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How to choose a multi-zone system?

Picture of a Honeywell controller and a smart TRV
Honeywell evohome multi-zone

Multi-zone heating control is the best smart heating solution for you to save energy and also be more comfortable.

What is multi-zone heating?

Most homes have a single thermostat that sets a target temperature for your whole house. It’s usually positioned somewhere that you never live in, like the hall. When your hall gets to the target temperature your boiler is switched off. No matter how cold you are in the living room and how much you turn the radiators up, the boiler won’t kick-in again until the thermostat target increases or the hall drops in temperature.

A single thermostat for the whole home is not energy efficient

The downside of this system is that it wastes a lot of energy and you end up heating parts of the house you don’t need to or turning the thermostat up in order to get just one room right.

Newer homes have 2 or more thermostats, maybe one for upstairs and one for downstairs. If you have 2 or more thermostats already – it’s because you have separate plumbed in heating circuits which means that one can be on while the other is off. These are effectively zones and if you want to automate them you may want to consider replacing these thermostats with Nest Learning Themostats instead. You will not get room by room control but you will get smart heating control and it is more cost effective.

Multi-zone heating control like the Honeywell Evohome system makes each zone independent by giving it a thermostat that controls the boiler. On each radiator you will have automatic valve with a thermostat that will tell the boiler to fire up when needed. You no longer have a single thermostat for the house. So if you want to have the living room at 23C and study at 19C, you can. And most importantly without effecting other zones/rooms in the house.

Illustration of temperature control for different rooms with Honeywell evohome multi-zone smart heating (c) homesm.art 2019
Set temperature room by room

This means that you can just heat one room if you want and you get more comfortable without wasting energy heating rooms you don’t need to. A true win-win. 

You can do this with your existing system, plumbing and boiler.

Image of Honeywell evohome controller showing touch screen control of individual room temperatures - (c) homesm.art 2019
evohome controller

How does evohome multi-zone heating work?

Zones or Rooms

There is no limit to the number of radiators that you can have in a zone but if it gets too big we might need to look at your set-up again.

With Honeywell evohome multi-zone control you can have up to 12 zones as standard. That means you can normally create a zone per room but sometimes you may need to group 2 rooms together to create a zone.

Smart Radiator Valve

Each radiator that you have in your multi-zone system will have a new smart thermostatic radiator valve (TRV) fitted. There is a battery powered motor and thermostat in each valve. When the valve gets a wireless signal to heat a room it opens the valve until the correct temperature is reached.  It then closes automatically and sends a signal back to the the controller. The same is true for underfloor heating.

If you have 2 or more radiators in a zone they are all linked to set a temperature for the whole room or zone. One thermostat will be the master sensor.

Some of your radiators may be “boxed in” behind radiator covers. The problem here is that a lot of heat is kept in the box. This plays havoc with the thermostat in the radiator valve and you will either need to link it to a radiator that is not boxed-in or have a seperate room thermostat to set the correct temperature.

Evohome Controller

The evohome controller is a hub that you can plug in anywhere and is the brains of your system. With it you can set the required temperature for each zone. It does many clever things but the most important are telling the boiler to start, telling the valves to change and showing you the temperatures and your heating schedules.

It connects to your internet via wi-fi but it connects to all the Honeywell components via its own wireless system. So, if your internet goes down your heating keeps working!

Honeywell Home app showing room temperatures controlled by evohome multi-zone smart heating
Control from the Honeywell app

You can also control your heating from the very nice Honeywell Total Connect app on your mobile phone (pictured above) or a smart speaker such as Amazon Alexa or Google Home.

Other communications devices

Homesmart also install smart ”relays” connected to your boiler. The relays send and receive signals from radiator valves and your evohome controller to the boiler but are hard wired to your boiler.

If you have a hot water tank we also wire in another relay and thermostat to that. If your water gets cold it triggers a signal to the evohome controller and boiler relay that it needs heat. With this system you can choose the temperature of your hot water and obviously the times it should be on.

Should I include all radiators?

Many people do not automate every radiator in their multi zone system. The main reasons being cost or that is simply unnecessary.

What happens if you leave a radiator off your multi-zone system?

Any radiator left with traditional manual or TRV valves will still work with a multi-zone system. However, what does change is control. Because you no longer have a central thermostat the boiler is now triggered by the individual commands from your zones or hot water. Every time the boiler is triggered it will provide heat to your system. Any radiators with traditional valves left open will heat up. Of course, you can manually turn these off.

Should I leave rooms out from a multi-zone system?

This can make good sense for rooms that you either want heated most of the time (bathrooms) or not heated most of the time (spare room in the attic maybe?).

The most common is a bathroom or utility. In my house I have traditional valves on these. In the morning & evening heat is being provided for various radiators and hot water on my multi-zone system so heating the bathroom at that time also matches my lifestyle. During the day and night, the bathroom is not heated unless another zone is on, in which case I can turn off the radiator.

I should really automate my bathroom as it is slightly innefficient doing it like this but we have always been warm enough so I haven’t seen the need.

The same can be true for little used rooms. Keeping a traditional valve there may be a choice as you generally have it turned off. The thing to bear in mind is when you do need to use the room, heat will only be provided when the boiler is on. 

What type of valves have you got?

Manually operated TRV (thermostatic radiator valve)
TRV (thermostatic radiator valve)

You need TRV valves to fit smart thermostatic valves. We simply unscrew them and put on the automatic smart ones. Then connect up wirelessly to the system.

If you have manual valves you need to change the physical valve to a TRV type. You can tell them apart by the TRV having numbers while the manual do not.

Wheelhead or manual radiator valve
Manual Valves need replacing

Replacing a manual valve is straightforward but not one a plumber likes doing as they generally have to drain the heating system first. This takes a long time and becomes an expensive job for such a small item.

If you’re going to do this please consider our service which we can do while we’re installing your multi-zone system which helps keep the costs down.

Multi-zone heating systems from homesmart

Homesmart Solutions provides multi-zone heating systems from Honeywell Evohome. As well as installation, we also provide service and support with our unique service plans.

Find out more on our multi-zone heating page

Installation of multi-zone heating

You can find out what to expect in having a multi-zone heating installed by Homesmart Solutions please read here.