I moved the project to some acrylic in what is possibly the final stage for the project.While I thought the software reset for the Ethernet chip would suffice for connection problems, it appears this isn’t the case. I’ll try reprogramming the chip with an interrupt reboot for the main program loop, currently the device isn’t sending info to ThingSpeak.
Once the code is running smoothly (for at least a week) I’ll add email notifications. In the future I won’t use this Ethernet chip, there is a similarly priced chip I have which is much more capable.
I’ve setup the two temperature sensors at the inlet and outlet of the cabinet and I’m seeing around 5 degrees difference between the two, so I guess its critical the fan is running, I guess a lesson there is the importance of passive cooling.
There is only one voltage regulator for the device, despite having a 5v USB input and the 12V cabinet PSU, to switch between the two there is a pin header with a jumper. I tried using a diode, but this I think is the best solution. The voltage regulator outputs ~3v3 with either input.