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Best smart thermostats 2021: Save on heating costs now

If there’s one smart device that’s guaranteed to make a difference in your home, it’s the smart thermostat. That’s particularly true given the rising energy prices, as smart thermostats have the power and control to help you cut costs.

I have reviewed every single smart thermostat available and personally run four systems in different locations permanently so that I can truly tell the difference between them.

The reviews are updated with new features yearly, as is this guide. Here, I’ve got everything from single thermostats to full-on multi-room systems with individual control.

How We Test

Learn more about how we test smart thermostats

Testing smart thermostats is as much about consistency, so I have built a custom rig that lets me wire thermostats into an electric heater, giving me the option to quickly change units. All single thermostats are tested in that way.

For multi-room systems that use radiator valves, I test at the Trusted Reviews home appliance lab, which has three radiators that I can individually control.

I test for quality, ease of use, ability to maintain temperatures, and how the systems interact with other smart systems, including Alexa, SmartThings, IFTTT and so on.

Honeywell Evohome

The best smart heating system
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Pros

  • Extremely flexible
  • Touchscreen controller
  • Powerful Quick Actions

Cons

  • No geolocation
  • Expensive

No company has as much experience in the heating arena as Honeywell, so it’s no surprise that its first smart product offering has been extremely comprehensive. Rather than replacing your basic smart thermostat, the Honeywell Evohome adds room-by-room control through smart TRVs, but also supports underfloor heating and even heat pumps.

Although this adds to the initial set-up cost – you’ll need a £59 TRV per radiator – it should save money thereafter, since you’ll only need to heat the rooms you’re using. Also, each room is set to its perfect temperature, making for a more comfortable home environment. You can even go beyond radiator control with support for underfloor heating and zone controls, too.

The level of control on offer is impressive, with the ability to set schedules per room. We love the Quick Actions, too, which let you make system-wide changes at the touch of a button, such as turning on the Economy mode (three-degrees colder in each room) to save money when you go out. There’s support for Google Assistant and Amazon Alexa, too. New this year is weather compensation, which can dial your heating up or down based on the temperature outside. It works brilliantly, making our home more comfortable.

Evohome continues to be a powerful multi-room system, ideal for larger homes featuring a range of heating sources.

Reviewer: David Ludlow

Full review: Honeywell Evohome review

Nest Learning Thermostat

The best single smart thermostat
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Pros

  • Looks fantastic
  • Learns how you use it
  • Sharp and clear display

Cons

  • Can’t expand to radiator control

The Nest Learning Thermostat is among the best-known smart thermostats around, and for good reason. This product has shown how powerful smart heating can be. Now in its third generation, it remains one of the best smart thermostats you can buy.

As the name suggests, the thermostat learns how you like your home heated, using this information to create an automatic schedule for you. Not surprisingly, there’s an initial learning curve – in the first few weeks, the Nest may not work quite the way you want it to. Over time, however, it should prove more effective than a manually set schedule on rival thermostats. In addition, the thermostat uses presence detection to turn on and off automatically, depending on whether anyone is at home.

With support for Amazon Alexa and Google Home (although HomeKit support doesn’t seem likely), Nest covers the basics; since Google turned off the Works with Nest programme, though, the thermostat has lost a few features.

This latest version supports dual-zone plumbing and can be extended to support hot water systems as well. Note that there are no smart radiator valves to add full zoning, however.

Reviewer: David Ludlow

Full review: Nest Learning Thermostat review

Genius Hub

The best system for flexibility
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Pros

  • Looks fantastic
  • Learns how you use it
  • Sharp and clear display

Cons

  • Can’t expand to radiator control

If you’re looking for the most powerful and flexible heating system, then the Genius Hub should be top of your list. Designed and built by a UK company, this is a seriously impressive heating system that can control practically all types of heat source, from combi boilers to electric. As you’d expect from such a system, control over individual rooms comes courtesy of smart radiator valves.

Genius Hub goes further than the competition, thanks to its motion sensors. In the app, you can use the motion sensors to automatically set up a heating schedule via room occupancy (Footprint mode, which is free forever), or you can use the new Sense mode (subscription required) to set a schedule as standard; but you can also choose to use the motion sensor to only turn on the heat when there’s someone in the room. For example, you could set your living room to use the motion sensor during the day, so if you do have the day off work then your heating can be set to turn on automatically. That’s what we call smart.

There’s an Amazon Alexa skill, but no dedicated Google Assistant skill – although you can connect the system via IFTTT for some basic control here. A high price may put off some, but the Genius Hub system is designed for the largest homes or for those wanting the biggest savings. In our experience, Genius Hub works brilliantly and is worth every penny.

Reviewer: David Ludlow

Full review: Genius Hub review

Tado Smart Thermostat

The best HomeKit smart thermostat 
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Pros

  • Looks fantastic
  • Learns how you use it
  • Sharp and clear display

Cons

  • Can’t expand to radiator control

Tado launched with the goal of making smart heating systems easy to use, and it certainly succeeded. The Tado Smart Thermostat is designed to track your location so that your heating goes off when you’re out and turns back on when you’re on the way home. It works brilliantly and has the most reliable presence detection we’ve tested.

Since launch, Tado has updated the apps and web interface to add a new heating scheduler, so you can choose the home temperature that you want hour by hour. There are also options for when you’re out – choose from maximum savings (which may mean you return to a colder home) or maximum comfort (you’ll spend more to keep your home warmer). The app is simple to use, making the Tado Smart Thermostat one of the easiest systems to program.

