How do smart radiator valves work, and are they worth it?
How do smart radiator valves work? They swap the numbered head on your radiator valve for a battery-powered one that you control from your phone. Each radiator can then hold its own room temperature, on its own schedule.
Here's what goes on inside one, what it needs to work, and when smart radiator valves are worth the money.
Quick answer: A smart radiator valve (also called a smart TRV or smart radiator thermostat) is a new head for your radiator's thermostatic valve. A sensor reads the room's temperature, and a small motor pushes the valve's pin in or lets it out. That lets less or more hot water into the radiator. You set the temperature and times in an app. It doesn't run your boiler: a timer, room thermostat or smart thermostat still does, and the radiator only warms while the heating is on. A compatible linked smart thermostat can ask for heat when it's needed.
How do smart radiator valves work? A sensor, a motor and an app
A smart radiator valve does the same job as an ordinary thermostatic radiator valve (TRV). It controls how much hot water flows into one radiator. The difference is what does the work.
- A temperature sensor in the head reads the air. Hive says its valves use an algorithm to estimate the temperature in the middle of the room, not just next to the radiator.
- A small motor moves the pin on top of the valve body. Pushing the pin in slows the hot water. Letting it out lets more through. Hive describes its motor as "ultra quiet".
- A radio links the valve to your app. Hive's valves use Zigbee (a low-power wireless standard for smart home kit) to talk to a Hive Hub. tado's X valves need a tado Bridge X, or a compatible Thread border router (a hub from another smart home system that speaks the same wireless language).
- Batteries power it all, so there's no wiring at the radiator.
You'll see them sold under lots of names: smart thermostatic radiator valves, smart TRVs, smart radiator thermostats, and wireless, Wi-Fi, digital or electronic radiator valves. Some shops call them digital radiator thermostats.
You choose a temperature in degrees, such as 19°C, and the valve keeps adjusting the flow to hold the room there. That target is the room's air temperature, not the radiator's.
Text version: how a smart radiator valve works. A TRV with a sensor, a motor and an app.
- You set a temperature: in the app, by voice, or on the valve itself.
- A hub may pass it on: for app control, many smart valves talk wirelessly to a hub on your router.
- The sensor checks the room: a sensor in the head reads the air temperature.
- A small motor moves the pin: pin pushed in, less hot water. Pin let out, more hot water.
- The radiator warms or cools: it can only get hot while the heating is on. A compatible linked thermostat can ask for heat.
Based on Hive and tado guidance. plumbworld.co.uk
Why a new smart valve needs time to calibrate
Every valve body is slightly different, so a smart head has to learn its own. tado says its valves find the points where the valve is fully open and fully closed, then store them. It calls this calibration.
Hive says calibration normally finishes within 24 hours while the heating is on. Until then, the radiator may warm up more slowly. Even once it's calibrated, a Hive valve can take 5 to 15 minutes to fully open after you change the temperature. That slow, steady movement saves battery and stops the room overshooting.
How do thermostatic radiator valves work without the smart part?
An ordinary TRV works on the same pin, with no motor or batteries. Its head (the part many people call a radiator thermostat) holds a wax, liquid or gas that expands as the room warms. That pushes the pin down and slows the hot water. As the room cools, the filling contracts and the pin lifts again.
So a standard TRV already turns itself down as the room warms, as the Energy Saving Trust explains. Its numbers are rough settings, though, not degrees. A "3" on one brand isn't the same as a "3" on another.
To turn a standard TRV up, turn the head to a higher number. On most manual valves, turn the control anticlockwise to open it and clockwise to close it, as Stelrad explains. Never try to turn or undo the valve body itself.
A manual valve has no sensor at all. It works like a tap and usually has no numbers. A smart head won't fit one, so you'd need a new thermostatic valve body first (more on that below). Our guide to what radiator valves you need explains all the types.
What smart radiator valves can do that a standard TRV can't
The big change is control. A numbered dial is a bit of a guessing game: you can't be sure which number gives the heat you want, especially in a new home or with new radiators. And if you want different heat at different times of day, you have to walk round and turn every radiator by hand.
With a smart valve, you set an exact temperature for each room and decide when it applies. For example, the Hive Smart Radiator Valve offers:
- Room-by-room schedules, so the spare room stays cool while the living room warms up for the evening.
- Remote control from your phone, whether you're home or out. Home later than planned? Change the settings from your phone instead of heating an empty house.
