Smart thermostats for radiators: which need a hub and which use Wi-Fi
Smart thermostat sets under €250
A radiator knob is one of the few things in a home that nobody thinks about until the heating bill lands. Numbered one to five, it holds a room at one rough temperature all day. The only way to change its mind is to walk over and turn it. A smart thermostat takes the place of that knob, or of the box on the wall behind it, and gives every room a plan for the day.
Two different products are sold under the same two words. One kind of smart thermostat screws onto the radiator and rules a single room. The other hangs on the wall, wired to the boiler or to a water-based underfloor loop, and tells the whole system when to fire. A house often ends up with both, and the order they are bought in decides how much the second buy costs. Then comes the next fork: some smart thermostats need a hub before they work at all, and others are happy with the router that is already in the flat.
This smart thermostat comparison lines up four sets on equal terms: the tado° Smart Radiator Thermostat X in its trio pack, the tado° Smart Thermostat X starter kit for boilers and underfloor heating, four SONOFF Zigbee thermostats for a Home Assistant house, and three SALCAR thermostats that join plain Wi-Fi with no gateway at all. In most stores each set stays under $280, and the group sits near $170. The figures come from the listings and the views from owners. The per-store prices sit in the cards.
Models in this comparison
Typical price across these models: about €169. Rough figures from store prices converted at fixed rates: what you pay also depends on the store and the region you order from. With our browser extension you can compare every Amazon store at once, right on the product page.
tado° Radiator Thermostat X trio pack: three radiators in one box
tado ° Smart Radiator Thermostat X - Trio Pack, Heating Control via App and Smart Speaker (Alexa, Siri, Google Assistant), Energy Saving, DIY Installation, Not Compatible with tado° V3+
ASIN: B0CWPDXWHP
- ✓Three radiator thermostats in one box, with an adapter set for each
- ✓Thread and Matter, so the thermostats join a smart home beyond the maker's app
- ✓Rechargeable cells in the box, instead of fresh AAs twice a winter
- ✓A backlit touchscreen on each thermostat, plus Alexa, Siri and Google
- ✓Fitted by hand: old head off, new thermostat on, paper template supplied
- Units in the box
- 3 thermostats, 3 adapter sets
- Connectivity
- Thread, Matter
- Voice control
- Alexa, Siri, Google Assistant
- Power
- 3 rechargeable lithium-ion cells, included
- Display
- Touchscreen, backlit
- Voltage
- 24 V
- Size
- 4.9 x 6.7 x 6.7 cm
- Fits
- Not tado° V3+ or older
Three thermostats in one box is the practical part of this offer. A flat with a living room, a bedroom and a study is covered in one order, and the same smart thermostat is sold singly for the fourth radiator later. Each thermostat has a backlit touchscreen and rechargeable cells in the box. Each speaks Thread and Matter rather than a closed protocol, which is why it answers to Alexa, Siri or Google.
Two lines in the listing matter more than any feature. The trio pack holds three thermostats and no bridge, so a Thread border router has to be in the house already. The X range does not talk to tado° V3+ or older kit, so an owner of the old range starts again rather than adds on. The 4.3 average from 3,661 ratings is the longest record here by a wide margin.
These thermostats suit a flat with several radiators, where heat is worth splitting room by room and a Matter hub or a smart speaker is already plugged in. Skip these thermostats if the radiators still carry old-style valve bodies, and skip them too if the house runs tado° V3+ kit that would have to go.
Fitting comes first in the reviews, and nobody struggles. A German owner took the old heads off, screwed the new thermostats on, opened the app and paired them in under five minutes per radiator. An Italian buyer set the whole trio up in less than half an hour by following the steps in the app.
The daily gain owners name is room-by-room control. Buyers in Germany, Italy and France give each room its own plan: the heat drops on its own when the house is empty, and goes back up from a phone when they leave work early. Several report that the thermostats spot an open window and stop heating the street, and one says they read room damp as well as heat. Owners call the link stable, the updates painless and the thermostats quiet enough to forget. More than one buyer writes that the heating bill fell after a winter of this.
The gripes are few but concrete, since every recent review here carries five stars while the average of all 3,661 sits at 4.3. A Dutch owner gives the warning worth reading twice: these thermostats screw onto thermostatic valve bodies, and on a plain old valve they will not work at all. The listing adds two more: no bridge in the box, and no link to the older tado° range. The printed manual may not be in English either.
