Nest Thermostat Review (3rd gen)

Nest Thermostat Review (3rd gen)
The Nest is one of the best-known smart thermostats, but is it the best? We explain everything you need to know in our in-depth UK Nest thermostat review.

Should I Buy The Nest Learning Thermostat (3rd Generation)?

Our Verdict
  • Being reliable, well-designed and easy to use, the Nest thermostat is a great choice. It doesn't have the array of accessories and compatibility of systems such as Honeywell Evohome, but you can buy separate smart TRVs to control radiators without changing your plumbing.
  • The Nest Protect smoke and carbon monoxide alarm also works with the thermostat, as does the Nest Cam camera. The 3rd generation can also control your hot water, making it even better, and the latest app update means your phone can tell it when you've gone out.

Price When Reviewed

  • $249.99
Smart thermostats let you control your heating from your phone, and usually have intelligent features to heat your home more efficiently and save money. We've reviewed Hive Active Heating as well as plenty of other so read the Best smart thermostats to buy right now.

Nest has added two-factor authentication to its app to better protect your kit - thermostat, smoke alarm and cameras - from hackers. To enable it go to the Nest app, tap the menu icon at the top left, then go to Account security. You’ll see an option there to activate ‘2-step verification’. The next time you sign in (you may have to sign out manually) you'll enter your password as usual, but then you'll get a text with the verification code. Tap this in and you'll get into the app.


In November 2015, Nest announced that the 3rd-generation thermostat which costs £199 from Amazon, or £249 with installation. It's actually the second version, not the third, available to buy in the UK, as the first was never sold in the UK. Here's a summary of the features which changed:
  • Hot water control: you can give a hot water boost and adjust the schedule from the thermostat or your phone. It works with Auto-away and turns off the tank heater after two days.
  • Bigger, higher-resolution display: the display is now 53mm across, up from 44mm, and has a resolution of 480x480 instead of 320x320. A new Farsight mode lets you set the display to show the target temperate or a clock so you can see it from across the room.
  • OpenTherm support: Works with compatible boilers to enable two-way communication instead of simple one-way on/off commands from the thermostat. With OpenTherm, the Nest helps the boiler work out the exact amount of gas to burn to reach or maintain the temperature. This should save energy and prolong the life of your heating system.
  • Thinner profile: The new unit sits more flush against the wall. There's also a new stand, sold separately at the same price as the old one: £29.
With the 3rd-gen model you can now choose between four colours. In addition to the stainless steel model, there's copper, white and black. They cost the same as the stainless steel model - £199 - and these new colours aren't surrounds so you can't add them to an existing thermostat or swap between devices. 
Nest Thermostat Review (3rd gen)

In most other respects the 2nd generation model, reviewed below, is identical to the 3rd-gen and its capabilities are the same. Put simply, it replaces your existing thermostat and allows you to control your heating in the old-fashioned way by walking up to the thermostat and turning the dial. You can also change the temperature the modern way by using the app on your smartphone or Nest's website, from anywhere in the world with an internet connection.

Unlike more expensive systems such as Honeywell Evohome, the Nest is really designed for smaller homes or those where only one or two thermostats are needed. It supports multiple zones, but only if your heating is already plumbed into separate zones. With Evohome (and also Heat Genius), you install one or more smart radiator valves which gives you control over heat at each radiator, and there's also support for under-floor heating.

With Nest, the thermostat controls only the boiler, so it heats the whole house and can't control individual radiators. With the 3rd-gen Nest, you can also control a hot water tank, but if you have a combi boiler, then this feature is redundant.
Nest Thermostat Review (3rd gen)


The Nest stands out because of its circular colour LCD display, which makes it a gadget you'll want to show off rather than hide away as with the Hive. Because there's a display, you don't need to launch a smartphone app to change the temperature, yet the kit is no more expensive than others which omit a screen.
Nest Thermostat Review (3rd gen)

The stand was developed especially for the UK, but it's not included in the box - it'll cost you an extra £29 and they're different for the 2nd- and 3rd-gen thermostats. However, while the stand might be useful in some cases, most people should be able to use their existing in-wall thermostat wiring to power the Nest's screen. The kit even includes a big plastic plate to cover up the old wallpaper, paint or holes you find when your installer removes your old thermostat. That's because the display is much smaller than you expect, measuring just 83mm wide. (The new 3rd generation is just 1mm wider.)
Nest Thermostat Review (3rd gen)

The display itself is has a 44mm diameter and a resolution of 320x320 pixels (the same as the latest Android Wear smartwatches). Viewing angles are good left to right, but not when viewed from below. That means if your old thermostat was mounted quite high up on the wall, contrast is not all it could be.

There's a rotating dial surrounding the display which oozes quality. It doesn't click: the sound you hear is actually coming from the speaker inside the device. The whole unit can be pushed to select options (and enter the menu), but all the settings can also be made from the free app, which is available for iOS and Android. There's no official Windows Phone app but Nest has approved the third-party Cozy app. You can also check and adjust settings from the Nest website, where you can also look at energy reports.

