Background
We have an immersion heater. Not used much until we had solar installed. We found it was a good way to use up surplus solar. Built an automated system from a commodity part to do this, and just posting an update. The system worked fine for many years (2020 onwards), but then it stopped. Testing the voltages, I saw 240V coming out of the contactor, but only 70V AC on the heating element.
So the fault was between the two, and the only thing was a junction box rated at 40 amps...
So the fault was between the two, and the only thing was a junction box rated at 40 amps...
- Opening the perfect-looking junction box. I could see the casing had done its job!)
- Junction box removed and heat-resistant flex with ferrules added.
- I had to install an access point near the unit as the WiFi reception was poor. This is likely due to increased RF noise and Wi-Fi/ISM transitions, as we have upgraded to fibre and Wi-Fi 7. Plus new wireless IoT devices nearby
System seems fine now, all working as normal. Shows the value of using standard parts.
If you want to read more about this project, it's mostly Node Red, so almost no code, so simple to manage, the heavy lifting is done in C/C++ on IoT hardware, a few Flask calls for data packaging, e.g., JSON as a string suck in C/C++! Each device is software-defined. I use the ESP 8266 chips and relays, $1 each. Each runs a web server and an MQTT server, making integration simple. There is a local web server on each $1 computer, so I can manage them directly if needed (for setup). It also has console and local functions, like timers, so the IoT stuff can operate during a network or comms outage.
Here is a potted history of the idea to its daily use now for >6 years
