The picture above show readings from furnace in our house (the HULK). The first diagram show the boilers water temperature. One can see when the stove is active. As seen it failed to start this morning. Alarming me with SMS, email and telegram so I could handle it.
The second diagram show the temperature in the core of the warm water reservoir. This is the supply of hot water.
Third picture is hot water temperature measured on the pipe out to the house from the hot water reservoir. When no water is taped the temperature will fall. When hot water is taped the temperature will rise to the hot water temperature as expected.
The interesting part here is the sensor connected to the boiler container. It does not do aging very well and will go more an more of over time showing a higher temperature then it should. The sensor is a 10K NTC sensor. I have changed this sensor several times now over the years and I probably have done this twice a year.
I use many NTC sensors and this is the only one that behaves in this way. No idea why!?
The setup here is a Kelvin NTC 10K connected to a Raspberry Pi running the latest version of the VSCP Daemon which send the data to three MQTT brokers. This data is in one place handled by a node-red setup and the UI above is shown on that machine.
Investigation of this continues…