Smart Thermostats near you

Anything with an app gets called smart, so it helps to separate the functions and buy the ones you will use. Approved Document L's own definitions are a useful yardstick: automation is a control function that automatically adjusts time and temperature settings based on occupancy detection and/or stored data from user adjustments over time. That is an adaptive control, not a remote control. Weather compensation is defined as a system that varies the operating flow temperature of the heating system, with an external sensor communicating with one inside the boiler. Load compensation is defined as a control function that maintains internal temperature by varying the flow temperature from the heat generator relative to the measured response of the heating system.

The single most common disappointment here is buying a control the system cannot use. A combination boiler with a single thermostat and no cylinder is a different proposition from a system boiler with a hot water cylinder, motorised valves and a wiring centre in the airing cupboard. The control you can fit has to match the number of channels the system needs: space heating, hot water, and however many zones exist.

The connection between the control and the boiler matters as much as the app. A simple on-off connection tells the boiler only to run or stop. A communicating connection lets the control and the boiler exchange information so the boiler can modulate its output and its flow temperature, which is the mechanism behind load compensation as Approved Document L defines it. If a quote promises compensation, ask which of these it is using, because the same thermostat can do either depending on how it is wired.

Physically, the choice is usually between a wired thermostat replacing an existing one on the same backplate, a wireless control with a receiver near the boiler, and a control that needs a permanent supply where the old one had none. Solid walls, thick plaster and a house with no convenient cable route are the usual reasons an installer recommends wireless. Under the Building Regulations in England, this sort of work is generally not notifiable: Approved Document P sets out that notice is needed for a new circuit, a consumer unit replacement, or an addition or alteration in a special location, and a thermostat in a hallway is none of those. Work inside a gas appliance is a different matter and belongs to a registered gas engineer.

People often treat smart controls as an optional extra, when in fact replacing the heat generator triggers control requirements in their own right. Approved Document L Volume 1 provides that for heating systems in new dwellings, or when a heat generator such as a boiler is replaced in an existing dwelling, each room should be provided with thermostatic room controls capable of separately adapting the heating output in each room served by the appliance, with zone control instead of room control only where that is justified, for example in a single-storey open-plan dwelling where the living area is more than 70% of the total floor area, or for two adjacent rooms with a similar function such as a kitchen and a utility room.

Crucially, the approved document sets out more than one way to satisfy that. It may be met by a thermostat in a room the circuit serves plus individual thermostatic room control on every heat emitter outside that room, noting that thermostatic radiator valves should not be used in the same room as the thermostat; or by an individual room or zone thermostat for each room or zone; or by an individual networked heat emitter control for each emitter. That last route is the one smart radiator controls occupy, and it is worth knowing that the guidance already anticipates it.

Other requirements travel with the same job: work on a system that includes a boiler should have a boiler interlock installed, a replacement hot water cylinder should have electronic temperature control such as a cylinder thermostat, and domestic hot water and space heating should have separate time controls unless they were already controlled together. For heat pumps the guidance is that external controls should include weather compensation or internal temperature control, and a timer or programmer for space heating. A 2026 edition of Approved Document L has been published and carries similar per-room control provisions, and it states that it takes effect on 24 March 2027 in England for building work not connected with higher-risk building work, so the 2021 edition incorporating the 2023 amendments is the one currently in play. Wales, Scotland and Northern Ireland have their own building regulations and their own guidance documents.

These are not competing products so much as different layers, and the right order depends on what your house actually does wrong. A single smart thermostat helps a house that is heated as one space and wastes energy on empty hours. Smart radiator controls help a house where different rooms are used at very different times. Compensation helps any wet system that has been running at a needlessly high flow temperature, which in Britain is a great many of them.

A control decides when and how hard the heating runs. It cannot change how much heat the house loses, how well the system distributes it, or whether the radiators were sized for the flow temperature they are now being asked to run at. A smart thermostat on an unbalanced system produces the same cold back bedroom as the old one did, just with better graphs.

Placement causes more complaints than firmware. A thermostat in a hallway with the front door opening onto it, in a draught, above a radiator, in direct sun, or in the one room nobody occupies will control the house to the wrong number. The guidance's own point about not fitting a thermostatic radiator valve in the room containing the thermostat is the same idea: two controls fighting over one room's temperature is a recipe for a house that never settles.

And there are things that are simply not the thermostat's job. Cold rooms at the end of a long circuit, a boiler short-cycling, hot water that runs out, a system that clanks: those are system faults to be diagnosed by a heating engineer. Fitting a smart control first and diagnosing afterwards is a common and expensive order of operations.

A smart thermostat is a connected consumer product, and in the UK that now carries statutory obligations on the people who sell it. Under the product security regime that came into effect on 29 April 2024, manufacturers of relevant connectable products must publish information on minimum security update periods, including the minimum length of time security updates will be provided along with an end date, in clear and accessible language. There are also requirements around unique or user-definable passwords and a way to report security issues with expected response timescales.

So before you buy, look for that support end date. It is public by law, it tells you how long the product will be maintained, and it is the single most useful specification on the box for something that will be screwed to your wall for a decade. Then do the unglamorous admin: use a password that is not the default, set up the account in the householder's name rather than the installer's, and write down which account controls the heating.

Think about what happens when the connection does not. A sensible control still runs its schedule with the internet down and can be operated from the wall. Ask the installer to show you how to run the heating manually, and to leave the system's own documentation, including the boiler's commissioning paperwork, with the house.

The British heating season is long, mild and damp rather than short and severe, which changes what a smart control is good for. Most of the year the house is being held at a comfortable temperature against a modest outdoor difference, so small, steady improvements in flow temperature and run time matter more than dramatic setbacks.