After several months of using the original version - I ran into some problems. The biggest issue was I neglected to add any transient voltage suppression to the board - esp on the 12v input that is attached to the Van alternator. I think there were some serious voltage spikes on this line and fried my Arduino a couple of times. I added a power switch too!
The original design goal was to use a little power as possible, so I wanted to use the eInk as a way of reducing the draw. I also really liked the resolution and contrast. I also found the eInk display to be really slow. The only UI in the van is the display, so updating it quickly turned out to be important. Also turns out, being hooked up to house power - there's tons of power, so no real power issue. I switched to a 128x64 OLED and now can update the info a lot more frequently. It's a better UI and makes it easier to understand what's going on.
Since I can update the display more frequently - I added the concept of error messages. Shown in the pic is an error the fridge temp is high. This is fair as the fridge is off and the temp IS high.
I also had problems with 2 of my temp sensors. The original location for my outdoor sensor (between the sliding door and the kitchen cabinet) was actually too "inside". I managed to find a penetration for the hydronic lines under the kitchen cabinet, so I remounted the sensor under the van and secured it to some lines under the vehicle. My indoor sensor was mounted to the original PCB. Unfortunately this always read high - I think the uC and other stuff right there was generating heat. Also I wanted this to more or less agree with the Timberline thermostat, so I relocated the sensor to be next to the Timberline one. (I also moved the Timberline sensor to the 2022R location next to the bathroom, as it was mounted above the bench seat - in a heat island!).
The above changes has allowed the system to run with no real issues for a few months now. It survived a 10 day trip, so I think the voltage spike issues have been solved.
Next up are some updates to the iPhone app, but that's for another time.