I have had a ThermoPro Thermostat model TP-55 for quite a while and have been annoyed with it’s readings being obviously off.  I compared it’s readings with diagnostic devices and found that it was giving two degrees too high.  I then downloaded it’s manual and can not find any method to calibrate it’s readings.   I then calibrate the device by attaching a label showing how far the readings are in error.  I just might donate this unit as I despise inaccuracy.