- Group control, to change several radiators with one tap.
- Open window detection, to turn the heat down when you open a window. Hive does this with its separate window sensors.
- A child lock, so little hands can't change the setting.
- Voice control through Amazon Alexa, Google Assistant or Siri Shortcuts.
- Heating history in the app, showing how quickly your home heats up and cools down. Hive's support page says Heating History is a Hive+ feature that also gives cost estimates, worked out from your heating activity and energy tariff. Check which views your own system includes.
You can still set the temperature on the valve itself, and many show it on a small display.
Do smart radiator valves need a hub, Wi-Fi or a smart thermostat?
Many need a hub. And to warm a radiator, they all need hot water from your heating. Check both before you buy. Also check the maker's advice on wireless range, especially for radiators far from the hub or router.
Hubs and bridges
Many smart valves connect to a small hub that plugs into your router. Hive's valves need a current Hive Hub or Hub 360, as the original Hive Hub 1 doesn't support them.
tado says its X system needs a Bridge X, though some other tado X devices can do the same job, and its valves can also join a compatible Thread border router. Some other makes connect straight to your Wi-Fi. Check whether the kit needs a hub, sometimes called a gateway, and whether it includes one.
Can a smart valve switch the boiler on?
Not by itself. Hive says its radiator valves don't talk directly to your boiler: your thermostat still controls it. Without a Hive thermostat, turning up a Hive valve only warms the room if the heating is already on.
Link the valves to a compatible smart thermostat, and that changes. With a Hive thermostat and Heat on Demand switched on in the app, a Hive valve that needs heat can turn the heating on. tado says its valves sync with its smart thermostat, so each room can ask for heat. Our smart thermostat guide explains those, and you can browse Plumbworld's smart heating range.
Safety: Hive's boiler receiver, which replaces a heating timer, is wired into the mains. Hive's installation guide says its receiver should only be fitted by an "electrically skilled person competent in the installation of electrical accessories", with the power isolated first. We'd have a registered electrician or a qualified heating engineer fit one. Gas work, such as installing, servicing or repairing a gas boiler, is a job for a Gas Safe registered engineer.
Smart thermostat or smart radiator valves: what's the difference?
They do different jobs, and many homes use both. A thermostat sits in one place, reads that room and tells the boiler when the home needs heat. A radiator valve, smart or standard, only sets how much hot water gets into its own radiator.
Text version: who controls what. Heating controls run the boiler. Valves trim each radiator.
- Heating controls switch the boiler: a timer, a room thermostat or a smart thermostat tells the boiler when the home needs heat.
- The boiler sends hot water to the radiators: each radiator can only warm up while the heating is on.
- Radiator valves set each radiator's flow: a standard TRV or a smart valve reads its room and lets more or less hot water in. A smart valve on its own can't switch the boiler on. Linked to a compatible smart thermostat, it can ask for heat.
Based on the BEIS Boiler Plus review, Hive and tado. plumbworld.co.uk
Boiler interlock and the rules in England
You still need a way to switch the boiler on and off. A government review of the Boiler Plus rules (BEIS, 2021) calls the wiring that switches the boiler off when there is no demand for heating or hot water the "boiler interlock". For a combi boiler, it says, a room thermostat provides it.
In England, the Boiler Plus rules have applied since April 2018. They say a new gas or oil boiler in an existing home needs time and temperature controls and boiler interlock. A new gas combi boiler in an existing home also needs one of four extra measures:
- Flue gas heat recovery reuses heat from the waste flue gases to preheat the cold water entering the boiler.
- Load compensation adjusts the boiler's output temperature to the heat the home needs.
- Weather compensation adjusts it for the weather outside.
- Smart controls means a smart thermostat with both automation and optimisation, or with load or weather compensation. Automation adjusts heating to a set programme or whether someone is home. Optimisation works out when to start heating so your home reaches the chosen temperature on time while using less energy.
Smart radiator valves aren't one of the four.
Approved Document L, the England guidance on the energy rules, says that when a boiler is replaced in an existing home, each room should have thermostatic room controls. It allows exceptions: two adjacent rooms with a similar use and similar heating needs can share a heating zone, and it recognises that room controls may not be technically feasible in some cases. A networked control on each radiator is one way to meet it. Our radiator valves buying guide has the details. Wales, Scotland and Northern Ireland have their own building rules, so ask your installer what applies where you live.
Do smart radiator valves work with a heat pump?
