NSpanel thermostat

Hi, I have a NSpanel and if I set the thermostat to 21, the heating turns on when it goes down to 20 but instead it doesn’t turn off immediately when it reaches 22 but sometimes even after 40 minutes which is still one degree beyond what was set.

When is the half grade reading?

Are you sure that it turns on at 20 ? Mine set to 21 turns on at 19 and off at 23. It’s set to +/- 1° but it does 2° no matter how fast the temp changes. So it’s intentional in the software.