Pros
- Three radiators covered in one order, at a lower cost per room than singles
- Each thermostat is fitted in minutes, with no tools beyond a hand
- Room-by-room plans that owners say cut the heating bill over a winter
- Away-from-home and open-window sensing, with no sensors on the frames
- Thread and Matter, so heat sits in the same app as the rest of the house
- Rechargeable cells in the box, and a touchscreen on every thermostat
Cons
- No bridge in the trio pack: a Thread border router must already be there
- Nothing here works with tado° V3+ or older, so a move up means starting again
- Old-style valve bodies have to be swapped first, as one owner found
- The dearest route per room to the same room-by-room control
- Parts of the app are held back for a paid plan
- The supplied manual may not be in English
Thread, Zigbee or Wi-Fi: how a smart thermostat takes its orders
Every smart thermostat here is driven from a phone, but the road between the two differs, and it decides what else has to be bought.
The tado° thermostats speak Thread and Matter. Thread is a low-power mesh in which each mains-powered device passes messages along, and Matter is the shared language that lets an Apple, Google or Amazon home read the thermostat with no brand plug-in. The catch is the border router: something in the house must join Thread to the network. The starter kit holds the Bridge X for that reason, and one German owner reports that an Apple HomePod mini does the same job. The trio pack holds no such device, which is why buying those thermostats first is a mistake.
SONOFF takes the Zigbee route. Zigbee is also a mesh and also easy on batteries. These thermostats work with Home Assistant through Zigbee2MQTT, and two German owners had them found at once. But a Zigbee 3.0 hub is a must, and a British owner notes that the USB dongle it usually means is fine if you own one and a fresh cost if you do not. Zigbee's name as a shared standard has limits too: a Dutch buyer could not get these thermostats to join a Lidl Silvercrest network, and felt pushed towards the maker's own hub.
SALCAR skips the hub question. Each thermostat joins 2.4 GHz Wi-Fi on its own and answers the Tuya Smart Life app, with Alexa and Google following through the linked account. Owners name this as the reason they bought these thermostats. The price is paid elsewhere. Every thermostat holds its own link to the router, the phone has to sit on the 2.4 GHz band during setup, and one owner had a thermostat drop off the network after a year and refuse to rejoin.
Valves, adapters and batteries: what fitting a smart thermostat needs
None of these smart thermostats needs a plumber, but each asks something of the radiator. They are all made for the standard thermostatic valve body, and SONOFF names the M30 x 1.5 thread. Each set brings adapters for older shapes: RA, RAV, RAVL, Caleffi, Giacomini and M28. SALCAR ships eighteen adapters with three thermostats, and SONOFF a similar spread with four. Owners who needed none of them still count them as a plus. The one buyer who could not fit the tado° thermostats had plain valve bodies rather than thermostatic ones. That check is worth doing before ordering anything in this class.
Power is the quieter difference. The trio pack runs on rechargeable lithium cells and ships with them, and the wall thermostat takes six AAA cells. The SONOFF and SALCAR thermostats both use plain alkaline ones. That last pair is where the reviews part company. A SONOFF owner with ten thermostats reports 95 to 99 per cent of charge left after months of use with good cells. A SALCAR owner with nineteen thermostats gave them one star after nearly a year: plain cells lasted about a fortnight, rechargeables no longer, high-capacity ones one to two months, and support offered only a firmware update. Another SALCAR buyer with five thermostats saw four per cent used in two months and could not repeat the fault. The gap likely comes down to how hard each plan drives the motor.
Noise gets a mention too. A British owner calls the SONOFF thermostats a little louder than he expected, then adds that he hears them two or three times a day in winter, while the tado° thermostats are described as quiet.
tado° Smart Thermostat X starter kit: the one that talks to the boiler
This is the other half of the same system, and in most houses the half to buy first. Rather than sit on a radiator, this smart thermostat takes over the wired room thermostat on the wall, and from there it runs a gas boiler over OpenTherm or a relay, a heat pump, or a water-based underfloor loop. The Bridge X is in the box, which makes this the only product here that brings its own Thread border router, the piece the trio pack takes for granted.
