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Cooker hood / kitchen ventilation control, based on the speed of changing temp. + humidity values

The automatic cooker hood/ ventilation

This doesn’t measure an actual sensor value, but the speed at which a sensor value changes in time.
Natural temperature changes, like the heating turning on @ day, off @ night, or natural humidity changes are ignored. Because they change slowly in time.

This is only one way to go, and this can be extended with f.i. a 2 or 3 gang relais, or by adding a vibration sensor under the cooker.
I like to hear your ideas and improvements, or how to achieve something similar an other way.

Video with “proof” :wink:


  • a temperature + humidity sensor, i use the Aqara temperature sensor, with build in humidity sensor; sensor is glued centered right below the cooker hood, or about 60cm’s centered above the cooker.
  • a smart plug or a smart relais
  • the app Insight Trends
  • a numeric variable (in my example named ‘AfzuigkapTemp+VochtCombi’ which means something like CookerhoodTemp+HumCombi)


  • The 1st 2 flows analyze the temperature and humidity values of the sensor; to have enough data sets (measure points), I poll it every 11 and 12 secs, not both at the same time (for load spreading).
  • A little translation: Vocht = Humidity, Afzuigkap = Cooker hood

  • The 3rd and 4th flows are triggered as soon as the analyzing is completed.;
    While using a condition, ‘greater than’ the trend ‘index’, a decision is made whether to run the flow and to switch the cooker hood / ventilation system on
    (it doesn’t matter whether the temp or humidity measurement switches the ventilation on. The quickest wins).
    Example: [trend > 0.01] temp increases very slowly;
    [trend < -0.99] temp decreases very quickly
    We control it by means of a series of quick changes in time!
    It doesn’t matter how warm/cold or how dry/humid the air is (provided using this in a ‘normal’ home environment).
    A naturally changing temp/humidity value doesn’t trigger the flows.

  • The 5th and 6th flow decide likewise to switch the vent off

  • the 7th and last flow does the actual switching off of the ventilation, only when both flow 5 (temp) and 6 (humidity) set the ‘switch off’ signal
    This seems wise because the humidity or temp could quickly change because of the air flow going on.

Timeline’log’ during the Youtube video:

Have fun!