Category Archives: Smart Home

Steps in my smart journey

For more than a year now we’ve been building up our smart home capability. There are various ecosystems of such devices, but we’re using Apple HomeKit a decision initially motivated by the presence of multiple iPads in the home.

1My first step into smart home was to replace radiator valves with smart valves. Typically that results in replacing a temperature-only TRV with a smart valve with both a temperature set point and schedule. A schedule still operated within the central heating timer, but The schedule within the valve allows heating to be disabled in a particular room even though on elsewhere.

Applications for this include disabling lounge heating on weekday mornings, disabling the playroom heating after our daughter’s bedtime, not heating bedrooms during weekend daytimes etc..
2My second step was to add the ability to turn on the heating remotely so, instead of having schedules in both the central timer and the individual valves, the schedules exist only in the valves. Instead rules link the valves to the boiler so the boiler automatically runs from the first radiator valve on to the last radiator valve off.

Thus, instead of potentially needing to modify both a valve schedule and the schedule on the central timer to make a change, only instead a single change to the valve schedule is required. Similarly things like extending heating in the evening, to watch a late film for example, a simple Siri voice command to the radiator valve is enough rather than having to extend boiler hours too.

The hardware to achieve this is a standard smart socket, driving a relay which closes contacts across the correct terminals on the central heating wiring block alongside the boiler. The software to achieve this is two rules - a boiler on rule and a boiler off rule. The rules require a hub to which to run which initially was my iPad.
3My third step was to add an Apple TV unit as a hub to complement the iPad. This allows the heating rules to operate even when the iPad is not at home of has insufficient battery charge to act as a hub.

Extra capability from this additional hub allows control from remote locations, such as warming up the home if one will be home early or disabling vacation setting prior to starting a home-bound journey at the end of a vacation.
4My fourth step started a completely different non-heating theme. We’d had a few occasions where family members had left the house with windows open, so I started adding sensors on windows that were most likely to the left open - typically cloakrooms/bathrooms.

In this step we needed to use the Apple Home app, the Elgato Eve App, or Siri to check window status.
5My fifth step continued that different non-heating theme with the addition of our first smart bulb, now in a lightfitting near the burglar alarm control panel.

A series of rules combine both automated dusk-to-dawn white lighting and coloured lighting when any monitored window is left open.
6My sixth step continued the lighting theme with the addition of our second smart bulb, now in the outside light by the front door. This light had an integral dusk-to-dawn sensor but this failed leaving the light on continuously. Rather than replace the whole lamp I simply added a white smart bulb.

The existing rules were modified to add the new bulb to provide dusk-to-dawn white lighting.

This step was added August 15th, 2018.

Gas Usage to July 2018

This chart shows our gas consumption by month and year since we moved here in August 2015 (the first full month shown is September 2015),  Along the way several changes are marked which might be thought to influence gas consumption, although with natural variation month-to-month and year-by-year the effect of those changes isn’t dramatically obvious.

What is of course obvious is the dramatic difference in gas consumption between summer and winter as gas is our main means of space heating, and there’s no need for space heating in summer.  Most homes would exhibit such a pattern.  Ours is probably a bit more marked than many because of our water heating.  Many homes with gas will use the gas for both space and water heating, but for us the gas water heating is the back-up not the primary water heating system.  Our home is set up to divert surplus solar electricity from the PV panels to water heating during the day.  Only in the evening is gas water heating enabled and then it does no heating if the water is up to temperature.  The gas water heating thermostat is also set a few degrees colder than the immersion heater, so gas is separated from electric water heating by both time and temperature to prioritise electricity.

Previously I had just disabled the boiler in summer, but occasional dull days would leave my wife complaining about lack of hot water.  The new arrangement with the boiler operating later and with a lower temperature set-point has avoided that and is robust as long as your hot water cylinder is big enough for your daily needs so you only need to fill it once with hot water which is then stored available for use until the next day.

Over time 3 changes are called out which should reduce gas consumption further:

  1. In December 2015 we replaced the boiler, hot water cylinder and controls.  The previous boiler had demonstrated that it was incapable of heating the whole home as we went into our first winter so a replacement was rapidly arranged.  The new boiler is considerably more efficient which should reduce gas consumption for a given heat output, but it now heats the whole house, so that might counteract the improved efficiency.
  2. In late 2016 we upgraded the loft insulation from 100 to 270 mm which should be worth £73 in gas per year according to our EPC.  February, March and April 2017 do seem to show some benefit compared to 2016, but then there also variation in the weather year-to-year.
  3. In May 2017 we started adding smart heating controls which has gradually expanded over the following months.  The overall concept here is that most rooms now have smart radiator valves which are both thermostatic and contain their own schedule.  The schedules allow rooms to be heated for fewer hours: for example lounge not heated on weekday mornings, playroom not heated after children’s bedtime etc.

