Is openHAB/LC13 a good alternative to Danfoss Link Connect?

[OJEP (Ole Jeppesen)]

@sfjensen

Does the bias fluctuate significantly or change according to outside temperature? Otherwise I should think it would be easier to just adjust the setpoint according to how you perceive a given setpoint setting. I mean, your idea of a comfort temperature is worth no more than your perception of that room temperaure. That might as well be 22.5 °C on the LC13 unit as say 21.0 °C on your external sensor.

Below you can check out my temperature response. Red is my desired temperature, green is the actual measured. Pink is measured on top of 1 of the 3 radiators in the living room (so the control cycle of the LC13 can be seen.

My rule and temperature “controller” is here: https://community.openhab.org/t/got-an-arithmetic-exception-converting-value/34837/3

You cannot read the sensed temperature on the LC13 can you? Do you consider the difference between the external sensor and the setpoint to be the bias? Does “constantly” mean, that you deliberately overshoot the setpoint during a heating cycle (say when you go from night setting to comfort temperature)? Just curious?

No, LC13 does unfortunately not show the sensor reading. Yes, bias is the difference between desired and actual measured. I use a simple P-controller with saturation:

TempDiff.postUpdate(3*(Rad_TEMP_SP.state as DecimalType - Temperature_GF_Living2.state as DecimalType))		
	if(TempDiff.state > 1.5)
		{
		TempDiff.postUpdate(1.5)
		}
	if(TempDiff.state < -1.5)
		{
		TempDiff.postUpdate(-1.5)
		}

I have not done too much parameter tuning

How would the CLIMATE_CONTROL_SCHEDULE command class improve the control. As far as I can tell it just moves the schedule based automation from OH to the unit. In fact the ability for LC13 to run on schedule offline (through CLIMATE_CONTROL_SCHEDULE) would vanish when depending on an external sensor.

Well, i guess you are right that there will be no difference in response. Not sure how Danfoss have implemeted their PID controller. But then at least it will look a bit more nice, that the setpoint will be identical with the desired room temp, and the remaning calibration can be kept separate…