[ThePair]

I'm amazed your temperature values are so tight. If my wife opens the fridge and pokes around in there a bit getting food for a meal, I'll see a 2-4 degree rise on the temp, at least, followed by the appropriate drop when the door is closed and the heaters on the back kick on full time. With the door closed I'm seeing an approximate 2 degree swing, probably around my setpoint, so that's not an issue.

I'll be very interested in your settings, even if they're somewhat different. You seem to have changed some of your initial ideas viz: the settings, since you originally felt the SSR could handle fast switching, and now you're thinking the time should be longer? Or is that just a difference in the programming of the two PIDs?