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6 July 2021

How to buy the best smart thermostat

Use our expert smart thermostat reviews and buying advice to choose the smart thermostat that's right for you and your home.
Matthew Knight
Tado smart thermostat

Smart thermostats offer a wide range of different features, so deciding which ones are the most important to you is key to choosing the right smart thermostat for your home. 

Keep reading for our expert buying advice, or go to our smart thermostat reviews to compare and find the right one for your home.

Video: how to buy the best smart thermostat

What are smart thermostats

Smart thermostats are the latest trend in home heating. A smart thermostat can switch your heating on or off remotely via the internet - so you can use your smartphone to turn your heating on when you're on your way back from a weekend away, or off when you pop out unexpectedly. 

Many of these programmable digital heating systems show you how much heating you’re using. Some smart thermostats also monitor your usage and learn your routine. 

There are several brands of smart heating thermostats on the market, and each works in a slightly different way. Take a look at our smart thermostat reviews to compare thermostats from Nest, Hive, Honeywell, Tado and many more.

Smart thermostat features to look out for

Hot water control

Some smart thermostats can be used to control your hot water, as well as your central heating. If you have a combination boiler which provides hot water instantly when you turn on the hot tap or the shower, then obviously you won't need a smart thermostat that does this.

Not all smart thermostats with hot water control include it as standard - some charge you extra for it. 

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 nice hot shower when you get back, simply use your smartphone to turn it on again before you get home. 

As with a traditional thermostat, you can also program a schedule so you don't have to suffer a cold shower because you forgot to put the hot water on. 

The difference is you can use your phone, or some cases your computer, to do it. 

App and PC functionality

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 don't have a smartphone, you'll need to pick a thermostat that also has website control functionality. Check our smart thermostat reviews to find one that's right for 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 would be particularly useful if you have a larger home, and where parts of it often are not being used while people are in other areas.

So if you usually watch TV in the evening, you can keep your living room nice and cosy while you turn the heating down or even off in any rooms you're not using. 

To use this feature, you'll have to buy either an extra thermostat or another device for each area you want to use different settings for - so with two thermostats you could have different settings upstairs and downstairs. The extra thermostats or other devices aren't always cheap, though - some cost as much as the first thermostat you buy - so you'll need to weigh that cost against the potential energy bill savings you could make by not heating parts of your house which don't need heating.

Typically, though, you'll need an existing multi-zone heating system to be able to do this. 


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

This saves you the trouble of having to program a schedule yourself, but it does reduce the amount of control you have over your heating. 

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

Professional installation

Many smart thermostats require professional installation, which can add significantly to the cost. But some, like the Tado V3+ can be installed by a competent DIYer.


Smart thermostats with a weather-responsive function can adjust the internal temperature according to the weather 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 adjust your temperature settings to reflect the fact that the temperature is about to change.

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 so that it's at the right temperature for when you open your front door.

The Hive's geolocation feature works slightly differently - it 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 the house at irregular times - as otherwise, you can just rely on the schedule to turn the heating off when you leave and back on in time for your return home.

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

The best smart thermostats

Our testing has revealed the standout smart thermostats that make controlling your heating a breeze. 

We’ve highlighted these thermostats as they performed best in our tests. But if you’re looking for a model with zonal heating or GPS tracking we've picked a Best Buy that stands out in that area too.

Only logged-in Which members can view the results in the table below. If you're not yet a member, you can get instant access by joining Which?.

Best thermostat overall

  • 75%

    This is the best smart thermostat we've tested. It has great features, it's easy to use and it's incredibly accurate. Log in to read the full review and find out which smart thermostat we are talking about.

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Best thermostat for zonal heating

  • 70%

    The Honeywell Evohome wi-fi connected thermostat pack can create and individually control 12 individual heating zones. It promises to be suitable for all boilers and easy to use. We sent it off to our test lab to see how easy it is to install, how accurate the thermostat is and whether it keeps your data secure. Read our full review to find out.

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    First month only £5, then £9.99 per month, cancel any time

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Best thermostat for GPS tracking

  • 71%

    This is a very good smart thermostat that we're happy to recommend. Although the app can be confusing, it's easy to control the device manually or through the web portal. It also reads temperature accurately and is easy to install.

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    First month only £5, then £9.99 per month, cancel any time

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Tables last updated 06 July 2021