Owners describe a longer job than screwing a thermostat onto a radiator, and a well-guided one. A British buyer had the system running in about forty-five minutes and praises steps that covered every kind of older thermostat with wiring diagrams. A German owner with an old boiler was unsure it would fit, and found the setup helper enough. Two features get named again and again: several people can share the app, which one buyer uses to manage heat for an elderly relative, and a Dutch owner found the app pointed at a fault clearly enough to show the landlord and the engineer. The complaints are just as concrete. The app holds back holiday mode and long-term energy history behind a paid plan, so without it that Dutch owner sees detail for 24 hours only. One German buyer also found that OpenTherm on the box did not mean his Buderus control unit was covered.
tado° Smart Thermostat X - Starter Kit for Underfloor Heating & Boilers | Control via app, smart speaker compatible (Alexa, Siri, Google Assistant), DIY installation
ASIN: B0CWPHCWK6
- ✓Bridge X in the box, so the Thread network other thermostats need is set up
- ✓For OpenTherm and relay gas boilers, heat pumps and wired underfloor heating
- ✓Plans, geofencing and open-window sensing with no window sensors
- ✓A 104 mm LCD that can be set by hand on the wall as well as from the app
- ✓Money back within the first year if the thermostat does not suit the house
- Units in the box
- Thermostat X, Bridge X, 6 AAA cells, mounts
- Controls
- Gas boiler, heat pump, underfloor heating
- Boiler link
- OpenTherm or relay
- Connectivity
- Thread, Matter
- Display
- LCD, 104 mm, backlit
- Power
- 6 AAA cells, included
- Size
- 104 x 18 x 104 mm
- Fits
- Not tado° V3+ or older
Pros
- The Bridge X is in the box, so no other Thread device has to be bought
- Wiring steps that a British owner says covered every kind of older thermostat
- Runs a gas boiler, a heat pump or a water-based underfloor loop
- Several people can share the app, which one buyer uses for an elderly relative
- The app named a heating fault clearly enough to show a landlord and an engineer
Cons
- Holiday mode and long-term energy history sit behind a paid plan
- Without that plan the energy detail covers the last 24 hours only
- OpenTherm on the box did not cover one owner's Buderus control unit
- One thermostat only: the radiators still need their own valve heads
- A wiring job rather than a five-minute swap
SONOFF TRVZB: a Zigbee radiator thermostat for a Home Assistant house
Four thermostats in one box makes this the largest set here, and the one that assumes the most about its buyer. There is no Wi-Fi and no Bluetooth, a Zigbee 3.0 hub is required, and the listing names the maker's own dongles, bridges and panels. What that buys is the openness keen users want: Zigbee2MQTT, Home Assistant, six months of energy history, group control and plans in the eWeLink app.
The reviews split neatly by household. Owners already on Zigbee are delighted. The thermostats were found at once in Home Assistant and paired with the maker's own heat sensors as outside probes, and one German buyer who owns ten of these thermostats calls them the best value in this class. A British owner adds useful detail: each thermostat reads a little off until an offset is set in Home Assistant, the heads feel flimsy until they are tightened onto the valve, and control through Home Assistant brings HomeKit and Siri along, with some know-how. The other half of the reviews is the warning. A Dutch buyer could not join these thermostats to an existing Lidl Zigbee system at all, and a German owner found the app cluttered and was cross that setup wants a 2.4 GHz network. Buy these thermostats for a house that already has a Zigbee hub, and skip them if the plan was to avoid one.
