Intelligent Heating - Radiator Boiler - Multi-Zone

Multi-Zone Heating Options

Before looking at how to install home automation into your heating system, you need to first determine how you want the system to work.

There are an infinite number of ways to configure a Multi-Zone heating system, but we see two basic options; Simple Multi-Zone and Full Multi-Zone. The following sections explain the differences, how they would work, and important things to consider.

1. Simple Room Control

The first option, and the simplest, is to run the heating system as shown in the Basic Boiler Radiator system guide and add Z-Wave TRVs (Thermostatic Radiator Valves) to the radiators you wish to run at a lower temperature or off. This option is great if you have rooms that are rarely used or only used at the weekends - you can run your heating as normal but have these room's radiators turned off or reduced to a minimum temperature, helping to save heat and reduce costs.

This type of 'Simple' zoned heating is easy to implement, you can start by adding just one Z-Wave TRV to a radiator.

How it Works

The heating system is still controlled by the main Z-Wave Thermostat and Receiver (see Basic Boiler Radiator system), it will turn On and Off based on your programmed times and temperatures, all radiators without Z-Wave TRVs will be On when the system is On. However, you are able to control the radiators with Z-Wave TRVs wirelessly - selecting times when they are Off or run at a lower temperature compared to the rest of the system. You can also wirelessly change their 'Setpoint' temperature so they increase their temperature inline with the rest of the system. The TRVs would normally be controlled by a Schedule 'Scene' running in the Z-Wave controller.

The important aspect of this option is that the 'Zones' can only be On when the rest of the system is On - they are not totally independent and cannot independently 'call for heat'. When the system is Off or the main Z-Wave thermostat has told the boiler to turn Off as it has reached its 'Setpoint', then all radiators are Off.

2. Full Multi-Zoned Heating

Full Multi-Zoned heating means that each zone can call for heat - each one can independently tell the boiler to turn On and start supplying hot water to the radiators in that zone, and not to other zones. This approach gives you the most flexibility and will deliver the most cost savings. You are able to create as many zones as you like (floors, rooms or areas) and each will be able to be individually controlled - independently of all other zones.

This type of system is also the most complex to create and configure. Even though it uses the same Z-Wave components as the Simple MultiZone system, you will need to pay special attention to how you control it using 'Scenes' or 'Scripts' running in the Z-Wave controller.

How it Works

Each Zone will have TRVs installed on the radiators in that zone, these allow you to control whether the radiators are On or Off - whether hot water is actually flowing through the radiators. In this respect you are using them in a similar way as actuator valves to control the flow of hot water to the zones/radiators. This is similar to how you use them in the 'Simple' system.

The difference in this system is that each zone will have a thermostat or temperature sensor, rather than having a single thermostat that governs the system as a whole. Each thermostat reports its zone's temperature to the Z-Wave Controller. The Z-Wave Controller runs a 'Scene' that determines which zone should be on and whether it requires heat. If it does require heat, then the Z-Wave Controller tells the boiler and pump to turn On and supply hot water - the TRVs then control which radiators receive the hot water. Just as importantly, the Z-Wave Controller monitors the zones, when it detects that no heat is required, as all zones are up to temperature, it turns the boiler Off - this is also know as the Boiler Interlock.

Important Considerations

After you've decided how you'd like the system to behave, you should take note of some important points - some are required by current Building Regulations.

Boiler Interlock

Don't forget about the Boiler Interlock!

The heating system must be able to turn off the boiler when no heat is required. For example if you just used TRV's on the radiators and no way to monitor the zone or room's temperature you would quickly have a situation where all the radiators are turned off, as the TRVs have reached their 'Setpoint' temperature, but the boiler is still on. This would result in the boiler sending hot water around the system (but not through the radiators) and therefore wasting energy and money. This would continue until the room temperatures reduced or the heating system was turned off.

The Boiler Interlock is required by Building Regulations.

Hot Water Flow

In the Boiler-Radiator system the hot water is pumped around the system through the main pipes. Each radiator is connected in 'parallel' to the main pipe - hot water flows through the main pipe as well as the radiator. If the radiator's valve is turned off, then the hot water does not flow into the radiator, but continues flowing through the main pipe. This is an important distinction as it means that you cannot stop the water flowing through the complete system by turning off one radiator valve - this is why all radiators you wish to control must have their own TRV.

Multi-Zone Control

For full Multi-Zone systems, creating 'Scene' and control 'algorithms' can become complicated very quickly, so you need to plan your system before you start implementing it. You should plan how the 'Scene' logic will actually control the system - making sure that each zone can control the boiler and that the boiler will be turned off when no heat is required by any zones.

All Z-Wave Controllers will be able to run this type of control logic, but few of them will be able to do it using their standard scene editors. Most people use LUA scripting to control more complex multi-zone heating systems. Before going too far, it's worth researching examples of how this is done - so you can decide if it is something you're capable of developing for your own system.

Design the best system for You

The Full Multi-zone system is probably what you'd love to have, but it may not be what you actually need. The Simple system may be a better fit and very easy to install. So go for the system that makes practical sense for your home - and remember, you can always expand it later as Z-Wave devices can be fitted at anytime.

Components - what they do

Whichever type of Multi-Zone system you decide to implement, they both use the same Z-Wave devices.

