During a long period of the year we get the hot water in our hose from the sun. We use hot water for showering, our hot-fill washer and our hot-fill dish washer. If the sun is not shining (living in the Netherlands it sometimes happens ) the central heater unit warms the boiler. Of course I wanted to know when I can switch off the central heater, mostly its in May.
So for the measurements I’ve connected a few One Wire Digital Temperature Sensor (DS18B20) to a Netduino-2 and wrote a small C# program which sends each 2 min. via WiFly the data to ThingSpeak. For measurements look here.