What are smart thermostats and how do they work?

Wireless smart thermostat on a table

To take full control of the heating in your home, control the temperature remotely using a smart thermostat. Want to know more? Don’t touch that dial.

After being kept late at work, or having a train delayed (or both), getting home to a warm house is a blessing. And thanks to smart thermostats, you can time the heating to come on shortly before you get home – regardless of when that might be.

They’re also a good way of potentially saving money on your energy bills, because you’ll be fully in control of when your home is being heated. It’s also worth doing an energy comparison to find the best gas and electricity deals for you.

So what’s the tech behind them? And do you need one? Here we take a closer look at smart thermostats.

How do smart thermostats work?

Smart thermostats are a really handy energy gizmo. They connect your heating system to the web, allowing you to control the temperature in your home from your smartphone or device when you’re out.

But what’s the best temperature to set it to? Find out the ideal average room temperature.

To ensure you can access your thermostat from wherever you are in the world, it’s a good idea to have a good broadband connection.

A smart thermostat comprises three basic components. One part plugs directly into your heating, ventilation and air conditioning (HVAC) system. This part communicates directly with the second part, which is the thermostat control itself. The third and final part is the smart thermostat app, which is downloaded to your smartphone, device or computer.

Smart thermostats don’t just allow you to control the overall heating at home. These are among the other functions of higher-end models:

  • Multi-room control. Heating different parts of your home independently, although you’ll have to pay extra for smart thermostatic radiator valves to do so.

  • Hot water control. Usually only if you have a separate hot water tank, you can switch hot water off when you go on holiday and turn it back on before your flight home. No more waiting for it to heat back up when you’ve just got back from a long flight and need a warm bath more than anything else in the world. It may also be worth reducing your hot water temperature.

  • Geofencing. Where technology is used to create a virtual boundary for a real geographical area. As such, it knows when you leave or return home and switches your heating on or off automatically, or asks you what you want to do.

  • Draught detection. Some models can detect if you’ve left a window open and even send you a notification to let you know.

  • Safety modes. Automatically limits energy consumption when you implement safety or holiday mode, only heating if your home drops below a safe limit to stop your pipes freezing in winter.

  • Feedback on heating patterns. How many hours you’ve spent heating your home, compared to previous months. Gives guidance on energy-efficient settings too.

Is a smart thermostat like a smart meter?

Smart thermostats and smart meters are very different beasts. Smart meters show you how much energy your home is using in pounds and pence, in almost real-time, through an in-home digital display. They help you track what you use, so you can understand where to make reductions in your energy consumption.

Smart thermostats, on the other hand, give you complete control of your heating remotely. So you can turn on the heating exactly as and when you need it.

How to install a smart thermostat

Make sure your smart thermostat is compatible with your system and wiring before committing to buy. Certain producers offer compatibility tools and checklists online to save you from buying the wrong one.

Otherwise, it’s a simple seven-step process:

  1. Turn off your HVAC system.
  2. Remove the faceplate of your old thermostat.
  3. Remove the thermostat wires from the backplate.
  4. Add a C-wire (if your system already has this then skip).
  5. Use the new thermostat’s backplate and pencil to mark the wall, drilling holes at the marks for the backplate screws.
  6. Reconnect the wires once the new backplate is attached.
  7. Snap the faceplate of your new thermostat onto the backplate and turn on the breaker for your HVAC system.
  8. Connect the thermostat to Wi-Fi and get heating.

If any of these steps seem dangerous or you aren’t sure how to connect the wiring, get a professional electrician to help.

Do smart thermostats save you money?

Whether or not smart thermostats save you money completely depends on how you use them. If you use them smartly – limiting your energy consumption when you’re out or on holiday – you’ll make savings over time.

But if you’re sitting on the sofa blasting extra heat every night to get you through winter, it’ll naturally set you back more. 

They do come at a cost to buy, ranging from between £139-£300. These are the best buys according to consumer magazine Which?:

  • Hive from British Gas – £161 or £139 for the Hive Mini. Add £99 for installation.
  • Nest from Google – £219 for Nest Learning Thermostat, or £199 for a Nest Thermostat E.
  • evohome from Honeywell – £260 for base unit not including installation, plus extra for each ‘smart zone’ you add.

Your energy supplier may also offer a smart thermostat to customers, so it’s worth seeing what they have available.

What other gadgets and appliances will save you money?