PID Mixing Valve Temperature control

[sokomm]

My first run of PID, oscillation is happening the first 30 min (30 measurements), then it settles and again starts oscillating. What should i change in the pid settings. This is the first time I use PID, the link for the tuning guide is dead.
http://blog.clanlaw.org.uk/2018/01/09/PID-tuning-with-node-red-contrib-pid.html

My PID Settings