How does smart heating work?

Nest Learning Thermostat on wall showing current temperature

Smart heating replaces your old manual thermostat with automated smart controls allowing you to control your heating from an app or host of other devices.

The good news is that you can upgrade to smart heating control without any need to change your boiler or plumbing. With the right system you can even control temperature room by room.

Smart heating control will save energy and make you more comfortable. There is a perfect win-win for you and the planet.

This article will give you a good introduction to smart heating control, how it works, the types, what you need and the benefits of it.

What does smart heating do that your old thermostat doesn't?

Let's get some basic jargon out of the way.

A thermostat regulates the temperature of your home. It measures the temperature of the surrounding area and sends a signal to your boiler to either turn on or off. Most homes have 1 or 2 like in the picture below. You turn the dial to your target temperature. You will know that when turning the dial you get a click - that tells you the temperature of your room.

A smart thermostat automates all the things your old analogue thermostat does now:

    • Setting temperature 
    • Running heating schedules
    • Telling your boiler to turn heat (and hot water) on and off

But smart heating control can automate a lot more things that you probably hadn't even thought of or couldn't do.

    • Learning how long your home/rooms take to heat up an adjusting timings accordingly.
    • Varying the temperature according to outside weather.
    • Adapting heating turn off times.
    • Switching off when you’re not there.
    • Enable you to contorl your boiler remotely from your mobile phone for instance.
    • Learning your schedules and creating its own heating programs
    • Detecting moisture and movement.

And much more that would make this list too long.

What are the different types of smart heating control?

We go into this in a lot more detail below but there are basically 2 different types of smart heating control for residential homes in UK.

  1. Single Zone. A Smart Thermostat which simply replaces your existing thermostat
  2. Multi Zone. More sophisticated room by room smart heating control system which adds control to your radiators and rooms.

We will talk about single and multi-zone heating later but suffice to say that both will work with your current plumbing without any major changes.

Why upgrade to a smart thermostat?

Your old thermostat and programme timer probably work ok.

What’s more you know how they work. It’s simple to turn the dial up and get the satisfying click followed by the boiler firing up.

The programs are probably a thing you set up ages ago and the only changes you make is press the +1-hour option and “off” when you go on holiday.

So, why should you change?


Analogue Thermostat

Benefits of smart heating control.

1: Smart Heating cuts energy waste and saves money.

No matter how assiduous you are in setting schedules and temperature to match what you want, you will always get it wrong.

Smart Heating Control or a smart thermostat takes the guesswork out of heating control and eliminates a lot of energy waste.

Did you know?

In the UK, 62% of your energy is used for heating, 17% for hot water, 18% for lights and 3% for cooking.*

On average we use 18,000 kWh of gas per year to heat our homes (The range is 5-30,000 kWh depending on size).

This is not only expensive but has a big impact on your CO2 emissions. 18,000 kWh of gas represents about 3.5 tonnes of CO2. You'd need about 166 trees to absorb that each year.


a single zone thermostat can cut 15% off your heating energy, a multi-zone system can reduce your heating by as much as 40%.

* source: Eurostat 2016

There are a lot of claims from different manufacturers about the amount energy savings from installing smart thermostats.

What is clear is that smart heating control can definitely cut your energy usage and save you money.

Nest 3rd Generation Smart Thermostat has the most installs and they have aggregated data from all the smart thermostats installed by country and have come up with different estimates based on 2 scenarios:

  1. Homes heating at 20C all day and night
  2. Homes at 20C all day turning down to 9C for 7 hours at night

Their estimate on savings is between 8.4%-16.5% for the UK. You can read more about how they calculated that here.

We think that this is the most realistic estimate of the many single zone thermostat manufacturers.

Multi-zone heating control will save you more money than any other smart thermostat.

That’s because with multi-zone you’re not wasting energy heating empty rooms.

Honeywell Evohome can save you up to 40% on your heating energy usage. Honeywell back this up with some academic research (DECC report) but probably even more convincing are the pages and pages of reviews on forums from very satisfied customers who rave about the savings they have made.

2: Smart Thermostats give you more control

Smart heating gives you more control over your heating.

The smart bit means that your thermostat system is packed with intelligent controls that adjust to things like the weather, the efficiency of your exsiting heating system, your movement etc.