TRV - Thermostatic Radiator Valve

Control when hot water is allowed to flow into the radiator based on the TRV's setpoint temperature. When the ambient temperature is lower then the setpoint, the radiator valve is 'Open' and water flows through the radiator. When the setpoint is reached, the valve closes, stopping the water flow and allowing the radiator to cool. Some TRVs have complex algorithms that automatically how quickly the temperature changes, this reduces the chance of over-shooting the setpoint and wasting heat. Some TRVs report the actual ambient temperature to the system, these can be used in place of a wall thermostat, but the temperature readings may not be very accurate as they are positioned very close to the hot radiator.

  • Fibaro Radiator Heat Controller
    Controls the radiator's temperature - you can change the 'setpoint' temperature via Z-Wave and reports the ambient temperature back to the Z-Wave system. It also allows running of schedules and override. The optional Fibaro Radiator temperature sensor allows all radiators in a room to work together (also needed if you mount the TRV vertically).
  • Fibaro Radiator Temperature Sensor
    Monitors room temperature and regulates up to three radiators using the Fibaro Radiator Heat Controllers (TRV).
  • Danfoss TRV
    You can wirelessly change the Danfoss' 'Setpoint' although it does not report the room's temperature back to the Z-Wave system. The Danfoss does include an LCD to indicate the current setpoint and buttons that enable you to manually change the setpoint. It also features in-built algorithms to open and close the valve as efficiently as possible.
  • StellaZ TRV
    StellaZ TRV can have it's 'Setpoint' changed wirelessly and reports the ambient temperature back to the controller. It does not feature any manual control, so all changes have to be made wirelessly via the Z-Wave Controller.

Boiler Receiver

This is a Z-Wave Switch (Relay) that replaces your existing heating controller/timer. It enables the Z-Wave system to control when the boiler is On or Off. If you have a Combi boiler, you will need a single-channel receiver, if you have a Y-plan or S-plan system you will need a 2-channel receiver or switch as you will also need to control the hot-water system. More Details - Basic Boiler Radiator system with Single Thermostat

  • Secure Single-Channel Boiler Receiver
    Purpose designed Z-Wave Receiver for controlling a Combi boiler. It enables the Z-Wave system to control the boiler and has buttons and LEDs for manual On/Off control.
  • Secure 2-Channel Boiler Receiver
    Purpose designed Z-Wave Receiver for controlling a Y-plan or S-plan boiler. It enables the Z-Wave system to control the boiler and has buttons and LEDs for manual On/Off control of the heating and hot-water.
  • Fibaro Switch 2 (Double)
    Dual relay that can control the boiler's heating and hot-water channels.
  • Qubino Relay x2 Plus
    Double switch (relay) module can control the boiler's heating and hot-water channels.

Wall Thermostat

Communicates directly with the Boiler Receiver or Relay to control the boiler (heating) depending on the room's ambient temperature and the 'set-point' temperature you've selected. This allows the system to run the heating system with the optimum efficiency as the thermostat has in-built heating algorithms that optimise the boiler On/Off periods. You can change the thermostat's set-point temperature wirelessly, giving you complete control over your heating system. More Details - Basic Boiler Radiator system with Single Thermostat

  • Secure Wall Thermostat (SRT321)
    Wall mounted thermostat controls the boiler (via the receiver) and can have it's set-point changed by the Z-Wave controller. All heating schedules will be run in the Z-Wave controller and the heating's On/Off periods controlled by changing the wall thermostat's set-point.
  • Secure Programmable 7-day Thermostat (SCS317)
    Very similar to the Secure Wall Thermostat, except it has an integrated 7-day timer that enables it to run the heating based on schedules you program into the thermostat - it can have up to 6 temperature periods per day.

Temperature Sensors and more...

Can be used as an alternative to Wall Thermostats or as an extra 'independent' sensor to monitor the temperature of different parts of the house. For example, your Wall Thermostat may be positioned near the light switch, but may not be the best place to measure the room temperature - perhaps next to the sofa is more appropriate. Adding additional Temperature sensors allows you to fine tune the heating to suit the use of the room - perhaps you could create an averaged Temperature reading between the Wall Thermostat, TRV and the additional sensor and control the system based on that.

  • Secure Wall Temperature Sensor
    Wall mounted temperature sensor can report the room's temperature to the 'Scene' running the heating control.
  • Fibaro Radiator Temperature Sensor
    Monitors room temperature and regulates up to three radiators using the Fibaro Heat Controllers (TRV).
  • Danfoss Temperature Sensor
    Wall mounted sensor sends temperature to Z-Wave controller so that you can use this to control the heating.
  • Fibaro Door/Window Sensor (Gen5) with Temp Sensor
    Flexible Door/Window sensor can also use the optional DS18B20 temperature sensor to report the room's temperature - gives you extra functionality and helps optimise your heating control.
  • Fibaro 3-in-1 Motion Sensor (Gen5)
    Tiny Motion sensor that also monitors temperature - this can also be configured to account for temperature differences if it is positioned near the ceiling.
  • Aeon 6-in-1 MultiSensor
    Versatile sensor for motion, temperature, light and humidity - control your heating automatically from any of these sensors.

Z-Wave Controller

The controller enables you to add and configure devices to your Z-Wave system and run 'schedule scenes'. It also acts as a gateway allowing you to control the system from a smartphone even when you are away from home. In the case of heating, the controller will run the schedules to control when the heating is On/Off and at what temperature, it will also run the hot-water times.

For more information take a look at our How to Choose a Z-Wave Controller Guide.

Home Automation - Z-Wave Controllers Vesternet

Technical Guides

These guides and videos show how these various systems can be integrated with Vesternet's home automation products.

Copyright Vesternet 2018

Updated: 21/09/2018