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Smart Thermostat Guide: How Much You Save Money, the Best Options for UK Systems and What Installation Involves
Whether a smart thermostat really saves money, which models suit UK heating systems best, and what installation involves — with realistic saving figures.
Published 2026/07/15 · EPC & ratings
A smart thermostat is the cheapest item in this series and the only one you can fit in an afternoon. It’s also the most oversold: the “up to 31% savings” figures on boxes assume a house with no working heating schedule at all. The honest case for a smart thermostat is still good — it just lives in the 5–12% range, which at 2026 gas prices is real money for a £100–£220 device.
This guide covers how a smart thermostat helps you save money in practice, which of the best UK options fits which heating system, and what installation involves before you buy.
How a smart thermostat helps you save money
The honest answer to whether these devices save money is: only if the schedule actually matches your life. A dumb programmer heats the house on a fixed clock whether anyone’s home or not. A smart thermostat attacks that waste from several directions at once:
- Schedules you’ll actually use. Changing the heating pattern from a phone app beats a boiler-cupboard programmer with three buttons, so the schedule matches your life and gets updated when life changes.
- Geofencing. The system winds down when the last phone leaves and warms up on the way home — the single biggest saver for households with irregular hours.
- Weather compensation. Milder tomorrow means later firing; several models adjust for the forecast automatically.
- Visibility. Usage graphs are what persuade most people to try 19°C instead of 20°C — and that 1°C is worth roughly 8–10% of the heating bill on its own.
- Zoning. Smart radiator valves stop heating bedrooms all evening. On larger houses zoning is where the double-digit savings genuinely come from, at £40–£70 per radiator extra.
Put together, Energy Saving Trust-aligned expectations are £60–£150 a year for a typical semi. Payback of one to three years, faster with zoning in a bigger house. A smart thermostat also picks up minor EPC points under the heating-controls section — the EPC rating guide covers where controls score.
The best smart thermostat for each UK setup
Reviews tend to rank on app polish; what actually matters is compatibility with your heating. How the main UK options divide up:
| Model | Typical price | Best for | Radiator zoning | OpenTherm |
|---|---|---|---|---|
| Tado X | £100–£200 | Combi + system boilers, renters (wireless kit) | Yes | Yes |
| Drayton Wiser | £120–£180 | UK backplate swap, multi-channel systems | Yes | Yes |
| Google Nest | £180–£220 | Set-and-forget learners | No (UK) | Yes (Heat Link) |
| Hive | £120–£180 | Simplicity, British Gas installs | Yes | No |
| Honeywell Evohome | £250+ | Whole-house zoning on larger properties | Yes (core feature) | Yes |
Three buying rules do most of the work. First, match the channels: a system boiler with a hot water cylinder needs a two-channel kit, a combi needs one. Second, prefer OpenTherm where your boiler supports it — modulating the flame beats switching it on and off, and quietly saves another few percent. Third, if you have (or plan) a heat pump, the best smart thermostat is usually the pump manufacturer’s own control; generic on/off stats undo the low-and-slow logic that makes a heat pump efficient — see the air source heat pump guide for why flow temperature rules everything.
Renters aren’t excluded: wireless kits like Tado’s sit alongside the existing stat and move out with you.
Smart thermostat installation: DIY or fitted
What installation involves depends entirely on what your current setup looks like:
- Replacing a wireless room stat — the easy case. The new receiver wires into the same terminals as the old one, the stat itself just needs a shelf or a wall plate. Confident-DIY territory, 30–60 minutes.
- Wired stat on the wall — usually still a like-for-like swap at the same backplate (Drayton’s whole pitch), but mind which wires are live and switched; photograph everything before you disconnect.
- At the boiler / OpenTherm / hot-water channels — get it fitted. Wiring into the boiler backplate or adding an OpenTherm link is £50–£120 for an electrician or heating engineer, and most retailers sell installation bundles at much the same price.
- Radiator valves — screw onto standard TRV bodies by hand; the only tool is the adapter ring chart in the box.
One honest warning: a smart thermostat can’t fix a badly balanced system, radiators that need bleeding, or a boiler flow temperature set to 80°C. Do those free jobs first — then the thermostat’s savings arrive on top, and the graphs it draws will tell you whether the bigger retrofits on this site (insulation first — start with the loft) are doing what they promised.
Frequently asked questions
Do smart thermostats actually save money?
Yes, but modestly: realistic savings are 5–12% of heating costs — £60–£150 a year for a typical gas-heated semi. The saving comes from schedules you actually keep, geofencing that stops heating an empty house, and turning the whole system down 1°C once you can see what it's doing.
What is the best smart thermostat?
There's no single best — it depends on your system. Tado and Drayton Wiser suit most UK combi and system boilers and both support radiator-level zoning; Nest's learning approach suits people who won't program schedules; Hive is the simple all-rounder. Heat pump owners should use the manufacturer's own control first.
Can I install a smart thermostat myself?
Kits that replace a wireless room stat are a reasonable DIY job — the receiver wires into the same terminals. Anything at the boiler backplate, a hot-water channel, or an OpenTherm connection is electrician-or-installer territory, typically £50–£120 fitted.
Do smart thermostats work with heat pumps?
Sometimes, but carefully. Heat pumps run best at low, steady flow temperatures with weather compensation, and an on/off smart stat can fight that logic. Use the heat pump maker's own smart control, or one that speaks the pump's protocol, rather than a generic boiler thermostat.