MAX! Funk-Heizungsregler-System

Herr Müller / all,
I have seen 2 answers from your site, about the PI bahavour of the MAX! actuators. I have the impression the I(ntegral) behaviour does have a negative effect in some systems (where the water-temperature is not constant). I'll try to explain:

I don't know if it's special for the Netherlands, but most of the modern heating systems in the Netherlands are not on-off controlled (with fixed water-temperature), but modulating. The burner can be active in a range from 10 - 100 % based on a lot of parameters, mainly from (modulating / opentherm) living-room thermostat and optional outdoor temperature sensor. These systems try to have the water-temperature as low as possible (around 30 C), because that's most efficient. But, if needed (e.g. heating in the morning on a very cold day) the water-temperature can go up to e.g. 70 C. The intelligent (opentherm) living-room thermostat is aware of all these parameters and is able to control the room temperature very precise.
The Max! actuators are not aware of the (fluctuating) water-temperature which makes is very difficult to predict the right valve opening. Especially the Integral behaviour can make it worse.

My experience during normal usages is the temperature control from the standard mechanic Danfoss actuator and an electronic Honeywell Rondostat actuator is much better than the Max! actuators. I guess it should be possible to get a similar result with the Max! actuators!

Is the Max! system designed for modulating heating systems? Why is choosen for PI-control and not P or PID?
If the system is not designed for modulating heating systems, can it be adapted? Maybe by getting an option in the firmware to choose P, PI or PID control?

P.S. I have also experienced the temperature in all rooms with MAX! actuators did get much to high after we went back from holiday. In the holiday period the system was - via the room thermostat - in holiday mode, the living room temperature was set to 12 degrees. The Max! actuators did have their normal week program, which means the tried to get the temperature at 15/19 degrees. Off-course that was not possible because the water-temperature was too low. After I came back from holiday the first couple of days the room temperature did become much too high.

Hello blb

When using the Max-system, you should take into account that the weekly program matches the adjustments of your heating system. For instance, if the heating system goes down into the night setback at 22:00 o’clock, you should reflect this in your weekly Max programming. If the programmed target value of the Max heating control cannot be achieved, the I-value of the heating control goes up. As a consequence, the temperature might be too high for one or two days when it can be reached again (during this period the I-value goes down again and the system gets stabilized again).

We would like to ask you to check whether your weekly programm of the Max system is aligned with the settings of your heating system.

hello Michael,

Thanks for your reply. I did not have the week schedule of the Max! thermostats aligned with my room thermostat. It will make the control a bit more complex, but I agree that's the way to go with the I-control behaviour of the Max! thermostats. Before the next heating season I will make sure I'll align the two.