Ask your heat pump installer and the valve's maker before you buy. A heat pump runs more efficiently when it heats the water to a lower temperature. That outgoing water temperature is called the flow temperature. Valves that close change how much water flows round the system.
BEAMA, the heating controls trade body, has a report dated January 2026 on an Energy House test at the University of Salford. It used a Victorian solid-wall terrace inside a test chamber, with an air source heat pump.
Using traditional or smart TRVs to trim some rooms by 2 to 3°C cut space heating energy use by 6 to 8%, without a significant effect on the heat pump's efficiency.
The report advises lowering the flow temperature and setting whole-house setbacks through the heat pump's own controller first. A setback means a lower temperature overnight or while you're out. TRVs then trim individual rooms. In a separate test, smart TRVs on every radiator set the setback instead. That increased the heat pump's on and off cycling and cut its efficiency by 5%, so it made no energy saving.
The report also says a volumiser and an automatic bypass valve should be installed alongside the heat pump. A volumiser adds water volume. A bypass valve gives the water somewhere to flow when radiator valves close.
That was one test house and one heat pump, so it isn't a promise for yours. Our guide to radiators for heat pumps explains why heat pump radiators are sized differently.
Check your system's advice for the thermostat's room
Hive recommends not fitting its valves in the same room as your main thermostat. If the thermostat is set higher than the valve, the heating can stay on all the time. Danfoss gives the same advice for standard TRVs. Other systems differ: tado's own thermostat can measure the temperature for a tado valve in the same room. Some boiler makers go further. Worcester Bosch's instructions for its Greenstar Highflow, for example, say one radiator, in the room with the room thermostat, must be left without a TRV, uncontrolled and unrestricted. So follow your system's guidance, and check your boiler's instructions or ask your installer before you fit valves everywhere.
Will smart radiator valves fit my radiators?
Usually, if your radiators already have thermostatic valves. Look for a numbered dial on the valve. If it has one, it's a TRV, and a smart head can normally go straight on in its place.
- You need a thermostatic valve body. Hive says your radiators need TRVs before you can fit its valves, and tado's help pages say its smart heads don't work with manual valves. If you have manual valves, we recommend having a plumber or heating engineer fit thermostatic radiator valves first. Replacing a valve body means draining and refilling the heating. Only do it yourself if you're experienced in draining, refilling and repressurising your type of system, and the maker's instructions allow it.
- You may not need an adaptor. Many TRV bodies have a 30mm screw thread, known as M30 x 1.5. tado says it's the most common type, and its X valve screws straight onto most of them. Other bodies need an adaptor. Hive includes three in the box (M30, M28 and Danfoss RA).
- Some systems don't suit them. tado says its V3+ and earlier valves aren't compatible with single-pipe (one-pipe) heating systems. Hive says its valves won't work on electric radiators.
- Give the head some air. Hive says furniture pressed against a valve can make it read too high or too low. The Energy Saving Trust adds that radiator covers can trap warm air around a TRV.
Can I fit one in the bathroom?
Hive says yes, as long as the valve won't get wet. Its valves aren't waterproof, so keep them where they won't be splashed.
Fitting a smart radiator valve: usually a head swap
On a working thermostatic valve body, fitting a smart valve doesn't involve draining anything. You swap the head, and the water stays behind the valve body. Hive says its app walks you through it in around 10 to 20 minutes. In outline:
- Set up the app and hub first, if your valve's maker asks you to.
- Turn the old head to its highest setting, then remove it as its maker says. Many have a collar that unscrews by hand. Take off only the head: never undo the valve body or the pipe nuts.
- Check for drips. Hive says a few drops of water when the old head comes off may mean the valve body is leaking. Have a plumber look at it before you go on.
- Fit any adaptor your valve needs, following its maker's guide. Some adaptors screw on and others click into place. If you're not sure which one your radiator needs, check the installation guide or contact the maker.
- Fit and pair the smart head in the maker's order. Some apps ask you to register or pair it before you mount it. Others say to screw it on first. Then follow its maker's calibration instructions. Hive's valves need the heating on while they calibrate.
Our step-by-step guide on how to change a thermostatic radiator valve shows each stage, and when a job needs a professional.
What powers them: batteries, not wires
Smart valves run on batteries, and how long they last varies. Hive's valves take two AA alkaline batteries, and Hive says not to use lithium or rechargeable ones. tado's X valve has a rechargeable battery that charges over USB-C. tado says one charge lasts up to a year, and suggests charging it before each heating season.
