Richard is the PC Hardware Lead at XDA and has been covering the technology industry for almost two decades. He's been building PCs since young, and when not creating content, you can often find him inside a chassis somewhere.
Central heating is wonderful. Using gas boilers, we can heat up the entire home through pumping hot water to multiple radiators. It's effective but consumes fossil fuels that are only increasing in price. That's where electricity comes into play. We don't have gas or oil in our property. It's all electric, which limits our heating capabilities. We used to have old storage heaters, which were awful, and have since switched to oil-filled radiators and smart plugs to create a semi-smart heating system.
The goal is to eventually utilize heat pumps and multi-split air conditioning, but until we eventually have it installed, we're planning to make the most of our current setup. To achieve this, we've used Home Assistant to handle heating for a year, and we've saved some money in the process.
Making the most of heating
Home Assistant and its incredible automations
The primary issue with using oil-filled radiators is not that they're inefficient, because they essentially convert electricity into heat with minimal loss, but heating in general using electricity is so expensive. We're on an energy tariff designed for energy storage and electric vehicle charging, providing low-cost electricity during the hours of 00:30 and 05:30 at $0.10 per kWh. Our price for electricity outside of this window is $0.60, so it's vital we make the most of the cheap power.
This is where Home Assistant can come into play. I have various automations configured for the smart plugs controlling our radiators, but there's always one automation that runs when any of them turn on. As soon as Home Assistant turns on one of the radiator smart plugs, a countdown starts that limits output to the span of 60 minutes. This is largely enough to heat any given room to a comfortable temperature and allows us to set each radiator to maximum so it heats up the room fast.
Through integrating Home Assistant into our electricity provider, we can use automations to fire up heating when the sun has fully topped up our batteries during the winter months. It can also run the heating throughout the home for an hour at 04:30 so the house is relatively comfortable when we surface between 06:00 and 08:00. This is a smart way to make the most of the available heating capacity without incurring ridiculously high energy costs. Running just one of our radiators for an hour costs around $1 at peak pricing.
None of the radiators will turn on if the temperature outside is above 10 degrees Celsius. Autumn and winter seasons can sometimes produce relatively mild days, so we don't want automations kicking on when there's less of a need. Home Assistant can use current temperature readings as an input, which can be sourced from online providers or through local temperature sensors. We use a combination of both, taking readings within the home as well as outside.
Not relying on human intervention
The worst thing we could do for our home is to rely on our stressed minds to remember to disable radiators when the room is comfortably heated or if we're leaving the house. Because we have to manage each radiator manually, there are times we forget. Home Assistant's automations remove this part of the equation. There's always a one-hour cutoff to prevent one from running for too long. The schedule ensures we don't need to worry about turning on the heating.
Creating some seriously simply yet effective automations
Creating a DIY heating system with smart inputs is easier than I thought
If you happen to be in a similar position as me, do yourself a favor and buy some smart plugs. Make sure they're rated for handling sustained loads and you're good to go. The actual automations that will save money and control everything don't need to be elaborate either. Temperatures, times, geo-location, and motion/infrared sensors can all be used to determine whether a room is occupied to have heating enabled and running.
I started simple with three time-driven automations. At 04:30, turn on all radiators. Then a second script starts running per radiator, which counts down from an hour. Once that timer ends, it turns off the switch. I did it this way so I can quickly toggle these timers depending on whether I want specific radiators to run for longer, etc., without having to edit existing automations. Helps keep it simple for others within the household to use the system manually too.
The second automation for all downstairs radiators kicks in at 17:00. Upstairs radiators are activated at 20:30, providing some warmth for the bedrooms before everyone hits the pillow. I could have left it like this, and we would have a capable system that kicks in much like a normal central heating counterpart would do, just with fewer radiators and considerably higher operating costs. That's when I started to add more parts to the automations.
First was temperature, to ensure the radiators are only coming on when the room they're located in actually requires additional heating (it's usually the case when dealing with stone walls). External temperatures are provided by an online source using approximate location. Then we can use Alarmo integration. If the system is set to Away, there's no one home, and thus radiators don't need to activate.
Creating my own heating system
Home Assistant was already capable enough and proved itself to save us money through controlling our home solar and battery storage setup. But this past year has shown just how much we can effectively save with automations, at least compared to manually using our radiator configuration. Until we eventually get a heat pump installed with some air conditioning, this is going to be about as good as we can get with limited hardware and software control.
Smart plugs are the unsung heroes, allowing us to go from almost 10k Wh of power per day for radiators that someone may leave running is around 4 or 5 kWh depending on usage and how cold it is outside. That's a substantial saving, especially when much of it can be covered by our batteries that can take advantage of cheap charge rates through the night. Some may assume it's the complicated automations that will make the most difference, but it's quite often the opposite.