Category Archives: Gas

Heated debate

So here’s the question – is it better to heat the home continuously or to only heat it when you need it? You may think that’s obvious as I did but a recent debate elsewhere suggests that there’s a variety of opinion out there, so let’s explore the relavent issues:

  • Heat loss from the building
  • The efficiency of the heating appliance (boiler, heat pump etc)
  • The degree to which the building acts as a thermal store.

Heat Loss from the Building

Heat loss from the building

Whether we consider walls, floors, roofs or windows everything around the boundary of a building contributes to heat loss. However well insulated there will be a flow of heat through the structure (let’s assume brick for the moment). Heat will travel from hot places (usually inside the building) to cold places (usually outside the building). Insulation can help reduce the flow but the flow still makes place. One key way to reduce the flow is to reduce the internal temperature so, for example, if the outside temperature is 10 C and you reduce the internal temperature from 20 C to 19 C then you’d expect to reduce the loss by 10% – was driven by a 10 C temperature difference now driven by a 9 C temperature different which is 10% less than 10 C.

I’m an advocate of switching heating off when not needed – typically overnight when in bed asleep or during the day when out at work. Turning the heating off obviously immediately cuts the energy use, the temperature of the house then starts to drop as the heat flows out through the walls and other components of the boundary, the energy flow gradually reduces as the internal temperature drops towards the external temperature, and eventually the flow stops if the internal temperature reaches the external temperature.

The question is then how much heat energy does it take to get the temperature back up to a comfortable level and potentially are there issues with efficiency of the heating appliance.

Efficiency of the Heating Appliance

Any heating device will have an efficiency at which it coverts energy in the fuel to useful heat output. Typically these are less than 100% as some of the fuel energy ends up as waste energy rather than useful heat. The exception to this is a group of electrical heating devices known as heat pumps. Heat pumps as their name suggests pump heat from one place to another – typical from the outside air or under the ground – so as they heat the house they also cool the source and thus their efficiency is more than 100% since much of the heat output comes from the source being cooled and not from the electricity supply. However I’m going to consider a condensing gas boiler as one of the most common domestic heat sources in the UK.

Boiler temperature controls

A condensing gas boiler is more efficient than prior generations of gas boiler as it uses waste heat in the flue gas to preheat the water before it gets heated in the conventional main boiler. To get the preheating to work efficiently then the flue gas has to be hotter than the return water.

Typically the user sets the temperature if the hot water generated by the boiler (which may vary seasonally) – the flow temperature. The hot water is then pumped round through the radiators causing the radiators to heat the rooms and the water temperature to drop, the return water is preheated by the flue gasses and then heated in the boiler itself before going round again. Best efficiency is obtained by maximizing the extraction of heat from the flue gasses, which typically requires the following conditions:

  1. The flow temperature is below 70 C
  2. The return temperature is below 55 C
  3. The difference between the above is around 20 C

There are arguably two typical uses of the boiler for space heating: (i) relatively low demand to maintain the current temperature and (ii) relatively high demand to get the building to the required temperature. The latter would be expected to push the return temperature lowest and thus most likely to condense, so if the size of the load makes a difference at all then you’d expect high load to be more efficient. That’s good news for those who tend to turn their heating off at times, as the resulting peak loads shouldn’t have lower efficiency than continuous use.

Thermal Mass

The thermal mass of the building is its ability to store heat. Storing heat alone over time doesn’t really add to the energy requirements to heat a home, but it can make a home slower to cool down or faster to heat. You might imagine a stone cottage for example having a relatively high thermal mass. On the other hand a modern house have a stud walls internally (and even externally if it’s a wood-framed home) which have very little thermal mass. At the other extreme I’ve seen experimental homes with so much mass (such as earth banks) that it can take over a year to warm up.

The combination of the amount of thermal mass and the amount of insulation will determine the time constant associated with heating and cooling or how long it takes for the structure to warm up.

In extreme, if your thermal mass is enormous, then you may be able to heat your thermal mass enough in summer to heat the house in winter but you’d need to actively heat the thermal mass in summer – such as by diverting the output from solar panels – just having a big thermal mass without actively heating it would leave the mass at an average annual temperature likely below what is comfortable in winter.

How thermal mass works

So where does that leave me with the question of turning off my heating when not required? Well, it would seem that (i) a reduced internal temperature would reduce heat losses while the heating is off which should mean less heat input to get the air temperature back later and (ii) running the boiler at relatively high load to get the temperature back isn’t an efficiency issue as high demand promotes a low return temperature.

