Is temp way below target temp

[jonalange]

What am I doing wrong?
As you can see in this chart, the IS temp is way below the target temp.
My setup:

• Thermostat: TP Link KE100
• external Temp Sensor
• Tolerance: 0
• Calibration: Offset based, AI Time Based

Graph:

Other rooms don't have this problem, but have the same setup.
Any clue what this could cause this?
Do you need any additional info to better get the whole picture?

It's not like this room is enormous in size compared to the other rooms. I can't tell if the radiator is actually on all the time, because I didn't check very often. But at the times I checked it was on when it should be on.

[cl445]

Two compounding problems with your config:

1. AI Time Based at cold start: this mode needs heating cycles to learn before the math gives good output (heating_power starts at the default 0.01 °C/min and is updated only after full heating cycles). See BT not heating to target temp #1812 for the deeper explanation.

2. Tolerance 0: that's too tight — BT will flip between heating/idle on tiny fluctuations, and combined with AI Time Based's slow correction the TRV's local sensor can flicker idle/heating.

Recommended for KE100 (which only has local_temperature_calibration, no direct valve control):

• Switch calibration mode to Normal (CalibrationMode.DEFAULT)
• Set tolerance to ~0.3 °C