🚿 Bathroom Humidity Exhaust Fan


Hi Frank, Firstly welcome to the community :+1:

Thanks for the feedback :hearts: nice to just get a positive one… your welcome :wink:

Blacky :smiley:

I just implemented this BluePrint - looks good and I like it. However I was wondering if you have a tip for this scenario:

I also want the manual switch for the fan to work and turn it off after 15 minutes or so when the button is pressed.

Whilst this is straight forward I am wondering what happens if I have this automation how it interacts with the humidity blueprint.

If the humidity blueprint starts the fan would the other timed automation also kick in and turn off the fan regardless?

How could I solve this?

Please note that it appears to me the bypass option cannot be used as this would be the same entity as the fan being used in they humidity automation.

I hope that makes sense.


Hi Markus. With this automation the trigger is the derivative sensor. You dont want the fan to be a trigger. If you have a switch that turns the fan ON then the fan will be the trigger and that is not good. I would look at having a independent switch and make that the trigger so when you turn it ON it turns the fan ON with a time delay.

I am assuming you have a toilet in the bathroom. If so maybe consider my Toilet Exhaust Fan with time delay blueprint and once you have a independent switch (maybe have a push button would be good, on / off in one push) use that as the trigger in the Toilet Exhaust Fan blueprint.

Hope this helps.

Hi @Blacky

Thanks for that. Having a seperate button is nothing I would like to do. The spouse will freak out.

I think the best way forward here is to have a boolean variable which sets to true when your Automation fires. I can then have a condition check on my Automation for the button saying when it is turned on, check if it was turned on by the Automation (with the boolean variable) and if so, do not run the 15 minute delay and cancel the Automation.

And if your automation ran and finished, set back the boolean to false.

I am not sure if I can implement this myself using your Blueprint. Thoughts?

Hi @Smartdrive78

Agree, :thinking: maybe consider just using your existing switch, disconnect the switch from the fan and install a Shelly Plus i4. Then when you turn that switch on (Shelly Plus i4) the fan comes on.



I modified the blueprint to set an input_boolean before turning the fan on/off.

My other blueprint is just:

  • when the light switch is on for 10 minutes
  • condition: input_boolean is false
  • turn off fan

Am I crazy, or is the Entities card not what was used in the example above? Here is what it looks for me, or am I totally missing something too?

Figured it out. It should be a History Graph Card, not an Entity Card.


Thanks for the heads up and sorry for the confusion :+1:. We will update the FAQ.

Is there any way to make the automation not trigger once the switch has been manually turned off?

@Blacky Wonderful Blueprint! In my bathroom I find that the timer triggers more often than the drop in humidity but that’s fine. I use an Aqara temperture and humidity sensor and have placed it near the shower enclosure rather than fan, hopefully to get a faster trigger? For the fan control I use a Sonoff Mini Zigbee and have the existing manual fan pull cord connected to this as an “Overide”, but since I started using this Blueprint it’s not been used!

The Automations I created before I found this Blueprint worked but had no “finese”. The only thing I miss from my automation is that I set a flag when the fan was turned on and used this to turn on a heated towel rail later to dry the used towel. I’ve adding this function by creating another automation that is triggered by the fan switching on that now sets the flag.

This seems overkill for my use case, I was wondering if there’s an easy way to add the setting of this flag in the blueprint? The flag is cleared by the heated towel rail automation.


Hi @pdawg17

Currently the only way to do this it to turn the by-pass ON. If you use the fan switch it will not work as the automation needs to turn the fan ON and OFF. Example: If the automation turns the fan OFF it is the same as the switch being OFF in HA… then the automation will never run. So we will need to use another switch for the by-pass.

Hope this make sense


Hi Chris :wave:


Nice :+1:

I love the idea and nothing is an overkill, it is why we use HA. If I told what I wanted to do but was shut down by my better half,… now that was out of control.

Please be assured your input has not been waisted. I love ideas :+1:. I will put it on the list.

@Blacky “nothing is overkill” is not something my wife understands! Having said that she really likes the bathroom fan and the automatic lights in various parts of the house!

Just need to get the mmwave presence detection refined and then …

Couls this support having another sensor in a hallway to compare with, to not get false positives? Or is it never wrong? :slight_smile: I am in Netherlands so humidity varies

@SamJongenelen I’m in the UK. I find this Blueprint works absolutely fine to trigger the fan on but the timer triggers the off more often than the humidity drop.

My last 6 months of humidity data shows the bathroom humidity varies between 30 and 70 as measured by the sensor without shower and the rate of change is much greater when showering than background.


Nice one. Not sure if you checked it out yet but I also have a sensor light blueprint that will help you control your lights. The mm wave sensors will work but you will need to group it if you have multiple triggers. That’s a different forum and blueprint. Maybe check it out.

I have tried this set up before but I wasn’t happy with it. It was the reason why we created this blueprint. It works by creating a Derivative Sensor Helper. It is easy :+1:

I must say for me it has worked a minimum of 5 times a day every day getting close to a year and not once has it ever failed and I have never got a false positive. Not saying it can’t happen as there are many factors but… Humidity varies is not a problem. The one thing I realy recommend is… you follow the FAQ. This is critical for this automation to work correctly. Below are the two FAQ’s that are critical. Try it and let us know how you go :smiley:

Q: How do you set up a Derivative Sensor Helper?

A: Please follow these steps Click Here

Q: I have set up a “Derivative Sensor Helper” but how do i set up the automation settings?

A: Please follow these steps Click Here

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@Blacky Experimentation is needed… I’ve had a HLK-LD1115 for a while and it’s taken A LONG time to fine tune it, I won’t be getting another one. I’ve also got HLK-LD2410B and HLK-LD2410C that I’ve been evaluating for a few months. Their Bluetooth connectivity appears weak but I’m looking forward to the new ESPHome LD2410 integration, that will allow configuration without having to use the HLKRadar app.

Like I said experimentation… That’s why Homeassistant is great!!!

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Thank you for excellent explanation. I don’t think the Netherlands beats the UK in humity-range :smiley: so I guess this blueprint is on the list

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