SONOFF TRVZB Zigbee Smart Heating Thermostat, Pack of 4, Smart Radiator Thermostat, Energy Saving, Schedule, Smart Thermostat, Compatible with Alexa/Google Home/Home Assistant, Requires Zigbee 3.0 Hub
ASIN: B0CL9K8Y69
- ✓Four radiator thermostats in one box, the largest set in this comparison
- ✓Home Assistant through Zigbee2MQTT, plus Alexa and Google Home
- ✓Six months of heating history to read by day, week or month
- ✓Fits the M30 x 1.5 thread, with RA, RAV, RAVL, Caleffi, Giacomini and M28 adapters
- ✓Plans, group control and an auto shut-off when a window opens
- Units in the box
- 4 thermostats plus valve adapters
- Connectivity
- Zigbee 3.0, hub required
- Voice control
- Alexa, Google Home, Home Assistant
- Power
- Battery, 4.5 V
- Display
- LCD, backlit
- Valve thread
- M30 x 1.5 mm
- History
- Up to 6 months
- Weight
- 154 g per thermostat
Pros
- Four thermostats in one box, the largest radiator thermostat set here
- Found at once in Home Assistant through Zigbee2MQTT, two German owners report
- Pairs with the maker's own heat sensors as outside probes
- Six months of heating history in the app, with no plan to pay for
- Called the best value in this class by an owner running ten of them
Cons
- A Zigbee 3.0 hub is required and is not in the box
- Would not join a Lidl Silvercrest Zigbee network at all, one Dutch buyer found
- Each head reads a little off until an offset is set
- The heads feel flimsy until they are tightened onto the valve
- A little louder than one British owner expected
- One German owner calls the app cluttered and dislikes the 2.4 GHz requirement
SALCAR TRV801W: a smart thermostat without a hub
This set answers the question that stops most people buying into smart heat: what else must I buy? Nothing. Each thermostat joins 2.4 GHz Wi-Fi on its own and the Tuya Smart Life app takes over, with Alexa and Google following from the linked account. Three thermostats, eighteen adapters and nine AA cells come in the box, and the screen sits on the housing rather than on the valve body, which owners say makes it easier to read on a radiator under a window sill.
Buyers praise the same three things: setup in minutes, no gateway, and a clear screen. Window sensing, a boost button, frost guard, a child lock and four modes all get named in use rather than in theory. Service earns rare credit too: an Italian owner whose thermostat dropped off the network after a year was sent a new thermostat without asking. The battery question is the reason to think twice. One owner with nineteen thermostats reports two-week cell life that no brand fixed, and support that offered only a firmware update, while another with five saw almost no drain in two months but drives them by hand rather than on a plan. A third owner is happy with the thermostats and unhappy with how sharply the asking price has moved.
SALCAR Smart Home Radiator Thermostat TRV801W Set of 3 WiFi Thermostat Compatible with Amazon Alexa & Google Assistant Programmable Tuya Heating Thermostat, No Gateway Required
ASIN: B0CDZLMDGC
- ✓Each thermostat joins 2.4 GHz Wi-Fi on its own, with no gateway or hub to buy
- ✓Three thermostats, eighteen valve adapters and nine cells in the box
- ✓The screen sits on the housing rather than the valve body, so it stays readable
- ✓Window sensing, boost, frost and limescale guard, and a child lock
- ✓Auto, manual, comfort and energy modes in the Tuya Smart Life app
- Units in the box
- 3 thermostats, 18 adapters, 9 cells
- Connectivity
- Wi-Fi 2.4 GHz, no gateway
- App
- Tuya Smart Life
- Voice control
- Alexa, Google Assistant
- Power
- 3 x 1.5 V AA per thermostat
- Display
- LCD on the housing, backlit
- Adapters
- RA, RAV, RAVL, Caleffi, Giacomini, M28
- Extras
- Child lock, frost and limescale guard
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Pros
- Nothing else to buy: each thermostat joins 2.4 GHz Wi-Fi by itself
- Owners report setup in minutes, adapters and cells already in the box
- A screen on the housing that stays readable on a radiator under a sill
- Window sensing, boost, frost guard and a child lock, all named in daily use
- An Italian owner was sent a replacement thermostat without having to ask
Cons
- Battery life splits the reviews: one owner of nineteen changed cells every fortnight
- Support answered that battery complaint with a firmware update only
- The phone has to sit on the 2.4 GHz band during setup
- One thermostat dropped off the network after a year and would not rejoin
- Buyers report the asking price moving sharply since launch
Four smart thermostats side by side
The figures behind these four smart thermostats fit in one table, where the trade-offs show faster than in any paragraph.
