Hey,
I’m looking for a quick and simple way to build an advanced flow which will detect a spike in an Aqara T1 Temperature & Humidity Sensor.
I’m aiming to turn on my bathroom shower fan automatically when a spike in humidity of 5-10% within one minute is detected
Building this in with logic seems to be a bit more challenging than I thought it would be.
Also should say that I live in the UK so building in a simple flow, like “Humidity increases above 70%” isn’t very practical as the ambient humidity generally fluctuates in the room between 50-75% in the winter, because we like to keep the thin horizontal bathroom window slightly open most days to circulate air.
If you have the option to mount the sensor near the shower then using a high relative humidity percentage is an option in combination with the sustained value flow card.
I am using the same sensor to check whether the RH is higher than 80% continuously for a period of 30 secs.
This will enable the fan, but only if the outside absolute humidity is lower than the inside absolute humidity, in order to prevent that even more humid air enters the house. The latter is an additional AND condition in my flow.
If you want to use a spike as a trigger, then you might want to check out the Insights Trends app, that allows you to act on a specific trend in a given period.
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I am also in the UK and use the exact same sensor to do the exact same thing. After lots of trial and error I found that looking for a change of >3% up in a single update from the T1 was the optimum for turning the fan on and for turning it off I found that doing so as soon as humidity recorded as falling was about right (my fan has an overrun of 4 mins after that so you might need to tweak the values accordingly).
Even then the flow was non-trivial. I use the ‘shower detected’ event for other things also hence why I have a virtual button that gets pressed as well as turning the fan on when a shower is detected. I’m half hoping that someone will point out a way to simplify this flow but half not as it took me ages tow work out!
I just made a copy to take all the comments, logging and other stuff out to just leave the core logic. Still probably not “quick and easy”! But maybe a bit easier to follow…
This has been working for me for several years now with minimal false positives either way.
EDIT: actually now I look at it, all the stuff in the middle could probably be replaced with a delay of a second or two triggered after the sensor reading is received. It just needs to make sure the new reading overwrites the previous one in the variable but not until after the other comparisons have been made
Thanks for the suggestions, but both the above solutions are a bit complicated for such a simple bit of logic.
After a longer search, Iended up using the V Thermo app which has a really handy card:
‘Humidity has increased by X% points in the last X minutes”
Humidity falling logic isn’t very precise with this sensor as the reporting timeframes are so poor, so I just have a 20 minute delay for turning the fan off, after it’s been turned on by the above card.
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