What about experimentally?

Effects of turning the heating off overnight

The above graphic shows a very typical winters day with the home occupied. The blue upright bars are half-hourly gas consumption readings from my smart meter. The blue bars show six hours of no heating overnight, an hour and a half of relatively high demand to heat the house up to temperature, and then lower demand (generally to maintain the temperature) through the day. The orange dashed line shows the typical level of heat input required to maintain the temperature – 2 kWh/half-hour. The green box shows the period overnight with no heating. If the home had been heated during this time that would have been 6 hours of heating at 2 kWh/half-hour = 24 kWh of additional heat input. The red box shows the actual heat input required to reestablish the comfort temperature – 2 kWh + 6 kWh + 4 kWh in each half hour respectively = 12 kWh. Over all I saved around 24 kWh – 12 kWh = 12 kWh overnight and more if the heating had been off during the day too. Since the data is taken from the incoming gas supply then the above savings include the effects of any variation in boiler efficiency between low heat demand to maintain temperature and high heat demand to establish temperature.

It thus seems that turning off the heating when not required saves energy compared to running the heating at a constant temperature both theoretically and experimentally.

Eve Thermo Versions 1 and 2 compared

We currently have eight Eve Thermo electronic thermostatic radiator valves (eTRVs) in service. These valves allow us to set heating schedules and target temperatures for rooms individually, for example don’t heat the lounge of weekdays before the evening or don’t heat the playroom after the children’s bedtime. All the existing valves are the original version.

However I’ve just bought two more valves with a view to expanding control to the bathroom and ensuite. I want to add these rooms as they tend to be rooms where the windows are left open (allowing heat to escape) and the ensuite in particular is often too hot and difficult to it’s difficult to regulate the temperature as it’s immediately above the boiler. These new valves are the second generation. So what are the differences between versions?

The two versions are very similar if not the same size. The most obvious difference is that the new version has a small display and buttons allowing the temperature to be adjusted. A setup item allows the orientation of the display to be adjusted so that the temperature display is the preferred way up. The display illuminates briefly when the buttons are used to adjust the temperature.

However there are other small differences:

  1. Vacation mode. The older version has a vacation mode for winter vacations when the schedule is disabled, but heating will be enabled below the lower temperature set point. The newer version doesn’t seem to have this mode, so my existing vacation scene sets these individually: mode = on, schedule = off, temperature = 10 Celsius to achieve the same result.
  2. Lower temperature set point. In the older version the minimum possible scheduled temperature stored in a valve was 10 degrees, but a scene could set a lower temperature down to 5 degrees. I use this facility overnight to stop a rarely-used room pulling on the heating overnight in winter while still providing frost protection. However the newer version seems to have a common minimum temperature of 10 degrees. I have thus modified and renamed a scene that previously explicitly set 5 degrees to set minimum temperature, that is either 5 or 10 degrees according to valve generation.

I plan to install my two new valves in the lounge which has two radiators, and use the displaced older valves in the bathroom and ensuite.

After installation we’re now up to 10 eTRVs divided between 8 rooms (bathroom, cloakroom, daughter’s bedroom, ensuite, lounge x2, master bedroom x 2, playroom and wife’s study). Most of these rooms have individual schedules; while bathroom, cloakroom and ensuite heating is on when any other room heating is on. The latter also have window sensors and are disabled while the window is open, while the lounge also has a movement sensor which curtails heating in the evening if no movement is detected (which otherwise provides heating for my wife’s late film viewing).

Valve position for the ensuite eTRV.

The image above shows the operation of the eTRV in the ensuite which was previously the room with the greatest difficulty in maintaining an appropriate temperature – often being too hot as almost directly above the boiler. Here we can see brief morning openings and much longer evening openings on weekdays, and heating all day on Saturday. In all cases the valve initially opens wide (60-80%) to warm the room up, and then gradually closes over time until the temperature is maintained with a relatively small opening (~10%).

The system has several modes:

  1. Summer – which provides temperature monitoring, but no control.
  2. Vacation – which provides minimum temperature control, but no schedules.
  3. Winter – which provides temperature scheduling with two schedules available – one for working days and one for non-working days (not necessarily weekdays and weekends) selected from a standard Apple calendar.

Thoughts on intensity (of the CO2 variety)

CO2 production is increasingly of interest as the world struggles to limit man-made climate change. As we use different energy sources each represents a certainly amount of CO2 reflecting a combination of the energy invested to create that power source (e.g. the wind turbine may generate wholly renewable power, but its construction created some CO2) and the CO2 created as it generates energy once constructed (nothing for renewables but relatively high for fossil-fuelled generation).

