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smart thermostats explained

What are smart thermostats?

What can they do and are they worth it?

Andrew Capstick
Andrew Capstick | Edited by Guy Anker
Updated 16 January 2023

Smart thermostats are a nifty way to control your heating on the go from your phone, tablet or other device. They're touted as a great way to save cash, but they're not cheap – so whether one will save you money depends on how you use it and what type of home you have.
 

So, what can they do and are they worth it? To help, this guide examines the basics and more...

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Smart thermostats need-to-knows

  1. What are smart thermostats?

    Smart thermostats are a nifty piece of kit that connects your heating system to the internet – letting you change the temperature or switch your heating off using your smartphone or other device when you're out and about, or with your computer.

    You need an internet connection to use them of course, but seeing as you're reading this we'll go ahead and assume you do.

    Remember that these are different from smart meters – which most energy firms are currently offering to install for free. For more, see our Smart Meters guide.

    Plus, unlike smart meters, you install or arrange installation of smart thermostats yourself – so it doesn't matter which energy provider supplies your energy. Also, they don't affect switching suppliers.

    Quick questions

    • How does the programmer work on smart thermostats?

      Programmers or schedulers are the most basic feature of any thermostat – whether smart or traditional. They let you set up a plan for when your heating comes on and turns off, and the temperature.

      This is much easier with smart thermostats, as you do it on your phone or computer. Plus, in comparison with traditional thermostats, you can have a much more varied heating schedule.

       

    • How are they different from my standard thermostat?

      As the name implies, they're smarter versions. The basics remain the same: you can programme a schedule to suit your needs, or boost the heat if you're cold and turn it off when you're too toasty.

      Yet there's tons of additional technological wizardry going on with smart thermostats. They have functions such as learning how your home heats up, what temperatures you like, and detecting open windows or unexpected draughts.

      Some can even keep track of when you leave home or if you're on your way back, and adjust your heating for you, or make sure your pipes don't freeze if you're on holiday escaping the cold.

       

    • Will it work with my boiler?

      They typically work with most boilers – including standard gas boilers, heating oil and electric boilers – but not all. As long as the system can be controlled by a standard thermostat or programmer, you'll likely be fine.

      If you've a communal or district heating system, most smart thermostats are still compatible as long as you already use an individual thermostat. However, most won't work with storage heaters and heat pumps.

      Most manufacturers list which boilers they'll work with, so whether you have Hive, Nest or Tado, or any other brand, you should be able to find out on their support or FAQ pages online.

       

    • What if my internet goes down?

      If your internet goes down, don't worry too much – the heat will stay on and your smart thermostat system will usually continue to run your schedule.

      You won't be able to control it via the app or online, but you can use the manual controls on the thermostat to adjust it if needed.

       

  2. How much do smart thermostats cost?

    Smart thermostats typically cost anywhere between £120 and £220, depending on make and model. Most makers also offer professional installation. This usually adds about £30 to £80.

    But there are now several options on the market which don't require the help of a professional, and can be easily installed yourself - most brands have installation instructions. For where to pick one up, see the main thermostats and where to get them.

  3. Can smart thermostats help you save money?

    There's no guarantee you'll save money – it all depends on your habits: 

    • Good for you if you come home at different times every day; if you're home a little later one day, you can delay the heating coming on remotely with smart thermostats.

    • Not so good for you if your routine is set (you leave the house at the same time every day, returning at the same time). As you can programme most thermostats to come on at specific times, a traditional thermostat would do. Similarly, if you work from home, you can turn the heating up (or down/off) manually if it gets cold (or too warm) in the property.

    If you don't have any controls – smart or traditional – either are worth it to avoid wasting heat or going back to a cold home.

    Plus, see if you can save by making your home more energy efficient with our 70+ Energy Saving Tips, or see if you're eligible for free insulation or a new boiler.

    • Be wary of savings estimates

      Manufacturers' savings figures vary – Nest says about 8% to 17%, while Tado says up to 31% a year.

      Be wary with these figures though; makers often base the savings on someone using a consistent heat at all times – say 20°C – or only assume the heating is turned down over night and not at other times.

