Heat Pump mythbusting

An AI generated image of a heat pump outside a house

Whilst we currently still have a traditional gas boiler for our heating and hot water, should it ever break down or need replacing, we’ll get a heat pump instead. Heat pumps use electricity to provide heat, and are about three times more efficient than even the newest condensing gas boilers.

There’s a really good visual explainer from The Guardian here about how heat pumps work. Basically, they work like fridges in reverse. Heat pumps extract any heat from the ground or air, and pressurise it using a compressor. The pressure heats the air, and the resultant hot air heats up water. This water is then pumped around your central heating system, or into your hot water tank. Using pressure to heat air in this way uses significantly less energy than heating it directly.

But there’s a lot of misinformation out there about heat pumps. This page on CarbonBrief.org lists 18 myths. Of these myths, 12 are outright debunked and the remaining six are in a grey area. And it seems to be an issue largely limited to the UK; in 2021, we had the lowest uptake of heat pumps out of 21 European countries.

Heat pump uptake in Britain

So why is Britain in particular so behind on heat pump uptake? It seems like political lobbying has a role. Boiler manufacturers are trying to push back phase-out dates, presumably as they have huge amounts of stock that would be otherwise worthless.

But also Britain is relatively unique in the world in that we have a privatised gas network. Different private companies each produce the gas, distribute the gas, and bill us for the gas in our homes. The gas producers can sell this gas on the open market, which is why our energy bills rocketed when Russia declared war on Ukraine and the wholesale price went up. Gas is distributed by the privatised National Grid, and in local areas by companies like Cadent and Northern Gas Networks. And then we pay consumer energy companies like British Gas, Octopus, EDF and e-On to get the gas into our homes. In other words, there’s a lot of money to be made from gas, and therefore vested interests in keeping gas supplies going.

Our move away from gas

When we bought our house in 2015, it was very reliant on gas. As well as a 40+ year old gas boiler supplying central heating and hot water, there were two gas fires, a gas oven and gas hob. We got rid of the two gas fires even before we moved in, and replaced the gas boiler with a more efficient condensing boiler. At the same time, we had a Nest smart thermostat fitted. Then in 2022, we got a new kitchen with a dual electric fan ovens and an induction hob. So our boiler is our only remaining gas-using appliance.

I suspect we would have opted for a heat pump instead if they had been more widely available and affordable. As it is, our boiler is only just out of its warranty period and so it’s not worth replacing yet. But when it is time to be replaced, we’ll get a heat pump. After all, we generate our own electricity using solar panels. It would also mean we could have our gas supply turned off, saving us from paying the daily standing charge. This is currently 29p per day, which adds up to over £100 per year.

Meross energy monitoring smart plugs

A photo of a Meross smart plug in a UK plug socket

I’ve recently bought a pair of Meross energy monitoring smart plugs (sponsored link), and by integrating these with Home Assistant, I now get notifications when the washing machine and tumble dryer have finished.

Previously, I’ve used Tuya smart plugs. Which are fine, but these ones don’t do energy monitoring, don’t work with Apple HomeKit and I have some privacy concerns. The Meross plugs, on the other hand, do offer energy monitoring, can be used with 13 Amp devices, and also work with Matter. They’re also smaller, and feel more solidly built than the older Tuya plugs.

Matter support

These smart plugs also support Matter, the open smart home standard. This should mean that you can use them with any smart home ecosystem, whether that’s Amazon, Google, Apple HomeKit, Samsung SmartThings or Home Assistant. I was able to get them to pair with Home Assistant, but not with HomeKit. It turns out I need a device that can act as a HomeKit hub, which can be a permanently plugged-in iPad, Apple TV or Apple HomePod. It won’t just use any other Matter server on my home network. This is ironic as the Home Assistant app uses the same Matter provisioning process on iOS devices.

It’s also worth noting that Matter support is limited to turning the smart plugs on and off. I’m guessing the Matter specification doesn’t include energy monitoring as yet. Also, these smart plugs connect over 2.4 Ghz Wifi, which is worth noting if you’ve configured your Wifi network to only use 5 GHz. They don’t use Thread.