I’ve previously shared this table showing the IPCC’s view of the embedded CO2 in different sources of electricity generation.

IPCC’s view of embedded CO2 in different sources of electricity generation

A recent question and resulting discussion in an on-line forum prompted me to think more about the area of embedded CO2.

My first observation would be that my rooftop solar panels do quite well on this scale with a CO2 figure of 41 gCO2/kWh.

The second observation would be regarding energy storage. My view would be that any energy storage device from a small scale domestic battery like my own to a large pump storage scheme can never deliver better embedded CO2 that the source of its energy. So, for example, if I charge my battery from my own solar at 41 gCO2/kWh with a cycle efficiency of 80% (the maker’s claim) then the embedded CO2 in the energy coming out of the battery cannot be better than 41 gCO2/kWh / 80% = 51 gCO2/kWh. Indeed it would be worse than that as this doesn’t account for the CO2 generated in creating the battery nor its operational life, but I don’t have figures for those.

Example of UK grid CO2 intensity

Thirdly, as my own embedded CO2 is relatively low whether exported directly from my panels or indirectly via the storage battery, then the CO2 intensity of the grid always benefits from my export. The 116 gCO2/kWh illustrated above is pretty low for the UK grid which varies widely but is still more than my solar PV directly or stored solar PV. Indeed had I exported onto the grid at the time illustrated above then my 41 gCO2/kWh versus the grid’s 116 gCO2/kWh would have saved 75 gCO2 for each kWh that I exported.

However if, for example, I export electricity but need to then buy more gas to make hot water then that too has a CO2 impact.

CO2 intensity of different fossil fuels (source: Volker Quaschning)

If I need to buy a kWh of gas to make hot water that’s 0.2 kgCO2/kWh or 200 gCO2/kWh even before I’ve accounted for the relative inefficiency of the gas boiler versus my electric immersion heater. If I assume that the gas boiler is 90% efficient then I will be responsible for 200 gCO2/kWh / 90% = 222 gCO2/kWh for a kWh used to make hot water. Thus, while exporting 1 kWh of solar PV may save the electricity grid 75 gCO2/kWh, it’s added 222 gCO2/kWh to gas consumption – a net deterioration of 147 gCO2/kWh.

Natural gas of course is the lowest CO2 of the fossil fuels listed above – if your home is heated by oil, coal or wood then the analysis is further skewed towards using your own self-generated power rather than exporting electricity and importing another fuel for heating.

The electricity grid’s carbon intensity also varies. In 2019 the UK average was 256 gCO2/kWh (a little higher than my estimate for gas) however this varies considerably through the year with the highest embedded CO2 in early winter evenings when I have little if any solar PV to contribute to the grid, and may well be lowest when I and others have surplus solar PV. My understanding is that the lowest grid CO2 occurs with a combination of high renewables (such as particularly windy weather) coupled with low demand (such as summer nights).

Thus my own strategy is to:

  1. Maximise self-consumption of my own solar PV as my energy source with the lowest embedded CO2 (except in the event of an extreme plunge pricing event when the grid is under highest stress)
  2. Make best use of storage to minimise consumption from the grid in the evening peaks when embedded CO2 is likely to be highest.
  3. When a solar-shortfall is anticipated then buy electricity selectively from the grid at lowest CO2 (using Agile electricity price as a surrogate for CO2).

The ‘Appiest Days of My Life

One of the consequences of integrating a smart home is the large number of different apps, web portals and potentially sources of APIs involved. The ones I use include:

TitleAppPortalAPIPurposeComment
BrightYNYReads and stores consumption from smart meter.No price data for my tariff due to smart meter limitations.
EveY /3NNEve’s alternative to Home for all HomeKit accessories with additional functionality for Eve’s own devices.I prefer this to Home for editing rules.
I use Eve products mostly for central heating control.
HomeY /3NNApple’s own app for the HomeKit smart home ecosystem.Need to refer to device manufacturers own apps (such as Eve or WIFIPLUG) for some configuration and data.
HEMSNYN My own web portal to view HEMS schedule and status via Apache web-server on Raspberry Pi.
MyImmersunYYY /1Control of ImmerSUN power diverter.Available API provides some measurement and status data as per main screen of the app.
PowervaultNYY /2Control of Powervault storage system.Available APIs provide some user scheduling and status capability.
OctoWatchdogY /3YYFuture cost, and historic costs and consumption (30 prior days) from Octopus (electricity supplier).APIs provided by Octopus.
App developed by an enthusiast using Octopus APIs.
Octopus’s own web portal provides historic consumption but does not pair this with cost. Monthly statements show graph of consumption and cost for each day.
WIFIPLUGYNYControl and measurements from own brand smart plugs.Plugs also appear in Home and Eve apps.
I use for dishwasher and washing machine.

