I think these look very interesting to do with small children may be able to stimulate their curiosity, the current video games are too much influence on children, occasionally the family together to do their own small games is a new experience.
@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.
No problem, I am running the nrf24 mqtt gateway on the rpi and it is working with no problem with domoticz. I choose the mqtt client gateway because I wanted to tinker around MQTT, but you could go for the ethernet gateway that is easier to manage.