@kimot I am not handling that situation. I'm taking for granted ssr will do his job. Maybe there's some ssr safety topic I'm unaware? Suggestions for a v3.0 are welcome.
About the temperature measuring... I use two sensors. The one in the board protects electronics from temperatures beyond design (60°C). It's near the ssr because the ssr's derating curve is the most limiting condition.
The control sensor is placed in the bottom of the heater. It connects to the board through a 3 pin header connector.
@fets So far, I have only built the 5x5 board (but the others should be schematically identical). The only issue I have found so far is that I cannot get the ISP port to work. But I have checked and I have an identical setup on the 1.0 board and that worked, so I suspect the programmer is too weak to drive the net on this one. So it is not a board-issue per se, and might only be an issue on the 5x5 board as routing is the most complex on that one due to the size.
