PI-Regler oder P-Regler / PI-Actuators or P-Acutators, was is besser / what's better?
09.03.2012, 13:10
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.
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.