Chiller PID

[PDP8]

Hello, I'm Roland and I'm new here.

Currently I have a ds18b20 for measuring the temperature of a chiller
and logging on a Raspberry Pi with Domoticz... This works great.

But now I would like to use this system to control the chiller.
I want to have the possibility to set different temperatures at several times.
My idea was to connect a solid state relay to one of the GPIOs of the Raspberry pi
to switch the compressor. So nothing really special on this...

But is there a PID construction for Domotics? Jumo has regulators which have
even an "auto tune" function to determine the system parameters. That would be great.

Can anyone help me to get a PID sample project just as simple to have
one temperature sensor to regulate the temperature in one area?

Thanks in advance!
Roland