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How To LOWER your GAS COSTS DRASTICALLY with Home Assistant!

This video is made possible thanks to Stiebel Eltron and Savvycons.

Hey! Today we are going to do something different to save on energy costs. We are going to install a boiler that heats up at times when my solar panels generate enough power using Home Assistant. Let’s do this!

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Today is a special day because we are going to install a boiler from Stiebel Eltron to save energy costs. I am waiting for Roy from Savyconns who will install the boiler for me. After the boiler is installed, we are going to try to use Home Assistant to make this boiler Smart so that it only heats up when my solar panels generate enough power. Let’s see if we can make this work.

Ah, there’s Roy with the boiler!

Let’s open the box and see what’s in it.


The boiler is a Stiebel Eltron SHZ 100 LCD boiler. This is a 1-4 KiloWatt boiler of 100 liters. It has a mixing water capacity of 220 liters and can be heated from 20-85 degrees Celcius. It can produce 18 liters per minute.

The size of the boiler is 1050 by 510 by 510 millimeters and weighs 39,5 kilograms when it’s empty.

The price of this boiler is € 711.

I use this boiler in a household of three people and it has more than enough capacity for us all.


You can install the boiler yourself, but I wouldn’t recommend it if you’re not a professional installer. Roy from Savvycons installed the boiler at my place. He put it next to my gas installation. The installation looked straightforward. It was a matter of measuring where the boiler should hang and drilling two bolts into the wall. Then the boiler could be hung up and it had to be connected to the water supply. Roy then connected the pipes and screwed the cover on the boiler.

If you’d like to have a boiler installed by a trustworthy installer, you can contact Roy from Savvycons using the link in the description of the video. Savvycons installs boilers in the Netherlands, Belgium, and Germany.

How to make the boiler smart?

This boiler is not a smart boiler, but a boiler is in fact just a big kettle, so I decided to use a Shelly Plug S to switch the boiler on and off. This plug also has power measurement, so that I can see how many Watts the boiler is using. We’ve set the boiler to use 2000 Watts so that the Shelly Plug S is safe to use.

Now that the boiler is installed, the installation works as follows. If I need hot water, it is first taken from the boiler, and only when the boiler can no longer supply enough hot water, my gas installation is used. I want my boiler to heat up when my solar panels generate enough power or when the boiler hasn’t been heated for a couple of hours to prevent a possible legionella infection inside the boiler.

This solution only works for tap water. It does not work for my heating system because that’s a different system, but it will still save you quite some money. I went from this gas usage to this gas usage. You can clearly see when the boiler was installed.

How to make a dumb boiler smart?

Now, let’s make our dumb boiler smart using Home Assistant. It’s actually very simple to do. The only thing that you need is a smart plug that can handle enough Watts. As said before, I use the Shelly Plug S for it, but you can use any other smart plug that supports 2500 watts or more. And you need a boiler and solar panels of course. I use the Solaredge system for my solar panels and have the Solaredge integration installed into Home Assistant.

What do we want to achieve with our Smart Boiler?

I want to switch the boiler to on when the net power in my house is below minus 2100 Watts and I want to switch the boiler off as soon as the net power in my house is less than 0 Watts. Next to that, I want to switch the boiler on when the boiler has been off for 10 hours.

So, first I need to determine the net power usage in my house. I am lucky because my electricity provider delivers me the current watts usage in a sensor in Home Assistant. If you’re not so lucky, you need to create a custom template sensor that subtracts the solar panel production value from the electricity consumption value in your house. If you want to know more about how to create custom template sensors, then check out this video.

Create a helper to store the trigger time

Next to checking the net power, I want the boiler to turn on automatically when it has been off for 10 hours. I need to create a date and time helper for this.

  • Go to Settings -> Devices & Services and click on the Helpers Tab.
  • Click Create Helper.
  • Select Date and/or time helper.
  • Give your Helper a name. I call it Boiler Trigger Time and select the icon water-boiler-off
  • Don’t forget to check the Date and time radio button.
Create the automation

We will now create an automation that handles the boiler based on the net power and time that has passed after the boiler has been shut down. I’ve already created this automation and will show how I’ve put it together.

The automation looks like this:

Define the triggers
  • I defined three triggers:
    • One when the current power usage is below minus 2100 Watts.
    • One when the current power usage is above 0 for 10 minutes.
    • One when the boiler has been off for over 10 hours.
  • The first trigger checks if the power usage is below minus 2100 Watts. My boiler is set to consume 2000 watts, so, to be sure, I want it to turn on as soon as my net power is below minus 2100 Watts. This trigger has Trigger ID “turn on”.
  • The second trigger checks if the power usage is above 0 Watts. This trigger has Trigger ID “turn off”. I can understand that you are wondering why I check if the net power is above 0 Watts and not above minus 2000 Watts. It would indeed be better to check if it’s above minus 2000 Watts to make sure that the boiler only is turned on when there’s enough free power, but if I do that, the boiler is turned off a lot of the time. You can play with these values to suit your needs. I also check if the net power has been above 0 Watts for 10 minutes because sometimes the sun disappears behind the clouds and comes back after just a couple of minutes.
  • The Third trigger is a template trigger and checks if 10 hours have passed. What I do here is that I subtract the time that I stored in the helper from the current time and check if the difference is higher than 36000 seconds, which equals 10 hours. I will explain in a minute how I store the trigger time in the helper. This trigger has the Trigger ID “10 hours passed”.
Define the actions

Now, let’s head over to the actions.

I start with a “choose” action. Within this “choose” action I define three Options:

  • One when the boiler triggered to on.
  • One when the boiler triggered to off.
  • And one that checks if 10 hours have passed.

The first option checks if the boiler is triggered to on. I check if Trigger ID “turn on” is triggered. If this trigger is triggered, then I use the call service action switch.turn_on to turn on the Shelly Plug S which I called “Boiler”.

I do sort of the same in the second option, but this time I check on the Turn Off trigger. If the Trigger with Trigger ID “turn off” is triggered, I use the call service switch.turn_off to turn off the Shelly Plug S. Next to that, I call the service “input datetime set” and I set the value of the Helper that we’ve just created to the current time by using the template value Now().

So, the Helper will be filled with the current date and time as soon as the boiler switches off.

In the third option, I check if 10 hours have passed. I check if the trigger with Trigger ID 10 hours passed is triggered. If this condition is met, the action will fire. This action is a switch.turn_on action and the entity is the Boiler entity, which is again the Shelly Plug S. So, this action handles the 10 hours interval for the boiler.

Finished the automation

With this automation and helper, you fully automated your boiler to save on gas costs. You can type the code for free from the screen, but I also created a blueprint for you so that you can implement this yourself more easily into Home Assistant. You can download it for a small sponsoring fee via the download link in the description below this video.

Things to consider with a Smart Boiler

I am using this for more than one month now and I must say that it works pretty well for me. But, it’s summertime over here and my solar panels generate a lot of power these days. I am sure that I have to make this automation more complex once the summer is over. At that moment I will implement some triggers that will fire when the energy price is low during the day. And I will change the blueprint accordingly of course so that you can download the update for free if you ordered it before.

I want to thank William who recorded the installation and helped me a lot in getting a grip on making my videos more professional. And thanks to Stiebel Eltron and Savyconns for sponsoring the boiler and installation to help me save on my energy costs.

If my videos save you time, please consider becoming my patron just like these awesome people did. You play a vital role in keeping this channel alive. The links to Patreon, Ko-Fi, and Joining my channel are in the description of this video. Thanks for watching and don’t forget to give this video a thumbs up and subscribe to my channel. I’ll see you soon in my next video.

Bye Bye.

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