🚿 Bathroom Humidity Exhaust Fan

No problem,

Sometimes I find helpers in general can misbehave and if you refresh your browser or log out and then log back in it sorts itself out.

Blacky :smiley:

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G’day Blacky,
First of all, really appreciate the work you are making available to the HA community, and also the effort you put in replying to questions! I learned a lot reading through this thread, but also realizing how little I know lol! I started with HA, (and with home automation) only a mere couple weeks ago, its a massive learning curve for me but I’m already addicted!! Trying to get my head around all the related terminology still.
My 1st project is automating the bathroom fan, and I quickly realize that I cannot just use a humidity sensor as an on/off switch, due to the varying outdoor humidity etc. So I stumbled upon your blueprint, amazing work and I wouldn’t have been able to do a fraction of that even in the next 5 years or more!

I now have an Aqara ZB humid/temp sensor, it has really fast response and it is tiny. Which seems to be great. Currently experimenting on where to position it, using all the related graphs.

My fan switches off when I don’t expect it, it seems to miss the falling humidity trigger, I have the time delay at 5 minutes, and my fan turns off 5 minutes after it turned on.

My question is, if i set the derivative moisture falling humidity to -4%, does it wait for the humidity to fall to the -4%/min below the 0% /min on the x-axis of the graph, or when the humidity drops by 4% from the peak humidity achieved in the graph? (eg, the humidy peaks at +6%/min spike, and then drops to 2%/min, will the fan stop timer then kicks in?)



Firstly welcome to the community and for all your kind words. Well you picked a trick first automation but it is nice that you found this blueprint. It does take a while to set it all up correctly even making small adjustments for fine tuning as the years pass but it is one automation I really love.

Now to your questions.

When it is triggered the “Maximum Run Time” works from that point. The “Time Delay” works from when it passes your “Falling Humidity”. The “Falling Humidity” is the point you see on the graph. So if your Falling Humidity of -4% is the figure below the 0%, the actual -4% on the graph. I must say that is a high Falling Humidity. If you provide a screen shot of your derivative sensor when you have a shower then I can suggest a starting point for you.

hope this helps you and I am always here to help so if you have any question please ask.

Blacky :smiley:

Thank you for the welcome and your great explanations. I realize that I did misunderstand the startpoint of Max runtime, now that I get it I feel silly as it is actually quite logical hahaha.

You’re right, I see dramatic falling humidity, which did not make sense to me. And that so soon after starting a shower as in the screenshot. Then it dawned on me - I stuck the little sensor on the elbow of the pipe out of the wall into the shower. It picks up a humidity rise in about 15 seconds after starting the shower, which i liked, but the hot elbow heats up the sensor and i think this sharp rise in its temp is affecting how it is reporting the humidity. So I moved the sensor, sticking it on a tile where the humidity graphs makes much more sense and its behaviour is more in line with my expectation!

Here is the graph of 2 showers last night, with the redlines indicating the duration of each. This is before I moved the sensor: You can see the fan’s on/off above the graph:

And here is a shower after moving the little sensor to a wall tile where I observed the steam moving past at all times


Looks like your getting the hang of it. I have marked up your graph below. I have indicated where I think your shower was in green. I have also given you starting points of 2 for rising and -1.5 for falling. When falling triggers you can see your time delay. You will need to adjust this so when the fan turns OFF your humidity is okay. At the top I have shown a time line of what happens if the safe guard is used, if the falling humidity it triggered then safeguard is canceled. Seeing it on a graph can really give you a better understanding of how it works and how to adjust your settings.

Hope this helps you.

Blacky :smiley:

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Awesome, thank you Blacky! I think I am getting things dialed in by having the fan behaving as I’m expecting it to.
I built a card with several graphs to analyze the various related data points and came to the conclusion that I was literally drowning my poor humidity sensor on the original location I had it as it got some water spray on and struggled to recover. I think I have now found a sweet spot for it, but will keep on monitoring.

Thanks again, no doubt I will be back with more noobie questions :face_with_peeking_eye:

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