save, empowering you to make those changes.
• Those comfortable using smartphone apps If you're tech-savvy, you'll get the most out of the various energy-saving features a smart thermostat offers.
• Those with a busy, irregular lifestyle A smart thermostat will let you control your heating remotely, making sure the boiler isn't on when you're out and letting you adjust the schedule on the go.
• Those who are likely to stay in the same property for several years You'll recoup the cost of installation through savings on your heating bills.

 Who will save less with a smart thermostat?

• Those who won't use the smart features properly If you're likely to forget to use the app, or you're likely to overuse it and keep tinkering with it too much, you won't reap the full rewards.
• Those who already use heating controls well Getting a smart thermostat as well could offer further savings, but if you already use a timer to schedule your heating you'll save less than someone who doesn't.
• Those with a poorly insulated home Installing loft insulation or double glazing will improve the energy efficiency of the property, offering greater savings than by just installing a smart thermostat. Find out how to buy double glazing and how much loft insulation costs.
• Those planning to move home in the next couple of years You may not have time to recoup the higher initial costs of a smart thermostat. 

Is a smart thermostat better for the environment?

Potentially, yes. Smart thermostats enable you to reduce the amount of energy you use. If yours runs on fossil fuel, such as a gas or oil boiler, it will reduce your carbon emissions, heating your home in a more environmentally friendly manner.

However, like any tool, a lot depends on how you use it. If you leave your heating on when not in the house, or have the thermostat set to a high temperature all day, then there is still room for you to use your smart thermostat in a more sustainable fashion.

Here are some tips from the Energy Savings Trust to the best way to reduce your carbon emissions with your smart thermostat.

1. Avoid turning the thermostat up if you can. For every degree you increase the temperature, your heating bill increases by about 10%. Turning the thermostat down by a degree can reduce your carbon footprint by 300kg a year.
2. Set your thermostatic radiator valves to the best temperature for each room. This is typically 3 to 4 for most, or 18 to 21°C for smart radiator valves.
3. Turn the heating off when not in your home, or on frost protection mode (about 7°C) in winter if you're away for a while and there's a possibility of freezing.
4. Don't turn the thermostat up to try and heat your home more quickly. Turning the thermostat up doesn't heat it faster – it will just keep the heating on for longer and waste more energy and cost more money.

Heat pumps advice If you're looking to replace your boiler with a more environmentally friendly option, see if this low-carbon alternative is right for you

Which smart thermostat brands offer the best software and security support?

Software and security support are important considerations when buying a smart thermostat, dictating how long the brand will 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, when we asked again in 2023 it didn't respond.
• Google and Drayton both promised a minimum of five years of update support from launch in 2022, though Drayton didn't confirm that policy with us in 2023.
• Honeywell stated in 2022 it will offer at least two years support from launch, but didn't respond in 2023.
• 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.

Also notable is Hive, who announced it will discontinue Hive security cameras and Homeshield devices. Its smart thermostats and radiator values will still be supported, but it did not guarantee a minimum support period.

From April 2024, however, all manufacturers will be obliged to disclose their security 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.

Can you have a smart thermostat if you're renting?

Yes, but you should always seek the landlord's permission before installing a smart thermostat in a rented property, and in this situation get a professional engineer to carry out the installation.

There are other factors to consider before installing a smart thermostat if you rent:

1. Will you make your money back? Unless the landlord pays for the installation, you'll lose money if you pay to install a smart thermostat and then aren't in the property long enough to recoup your costs through savings on your heating.
2. Can you easily reset the smart thermostat? If you leave, you won't want the next tenants to be able to access your account or data. So make sure the smart thermostat you install can be easily reset and you can delete your account from the smartphone app. 

What to do with your smart thermostat if you move home

When you move home, you can either take your smart thermostat with you or leave it behind.

In all our smart thermostat reviews, we test how easy it is to reset the device and how easy it is to remove the device from your app account. We then also check that if a new user connects to the smart thermostat, they can't see a previous user's information or data. 

This means you can be confident (whether you keep or leave your smart thermostat) that the next tenant or homeowner can't access your information, and conversely if you move into a property with a smart thermostat, that the previous owners can't log in and tinker with your heating schedule.  

Taking your smart thermostat with you if you move home

1. Check that your new home's heating system is compatible with your smart thermostat If it isn't, it will probably easier to leave it behind, then buy and install a new compatible smart thermostat in your new property.
2. Reset the smart thermostat Some devices have dedicated buttons or come with clear instructions on how to reset the thermostat, while with others you have to restart the setup process.
3. Remove the thermostat from the app
4. Uninstall your smart thermostat and re-install it in your new home In general, you should have this done by a professional installer, unless you're a competent DIYer and the thermostat states that it can be self-installed, with clear instructions on installing and uninstalling.
5. Add your smart thermostat back to the app For some learning smart thermostat apps (such as Nest) you may need to select a new home in the app, so it knows the thermostat is connected to a new heating system and can re-learn your schedule.

Leaving your smart thermostat behind if you move home

1. Remove the thermostat from the app
2. Reset the smart thermostat Some devices have dedicated buttons or come with clear instructions on how to reset the thermostat, while others you have to restart the setup process.
3. If needed, delete your account If you aren't going to be using the app with a device in your new home, it's best to delete your account. For some brands you can do this from the app, but for others visit the website or contact the manufacturer to do this.

Getting a smart thermostat professionally installed

While some smart thermostats are described as being able to be 'self-installed', our tests have found that some don't have clear enough instructions or diagrams for this to be the case. Unless you're a component DIYer, or if the smart thermostat instructions don't say it can be self-installed, we would recommend getting a professional electrician to do it.

A Which? Trusted Trader will be reliable and trustworthy. All traders have passed our assessment process carried out by our Trading Standards professionals. Use the tool to find a professional electrician in your area. 

How we test smart thermostats As well as ease of decommissioning, see how else we put smart thermostats through their paces