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 
1 Like
Gâday 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 Iâm 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 wouldnât 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 donât 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?)
Best
Vic
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 âMaximum Run Timeâ works from that point. The âTime Delayâ works from when it passes your âFalling Humidityâ. The âFalling Humidityâ 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
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.
Youâre 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 fanâs 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
1 Like
Awesome, thank you Blacky! I think I am getting things dialed in by having the fan behaving as Iâm 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 
1 Like
Hi,
First off thank you for a great blueprint which was working but now for some reason has stopped working and for some unknown reason my derivative sensor is giving me strange readings and the fan doesnt activate at all when humidity is high.
As you can see from the picture the derivative is reading very low numbers and has been like it for a few days the only things ive done is the usual updates for HA.
I have tried deleting a redoing the sensor to no avail .
Welcome to the community.
Looking at your graph with a large range it is hard to see what is going on. Try and reduce the range so you can focus on the shower. Below is one of my showers just the other day.
Make sure your humidity sensor is reporting correctly as that is where I would start. Then maybe redo (or check the settings) your derivative sensor if it look like it is not following your humidity sensor.
Blacky
Good day to you and everyone here.
Is there an option to delay the fan from turning on once the humidity level is reached? This would be very helpful when the steam shower is being used, and having the steam sent straight out of the vent defeats that purpose.
I could trigger an external automation that would set the âdisable automation inputâ for a chunk of time. Though it would be a good solution to incorporate such a delay.
Thanks!
Never thought about the steam shower 
Could you try this and see if it works for you. I am guessing you are going to need it to run normally but when you have a steam shower you will need to do something to tell the automation you are having a steam shower. As a test before you go crazy and maybe use your voice to toggle the helper could you create a toggle helper and set up the bypass as shown below.
I created a toggle helper called âSteam Shower Toggle Helperâ. What will happen is when you turn ON the âSteam Shower Toggle Helperâ the fan will turn OFF. Then we enabled the bypass auto OFF and set the time for 15min. You donât need to do this you can manually turn OFF the âSteam Shower Toggle Helperâ if you like. If you do use the auto OFF it will then turn the âSteam Shower Toggle Helperâ OFF in 15min as per the setting.
This is a link to another blueprint of mine but is shows you how to create a toggle helper if you are unsure. Click Here
Let us know if this works for you.
Blacky
1 Like
Thanks for the help!
These two are how the blueprint is configured now.
This is the way to enable the bypass with a double click of a Zooz scene controller.
This is a simple toggle from a physical device to the input_boolean.
Iâll give this config a try next time I use it.
No problem.
Normally double click buttons have no state. So what we need to do is set it up so your double click action controls a toggle helper similar to turning on a light or a switch but use a toggle helper. You then use that toggle helper in the automation as the automation must see a state of ON / OFF and double click buttons normally donât provide that information to Home Assistant.
Blacky
Right, and that makes total sense. The Bath fan disable when double click automation. is doing what you described. I didnât include this level of detail before. The MBSSB is a helper that goes into your blueprint instance. From there, I set the instance to auto turn off the helper after 15 minutes (I think that was in your original screenshot).
1 Like
New Feature 
-
Collapsible Sections - Added collapsible sections to the blueprint. This enhancement improves the blueprint user interface by making it cleaner and more organized, allowing sections to be collapsed.
This feature was introduced in Home Assistant 2024.6, so you must have this version or later for the blueprint to work.
Maintenance 
- We have updated input descriptions to better help understand what they do.
Code Clean Up 
- Cleaned up code for reliability that could cause a bug.
If you like this blueprint? Consider hitting the 
button in the top post 
If you like my blueprints, and would like to show your support or just say thank you? Click Here 
Enjoy
Blacky 
Sorry for being a complete idiot here but can you explain a bit the purpose of the derivative sensor?
Iâm trying to determine if this blueprint is for me.
I added a derivative sensor for one of my humidity sensors (master bedroom) just to test and see its behaviour. I noticed over night the humidity within the room crept up as we slept to almost 80% but the derivative sensor never crept over 0.4%.
Iâm guessing the derivative is best served for a spike in humidity instead of a gradual increase? My worry is during a shower derivative kicks in the fan, lowers humidity and then turns off however the humidity then starts to gradually increase to a point the fan should kick in again but doesnât because the derivative is too low.
Thatâs pretty much it. You simply adjust the off-delay to prevent the fan from turning off due to the decrease in humidity that it causes by being on.
1 Like
And this is why we use the derivative sensor so the fan only comes ON when is needed.
Yes, when you Have a shower you should see a spike. When finished you should see a drop spike. You then also have the option to use âMaximum Humidityâ this will turn the fan ON but not OFF for when you have back to back showers. All this is explained in the FAQ Click Here.
Try it out and see it for yourself.
Blacky
I shall give it a go but I donât think it would be applicable in my scenario.
Ideally Iâd like the fan to come on / off regardless of how quickly the humidity incremented so may be better off just using set values for humidity and triggering automations based on that.
The whole point of this blueprint using derivative is to prevent the fan coming on simply because itâs a humid day. Using set values of humidity only will likely end up causing the fan to come on at odd times due to the weather. ie: in the middle of the night when you donât want it to.
1 Like