A smart thermostat puts the heating on a phone app, on a schedule and, with radiator valves added, room by room. In a UK home the right one depends less on the brand than on the boiler: a combi that heats water on demand, or a system or conventional boiler that heats a cylinder. This guide covers boiler compatibility, OpenTherm, hubs and WiFi, radiator valves, subscriptions and installation for tado, Hive, Google Nest and Drayton Wiser, then matches five kits to the homes they suit.
Match the thermostat to the boiler first. tado says its wired Smart Thermostat X suits combi boilers, while its wireless version also runs hot water cylinder schedules on system and conventional boilers. Hive says its thermostat controls hot water on conventional systems with a separate tank, and Wiser's 1 channel kit suits combis while its 2 channel kit suits conventional or system boilers. Each maker's compatibility checker confirms the exact setup.
Key Takeaways
- tado says its Wired Smart Thermostat X suits combi boilers and does not control hot water cylinders, while the Wireless Smart Thermostat X runs cylinder schedules on combi, system and conventional boilers.
- Hive says OpenTherm on its thermostat works with compatible combi boilers only and on single zones, and tado and Wiser's 1 channel kit list both relay and OpenTherm connections.
- tado's help centre says its Bridge X and Wireless Receiver X only connect to 2.4 GHz WiFi, Wiser's HubR connects to 2.4GHz WiFi, and Hive's hub needs a spare Ethernet port on the router.
- tado's AI Assist and Hive+ are optional subscriptions at £3.99 a month each, and Wiser says its kits carry no subscription fee.
- Hive says a DIY install needs someone competent in electrical wiring, and the Energy Saving Trust recommends installers registered with Gas Safe for gas boilers.
The Boiler Type Decides Which Kit to Buy
Start at the boiler, not the brand. The Energy Saving Trust's heating controls guide sets out the usual layouts: a single channel programmer for a combi boiler, which only controls the central heating because hot water comes on demand, a two channel programmer for a system boiler running heating and hot water, and three channel control for hot water plus two heating zones. A combi has no hot water cylinder, while system and conventional (regular) boilers heat one.
The makers follow that line. tado says its Wired Smart Thermostat X suits combi boilers and does not control hot water cylinders, while the Wireless Smart Thermostat X runs cylinder schedules on combi, system and conventional boilers. Hive says its thermostat controls hot water on a conventional system with a separate tank. Wiser's 1 channel kit is for combis, the 2 channel kit for conventional or system boilers, and the 3 channel kit adds a second heating zone. Google's Heat Link page says the 3rd gen Nest Learning Thermostat controls a hot water tank and the Nest Thermostat E does not.
OpenTherm Lets a Thermostat Turn the Boiler Down
Most room thermostats talk to the boiler through a relay, an on and off switch, and tado's help centre explains that in relay systems the heating turns fully on or fully off. OpenTherm goes further. Hive's page describes it as a communication protocol used by modern condensing boilers that lets the boiler reduce power when only a little heat is needed, and puts the extra saving at up to 12%, based on a class V directly modulating room thermostat against a standard room thermostat on a gas boiler.
Support differs by brand. tado says the Smart Thermostat X suits boilers that work with relay or OpenTherm, which it says is most of them. Hive limits OpenTherm to compatible combi boilers and single zones, and says its engineer will fit the receiver in whichever mode suits. Wiser lists both connections for its 1 channel kit and relay only for the 2 channel kit. Google says the Nest Thermostat E and 3rd gen Learning Thermostat support OpenTherm, and suggests looking for the OpenTherm logo on the boiler or asking its manufacturer.
Hubs and Receivers Mostly Need 2.4GHz WiFi
Every system here needs a link between the heating and the router. tado's help centre says its Bridge X and Wireless Receiver X only connect to 2.4 GHz WiFi, with the setup phone on that same 2.4 GHz network. The wireless kit needs no separate Bridge X, because tado says its receiver works as a Thread border router, though tado recommends one additional Bridge X per 100 m². Wiser's HubR also connects to 2.4GHz WiFi.
Hive works differently. Its hub page asks for a router with a spare Ethernet port and recommends setting the hub up on the cable, then moving it to WiFi if another spot gives better coverage. Google says most Nest products work on 5 GHz, but suggests 2.4 GHz for one installed far from the router.
tado's help centre even gives Virgin Media steps for running 2.4 GHz alone during setup, which the Virgin Media Hub band guide also covers. The same band rule catches out smart plugs, and a weak signal where the receiver sits calls for the two bars fix or budget mesh WiFi.
