Arduino ESP32 DS18B20 Temperature Logger

I would like to introduce you to my solution for monitoring the temperatures of our heating system. I had wondered what the individual temperatures of the heating circuits are, how warm the water is from the block power station and where the heat goes at our hot water tank. Now I can see how much the hot water tank loses temperature if no water is extracted, whether there is unwanted circulation in the pipes and when the circulation pump actually causes the water to circulate. I was then able to optimize these settings. I can look at the individual temperatures in the heating room on the board, or comfortably in the living room or on the go with the Android app IoT Sensor Data. In the app, the current temperature progression or the progression two weeks ago can also be tracked. If you want to recreate this and are a little artisanally gifted, you can do so. If you don’t have a soldering experience yet, you can venture through the project here. No programming skills are required. A program is flashed on the board and an app is installed from the google play store. I hadn’t found comparable finished solutions on the internet. There are ready-made temperature loggers with USB connection and a sensor, but not with many sensors.

Attention: There is now a new ESP32 version that also supports MQTT and Home Assistant Auto-Discovery.  https://github.com/SebastianHinz73/TemperatureLogger

Technologie Overview

The temperatures are measured by sensors (DS18B20) on the heating pipes, read out from the ESP32 board and stored on the SD card board. The user can query the current and all stored data via the Android app.

Example

In the picture, the temperature of the block power station (blue), the hot water temperature (purple) and the temperature of the charging forward flow of the hot water tank (red) can be seen. You can see that at 6:00, 17:00 and 21:00 the tank was heated and that a lot of warm water was taken at 6am. On the left side you can see the graphic view of the sensors in the house. The wallpaper is an SVG and can be replaced in the app. By clicking on the sensors, the graphs on the right side are switched on or off.

In the picture, the temperature of the block power station (blue), the forward flow of the heating (green) and the heating return (light blue) can be seen. The night shut is recognizable. Furthermore, it is visible that it has not been heated all the time, so that the heating forward flow (green) has also dropped. On the left, the standard view of the sensors can be seen. By clicking on the sensors, the graphs on the right side are switched on or off.

Hardware ESP32 WEMOS Lolin

The ESP32 WEMOS Lolin board is used. This board has a small OLED display, WIFI connectivity and can be programmed with Arduino, ideal for this application purpose. An SD storage board and a micro SD card are used to store the data. A web server running on the board that provides the data for the Android app. The data is measured with multiple DS18B20 temperature sensors connected to the board with a 3.5 jack plug.

IoT Sensor Data

In the Android app, the current temperatures can be queried by the sensors. The temperature progression of the current day or any recorded date can also be looked at. There is a demo version for Android that accesses a simulation on the Internet to get an impression of functionality.

Cost of replica

The replica costs approx for the hardware, 10 sensors and the case. 100 euros when ordering the parts in Germany. Especially with the ESP32 board, the sensors and the audio splitter, savings can be made (approx. 30 euros cheaper) if ordered from Alibaba Express. The software for the ESP32 board is free of charge. The printing files for the case (stl) cost 20 euros and can be purchased here via the reseller Digistore24. IoT Sensor Data is installed through the Google Play Store. The demo version is free and the correct version that can access your own board costs 25 euros.

You may also be interested in my other internet project: Build your Lyrat ESP32 Internet Radio

Alternatives

Maybe you are looking for another pre-assembled temperature logging solution? Have a look at www.openandhome.de