This means that you get heat when you want it - not before or after.

Smart control will save you money, give you more control and make you more comfortable. 

Because it’s connected to the internet it means it can be controlled from anywhere with a range of different devices.

On holiday and forgotten to turn off the heating? Hop on your phone app.

Staying up late with friends? Ask Alexa to keep the heating on a bit longer.

If you go for a multi-zone system like Honeywell evohome, it means you can set each room individually.

There’s something quite satisfying asking Alexa to turn the study temperature up to 20C without getting up from your chair.

Honeywell Evohome app controls heating room by room

3: Smart heating control will make you more comfortable.

Multi-zone smart heating control has the power to transform your existing heating to allow you to control temperature room by room.

Many people have rooms that are colder than others. Their answer is turn up the old thermostat to get that room warm but end up making all the others too hot in the process.

Multi-zone smart heating control like Evohome allows you to set the temperature room by room. Once it reaches the desired temperature it stays there until you want to to change it.

Even a smart single zone thermostat like the Nest 3rdGeneration Learning Thermostat uses a range of different sensors and information to ensure that the temperature is just right at the right time. No more waiting for the house to heat up or turning the heating down because it’s too hot.

Smart heating takes the guesswork out heating control.

Single Zone v Multi-Zone Smart Heating

We've talked about single-zone and multi-zone smart heating without fully explaining how it works. Let's try here:

There are essentially 3 different types of smart heating (for UK homes).

  1. Single Zone heating with a single thermostat controlling the whole house.
  2. "Multiple Single Zone" where you already have a number of plumbed in heating circuits each controlled by a thermostat.
  3. Multi-Zone which retrofits on to a single zone thermostat and automates radiators to create multiple zones.

You will find that most people talk about just 2 types: single zone and multi zone. We have added the second category as we have a lot of customers that fall in this category.

But there are a myriad of combinations especially if you have underfloor heating in some rooms and depending on what you want to control.

The good news is that this smart heating control retrofits onto your existing heating without the need for expensive and disruptive plumbing changes.

1. Single zone smart thermostats

Nest Learning Thermostat with Black Ring

Single zone is a heating area or zone consisting of a single heating circuit controlled by one thermostat.

If you have one thermostat for your whole house (usually in the hall) you have single zone.

Your boiler will heat water and pump it round a loop with radiators in your rooms.

Single zone thermostats set a target temperature for the whole house or zone they're managing.

Radiators with TRVs (Thermostatic radiator valves) help regulate temperature variations in your rooms. Some radiators might have manual valves which basically turn on or off with no degree of temperature control.

The downside of this system is that when the thermostat hits its target temperature the radiators all turn off even though you might still be cold. So, you might be cosy in the hall but not the living room.

Replacing your old thermostat with a smart single-zone thermostat like the Nest 3rd Generation Learning thermostat is the simplest and most cost-effective option.

You will still have a single zone but will gain impressive control and benefits.

You can more learn about Nest Smart Thermostats by clicking here.

In our opinion Nest 3rd Gen Learning Thermostat is the best single-zone thermostat for a UK home. Backed by Google it has a whole host of smart features which make it better than other products like Hive (developed by British Gas).

Evohome muli-zone heating control
Smart Heating Control saves you money plus improves your comfort and control

2. Multiple Single Zone Heating

Strictly speaking, this is not a recognised category. But we have added it because it is an option if you already have multiple zones plumbed in your home.

If you have a newer home or have renovated you might have 2 or more thermostats controlling separate heating circuits. Most commonly, you may have wet Underfloor Heating Zones (UFH) plus radiator zones.

This is multi-zone as there has more than one zone. Technically each zone is controlled in a similar way to single-zone.

You have a couple of choices when installing smart heating control.

  1. Upgrade each of your old thermostats with single-zone smart thermostats like the Nest. Each of the Nests can be controlled from the same app and become a multi-zone system. This is great if you have a number of UFH zones.
  2. You can go the full hog and automate your radiators as well.  With a full-blown multi-zone system like the Honeywell evohome below.


3. Multi zone Smart Heating Control

Multi zone smart heating control is the best solution you can get. It turns your existing centrally controlled heating to one that you can control room by room.