Notes to table:

  1. APIs not officially released. Reverse-engineered by an enthusiast and available on line.
  2. APIs not officially released. Used as part of a sponsored trial when I first got the battery and re-used by myself with some manufacturer support.
  3. iOS only. Not available for Android.

Some of these apps have similarities:

  • Both Bright and OctoWatchdog show whole of house energy consumption (and potentially cost) derived from the smart meter. However they have differences too. A smart meter sits on two networks: (i) the Wide Area Network (WAN) via which the meter communicates with the energy supplier and (ii) the Home Area Network (HAN) which links the devices in the home (electricity meter, gas meter, CADs/IHD and gateway). Bright connects to the HAN via small piece of hardware called a Glow Stick Wi-Fi CAD and collects its own data in real time and stores its own records of energy consumption in the cloud; while OctoWatchdog involves no extra in-home hardware, and takes data a day in arrears from Octopus not storing anything in the cloud itself. Bright’s USP is the real time consumption and current day’s data (neither of which OctoWatchdog supports), while OctoWatchdog’s USP is the availability of electricity price which isn’t available from the meter.
  • Both Eve and Home interact with all devices in the whole HomeKit ecosystem. Eve is best for creating rules and has more ability to configure Eve’s own devices, while Home is best for sharing access with family members. WIFIPLUG’s app is more limited only interacting with their own devices, and thus cannot see Eve or other HomeKit devices.
  • Both MyImmersun and WIFIPLUG apps, and the Powervault portal, allow configuration of their own manufacturer devices. They all have, for example, timer capability and data logging. MyImmersun is better for giving a whole-of-home view showing solar panel output and net input to house (so provides a more comprehensive energy monitor), Powervault shows no solar panel output but does give a view of whole-of-home, while WIFIPLUG provides only a view of the energy consumption of devices plugged in to the WIFIPLUGs.

And when the batteries go flat? (The previously unanswered question)

The height of summer is perhaps an odd choice of time for a post about heating, however we’ll get to that. Regular readers may recall that our smart heating controls enable the boiler when any radiator demands heat via its smart valve (eTRV) and disables the boiler when the last room is up to temperature. That rather begs the question what happens to the control logic when the batteries go flat. The HomekIt rules are not sufficiently sophisticated for the author to set that behaviour via the program, and I’ve seen no default behaviour described on-line.

Today the inevitable happened and a battery did go so low as to stop operation. The behaviour of the heating was to force the boiler on. Most rooms did not heat up as their own eTRVs recorded them already being sufficiently hot, although the bathrooms and cloakrooms did heat up (they generally lack eTRVs) as indeed did the room with the flat battery (my daughter’s playroom). Other symptoms included an icon in the Home app that would not grey out when disabled like other room eTRVs and the the boiler repeatedly being re-enabled even after manually disabled through the app.

Replacement with fresh batteries immediately restored normal operation.

Although any more heat input is unwelcome on a day as hot as today, we have at least demonstrated that the system is failsafe in a flat battery condition – I’d rather that the system heated up with a flat battery to prevent freezing damage in winter at the cost of some discomfort in summer due to excess heat.

It’s 265 days since my records indicate an earlier battery change, albeit for most of that time the heating hasn’t been on (so no power needed for valve movements). It’s over a year now that I’ve been using Ni-MH cells in these valves. The cells are slightly lower voltage than the recommended cells (1.2 versus 1.5 Volts) so do create spurious low battery warnings, but apart from that they seem to work well with adequate life before recharging. I thus anticipate continuing with their use of a means of reducing battery waste. I’ve had no cell failures to date.

The Big Picture

After a series of quite detailed posts, I think that the time has come for an updated high level overview of what we have.

Heat loss from the home

We moved to our early 1970s house almost 4 years ago bringing with us our electric vehicle. The house had already been refurbished with new double-glazed windows, had cavity insulation (although that wasn’t recorded on EPC so must have predated the prior owners), and a token level of loft insulation. The existing gas boiler was arthritic, couldn’t heat the whole house, but was quite good at heating the header tanks in the loft! We had gravity-fed gas hot water (i.e. no thermostat or pump on the cylinder) which was completely obsolete, the cylinder dated back to the building of the house and had no immersion heater (although we had the wiring for one). So what did we do?