       

  4. What can smart thermostats do?

    The clever feature of all smart thermostats is changing your heating with your phone – whether you're out and about, lounging on the couch or having a lie-in.

    Other features vary by thermostat, but common ones include multi-room control, hot water control, 'geofencing' to track when you leave and enter your home, draught detection, safety and holiday modes to protect your pipes when you're not there, and feedback on your heating patterns.

    Not every model will have all these features, but most are prevalent across different makes.

    Quick questions

    • What is 'zoned heating' and do I need it?

      Most smart thermostats also offer multi-room or multizone control, letting you heat different parts of your home independently.

      You'll need to buy additional thermostats or what's known as 'smart thermostatic radiator valves', though these won't be as expensive as the full smart thermostat starter kit (but will be by no means cheap).

      The size of your home can make certain smart thermostat systems more or less effective.

      For example, a small flat or house could likely make do with just the basic set-up of one smart thermostat – typically installed where your traditional thermostat lives. The heating for the whole home is then changed based on the temperature of that room, where the thermostat sits.

      This can be a problem in much bigger homes, where you could be heating rooms that are empty. This is where 'zonal' heating systems come in – by adding additional thermostats or smart thermostatic radiator valves in separate rooms or areas of your home, you have much greater control over your heating.

      Yet with more control comes more expense – you could pay between £50 and £80 for each smart thermostatic radiator valve or an additional £150ish for each new thermostat, but you'll be able to set the temperature and separate heating schedule for each 'zone' you create.

       

    • Do I need more than one smart thermostat in my home?

      No, generally one is enough for a typical house. If your home currently has more than one thermostat (some have one for upstairs and one for downstairs), then you may need more than one smart thermostat. You can opt to get more than one device if you just want more control over your heating, perhaps if you live in a bigger home, with lots of rooms. But in general, you can  control your entire home with one smart thermostat.

       

    • What is 'geofencing'?

      Geofencing is another common feature of smart thermostats. It's when technology is used to create a virtual boundary for a real geographic area. With a 'geofence' in place, software such as an app can know when a mobile device enters or leaves a particular location.

      So by using geofencing, your smart thermostat will know when you leave or return home, and will switch your heating on or off automatically, or ask you what you want to do, depending on your model.

       

    • Can they let me control my hot water settings?

      Certain thermostats also let you control your hot water – though usually only IF you have a separate hot water tank. This lets you switch the hot water off when you go on holiday, then on the way back you can switch it on again using the app. Depending on the make, you may need an additional bit of kit to do this.

       

    • How can smart thermostats learn my habits?

      Some, such as the Nest Learning Thermostat, say they can learn your heating habits. Just use it normally for a couple of days – turning the temperature up and down as needed, and it will begin to learn what temperatures you like and how your home heats up and cools down. It will then start to programme itself.

      However, you can always override this manually if you think the thermostat is getting it all wrong.

       

    • How does detecting draughts or open windows help?

      There are thermostats that can detect draughts in your home – say, if you left a window open – and can even send you a notification to let you know so you're not wasting heat.

       

    • How do they stop your pipes from freezing?

      All smart thermostats (and many regular ones) have a safety or holiday mode to help you save as much as possible when you're on holiday, only heating your home if the temperature drops below a safe limit – to stop your pipes freezing in winter, for example.

       

    • What kind of feedback about my heating can I get?

      Smart thermostats also give you feedback – typically on a monthly basis. They tend to give info on how many hours you've spent heating your home, and compare this against previous months. Some also guide you towards more energy-efficient settings – such as the leaf symbol which pops up on Nest's thermostat when you change it to a temperature a little lower than usual.

       

  5. Do smart thermostats work with other home tech such as the Amazon Echo?

    They do. Most can work with Amazon Echo, Google Home and IFTTT (which stands for 'if this, then that'; it's an online platform that can connect apps and devices to each other). A more limited number work with Microsoft Cortana and Apple HomeKit.

    Once you've connected your thermostat to your smart home device, you should be able to ask Alexa (Amazon Echo), Cortana or Google to set your heating at a certain temperature, increase or decrease the heating, or check what temperature your home is at – among other funky features.