A hidden sensor below the display detects movement and automatically turns the screen on when you walk past or raise your hand to use the dial. Another sensor detects if the sun is shining on the display and ensures it doesn't play havoc with the internal thermometer, which would otherwise signal that it's time to turn the boiler off.

Heat Link

The other gadget in the box is the Heat Link. This attaches to your boiler, and has built-in Wi-Fi to connect the system to the internet via your wireless router. Virtually every other smart thermostat has a third component which connects to an Ethernet port on your router, so this is a much neater solution if your Wi-Fi coverage is good enough.
Nest Thermostat Review (3rd gen)

The Heat Link has a button which can be used to put the Nest into manual mode, just in case you need it. Holding it for ten seconds resets everything.

Nest highly recommends you have the system professionally installed because of the high voltages involved. However, if you're comfortable changing a light switch, you'll have no problems installing Nest.

The Heat Link is compatible with the vast majority of heating systems, including combi-boilers, those with hot water tanks, underfloor systems, air source and ground source heat pumps and others. You can check Nest's website to see if your system is compatible.

How It Works

At its most basic level, you can use the Nest just like a dumb, old thermostat. You can walk up to it, turn up the heat and sit down again. If it's too hot, you can turn it down a bit.

Of course, it's a lot smarter than this, and you'll probably find you won't need to touch the dial (or app) much once the system has learned your schedule. This is where the learning part comes in. For the first week or two after installation, you're encouraged to turn the dial down when you leave the house, and turn it up when you come back in.

Alongside this 'training', the movement sensor detects whether anyone is still in the house. If not, it will turn down the heat automatically, and show Auto AWAY on the display. Pets won't set off the sensor, so you won't end up wasting gas by heating the house up for your cats.

As we've said, you can control the temperature from anywhere using the app. As long as you have an internet connection, you can change settings and turn down the heat remotely.
Nest Thermostat Review (3rd gen)

The thermostat is also a programmer, so you can use the display or app to set a schedule, just as you would a traditional programmer. However, instead of 'on' and 'off' you set the temperature you want your home to be when you're in, and a low temperature for all other times - this is known as a 'setback' temperature.

Thanks to the learning process, the Nest will automatically create a schedule for you, and you can see in the app whether changes in temperature were due to someone operating the dial or an automatic change based on schedule.

We've been testing Nest for over two years now, and it's safe to say the auto-schedule has produced some very odd timings. Rather than speculate about reasons why, we've instead decided to simply set our own schedule and then override it from the app if it turns out that we'll be home earlier or later than expected.

Auto-Away works well, but there's also Home/Away Assist. This uses your phone's location in conjunction with sensors on the thermostat (and Nest Protect, if you have one or more) to more accurately determine whether anyone is home or not. This might sound like geo-fencing - a feature offered by several of Nest's thermostat rivals - but Nest is keen to point out that geo-fencing isn't all that accurate. And that's especially true if the system uses the location of only one phone. The Nest way of doing things combines geo-location (by using the GPS information from your phone) along with the indoor sensors to figure out if everyone's out, or someone is still home. It should mean that the heating will be turned off more quickly when you forget, since the current Auto Away mode typically errs on the side of caution and waits a long while before deciding no-one is, in fact, home. The feature also means you can set your Nest Cam to automatically turn on when the last person leaves, and off when someone returns. And if you do have a Nest Protect, the monthly sound check will be carried out when no-one is home to avoid disturbing you.

Going hand-in-hand with Home/Away Assist is Family Accounts. It lets you create up to 10 accounts so everyone in the household can have their own login, and the system can use everyone's phone location (Android and iOS are supported) to make the Auto Away mode more accurate and responsive.

If you have Nest Protect alarms, these can improve Auto-Away's efficiency - and they work with Home/Away Assist - but you can't enable the feature if you have a cat or dog as these will make the system think someone's at home.

You can enable or disable some of the Nest 'senses' from the app or website. One is True Radiant, which learns how long it takes your home to heat up and cool down, and then fires up the boiler at the right time to hit your scheduled temperature. There's no adjustment for economy or comfort like you get with Tado though, so you may find it fires up the boiler far too early in the morning for your liking, but the solution is simple: just move your set temperature to a later time.

It's possible to check on the status of Nest's learning feature by going to the settings in the app or on the website, where each feature will either say 'Ready' or 'Learning'.

A fun piece of gamification is the Leaf which appears on the display when you set the dial to an "energy-saving temperature", encouraging you to keep the heat below around 19 degrees. You'll then see how many Leafs you've earned in the monthly report and how you're doing compared to other Nest users.


Some rival smart thermostats allow you to control the temperature in different 'zones' around the house. Nest can do this too, with up to 20 zones. You'll need to buy a thermostat for each zone, but the drawback (apart from cost) is that your plumbing also has to be set up so the boiler can heat different zones independently.

Older homes with a conventional gas boiler typically heat the entire house, and unless the pipework is physically changed to include two or more valves for different zones (upstairs and downstairs, for example) then adding extra thermostats is pointless.

Without multiple valves, all the boiler can do is send hot water to all radiators or underfloorheating at once. What we really want to see is Nest launch its own smart TRVs (thermostatic radiator valves) which can be used instead of heating valves to shut off individual radiators.