Space heating:

Eve Thermo eTRV
  • We substantially increased the loft insulation to reduce heat loss.
  • We had a modern condensing gas boiler installed to improve efficiency.
  • We updated to smart controls using eTRVs to set both temperature set points and schedules at room level. I built a smart interface to the boiler so that heating can be enabled remotely. I programmed a series of rules into Apple Home allowing the smart thermostats to enable the boiler when any thermostat wants heat and disable it when no thermostat wants heat. Some rooms also have additional rules linking heating to open windows or movement sensors. All of this reduces heat losses by only heating rooms that are (or will be shortly be) in use.

Electricity supply:

Solar panels
  • We installed our own solar panels given 4 kWp generation. (I also own a small share of a solar farm although there’s no contract that I’m aware of between that farm and my home energy supplier)
  • I invested in an immerSUN to maximise self-use of our own solar by enabling loads when surplus solar is available.
  • We switched to a green electricity supplier so when we need to buy electricity it comes from renewable sources.
  • We bought a small storage battery 4 kWh to store some of our solar production for use later in the day. Subsequently I can also use it in winter to buy when the electricity price is relatively low to avoid buying when the price is relatively high.
  • We chose a dynamic smart tariff to buy electricity at the lowest price based on market prices established the day before. The prices change each half hour and are established in the late afternoon on the day before.

Water heating:

Hot water cylinder
  • We replaced the old hot water cylinder with a modern insulated one (to reduce heat loss) with a low immersion heater (to allow more of the water volume to be heated).
  • Our principal water heating is now by diverting surplus solar electricity proportionately to the immersion heater, that’s backed up by the gas boiler which is enabled briefly in the evening for water heating in case the water isn’t yet up to temperature, and when the electricity price falls below the gas price I can enable the immersion heater on full power.
  • All accessible hot water pipes are insulated.

Electric car charger:

Electric car charger.
  • I built my own electric car charger that takes an external radio signal to switch between four settings 0, 6, 10 and 16 Amps to help me adjust consumption to match to availability of output from my solar panels. (Subsequently such products were developed commercially with continuously variable current limits, but the limitations of my immersun and on/off radio signal don’t allow me to go quite that far. Having said that my car only does 0, 6, 10 and 14 Amps so I would gain no benefit from a continuously-variable charger paired with a 4-level car).

Smart electricity controls:

Smart controls
top: HEMS (to manage bought electricity) and junction box
mid: radio transmitter (to car charger)
bottom: immersun (to manage self-consumption)
  • We have two systems for smart control of electricity:
    1. The immersun to maximise self-use of our solar electricity by proportional control of loads.
    2. A HEMS to manage the purchase of electricity (when necessary) at the lowest price by maximising consumption when the price is lowest.
  • When both systems want to enable loads (because the bought price is low and we have a surplus from our own panels) then cost is prioritised, so we’ll buy from the grid any demand not being met from our own panels.
  • Both systems are linked to 3 devices:
    1. Battery storage. The immersun is configured to work alongside the battery storage with the battery storage as the top priority to receive surplus solar PV. The HEMS can switch the status of the battery as required to charge from the grid when the price is lowest, or to discharge when the price is highest, or indeed to revert to default behaviour.
    2. Car charger. Second priority for the immersun after battery storage.
    3. Immersion heater. Third priority for the immersun after car charging.

The future

I have no firm plans for the future. I’m toying with adding to the HEMS various features including:

  • Making the display switch between GMS and BST as appropriate (it’s all UTC at the moment).
  • Edit configuration via the web interface rather than a virtual terminal.
  • Control a domestic appliance. Our washing machine was replaced relatively recently, but the dishwasher is playing up a little and may be a candidate for HEMS integration where the optimum start time is selected to deliver lowest energy price.

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.

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
ZonesSingleMultiple
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

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.

Discounted renewable power

img_0596We’ve recently moved to Bulb as our electricity and gas supplier. Bulb is a new company founded by Hayden and Amit providing 100% renewable electricity and 10% renewable gas and, for us, was the cheapest provider of the same.

Bill logo

Bulb logo

Bulb are currently offering a £50 discount to new customers via this link, so there’s even more incentive to go renewable.

They also have 9.8 out of 10 on TrustPilot, a UK call centre, and are a Living Wage employer.