Smart thermostat · current figures
Last updated 2026-06-24£75-150
a year saved (if upgrading controls)
8-18%
gas saving, learning models
£120+
typical unit price
5.74p
per kWh gas (price cap)
Savings: Energy Saving Trust, heating controls guidance (EST); real-world learning-model gas savings from live-home studies. Gas rate: Ofgem price cap, 1 April to 30 June 2026, Direct Debit. Savings depend on the controls you have now [verify each heating season].
How a smart thermostat actually works
A smart thermostat sits between you and your boiler, exactly where an old dial or timer used to. The difference is what it can sense and decide. Think of a normal thermostat as a light switch on a timer: it does what it is told, when it is told. A smart thermostat is more like a thermostat with a brain and a phone, it can be told from anywhere, and the cleverer ones work out the schedule themselves.
Three abilities separate "smart" from "programmable":
- ✓Remote control: change the temperature or boost the heating from your phone, on the bus home or from bed.
- ✓Learning: the thermostat watches your routine and how fast your home heats, then starts the boiler at the right moment so the house is warm when you want it, not an hour too early.
- ✓Sensing: geolocation turns the heating down when your phone leaves the house; weather compensation eases off on milder days. Both stop you heating an empty or already-warm home.
Crucially, it still runs the same boiler. A smart thermostat saves gas by firing the boiler less often and for shorter, not by making heat more cheaply. That is the whole mechanism, and it is why the saving depends on how wasteful your current control is.
The three types of smart thermostat
"Smart thermostat" covers three quite different products. Picking the wrong one is the most common, and most expensive, mistake. Here is the honest split:
| Type | Examples | How it works | Best for |
|---|---|---|---|
| Learning thermostat | Nest, tado° | Learns your routine and how fast your home heats, then sets itself. Senses when you leave (geolocation) and turns down. | Irregular routines, hands-off users. The biggest real-world gas savings (around 8 to 18%) come from this auto-adjustment. |
| App-programmable | Hive, Drayton Wiser hub | You set the schedule and target temperature from an app. No learning, but full remote control and boost. | People who like to be in charge and have a steady routine. Cheaper to buy than a learning model. |
| Zoned / smart TRVs | tado° / Wiser radiator valves | Smart valves on each radiator heat rooms individually, so you stop heating empty rooms. | Bigger homes where you only use some rooms at a time. The largest savings, but the priciest and fiddliest to fit. |
Which smart thermostat is right for your home?
Answer two quick questions. We point you at the type that fits, and flag when a smart thermostat will not save you much.
Best fit for you
Saving potential
A guide based on Energy Saving Trust savings ranges, not a survey of your home. The biggest variable is always the control you have today, verified June 2026.
The belief that wastes people's money
The marketing line is "fit a smart thermostat and save up to 30% on heating". The "up to" is doing enormous work. That headline figure is the saving for a household going from poor control (a dial left on, no timer) to precise control. If you already run a sensible timer and turn rooms down, the smart thermostat is mostly buying you a phone app, not a 30% cut. Believing the headline is how people spend £200 to save £15.
The honest framing: a smart thermostat is a tool that removes waste. If you have a lot of heating waste, it removes a lot and pays back fast. If you have little, it removes little. The device is identical either way, the saving lives in your starting point, not the gadget.
The insider view: the saving is in the rooms, not the brand
Here is the point the brand comparisons miss. People agonise over Nest versus Hive versus tado°, but a single wall thermostat, of any brand, controls your whole house as one zone. It cannot heat the living room and leave the spare bedroom cold; it heats everywhere to one target. So in a home where half the rooms sit empty most of the day, the wall unit's clever learning is still heating empty space.
Where the real money is The largest, most reliable savings come from zoning, smart thermostatic radiator valves that let each room have its own schedule. Heat the bedroom only at night, the office only in working hours, and leave the rest cool. In a typical UK home with under-used rooms this beats a single smart thermostat comfortably, because it attacks the biggest waste of all: paying to warm rooms nobody is in. The trade-off is cost and fitting, a valve per radiator adds up, so it pays best in larger homes with clear unused rooms.
So the smart move is not "which brand", it is "one zone or many?" If your home is small and used all over, a single learning thermostat is plenty. If it is larger with empty rooms, the budget is better spent on valves than on a fancier wall unit.
What you should actually do
Judge your starting point first
If you already use a timer and radiator valves well, expect convenience, not a big saving. If you leave heating on a dial, you have the most to gain.
Match the type to your home
Small home used all over: a single learning thermostat. Larger home with empty rooms: spend on zoned smart valves instead.
Do not chase the brand
Nest, Hive and tado° all control the same boiler. The saving comes from zoning and habits, not the logo.
Fix the basics first
A smart thermostat cannot beat a draughty room. Cheap draught-proofing and good radiator valves often pay back faster than the gadget.
The bottom line
A smart thermostat is a wi-fi heating control that can run the boiler for you, by learning your routine, sensing when you are out, or reacting to the weather. It saves gas only by firing the boiler less, so the size of the saving is set by how wasteful your current control is, not by the brand on the wall. Upgrading from a basic dial can save £75 to £150 a year; upgrading from an already-good setup saves little. And in a larger home with empty rooms, zoned smart valves beat any single wall thermostat. Decide whether you need one zone or many before you spend a penny, then check you are not overpaying for the gas itself.
Smart thermostat FAQ
The Selectra expert answers your questions
A smart thermostat is a heating control connected to your wi-fi, so you can change the temperature or schedule from your phone, anywhere. The cleverer ones go further: a learning model studies your routine and how quickly your home warms up, then heats only when needed; some use geolocation to turn down when your phone leaves the house, or weather compensation to ease off on milder days. It still controls the same boiler, it just decides when to fire it far more precisely than a manual dial.
It depends entirely on what you have now. If you control heating with a basic dial or leave it on a fixed timer year-round, a smart thermostat can save roughly £75 to £150 a year (Energy Saving Trust) by heating only when and where you need it. If you already use a good programmer and radiator valves well, the extra saving is small, you are mostly buying convenience. The saving comes from the control, not the brand badge.
A programmable thermostat switches the heating on and off at times you set by hand. A learning (smart) thermostat makes those decisions itself, using your habits, your phone's location and the weather, with little input once set up. Programmable means you do the thinking; learning means the thermostat does. Learning models cost more but tend to deliver the larger real-world gas savings.
Yes, most are designed for standard combi and system boilers, and the savings come from running the boiler less, not from changing the boiler. Pairing a smart thermostat with smart radiator valves adds room-by-room control, which is where the biggest savings sit in homes with unused rooms.
Expect roughly £120 to £220 for the unit, plus fitting if you are not confident wiring it (a heating engineer typically charges £80 to £150). Running cost is negligible, the device itself uses a few pounds of electricity a year. The number that matters is the heating it saves, which is why it only pays back where it genuinely improves your control.