Smart Radiator Valves Add Room-by-Room Control
Smart radiator valves replace the head on each radiator's valve, so each room keeps its own temperature and schedule. tado says that when it also runs the boiler, its Smart Radiator Thermostat X valves sync with the central thermostat so each room can request heat on its own. tado packs six valve adapters in each box, says the rechargeable battery needs charging about once a year, and connects the valves through a Bridge X or another Thread border router.
Wiser's FAQ says its radiator thermostats screw onto the valve that stays on the radiator, so nothing needs draining, and its kit pages allow up to 16 rooms and 63 Wiser devices per hub. Hive's fitting guide covers M30, M28, RA, Giacomini and Caleffi valves, and says manual plus and minus valves need a new valve body first.
The Energy Saving Trust says some programmable TRVs connect to smart heating controls to create a new zone for each room, and that adding TRVs to a system with a programmer and thermostat can save £30 a year in Great Britain.
Subscriptions Are Optional and the Savings Figures Are the Makers' Own
None of these thermostats needs a subscription to run the heating. tado's optional subscription, now called AI Assist, costs £3.99 a month or £29.99 a year and adds features such as Adaptive Heating, geofencing and open window detection, and tado says Smart Schedules keep running offline because they are stored on the device. Hive+ costs £3.99 a month or £39.90 a year for extras such as Saver mode and a budget tracker, and Hive says choosing pro installation brings a year of Hive+ that auto-renews unless cancelled. Wiser says there is no subscription fee.
Every savings figure here is the maker's own. tado claims users save 22% on average, based on its internal customer data collected up to 30 November 2023. Hive's up to £182 a year assumes Ofgem's medium gas use of 9,500 kWh at the October 2026 average unit price. Wiser's up to 30% cites BEAMA and Salford University research from 2021. The Energy Saving Trust is more cautious: whether smart controls save money depends on how you control your heating now.
Installation Ranges From App-Guided DIY to a Booked Engineer
Makers differ on who should fit the boiler end. tado says its thermostats are easy to install yourself, with app steps tailored to each system, and each box includes a manual for professional installers. Its UK shop sells fitting by a certified engineer from Smart Home Hero. Hive is more cautious, saying a DIY install needs someone competent in electrical wiring and DIY, recommending an experienced local tradesperson and offering British Gas engineers. Wiser says its HubR fits a standard wallplate, which it puts in around 80% of homes, and tells owners to consult a trained installer with questions. Google says the 3rd gen Nest Learning Thermostat should be installed by a professional, while the Nest Thermostat E can be fitted DIY or by a Nest Pro.
tado, Hive and Wiser all list 230V mains power for the receiver or hub that connects to the heating, so book help if unsure. The Energy Saving Trust suggests quotes from at least three installers certified with a scheme like TrustMark and registered with Gas Safe for gas boilers or OFTEC for oil.
Five Kits Cover Most UK Boilers
Run the checker before buying anything below. Hive's page lists controls it cannot work alongside unless an engineer removes them, including Honeywell SmartFit and the Vaillant VR 65 control centre, names several incompatible Worcester Bosch models, and offers a full refund within 14 days if the thermostat cannot be installed. tado says its X products are not compatible with its older V3+ range, so a V3+ home cannot mix in X devices.
Nest is not in the table. Google's Heat Link page for Europe covers the 3rd gen Learning Thermostat and the Thermostat E, and Google ended app support for the 1st and 2nd gen Learning Thermostats on 25 October 2025, offering eligible EU owners a discount on tado's latest thermostat. Wiser's kits sell through Drayton's own Wiser shop.
tado's Wireless Smart Thermostat X (2nd gen) kit is the all-round pick, handling combi, system and conventional boilers, and the 1st gen kit is the cheaper way into the same system. Hive's two kits split combi from cylinder homes, and tado's radiator trio adds room control.
| Product | Best for | Key specs | Price | |
|---|---|---|---|---|
 | tado Wireless Smart Thermostat X (2nd gen) Starter Kit Our pick | Combi, system and conventional boilers | Programmer X with hot water and OpenTherm, 2.4GHz WiFi | Check price → |
 | tado Wireless Smart Thermostat X (1st gen) Starter Kit Budget | The same tado X system for less, with a 1st gen sensor | Programmer with hot water and OpenTherm, 1st gen sensor | Check price → |
 | Hive Thermostat for Combi Boilers with Hub Combi boilers | OpenTherm combi boilers heating a single zone | 4 x AA thermostat, 230V receiver, Zigbee, hub included | Check price → |
 | Hive Thermostat for Conventional Boilers with Hub Hot water tanks | Conventional systems with a separate hot water tank | Hot water schedules and boost, 230V receiver, hub included | Check price → |
 | tado Smart Radiator Thermostat X Trio Pack Room control | Adding room-by-room control to a tado X system | Three valves, rechargeable battery, six adapters per pack | Check price → |