Tado’s system is also super-flexible. With the launch of its smart radiator thermostats, the system can be as powerful as Evohome’s. However, Tado’s radiator valves aren’t quite as smart, and the app’s zone handling isn’t quite as easy to use as that of Honeywell.

The addition of Amazon Alexa and Google Home support, IFTTT and HomeKit (via the V3+ internet bridge) make Tado’s Smart Thermostat one of the most powerful available. The downside is that the new system requires a monthly subscription to enable automatically turning off of the heating when you go out, plus the window-detection feature, which turns off the heating when a door or window is open.

By thinking of the subscription as payment towards ongoing development of the app and system makes it easier to accept. And you may decide you only need to pay for the extra features during the winter months, as you can cancel your subscription at any point.

Reviewer: David Ludlow

Full review: Tado Smart Thermostat review

Vestemi Radbot

The best simple radiator upgrade
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Pros

  • Looks fantastic
  • Learns how you use it
  • Sharp and clear display

Cons

  • Can’t expand to radiator control

Most smart heating systems require an app to provide fancy programming options. That’s all well and good, but it can make things complicated. The Vestemi Radbot is different: this smart radiator valve learns how you use a room automatically via its sensors, and then controls your heating automatically.

The Radbot looks like a standard TRV, and has a simple control dial that moves from 1 to 5 – these numbers correspond to a room temperature of between 15ºC and 24ºC. It would have been easier if Vestemi had put the temperatures on the dial, to be honest. But that’s our only criticism; otherwise, Radbots are brilliant.

The system learns how you use a room by tracking how light changes during the day – such as when you open the curtains, or turn the lights on and off. It turns the heating up when you’re in a room, and down when you’re not. And if you get cold, there’s a boost button. Even better, the Radbot works with your existing heating system, so there’s nothing to hook up to the boiler. If you want a smart solution that’s simple and cheap, this is the product for you.

Reviewer: David Ludlow

Full review: Vestemi Radbot

Nest Thermostat E

The best simple smart thermostat upgrade
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Pros

  • Looks fantastic
  • Learns how you use it
  • Sharp and clear display

Cons

  • Can’t expand to radiator control

Forget expensive installations and hassle – the Nest Thermostat E has been designed so that pretty much everyone should find it easy to install. The new Heat Link E battery-powered bridge attaches to the wires that were used by your old wired thermostat – and that’s it. Starting from scratch, most people should have the system up and running in under an hour. If you don’t have a wired thermostat, you’ll need to have the Heat Link E wired into your boiler, which will most likely mean a professional installation. While the system supports OpenTherm for increased energy savings, at this point your best option is probably a different product.

Nest has pre-programmed the Thermostat E with a schedule based on real data from existing Nest users. As you use the thermostat, it learns and updates your schedule.

The main thermostat has a diffused screen, helping it blend into the background. The screen displays the temperature, and you can use the outer dial to adjust it. The excellent Nest app provides even greater control, adding features such as geolocation to turn off your heating when you go out. True Radiant learns how your house warms up, so you can have it warm when you need to, and avoid overshooting your desired temperature.

If you’re looking for a simple, smart upgrade to an existing dumb, wired thermostat, then this is a great choice.

Reviewer: David Ludlow

Full review: Nest Thermostat E review

FAQs

What type of smart thermostat do you need? 

There are numerous smart thermostats to choose from, each offering a variety of features, so it’s important to pick the one that suits your lifestyle and home. First, you need to consider the type of heating system you want. A regular smart thermostat simply replaces your existing thermostat. You’ll still save money with such a system, but your heating settings will be applied to your entire home.

A zoned heating system offers room-by-room control via smart thermostatic radiator valves (TRVs). Such a system will save you more money since you’ll be heating only the areas you’re using at any given time. The downside is that the initial outlay for such systems can be costly: typically around £50 to £70 per radiator. They’re a better option for houses with a greater number of rooms.

What control options do I need? 

All smart thermostats should be controllable, to a degree, from the main unit as well as from a dedicated smartphone app. Voice control is becoming a more important feature, in the form of Alexa on the Amazon Echo or Siri using Apple HomeKit.

Being able to simply tell your thermostat to turn the heating up or down is a convenient way to control the temperature in your home. Alexa support is more widespread, with HomeKit support lagging somewhat.

Do I need “call for heat”?

This is the ability, particularly for smart radiator valves, to turn on your heating when they’re too cold. An increasing number of smart radiator valves can’t “call for heat”.

Instead, they offer finer control over a room’s temperature than a traditional mechanical thermostat, which will simply let you set your controls between one and five without giving you any indication what this means. Smart valves shut down radiators when the desired temperature has been reached.

So, why would you want to go down this route? If you have an old boiler that you can’t upgrade, or you’re a renter who isn’t in control of overhauling the smart heating system, these options can be a helpful addition. And if you’re looking for greater control over an existing smart thermostat then such devices can be useful.

Can they really save me money? 

In short, yes. According to Tado, UK customers can save up to 19% on heating costs in comparison to the costs of using a traditional dumb thermostat and normal heating controls, as our full guide to how much money a smart thermostat can save you explains

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Spec Comparison

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USA RRP
Manufacturer
Size (Dimensions)
Weight
Release Date
First Reviewed Date
Voice Assistant
Smart assistants
App Control
IFTTT
Boiler connection
Hot water control
Geofencing

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