Helpful video reference. We use Artisan Electrics' UK tutorial "The Ultimate DIY Smart Thermostat Install, How to install a Tado smart thermostat!" as the video reference here. Artisan Electrics is a UK electrical contracting business (Cambridge) with over 300,000 subscribers on YouTube. Jordan covers the wiring for dual-zone UK setups and gets the UK boiler wiring specifics right throughout.
1. Check compatibility
tado° works with the vast majority of gas combi and system boilers sold in the UK, including Worcester Bosch, Vaillant, Ideal, Baxi and Viessmann. It also works with oil boilers, heat pumps and underfloor heating systems that use a standard on/off switching input. It does not work with electric storage heaters or directly with electric underfloor heating cables or mats.
Use the tado° compatibility checker (available on their website) before you buy. You will need your boiler make and model, which is usually printed on the front panel.
Also check whether you want standard wireless control (Smart Thermostat V3+) or hot water control too (Starter Kit V3+ with Hot Water Control). On a combi boiler there is no cylinder, so you only need the Smart Thermostat. On a system or regular boiler with a hot water cylinder you may want to add the Hot Water Control as well.
2. Photograph the existing thermostat wiring
Remove the old thermostat faceplate. Most clip off or are held by two screws. Behind it you will find a back box, either surface-mounted or flush-mounted in the wall, with two, three or occasionally four wires connected to the thermostat terminals.
Take a clear, well-lit photograph of the terminals and wires before loosening anything. If the conductors are not labelled, write their positions on masking tape before removing them. This takes two minutes and could save half an hour of puzzling later.
3. Isolate the boiler supply
The boiler's fused spur is usually a white 3A switched FCU (fused connection unit) near the boiler, in an airing cupboard, or on a kitchen wall. Switch it off, or switch off the Heating MCB (typically 6A) in the consumer unit. Test at the old thermostat terminals with a voltage tester. Dead on all conductors? Good - remove the old thermostat.
Leave the existing wires in the back box. Do not pull them back through the wall - you need them all for the tado° base plate.
4. Wire the tado° base plate
The tado° Smart Thermostat V3+ has a back plate that mounts over the existing back box. It is designed to cover the standard UK single-gang footprint, so in most cases it will hide any marks left by the old thermostat.
Wiring depends on what you found:
- Two-wire low-voltage call-for-heat (the most common setup in UK homes, where the thermostat simply opens and closes a low-voltage circuit): connect the two wires to the NO (normally open) and COM terminals on the tado° base plate. Polarity does not matter for a simple volt-free switching circuit.
- Three-wire mains voltage (older UK setups where the thermostat switches a mains load directly): connect L to L, N to N, and the switched live output to the NO terminal. This is a mains voltage connection - be precise.
- Four wires: you likely have a more complex setup, possibly with a hot water switching function built into the thermostat. Check the tado° wiring guide for your specific configuration, or call an electrician.
Tighten each terminal screw firmly. Clip the tado° thermostat body onto the base plate. Restore power briefly at the fused spur to confirm the thermostat display lights up and shows a temperature reading, then isolate again before moving to the next step.
5. Connect the tado° Internet Bridge
The Internet Bridge is a small white unit that plugs into a 13A socket and connects to your broadband router by the Ethernet cable in the box. A steady green LED confirms it has a network connection. Place it near the router - the Ethernet cable needs to reach a free port.
The Bridge communicates with the tado° Smart Thermostat at 868 MHz, a frequency that passes through most UK plasterboard and brick walls well. In a large house or one with particularly thick walls, the range may occasionally be marginal - if that becomes an issue, tado° sell a range extender.
6. Commission in the tado° app
Download the tado° app (iOS or Android) and create an account. Follow the on-screen setup: add the Internet Bridge first (the app will detect it on the network), then add the Smart Thermostat by pressing the pairing button on the back of the thermostat when prompted.
The app then asks a series of questions: your boiler type (combi, system, heat pump), your home's postcode (for weather-based control and open-window detection), and the rooms you want to control. For a single thermostat controlling the whole house, one room covers everything.
tado°'s geolocation feature can track when your phone leaves home and set the heating back automatically - enable this in the app settings if you want it.
7. Test heating response and set a schedule
In the app, tap the heating zone and raise the target temperature well above the current room temperature. Within a minute or so you should hear the boiler fire. Check the thermostat display shows a call-for-heat indicator (a flame symbol on most tado° models).
On a combi boiler, run a hot water tap and confirm that works normally - tado° does not touch the hot water circuit on a combi, so it should be unaffected.
Create a weekly heating schedule in the app. tado° offers a home/away/sleep schedule which many people find more intuitive than a fixed timetable. Set a frost protection minimum (7°C is standard) so the heating kicks in on cold nights even if the schedule is in away mode.
When to call us
Most tado° Smart Thermostat installs are genuinely straightforward. The exception is a system boiler where the thermostat cable runs to a wiring centre rather than straight to the boiler, particularly on S-plan systems with separate zone valves. If your airing cupboard contains a wiring centre (a white plastic box with rows of terminals and several cables) and you are not comfortable reading a wiring diagram, it is worth asking Richard to check first.
Need a tado° thermostat fitted in east Kent?
Richard installs smart thermostats and heating controls across Sandwich, Deal, Dover and the surrounding area.
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