Hi all,
Is it possible to program a ventilation control in Home Assistant that prioritizes the highest percentage values from a CO2 sensor, a humidity sensor, and a person detection sensor?
The sensor data is received from KNX
Yes, if you have a controllable ventilation system.
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Yes, the fan is controllable, but the issue i have is that the temperature controller also uses the fan actuator, which is difficult to regulate all in ETS with only one actuator. (I couldn’t do it).
I need a logic so that all sensor data and the temperature controller can work together to intelligently control the fan
Can you define the logic you want, in words, in terms of the sensors and controls you have?
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I dont know how but
Logic to prevent conflicting commands between sensor data triggering ventilation and the temperature controller’s ventilation requests
and
In ETS, I can translate the sensor data (CO2, humidity, presence detector) into percentage values. My goal is for the ventilation system to prioritize the highest percentage among these sensor readings.
Let’s consider an example: if the CO2 sensor sends a reading of 1000 ppm (equivalent to 80%, based on a preset threshold) and the presence sensor detects 3 persons in the room (equivalent to 30%), the ventilation settings are as follows:
- Step 1: 10%
- Step 2: 50%
- Step 3: 70%
Upon receiving this data, the actuator should remain at Step 3 and not toggle between Step 1 and Step 3. Essentially, I want the ventilation system to prioritize the highest percentage value received from the sensors.
Hi 
!
You can use a “Maximum” combine-helper to do that. 
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Is it possible with the maximum combiner to retain the fan state for a brief interval, such as 10 minutes, before reading the next highest sensordata?
Can someone help me out with this ?. I am kinda stuck
What exactly are you stuck with?
How have you tried to solve it now?
Is the ventilation controller KNX too?
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I tried setting it up only in ETS, but unfortunately, it didn’t work as expected. Now, I’m considering visualizing the logic in Home Assistant instead. However, I’m unsure how to begin programming it. It would be really helpful if there are specific functions in Home Assistant designed to handle two different group addresses that utilize the same actuator without causing conflicts.
yes, the ventilation controller is also KNX
For example, my min/max values should only be sent to the ventilation controller when the room temperature controller is not accessing the ventilation controller
If you want the highest setting, you’d need to decouple the temperature controller from the ventilation controller in ETS. Then just add the temperature controller value to the max-helper and send the result back to KNX using expose https://www.home-assistant.io/integrations/knx/#exposing-entity-states-entity-attributes-or-time-to-knx-bus
Otherwise you’d need to play with locks / priorities, if your device supports these.
You can use cooldown with knx expose for this.
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Thank you for the quick response. I will try your approach tomorrow and hopefully it will work then 