NTC and arduino P.I.D. SSR

Projects General Guidance
1

Greetings to all !

If I may please ask for your advice on the following project:

I have 2 ΝΤC thermistors @ 10ΚΩ at 25C with B constant 3950K (they can read up to 200C) and wish to control two SSRs on the output of which, I will connect 2 heating elements (one on each), so two input temperatures independent one from the other, and two output channels again one separate from the other.

I would like to be able to read set and current values of the temperatures on a small LCD screen (maybe 2 lines?) and to be able to create a very simple gui on the board's LAN address to adjust settings from there, e.g. set channel 1 from 70C to 130C.

What would be (if possible) the smallest Arduino to use as P.I.D. controller based on the above with wifi capabilities? I have seen some libraries online but would like to ask the community for hardware connection opinions. Would I be able to do that on Arduino uno for example or any other? (Where I will install the electronics I have limited space)

Thank you in advance!

2

Any Arduino would do. Is PID really needed? Why not switch power on and off at the temperature set? What is the accurazy, the step responce You need?

3

If you want WiFi on board, look at the ESP8266 based boards; the WeMOS D1 Mini is probably the smallest around. NodeMCU isn't much bigger, though.

Mind that to read 70-130°C with reasonable accuracy you have to reduce the series resistor value to 1-2k, the value of your thermistor at around 100°C. You're probably better off with a 50k or 100k nominal NTC for those temperatures, as those low resistance values and consequently high currents cause self heating.