Imagine that you have a single thermostat controlling a single heating circuit, heating 12 rooms with 14 radiators.

Without any plumbing changes, you can upgrade your heating system to create 12 zones (one for each room). Each of these zones can be controlled independently - you set the temperature and schedules room by room. If you just want to heat one room you can - if you want room at 25C and another at 19C, you can.

Honeywell evohome multi-zone means you can control temperature room by room 

Honeywell Evohome multi-zone smart heating (c) 2019, 2020

How does multi zone smart heating control allow you to control temperatures room by room?

Honeywell evohome controller and smart TRVs as sold, installed and supported by Homesmart solutions
Evohome Hub and Smart Radiator Valves

A zone is created by upgrading your TRV radiator valves to smart wireless motorised valves with a thermostat built-in.

These smart radiator valves are used to control the temperature for each of the zones. (NB If you have more than one radiator in each zone, one will become the master for that zone.)

You control your heating room by room as a wireless signal is sent between your controller, your boiler and the smart valve.

The boiler will respond to signals from your radiator valves and only heat that room if you want.

In this way, you could set your living room to 20C, kitchen to 18C and study to 21C whilst the rest of the house is 16C.

This solves one of the biggest customer frustrations... that cold room. With multi-zone you can now get that cold room to the temperature you want without having to over-heat the rest of the house!

Multi-zone means you warm your home where and when you want.

My personal experience of using Evohome:

Typical mornings in our home start with the bedroom and bathroom warming up first - so it’s nice and cosy when we wake up.

The kitchen and hall are ready for breakfast. We are not heating rooms that we don’t use but are warm in the ones we do. The heating system is more efficient as it’s heating fewer rooms.

The bit that we had difficulty in getting our heads around is that the heating is no longer on or off. In effect, it is on all the time maintaining the desired room temperature all the time.

One question we had is how do the thermostats on the radiators detect the right room temperature not just the temperature around the radiator?

As long as you have enough air space around your radiator valve they work extremely well. We’ve tested room temperature against these valves and they have always been bang on. Note: If you have a radiator cover you will either need a separate room thermostat or you can use another radiator as the master.

Which smart heating control is right for you?

Evohome multi-zone is undoubtedly the best system for better comfort, control and energy saving. However, you have to factor in your lifestyle, size of house and how many people live in your home. Cost versus how much you can save is another factor covered below.

If you already have 2 or more zones in your home it might make sense to simply replace your manual thermostats with Nest 3rd Generation Thermostats. If you want more zones and control and then you should go with Evohome multi-zone.

If you currently have one thermostat, the choice is replacing that with a smart single zone thermostat (like Nest) or going for smart multi-zone system like the Honeywell evohome. Generally the bigger the house the bigger the benefit of multi-zone smart heating.

If you want to know more about multi-zone please read our article on Why Choose A Multi Zone System

Do smart thermostats control Hot Water?

Hot water cylinder controlled by smart heating

Both smart single and multi-zone systems will control your hot water.

The Nest Thermostat will control the time your hot water comes on and off and work with your existing hot water tank thermostat to manage the temperature.

The Honeywell evohome system goes a step further by replacing the thermostat on your hot water tank to enable not only on/off commands but also the ability to set the temperature of the hot water wirelessly.

If you have a combi-boiler you don’t need smart heating control to manage it. The water is produced on demand which is smart enough....

Control you heating from anywhere with smart control

One of the great things about smart heating control is the number of choices you have to interface with it.

Mobile App

The first stop is the smartphone app. We really like the Nest app which is very intuitive and slick. Would you expect anything less from a product by Google? It also gives you lots of nice feedback on your energy use and suggestions on how to save energy. Naturally, you can use it anywhere – from holiday for instance.

The Honeywell evohome app (pictured earlier) looks good and controls so much more – room by room. We like seeing the actual temp v target temp and be able to easily look at and change schedules etc.

Nest Thermostats Installation
Hand controlling Nest Thermostat

Manual Control

At home you can always manually over-ride as you do now. Turn the thermostat dial up or down on the Nest or turn the smart radiator valves on the Honeywell system.

You can also use the Honeywell controller to change programs, over-ride temperatures or use some of the pre-programmed options such as “eco” mode where all temperatures are dropped by 3C

Illustration of voice commands to Amazon Alexa controlling a Honeywell evohome multi-zone smart heating system

Voice Assistant

Both Nest and Honeywell system are compatible with Google Home and Amazon Echo.

When I’m working from home I don’t even need to look up as I ask “Alexa, turn study temperature to 20C”.

How luxury is that?

Works with Google Assistant logo
Amazon Alexa enabled logo

Stuff you don’t need to think about

Going on holiday or just away from home?

You've probably read about something called Geo-Fencing which uses your phones GSM to track where you are and turn your heating off without you having to remember.

Nest has this feature built-in called "home & away assist".

Honeywell evohome hasn't got this but you can set up the same thing using an app called IFTTT. (IF This Then That).

It's a pretty cool feature.


How much does smart heating control cost?

Photos of Nest Learning Thermostat and Nest Heat Link

Nest 3rd Generation Learning Thermostat with Heatlink

The only big question left is cost and payback. How much does smart heating cost and is it worth it?

The Nest 3rdGeneration Learning Thermostat costs about £209. (at time of writing!)

If the installation is using the existing wiring from your old thermostat it is a relatively straight forward job to install. Otherwise, you may need a stand costing another £35. Included with the thermostat there is a second box called Heatlink which wires into your boiler. Installation should not be attempted by anyone who isn't a professional Nest Pro certified installer. Installation will cost about £100.

Nest Pro logo

Honeywell evohome

A Honeywell evohome multi-zone system starts at around £600 and goes up depending on the number of zones you have. For an average home you’re probably looking at around £1000-£1500 including installation. However, in larger homes expect to pay over £2000.  It is a significant investment but if you’re looking at payback it should pay for itself in 2 years which still makes it one of the best home improvement investments you can make. What you can’t quantify is the outstanding benefits to lifestyle in comfort and control.

The Honeywell Evohome can take several hours to install and requires a lot more wiring to your boiler, hot water tank (if you have one) and UFH manifolds. Defintely not something to be attempted by anyone but an expert.

Honeywell evohome controller for multi-zone heating showing current temperatures and target settings for rooms

Return on Investment

Trying to quantify how much you will save and therefore what you can expect as a return on your investment is dependent on many variables. However, with 79% of your energy going on heating and hot water the savings can be quite significant.

A single-zone or multi-zone smart thermostat will typically pay for itself in 2-3 years and sometimes less. This makes it about the best investment you can make for home energy efficiency.

Other energy efficiency investments:

Loft insulation: 4-5 years

Most homes have this. Although some may have the thinner quality insulation. Even so, it pays for itself in 4-5 years. Cost about £350 for medium-sized house.

Energy-efficient boiler: 7-23 years

This is an optimistic view. Some estimates put this at 45 years. If your boiler is over 10 years it's likely to have a lower efficiency than a modern one. However, the cost of 85% efficient boiler is anything above £2,500 and the savings could be less than 10% per annum.

Double glazing: 46 years

This is about the worst payback you can get. But you don't do it for that, do you? And if your old windows need replacing you should put double glazing in. However, the cost is huge for little energy saving.

Cavity wall insulation: 50-100 years!

Less said.

what makes homesmart solutions different


homesmart has researched the market for the best smart heating products in terms of performance, quality, reliability and value for money.

we have chosen the best muti-zone smart heating control (Honeywell evohome) and the best smart thermostats Nest 3rd generation Learning Thermostat.


instant quote

we have created an easy to use tool to help you design what is right for you.

there's no hidden catch, we will give you a quote on-line without any high-pressure calls.

the price is what you will pay for an installed and supported solution. try it...


we install everything we sell but we go beyond this...

our local professional engineers are experts in Nest and Honeywell products. they are also Gas Safe registered and fully certified plumbers. during installation they will check your wi-fi, heating system and ensure that you know how to use your new system. afterwards we are always on hand to make sure your system stays working.


we sell our systems with a service plan. there are 3 levels to choose from.

why do we do this?

we want to give you outstanding value for money service and peace of mind. we think our service plans offer that and is fundamentally what we're about.

taking the hassle out of technology for you and having someone you can rely on

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