  6. You can still switch energy supplier with a smart thermostat

    Smart thermostats have no impact on switching energy provider. Yet right now, due to the energy crisis there's no deals worth switching to, as everyone is paying the same rates under the energy price guarantee.

The main smart thermostats and how to get 'em cheap

Prices of smart thermostats don't change much across retailers, though you can sometimes find discounts via electronic sellers such as Amazon, Currys and Argos.

Just remember to factor in installation cost. Whether you go through the manufacturers themselves – such as Hive or Nest – or through retailers, you can usually choose to buy them with or without installation. So if you're handy with DIY, you may save up to £100.

A number of energy suppliers also sell smart thermostats and install them for you, and it generally costs much the same as going direct to the manufacturer. Some energy tariffs also include a smart thermostat – they're often touted as freebies as you don't pay the upfront cost, but you generally pay via higher bills.

We've listed the major providers and what their kit can do, but as some of the snazzy types of controls may be unfamiliar to you, here's an explanation of what the different features actually do.

  • Smart thermostats – features and jargon explained

    • Multizone. Sometimes referred to as zonal heating. Allows you to add more thermostats or controls to different rooms so you can control the heating in different parts of your home independently.

    • Hot water controls. Gives you greater control over your hot water via mobile app or online. Only works with certain water tanks.

    • Geolocation. Also known as geofencing, this lets the smart thermostat speak with your smartphone to let it know when you enter or leave your home, and turn itself on or off automatically.

    • Temperature notifications. Lets you know if the temperature inside your home gets too high or low, so you don't waste energy, or return to a freezing home.

    • Weather forecasts. Takes current and forecast temperatures into account to heat your home to your desired temperature.

    • Open window detection. Senses sudden drops in temperature or humidity when a window is opened, and can notify you or turn off the heating.

    • Frost protection. Stops your pipes from freezing by firing up the heating if the outside temperature drops below a certain limit.

    • Holiday mode. Lets you set or automatically sets your heating to a low temperature or switches your heating off when you're away – plus, you can let it know when you're back and what temperature you'd like to return to.

    • Learn your habits. The Nest thermostat below says it can learn your heating habits – you use it normally for a few days and it begins to predict what temperatures you'd like and when.

    • Boiler modulation. The ability of a boiler to 'turn down' its output to the exact level of heat needed. Some smart thermostats can communicate with your boiler in real time to tell your boiler what it needs to do in the most energy-efficient way.

Hive (part of British Gas)*

Typical cost: £200ish for mini or £280ish for standard (including installation)

Key features: Hot water control, geolocation, heat and hot water boost function, frost protection, temperature notifications, multizone (up to six zones), and holiday mode.

Extra info: The mini version has all the same features as the standard version, except some of the features are only available on the app rather than the thermostat itself. Hive also gives you historical information on temperatures inside and outside your home. 

Nest (part of Google)

Typical cost: £300ish (including installation)

Key features: Learns your habits, hot water control, geolocation, frost protection, multizone (up to 20 zones), and holiday mode.

Extra info: Nest also says it can help you save on heating by using a green leaf symbol that pops up when you adjust your thermostat to an energy-efficient temperature.

Tado

Typical cost: £275ish (including installation)

Key features: Hot water control, geolocation, open window detection, weather forecasts, frost protection, open window detection, multizone (up to 25 zones), and holiday mode.

Extra info: Tado also gives you estimated savings from using its thermostat – based on the number of hours you'd be heating your home without it.

These are some of the main brands – all backed or partnered with major tech and energy firms – yet there are plenty of alternatives. Other popular ones include, Honeywell, Netatmo, Genius and Geo Cosy.

Smart thermostats are NOT the same as smart meters

It's easy to confuse smart thermostats and smart meters, but they're actually very different pieces of kit. While smart thermostats give you remote control over your heating system, smart meters mainly deal with your gas and electricity readings.

The new meters, which will be offered to all homes in England, Scotland and Wales by the end of 2025 (though they're not compulsory), take automatic meter readings and send them to your supplier, with the aim of ending estimated billing – as well as giving you more information on your energy use through the in-home display they come with.

Unlike smart thermostats, smart meters are free from your supplier. To see if these new meters are right for you, check our Smart Meters guide.

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