HeatGenius, for example, and Honeywell offer smart TRVs (thermostatic radiator valves) which allows you to control the temperature in the most important rooms.

With a single Nest thermostat, you're reliant on any existing 'dumb' TRVs to shut off radiators when the set temperature is reached. For most normal-sized homes this works well enough, and means you're still saving money compared to the £50 or so you'd spend on each smart TRV. If your home is brand new and over 150 square metres, it will have a two-zone heating system installed, so you can install two Nest thermostats and control each zone's temperature.

Update: You can buy and use third-party smart TRVs such as the Devolo Home Control or Elgato Evo Thermo to control individual radiators. Even though they won't communicate with the Nest thermostat, you can still set diferent temperatures in different rooms this way. The snag is that if you want to increase the temperature when the heating is off, you'll have to make this change in the smart TRV app as well as the Nest app. And that's why it would be best for Nest to launch smart TRVs which can talk to the thermostat.

One other feature is that you're allowed up to two 'homes' per account. You can therefore control Nest equipment: thermostats, cameras and smoke alarms at two different locations from the app or website without having to log into different accounts. And, as mentioned, the latest app update for iOS and Android brings multiple user accounts for the same Nest system, so everyone living in the house can log in with their own email and password.

Nest Protect

As well as controlling heating, the Nest system also integrates with the Nest Protect smoke and carbon monoxide detectors. These are available as mains- or battery powered versions, each costing £89.
Nest Thermostat Review (3rd gen)

Software Updates

Since launching the Nest in the UK, there have been quite a few software updates.The latest is version 5.6. Updates are installed automatically, so you don't have to do anything. Eco temperatures were added in 5.6, along with added support for PTAC systems. You can see the revision history on Nest's website.

Version 5.5 added Farsight improvements.

Going further back, version 4.3 added three new features: Enhanced Auto-Schedule, Quick View and System Test.

Nest refined the algorithm for determining an automatic schedule, and claims this could bring up to 6 percent extra savings. This is the third version of the algorithm which has a better understanding of how long your home takes to heat, and slightly reduces the time until the system switches to Auto Away. Enhanced Auto-Schedule "learns all the time and reacts quicker to changes in routine", such as school holidays and the Christmas break. We'll update this review when we've been able to see how the algorithm works in practice.

The second feature - Quick View - is much more noticeable since it's a new interface for the settings on the thermostat itself. The main temperature screen remains unchanged, but when you click it, you'll get a view like this:
Nest Thermostat Review (3rd gen)

This gives you a lot more information at a glance and means you don't having to go into submenus to see information such as yesterday's energy use or the next item on the heating schedule since the text in the centre changes as you rotate the dial. It's also much quicker to turn off the heating now, and easier to see if there's a problem as an exclamation mark appears in the centre of the settings icon if there's a problem.

Finally, System Test has been added to solve two issues. First, the installer can test the system and ensure it's working fine before leaving. It also lets you test the efficiency of your heating system to make sure it's working properly before winter sets in, and hopefully get a heads-up of any potential issues. It works by timing how long it takes to reach a set temperature, and warns if it's too long based on how long it has taken previously.

There are a couple of other minor updates  whcih add more time zones and weather information for Eastern Europe and Asia. More relevant for UK users is that error messages will now appear in the iOS and Android app instead of only on the thermostat's display. 

Bottom Line

Nest is the only smart thermostat system which also incorporates a connected smoke detector and a camera. Does that make it the best choice for you? It’s certainly easy to use and the circular display is a great talking point.

The smoke alarms are on the expensive side, especially if you need two or three to adequately cover your whole house. However, the Nest kit itself – without installation – is good value and should pay for itself within a couple of years if you're frugal with your schedule and temperatures.

Saving money, though, is only one benefit of smart thermostats: the ability to monitor and control your heating remotely is very useful. There are cheaper smart thermostats, but not with the wow-factor of the Nest.

One last thing to bear in mind is that you could buy a system that allows you to control multiple zones cheaply. Hive, for example, can control up to three zones. More sophisticated systems can be bought piecemeal. You could start with a basic thermostat, and add controllers for other zones later – potentially when funds allow, and this would be cheaper than buying multiple Nest controllers. Honeywell Evohome is particularly suited to this approach. But for those happy to have just one thermostat and rely on TRVs to control each radiator, the Nest is a fine choice, especially as the latest generation can also control your hot water.


  • Smart thermostat
  • 2.1in colour LCD,480 x 480 resolution at 229ppi
  • 802.11n Wi-Fi (dual-band 2.4 and 5GHz)
  • Bluetooth low energy
  • Requires: internet connection (Wi-Fi), Heat Link and Nest display must be within 30m of each other
  • Up to 10 thermostats can be controlled on one system

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About Wanni Arachchige Udara Madusanka Perera

Hey, I'm Perera! I will try to give you technology reviews(mobile,gadgets,smart watch & other technology things), Automobiles, News and entertainment for built up your knowledge.
Nest Thermostat Review (3rd gen) Nest Thermostat Review (3rd gen) Reviewed by Wanni Arachchige Udara Madusanka Perera on April 25, 2022 Rating: 5


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