Do smart radiator valves save money?
They can, when they stop you heating rooms you aren't using. How much depends on your home and how you heat it now.
In its heating controls guide (updated September 2026), the Energy Saving Trust says installing and using heating controls well could save around £100 a year in Great Britain (£110 in Northern Ireland). That's for heating controls in general, not smart valves alone. On smart controls, it says whether they save you money "will depend on how you currently control your heating".
A 2016 government review by Loughborough University found little robust evidence on what heating controls save. Its clearest result: room-by-room (zonal) control cut gas use by about 12%, compared with a system that met the building regulations. Those trials used full-size test houses with simulated occupants, not lived-in homes.
To get the most from them:
- Set a schedule for each room, so rooms heat only when you're likely to be in them.
- Close the doors of rooms you're not heating, as Hive suggests.
- Keep some background heat in rooms you rarely use. The Energy Saving Trust says this helps reduce the risk of condensation and mould.
What do smart radiator valves cost?
A smart head costs more than a standard TRV head, and prices vary by brand and pack size. Many systems also need a hub or bridge, so check what's in the box. Hive's valves need a current Hive Hub or Hub 360. As of 6 November 2026, Plumbworld's Hive Smart Radiator Valve page doesn't list a hub as included. Check before you order. See our smart radiator valves range for current prices.
If your radiators have manual valves, add the cost of having thermostatic valve bodies fitted first. Ask your heating engineer or plumber for a quote.
Are smart radiator valves worth it?
Smart radiator valves (smart TRVs) are most likely to be worth it if your rooms are used at different times. Room schedules can make you more comfortable and cut heating you don't need.
| Smart valves suit you if... | Think twice if... |
|---|---|
| Some rooms sit empty for much of the day | You heat every room the same, such as a small flat where every room is in use |
| You work from home in one room | Your radiators have manual valves, so budget for new valve bodies and any fitting costs |
| You come and go at odd hours | You have single-pipe heating, which some smart valves don't support |
| Your radiators already have TRVs | Your radiators are electric, which these valves don't work on |
What are the downsides of smart radiator valves?
They aren't right for every home, so weigh these up:
- They cost more than standard TRV heads, and some need a hub as well.
- Batteries need looking after. Hive's take two AA batteries. tado's X valve needs charging, up to a year between charges.
- They react slowly on purpose. A calibrated Hive valve can take 5 to 15 minutes to fully open.
- They don't run the boiler unless they're linked to a compatible smart thermostat.
- They don't suit every system. Manual valves, single-pipe heating and electric radiators all need a second look.
- Savings aren't guaranteed. They depend on how you heat your home now.
You don't have to do the whole house at once. Hive says a valve on just one radiator works fine for turning down a spare room. To make one room warmer than the rest, though, it says you need its valves on all your main radiators. Otherwise the radiators without one may warm up whenever the heating comes on.
Smart radiator valve FAQs
Do I need a smart TRV on every radiator?
No. Fit them where you want separate control. A radiator without one carries on as before, controlled by your main thermostat and its own dial. For full room-by-room control, follow your system's guidance on which radiators need one, including any in the thermostat's room. Some boilers need one radiator left open so water can keep flowing, so ask your installer before you fit valves on every radiator.
Can I control smart radiator valves with Alexa?
Many work with voice assistants. Hive's valves, for example, work with Amazon Alexa, Google Assistant, Siri Shortcuts and IFTTT. Check the product page before you buy.
Why is my radiator still cold after fitting a smart valve?
First, check the heating is on, because a smart valve can't warm a radiator otherwise. Then give it time: a new valve may still be calibrating. If it still isn't working, go back through the maker's instructions, or contact the maker.
If it shows an error, the valve's pin may be stuck. tado says limescale can block the pin, and suggests moving it in and out to free it. Our guide on how to check and maintain radiators shows how to free a stuck valve pin.
Start with the room you heat for nothing
Fit one where it makes the biggest difference first, such as a spare room or a home office, and see how you get on. If your radiators already have thermostatic valves, it's usually a quick head swap.
Browse Plumbworld's smart radiator valves, including the Hive Smart Radiator Valve.
You might also like:
- What radiator valves do I need? A guide to types and sizes
- How to change a thermostatic radiator valve, step by step
- Smart thermostat guide
- How to make central heating more efficient
- Boiler maintenance tips and heating checks for autumn
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