Helps a lotI saw a handover video of an Elddis pvc which suggested the top of the range was around 30 and the middle around 20. Must be very dependent on other factors though so extremely approximate. We left ours on 2/3 increments overnight in the peak district last week and I don't think it came on - if it did it was only briefly at around 5am. So that seems a good setting for overnight as we were not cold.
Not sure if all this helps much!