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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!


Looked at your solution. Since I use induction to cook our meals and use an itho Mcv as for ventilation I was wondering if I could use my powerconsumption to activate my Shelly operated MCV.
I use homewizard energy in combination with time slots of day to trigger the ventilation

With induction you can indeed check for a certain amount of power change.
I do this with my oven, to notify me when its pre-heated, and to notify me when baking time is up.
During the possible oven-in-use time slots, I write the power usage to variable every minute, and compare that value with the current power usage.
(This can also be used with the moisture/temp changes cookerhood flows).
Not 100% fool-proof, but it works most of the time :sweat_smile:

Leuk om te zien hoe je de flows gemaakt hebt. Ik vind ze zelf alleen een beetje te omslachtig om de ventilatie aan te laten gaan voor het koken. Zelf gebruik ik gewoon een simpele flow. ALS vermogen veranderd dan ventilatie aan. Ik laat het vermogen veranderen door de verlichting van de afzuigkap aan te doen.

Dank je, Ruud. Zoals met alles zijn er meerdere manieren en oplossingen.
Mijn uitgangspunt, en uitdaging, was om het puur op warmte&vocht detectie geheel automatisch te laten schakelen.
Het “omslachtige” is enkel de flows bedenken en aanmaken geweest :wink: