An Introduction to Smart Heating Control

Nest Learning Thermostat on wall showing current temperature

Smart heating control or smart thermostats are fantastic improvements to your home.

They will not only make you more comfortable but also save you money by cutting energy waste.

A win-win for you and the planet.

The good news is that they work with your existing central heating and hot water system. So, no need to upgrade even the most ancient of systems.

One caveat here is that if your boiler system is really ancient then it is also likely to be very inefficient and you should seriously look a installing a new boiler.

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

At a basic level smart thermostats automate all the things your old analogue thermostat does now:

    • Setting temperature 
    • Running heating schedules
    • Turning heat and hot water on and off

A smart thermostat does the things you could do but don’t.

Plus a load more that you never thought you could do:

Smart thermostats add:

    • Learning how long your home/rooms take to heat up an adjusting accordingly.
    • Varying  the temperature according to outside weather.
    • Adapting heating turn off times.
    • Switching off when you’re not there.
    • Able to be controlled remotely.
    • Learning your schedules and creating its own heating progrrames
    • Detecting moisture and movement.

And much more that would make this list too long.

Why you want 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?


A single thermostat for the whole home is not energy efficient
Basset Hound isolated on white background

Reason 1: Stop wasting energy

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

A smart thermostat takes the guesswork out of heating control and by so eliminates a lot of energy waste.

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

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 about energy savings from installing smart thermostats.

Some of them are impressive but not quite believable.

Nest has the most installs and they have aggregated data from all the Nest 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.

When it comes to multi-zone you can save even more.

That’s because you’re not wasting energy heating empty rooms.

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

Reason 2: More Control

A smart thermostat gives you more control over your heating.

The smart bit means that it is packed with intelligent controls that adjust to things like the weather, the efficiency of your 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 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 it means you 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.

Evohome App

Will smart heating control make you warmer?

Not warmer necessarily but definitely more comfortable.

As mentioned above multi-zone heating has the power to transform your heating allowing you to be warm in places that you could never get warm before and not so hot in the places that were also too hot.

But the real benefit of smart thermostats is the ability to intelligently regulate temperature to keep you cosy.

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 takes the guesswork out heating control.

Single Zone v Multi-Zone Heating

I’ve talked about single zone and multi-zone without fully explaining it. Let’s have a go here.

There are essentially 3 different types of smart heating (for UK homes). That’s simplifying it a lot as there are a myriad of different combinations depending on what your set-up is.

Single Zone heating with a single thermostat controlling the whole house.

Multi Zone where you have a number of plumbed in heating circuits each controlled by a thermostat.

Multi Zone which  retrofits on to a single zone thermostat and automates radiators to create multiple zones.

As I said there are a myriad of combinations especially if you have underfloor heating in some rooms and depending on what you want to control. All these examples are for smart heating control to retrofit without the need for expensive and disruptive plumbing changes.

1. Single zone

Nest Learning Thermostat with Black Ring

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

Your boiler will heat hot water and pump it round a loop with radiators in your rooms. Your thermostat will typically be placed in somewhere like the hall or living room.

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 single-zone smart thermostat like Nest is the simplest and most cost-effective option.

You will still have a single zone but will gain impressive control and benefits. An alternative to this is the option to install smart “multi zone” which is covered below.

2. Multi-zone (with plumbed-in zones)

If you have a newer home or have renovated you might have 2 or more thermostats controlling separate heating circuits.

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

Again, you have a couple of choices. Either replacing the old thermostats with smart single zone thermostats like the Nest (above) or creating even more zones with a smart multi-zone system (below).

If you already have plumbed-in zones we would normally recommend replacing your thermostats with Nest thermostats which can be integrated into a single system via the app on your phone to create a multi-zone system controlling your zones and hot water.

This type of multi-zone heating also works with underfloor heating zones. We often come across homes with 3, 4 or 5 zones (maybe 2 heating circuits and 3 underfloor rooms) and normally upgrade using Nest.

3. Multi-zone (retro-fitting onto a single zone)

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 to create 12 zones (one for each room). Your old thermostat and boiler programmer are redundant. Instead you will have a wireless hub to monitor and control the temperature of each of your “zones”.

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

Illustration of temperature control for different rooms with Honeywell evohome multi-zone smart heating (c) 2019

A zone is simply created by upgrading your radiators valves to a smart wireless motorised valve with a thermostat built in. These radiator valves set the temperature for each of the zones. If you have more than one radiator in each zone, one will become the master for that zone.

You can now control your heating room by room.

For instance, you could set your living room to 20C, kitchen to 20C and study to 21C whilst the rest of the house is 16c.

A wireless command is sent to your boiler to stay on until each zone reaches their desired temperature.

Multi-zone means you warm your home as you use it.

Mornings in our home the bedroom and bathroom warm up first so it’s nice a cosy when we wake up. Then the kitchen and hall ready for breakfast. We are not heating rooms 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 we had difficulty getting our heads round is that the heating is no longer on or off. In effect it is on all the time ready to hit that desired room temperature.

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 they work well. We’ve tested room temperature against these valves and they are always bang on. If you have a radiator cover you will either need a separate room thermostat or you can easily link it another radiator and use that to set the temperature.

Which system?

The decision of which type of control is right for you is dependent on you.

Multi-zone is undoubtedly the best system for better 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 is probably best to replace with Nest 3rd Generation Thermostats. Unless you really need more zones.

If 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.

If you want to know 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 from anywhere

One of the great things about smart heating control is number of choices you have.

Mobile App

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

The Honeywell 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.

thermostat_phone_uk 2

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?

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 pay back. How much does smart heating cost and is it worth it?

The Nest 3rdGeneration Learning Thermostat costs £219.

If the installation is using the 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 and installation should not be attempted by anyone who isn't a professional Nest Pro certified installer.

Nest Pro logo

Honeywell evohome

A Honeywell evohome multi zone starts at around £400 and goes up depending on the number of zones you have. For an average home you’re probably looking at around £800-£1200 or more. It is a significant investment but if you’re looking at pay back periods it should pay for itself in 2 years. What you can’t quantify is the benefits in comfort and control.

The Honeywell can take several hours to install and requires a lot more wiring to your boiler and hot water tank (if you have one). It also takes a while to name each valve and set-up correctly. Installation will start around £200 and increase depending on how complicated the system is.

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 so many variables that no one will be the same. However, with 79% of your energy going on heating and hot water the savings can be quite significant.

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

Other energy efficiency investments:

Loft insulation: 4-5 years

Most homes have this. Although some may have the thinner qaulity insulation. Even so 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 less than 10%.

Double glazing: 46 years

This is about the worst pay back 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 products in terms of performance, quality, reliability and value for money.

we have chosen the best single thermostat (Nest) and the best muti-zone system (Honeywell evohome).


your system

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.

service plans

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

create your system & order on-line

The first step to creating your smart heating solution

choose your product (Nest or evohome)

personalise to your home

The second step to creating your smart heating solution

choose your service plan

get your quote

The third step to creating your smart heating solution

see your energy savings

order on-line

The first step to creating your smart heating solution

choose your product (Nest or evohome)

personalise to your home

The second step to creating your smart heating solution

choose your service plan

get your quote

The third step to creating your smart heating solution

see your energy savings

order on-line