Fundamental rules for smart boiler control

Each rule in the smart home can consist of triggers, conditions and scenes. Triggers consist of one of more alternative events any of which cause the rule to be evaluated. The optional Conditions consist of one or more statements all of which must be true for the rule to be satisfied. Scenes consists of one or more scenes that are set when the rule is satisfied.

For my heating control I have two scenes that set the boiler on or off, and triggers and conditions reflecting the status of the radiators.

Any valve goes to closed .... and all valves are closed .... then cancel boiler.
Any valve moves off closed ..{none}.. then enable boiler.

As an alternative I considered rules using temperature, but that would make things more complicated if the temperature set point is adjusted as you might need to change the rules; whereas by having rules based only on (fully) closed and (partially) open then the set point can be adjusted without issue.  Additionally you can control around a very low vacation set point for frost protection.  Effectively there are four set points:

  1. Closed – which is forced by a summer setting, but also occurs at other times when no heat is demanded.
  2. Vacation temperature – 5 C for me – a low set point for frost protection, but from which it might take an extended period to warm up.
  3. Economy temperature – 10 C for me – a lower temperature limit during normal scheduled operation.
  4. Comfort temperature – 24 C for me – a minimum temperature avoiding complaints from my wife!

My system retains the original 7 day timer, which these days I use only to control water heating.  If I did enable the 7 day timer as well as the smart controls then the boiler would be enabled when either the 7 day timer or the smart controls demanded it.

Advantages of smart heating

I thought that I’d describe some of the features of the smart heating controls versus the prior single zone system with TRVs and a 7 day timer. My main interest is of course to save gas by heating the home more selectively, but there are other opportunities that you may consider significant.

I don’t yet have sufficient data to illustrate any operational savings, but continue to record gas consumption to compare with prior years.


 Prior system with 7 day timer and TRVsCurrent smart system with some eTRVs
Schedule7 day - working week plus weekendsInfinitely flexible home / working schedule based on iPad calendar
Adjustment of timers and thermostatsManualvia App (with voice control!)
Remote adjustmentNoYes - enabled by Apple TV as hub
Holiday settingNo Yes - sets low level heat for frost protection
Summer settingNo Yes - closes all valves
Integration with non-heating smart devicesNoYes

Oops no heat

No heat this morning (not that its absence is a major issues as the weather is fairly mild). Initial analysis via the Apple Home App is that some of the radiator valves can’t be reached, and thus I assume that the rules that enable the gas boiler can’t be satisfied.

As a short term fix I could have turned on the boiler manually via the app or using the central timer which is normally set to off for space heating (but not hot water) when using the smart controls, but I didn’t need to do that as I quickly found the root cause.

I initially thought that there was some corruption in the configuration of individual valves, so I was planning to delete them from the App and then re-pair them, but then I spotted that as I moved around the house I was losing different valves, so I turned my attention to the hub i.e. the Apple TV box.

Turning on the box it appears that it downloaded a software update overnight. As soon as I acknowledged a screen describing the changes then all the valves became reachable, the control rules were satisfied, and the gas boiler was enabled.

It would be more robust if you could specify a default value in a rule to be used if the actual value was unavailable from the device.  The actual value being unavailable would also happen with a flat device battery for example.

Here’s a little Tonik..

Today my energy supplier Tonik wrote to me inviting me to consider solar panels, a car charger, or a storage battery – all of which I already have.  However on their website I found a wider vision of the future home which they thought could halve energy consumption. I thought it would be interesting to compare their vision with my status.

As you can see from the table below the content is quite similar, although I have more ambitious use of solar and more sophisticated smart heating management.

Tonik's VisionMy status
Switch to Tonik for lowest cost renewable electricity.Done.
Smart meterWaiting on Tonik
Connected thermostat (whole of house device)Connected thermostats (individual room temperatures and schedules)
LED bulbsDone.
Smart tariffWithout a smart meter on nearest equivalent (Economy 7)
Solar PV Done.
Battery storage.Done.
-Surplus solar electricity diverted to charge electric car.
-Surplus solar electricity diverted to heat water.

Using an Apple TV box as a home hub

When I first set up the smart home system I used my iPad as a hub.  You don’t need a hub at all for the individual smart radiator valves to follow their daily schedules, but the use of a hub is required for devices to interact with each other (such as a valve calling for the boiler to come on) or indeed to identify which days are working days and which are non-working days (since this is taken from a calendar). However of course this doesn’t work when the iPad is removed from the home.