Screenshot of the hassio_appliance-status-monitor Blueprint being configured as an automation in Home Assistant

Making use of energy monitoring

If you want to take advantage of the energy monitoring capabilities of the smart plugs, you’ll either need the official Meross app (for iOS and Android), or use Home Assistant. Whilst I have installed the Meross app, I’ve set up the automations in Home Assistant. There isn’t an official Home Assistant integration for Meross, so you’ll need to install the Meross LAN custom integration which is available through HACS.

Once you’ve set it up and added your devices, you’ll need to set up the energy monitoring automation. By far the easiest way is to use this BlueprintBlueprints are essentially templates for automations that you can download and configure. Make sure you follow the instructions, as you’ll need to create four Helpers for each smart plug, and give them specific names.

You can then define actions to take when the energy monitoring detects the appliance has started and ended. In my case, I’ve told it to send a notification to my phone when the device has finished. In the case of my tumble dryer, this includes a 15 minute delay as it uses less power towards the end (and otherwise results in notification spam). You may need to tweak the power thresholds as well. If all goes well, then you’ll get a notification like the one in the screenshot below.

A screenshot of a notification from Home Assistant stating that the washing machine has finished, triggered by the energy monitoring smart plugs

Doing this means that you can get one of the key features of a smart device, without paying a significant premium. I paid £25 for the two plugs from Amazon, whereas it would have cost at least another £100 to buy a smart tumble dryer. Our washing machine is 9 years old and I’m not even sure that smart washing machines were on the market at the time.

Is there a Zigbee network in your house?

A photo of our Smart Meter which states it is Zigbee certified

If you’re in the UK, and have a smart meter, then your home probably has a Zigbee network that you may not know about.

What is Zigbee?

Zigbee is a wireless mesh networking protocol, that is commonly used for smart devices. If you have smart lightbulbs, such as the Ikea Trådfri or Philips HUE range (sponsored link), then Zigbee is what these devices use to communicate with their hub.

Zigbee isn’t the same as Wifi. Wifi devices belong to the 802.11 family of IEEE standards, whereas Zigbee is in the 802.15 family . There’s a difference at the hardware level, so a device that supports Wifi can’t use Zigbee unless it has a specialised chipset. However, there is commonality between the two; like Wifi, Zigbee uses IP addresses, and operates on the 2.4 GHz band.

Our In Home Display, which shows our usage from our smart meters and connects using Zigbee

If you have smart meters for your electricity and gas, then these will use Zigbee to communicate with your IHD (In Home Display). This is the small device that shows your current and daily usage.

Can you access this Zigbee network?

No. Even if you have a device with Home Assistant and a Zigbee dongle, it won’t be able to see the Zigbee network that your meters and IHD use. I suspect this is because your electricity meter has its own SIM card, to access the internet to send your readings. If you could access this Zigbee network, then it may use your electricity meter’s internet connection and not your own.

There are, however, some devices that will bridge between this Zigbee network and your own Wifi network at home. Some newer IHD devices offer this, and if you’re an Octopus Energy customer, you can join the waiting list for the Octopus Home Mini. I joined the waiting list a few months ago, but I haven’t heard anything yet. Meanwhile, you can also buy a Glow CAD (Consumer Access Device) for £65, which can connect to Home Assistant. Alas, it’s out of stock at the time of writing.

Another option for Octopus Energy customers is this Home Assistant addon, which brings in your usage data. However, it updates half hourly unless you already have an Octopus Home Mini.

Other ‘secret’ networks in your home

In our home, we also have a couple of Thread networks. Thread is related to Zigbee in that it’s also in the 802.15 family, and is arguably a successor. Nest developed it to enable their smart thermostats to talk wirelessly to the heat link that connects to your boiler, so this makes one network. Newer Nest thermostats can act as a Thread Border Router and so other devices using Matter can connect to it, but we have an older model.

We also have a pair of Google Nest Wifi devices (a hub and a point) which use Thread to communicate with each other. Google has updated these to offer a Thread Border Router, and so I’ve been able to access this with Home Assistant, ready for when we have some Matter compatible devices. So at least I can access one of the three non-wifi networks in my home.

Further reading

Whilst researching this, I came across this Hacking Your Smart Meter (Part 1) article, although there doesn’t appear to be a part 2. Instead, the author, Terence Eden, uses an API from his energy company as above.

The Smart Meter Home Area Network is also a really useful article, on what is quite a well balanced web site about the various pros and cons of having a smart meter. Because we export excess energy from our solar panels, we need to have a smart meter to be paid back for what we export.