Are Smart Radiator Valves Worth It? Smart TRVs Explained (UK, 2026)

Smart radiator valves are often sold on the promise of big savings, but a 2018 evidence review warned that claims about heating controls are “often biased, unsubstantiated, misleading, or incorrect”. The independent evidence is more modest. Here’s what smart TRVs actually do, what the research says, which systems work with a combi boiler, and when they’re worth the money.

What does a smart TRV do?

A normal thermostatic radiator valve (TRV) controls one radiator. The Energy Saving Trust (EST) explains that “TRVs work by sensing the air temperature around them” and “if the room is warmer than the setting on the TRV, the valve will close a little.” They usually have a 0–6 scale.

A smart TRV replaces the head of that valve with a battery-powered motorised one that connects to a hub and an app. That means you can:

• set a different temperature and timetable for each room;
• change settings remotely if your plans change, which the EST lists as one advantage of smart controls;
• if the smart system also controls the boiler, have the valves call for heat so the boiler only fires when a room needs warming.

What does the evidence say?

In other words, room-by-room control can save gas, but in real homes the average saving is small, and how people use it matters a lot. If you use smart TRVs to heat more rooms for longer because it’s easy, your bills can go up.

Compared with ordinary TRVs

The EST says adding ordinary TRVs to a system that already has a programmer and thermostat can save £30 a year in Great Britain and £40 in Northern Ireland, and that installing and using heating controls effectively could save £100 a year in Great Britain (£110 in Northern Ireland). If you have no TRVs at all, fitting basic ones is the cheapest first step.

Should you turn radiators off in rooms you don’t use?

Turn them down, rather than off. The EST suggests setting TRVs at 3 to 4 in the rooms you use most, and 2 to 3 for bedrooms and rooms you use less. Which? says turning radiators in unoccupied rooms to low settings “will suffice most of the time”, because “a little water will move around them and help your boiler to condense, and it will prevent damage from damp and freezing.” Smart Energy GB suggests turning TRVs in “non-living” rooms down to the midway point. This is exactly the job smart TRVs are good at: keeping spare rooms low and warming them only when needed.

Do smart TRVs work with a combi boiler?

Usually, yes. Drayton sells Wiser kits “suitable for combi boilers” and others for conventional boilers, and Hive says it works with gas combi boilers, though not some Worcester models. Check the brand’s compatibility guide. What matters is how the boiler is switched:

• Boiler interlock. Viessmann explains that TRVs should be installed with a room thermostat to provide boiler interlock, so the boiler switches off when no room needs heat. With a combi, that’s usually done by the room thermostat.
• Let the smart system control the boiler. tado calls the setup where tado° controls the boiler and its smart radiator thermostats control each room “the recommended setup for maximizing savings”. It adds that rooms without a smart radiator thermostat “will receive heat when the boiler is turned on”, so it suggests setting their ordinary TRVs to frost protection.
• Valve threads. tado’s head fits M30 x 1.5 valves, and the main brands include adaptors for other types (Hive supplies M30, M28 and Danfoss RA). Hive says some older valve types need the valve body replacing.

When smart TRVs are worth it

• Rooms used at different times, such as spare bedrooms or a home office. In the 2022 trial, savings came mainly from lower bedroom temperatures, especially in the evenings.
• Changing plans, such as shift or hybrid working. The EST says “you can make changes remotely if your plans change”.
• You’ll set them up properly. The 2018 review found zonal controls save energy “when appropriately commissioned”.

They’re less worthwhile in small flats where every room is used, open-plan homes, or if you already keep TRVs low in unused rooms and rarely change them.

The smart TRVs we’d consider

Frequently asked questions

Sources

• Energy Saving Trust — Take control of your heating and Thermostats and heating controls
• Beizaee et al. (2015), Energy and Buildings — Measuring the potential of zonal space heating controls to reduce energy use in UK homes
• Lomas et al. (2022), Energy and Buildings — Energy savings from domestic zonal heating controls: robust evidence from a controlled field trial
• Lomas et al. (2018), Renewable and Sustainable Energy Reviews — Do domestic heating controls save energy? A review of the evidence
• Which? — Avoid this radiator mistake that can increase your bills
• Smart Energy GB — Radiator valves
• Viessmann — What is boiler interlock?
• tado — Heating control setup and Smart Radiator Thermostat X starter kit
• GOV.UK — Approved Document L, Volume 1 (PDF)
• Drayton — Wiser; Hive — Boiler compatibility
• Drayton — Wiser Radiator Thermostat; Hive — Hive Radiator Valve

Related reading: what temperature to set your thermostat in winter, does closing internal doors save on heating? and how to bleed a radiator properly.