The solution is to configure an Apple TV box as a home hub – enabling devices to communicate via the TV box.  This also enables remote control so a user with an iPad can operate the system when away from the home – such as disabling the vacation settings while still on vacation to allow the house to warm up.

Of course the Apple TV box can also be used to watch TV which my daughter uses to watch CBeebies or YouTube kids TV via the appropriate apps.

To date we have 7 smart devices – 6 radiator valves divided between 4 rooms, and a socket which is used to enable the boiler when any smart valve demands heat.

Adding smart boiler control

In my previous post I described replacing conventional thermostatic radiator valves (TRVs) with smart valves (sometimes called eTRVs).  The smart valves include both temperature set points and a schedule which allows me to operate shorter on times in rooms not used so much – such as the playroom heating turning off after my daughter’s bedtime.

My latest update is to link the valves to the boiler so that heat demand from a smart valve fires up the boiler, regardless of the settings of the older central timer and hall thermostat.  That would mean, for example, that if my wife want to watch a late film then commanding heat in the lounge would restart the boiler even if outside normal heating hours.

The effect of this change can be seen in the attached image which shows three days of valve position information for the two radiators in the lounge: two days where the boiler was enabled by the conventional timer and central thermostat, and the third day with smart boiler control.

For the first two days you can see the valve open wide for an extended period during some of which time the boiler won’t be pumping hot water as the hall is up to temperature.  However on the third day, with the link to the boiler, the valve closes very quickly from its initial position and then modulates to maintain the temperature since the boiler is running all the time when any valve is open.

The system is controlled by two rules through Apple Home:

  1. If any valve moves off closed (triggers)  then enable boiler.
  2. If any valve moves to closed (triggers), and all valves are closed (conditions), then disable boiler.

The picture shows the actual mechanism to turn the boiler on or off via the Elgato Eve Energy (which is a switchable mains outlet and energy meter) in the right side socket outlet.  I use the Eve Energy to operate a mains relay (in the black box) which in turn closes a contact between two terminals of the heating wiring box, which bypasses the heating timer and hall thermostat, sending a mains control signal to the dual port valve for the heating thus opening the valve thereby enabling the boiler through the existing controls.

The first evening’s operation showed two issues:

  1. Room temperature was reported as overshooting in some rooms, but not in one room with a newly installed valve. It may thus be that the older valves have self-tuned their controls and need to re-tune to the new more dynamic system characteristics.
  2. I needed to manually turn down the radiator in the hall which was getting too hot.  If that persists then I may need to add a TRV or smart valve to the hall.

Internet of Things

Last night I made a small update to our heating system by adding some smart radiator valves. I’d been thinking for some time that there were efficiencies to be made regarding what rooms were heated when. Until now we’ve had a 7 day heating timer (so we have different heating schedules on weekdays and weekends) and thermostatic radiator valves (so we can set specific temperatures in each room) but now we’ve gone a step further.

Radiator valve

Radiator valve

These days there are in my opinion three types of radiator valves:

  1. Traditional proportional valves – these valves allow the flow to a radiator to be set manually, but there’s no control to maintain a set temperature. So if for example a room is south-facing it may get too hot on a sunny day as no account is made of the solar gain, or a relatively exposed room may get too cold on a windy day as no account is made for the extra heat loss.
  2. Thermostatic valves – here the user can set a temperature for each valve, and then internal expansion or contraction of the thermostat reduces or increases the flow through the radiator to maintain the set temperature; but all radiators heat at the same times as set by the heating timer.
  3. Smart valves – smart valves add the ability to schedule temperature and/or on and off periods in different rooms at different times.

Valve Schedule

In my case I identified 3 rooms (5 radiators total) in which I thought that the typical usage was different enough from the house as a whole to warrant smart valves. For the purposes of illustration only, I’ve also added the schedule for the boiler timer although this is programmed independently of the radiator valves. The three rooms are:

  1. Lounge – we don’t use the lounge on termtime weekday mornings.
  2. Master bedroom – we don’t use the room during the day, so the heating can stay off until towards bedtime.
  3. Play room – my daughter doesn’t use her playroom before nursery or after her bedtime.

The chosen smart valves are Elgato Eve Thermos which are Apple HomeKit compatible but are also configurable via Elgato’s own App; but not configurable via non-Apple devices. I initially tried setting up the required sequences via timed scene changes, but couldn’t see an easy way to schedule both workdays and days off; so I ended up downloading schedules directly into the valves via Elgato’s own App. This allows different schedules to be established easily for both working and non-working days with a schedule to identify non-working days set in as a calendar in my iPad. It’s easy to set up a recurring schedule for weekends and then other dates like bank or school holidays can quickly be added. Vacations when we’re away from home are still set up via timed scene changes.