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Reverse engineering the Essent E-thermostaat


Essent E-Thermostaat

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In every modern home nowadays, there are at least one or more home automation devices. Probably the most used kind of devices are smart thermostats. Often energy companies have there own devices which you can buy with a discount if you take a contract with them as well. There are also some standalone devices from third parties available on the market. Regardless of which device you choose, they all have roughly the same benefits over a standard thermostat: controlling the temperature when away from home, detecting if someone is actually at home and the overall ease of programming.

As I live in a studio in the attic of a building, it is not the most isolated place to be in. So when not heating, temperatures could drop quite low in winter and reheating the place could take some time. I don’t like to waste unnecessary energy by keeping my place at a constant temperature when I am not home, so I soon wanted to switch my simple thermostat to a more advanced one. Being a ‘geek’ as well I soon looked into these smart thermostats. I found some second-hand thermostats for 30 euros which have been issued by a Dutch energy company called Essent. Some research turned out these thermostats could be used even if you’re not a customer of Essent. So I bought one, paid ICY (the manufacturer of the thermostat) another 10 euros to transfer the ownership (I know, it’s ridicoulous) and started using the device.

As this ‘E-thermostaat’ is a device already released in 2011, it’s features are somewhat limited compared to today’s standards. Only 30 scheduling moments available, only 3 temperature presets/modes (comfort, save and away) and some very limited settings for controlling the behaviour of the thermostat. You can program the device via USB on a Windows computer using the supplied software, using the web portal via Essent’s website or via Essent’s app for iOS and Android. That’s basically it. No support for any third party home automation software. All the ‘smart’ communication goes via the servers of ICY. And this last point is of course a sore spot when a device goes end of life… And that is exactly what happened.

Last December, I got an email from ICY informing me that they will discontinue this product in February 2019. However, if enough people are willing to pay a contribution, they will keep their services running. The costs would be €1,95 per month so €23,40 to keep the service running for another year. Even though the costs are not that high, I still think it is ridiculous to pay that amount of money for a service with such limited features comparing to today’s standards. This is where my journey to reverse engineer this device started.

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8 thoughts on “Reverse engineering the Essent E-thermostaat”

  1. Enjoyed reading your article, too bad you didn’t succeed.
    I will check back later to see if you see if any progress has been made.
    In the worst case,. I have disposed of my e-thermostaat and help is too late for me

    1. Thanks for your response. For now I paid the 24 Euros so I can use the thermostat for at least another year. So probably no updates from my side, but if so I’ll let you know.

  2. Maybe it is possible to read the thermostat thermometer and rig the + and – button so you can control it with an Arduino or Pi Zero? Or even a step further, connect said Arduino or Pi to read the data that is going to the LCD?

    1. That’s probably feasible, however I doubt if that would be much less work than designing my own thermostat and letting my home automation system control it. If you already go the extra mile to get an additional device such as Arduino or Pi to read the pins, switching a relay and reading a temperature sensor is not that much work either though.

  3. I wonder if you were able to make any progress. The next year (for prolongate the subscription) is coming.
    I’m asking myself if it couldn’t be better to design an open source thermostat. But I also agree that another €23,40 shouldn’t be the problem.

    1. In the end I did design a very simple ESP8266 thermostat which communicates via SSL to my MQTT server. I can control it with my Home Assistant installation. It’s been working okay but because it sometimes crashes and I have to manually repower it, I haven’t released it yet. It’s designed to always fail safely so the heating turns off so it’s no big deal but it’s not ready to release.

      At the moment I am also considering flashing Tasmota, which I use for some of my lights. I think that is a better option.

      So to answer your question: no progress with this project and I probably never will. The thermostat was never perfect in the first place.

  4. Hi, thanks for this read! It’s a few years later now, and I was wondering if you ever did an attempt to try things out with the base station?

    1. Hi Robert, no I did not. This Essent E-thermostaat ship has sailed for me. I have moved in the meantime and am running a heat pump system now, so I have little need to control my thermostat remote anymore.

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