| Parameter | tado° X trio pack | tado° Thermostat X kit | SONOFF TRVZB | SALCAR TRV801W |
|---|---|---|---|---|
| Units in the box | 3 | 1 plus Bridge X | 4 | 3 |
| What it controls | Radiator valves | Boiler, heat pump, underfloor | Radiator valves | Radiator valves |
| Connection | Thread, Matter | Thread, Matter | Zigbee 3.0 | Wi-Fi 2.4 GHz |
| Hub needed | Yes, not included | Included | Yes, not included | No |
| Voice control | Alexa, Siri, Google | Alexa, Siri, Google | Alexa, Google, Home Assistant | Alexa, Google |
| Power | Rechargeable lithium | 6 AAA | Battery, 4.5 V | 3 AA per thermostat |
| Display | Touchscreen | LCD, 104 mm | LCD | LCD on the housing |
| Heating history | In the app | 24 hours free, more on a plan | Up to 6 months | In the app |
| Customer rating | 4.3 (3,661) | 4.2 (636) | 4.2 (531) | 4.2 (1,426) |
Read the last row with the third in mind. All four averages land within a tenth of each other, but they rest on very different ground: 3,661 ratings for the trio pack against 531 for the SONOFF thermostats. A high average on a thin listing tells you the first buyers were pleased, which is not the same as knowing how a smart thermostat behaves in its third winter.
What the apps give away and what they charge for
Two of these smart thermostats are sold outright and driven for free. Both tado° sets are the exception, and the reviews agree on where the line falls: basic control, plans and app use cost nothing, while the AI-Assist plan adds holiday mode, open-window rules and long-term energy insight for a monthly or yearly fee. One German owner runs the wall thermostat without the plan and says the basics are enough. Another docked a star because holiday mode sits behind it, and a Dutch buyer sees energy history for a day at a time only. Nobody reports the heat stopping without a plan: the thermostat keeps working, and it is the analysis that goes.
The two other smart thermostats charge nothing for their apps. A SONOFF thermostat keeps six months of heating history for free, and a SALCAR thermostat gives its plans, modes and window sensing in the Tuya app for nothing beyond the price of the thermostat itself. That is worth adding to the sum before the sets are compared, since a monthly fee outlives the box it came in.
Frequently asked questions
- Do I need a hub for a smart thermostat?
- It depends on the radio. The SALCAR thermostats join 2.4 GHz Wi-Fi on their own, while the SONOFF thermostats are Zigbee and want a Zigbee 3.0 hub. The tado° X range uses Thread and needs a border router: the starter kit brings the Bridge X, the trio pack does not, though one owner reports an Apple HomePod mini doing the job.
- Will these thermostats fit my radiators?
- They are made for standard thermostatic valve bodies, and SONOFF names the M30 x 1.5 thread. Adapters for RA, RAV, RAVL, Caleffi, Giacomini and M28 valves come with the SONOFF and SALCAR thermostats. The one owner who could not fit a thermostat had plain valves, so check the valve body before you order.
- What is the difference between a radiator thermostat and a wall one?
- A radiator thermostat takes the place of the knob on one radiator and rules that room only. A wall thermostat switches the boiler, heat pump or underfloor loop for the whole system. The two work together: the wall thermostat decides when heat is made, and the radiator thermostats decide which rooms get it.
- How long do the batteries last?
- Reports vary widely and depend on how hard the plan drives the motor. A SONOFF owner with ten thermostats saw 95 to 99 per cent of charge left after months. Among SALCAR owners, one with five lost four per cent in two months, while another with nineteen changed cells every fortnight. The trio pack ships rechargeable cells and steps around the argument.
- Can I add tado° X thermostats to an older tado° system?
- No. Both X listings state plainly that these thermostats do not work with tado° V3+ or older. A tado° household is therefore replacing its kit rather than adding to it, which is worth costing before the first box is opened.
Verdict
Every model on the same criteria
Score against price
- tado° X trio pack4.3 at about €246
- tado° X starter kit4.1 at about €165
- SONOFF TRVZB4.2 at about €122
- SALCAR TRV801W4.0 at about €142
The overall score divided by the typical price, with the best in the group as the full bar. A rough guide, not a verdict — a cheap model that misses the feature you need is no bargain.
Read the bars as trade-offs, not as a ranking, because no set here wins every row. The two tado° products score alike and answer different questions: one splits the heat between rooms, the other decides when the boiler runs at all, and a house that wants both needs the bridge before the radiator heads. The SONOFF thermostats give the most units per box and the freest app, and ask for a Zigbee hub in return. The SALCAR set is the only one that works out of the box with nothing else bought, and the only one whose battery reports contradict each other so sharply.
So the choice is settled by two things that exist before any box is opened: the radio already running in the house, and the valve body on the radiator. Answer those, and usually only one of these four sets is still standing.