Virtual sensor with max humidity

[Patryk Kopaczewski 4]

Hello. I have many humidity sensors, one in each room of the house. I want to create a "virtual" device with the maximum humidity among all the sensors. I need to use this for example to boost the ventilation if one of the shows has >60% humidity. It would be useful to have also another "virtual" device showing the average humidity. Is it possible to do so?

 

Yes, I know I can create a scene with a condition OR on all the sensors. But this would not be the best for me because I have many scenes using the max humidity or min temperature and I might want later to replace a sensor or else.

 

Thank you

[SmartHomeEddy 1,005]

You actually can’t compare relative humidity (%), because humidity is influenced by temperature (and airpressure). Unless your sensors are in the same temperature (and airpressure), you could sum it and calculative the average or min, max. 
 

You could first calculate the absolute humidity (g/m³) and compare or calculate with that. 

[Patryk Kopaczewski 4]

Leaving aside physics, I simply need a virtual device showing me the relative humidity of the room with highest relative humidity. For example two sensors measure 50% and 70%, I need a virtual one showing 70%. I am going to call it max relative humidity.

 

I don't care at all about the absolute humidity.

 

Yes, I agree with you that the average relative humidity doesn't make much sense. Please ignore it in my request.

[SmartHomeEddy 1,005]

The room with 50% humidity could have more moisture than the room with 70% humidity. So if you already want to make a quickapp to compare the humidity levels, why not first change it to absolute humidity and than compare. It is just a formula, nothing more, if you have the temperature in that room. 

[Patryk Kopaczewski 4]

Eddy, please let me disagree with you. I am a building energy engineer so I think I know what I am doing. Anyway it is always best to not trust 100% myself, so I asked chatgpt. Here the reply:

 

Cytat

To prevent mould, the most relevant metric to monitor is relative humidity (RH) — not absolute humidity or general moisture content alone.

 

Going back to the automation, where I really need your expert support, I need to ask you a clarification. I can do a quick app and calculate the max, ok. Can I use that value in another quick app? How? Should I store it as a variable? Or can I create a virtual device called average relative humidity to use in other apps?

[SmartHomeEddy 1,005]

If you create a quickapp, you could give the value of that quickapp the max of all humidity sensors, like self:updateProperty("value", maxHumidity).
 

You can use that value everywhere, in scripts, blockscenes, other quickapps (but why use a second quickapp), etc. You could also add child devices to the quickapp with all kinds of values. 

[Patryk Kopaczewski 4]

Thank you very much. I will try.

 

Why a second quick app?
Because I want a quick app dedicated to calculate the max humidity value and multiple other apps using it.
This way if I change a sensor I would need to edit only the quick app calculating that value.