On/Off Switch + Humidity Sensor

Playing on the “Switch + sensor” idea from Light Switch + light / motion sensor

I would be interested in a switch with a built-in humidity sensor to manage a bathroom exhaust fan.

This might not be a practical idea for a variety of reasons…

  • sensor accuracy
  • safety of a “water” sensor in a AC switch :slightly_smiling_face:
  • whether “high” vs “normal” humidity can be defined in the real world

BUT… here’s the pitch :slight_smile::

Novel Operating Modes (beyond normal scenes, timer, etc. from Lights Out et al):

  • Single Shower Mode: Tap on, Humidity monitor off.
    • Tap to turn on
      • Snapshot current humidity.
    • Stay on during a shower
      • Monitor humidity increase of >= X% due to shower
    • Auto-off when humidity returns to normal
      • Monitor humidity decrease back to baseline +/- Y% due to exhaust fan after shower’s over
  • Humidistat for a exhaust fan/dehumidifier
    • Auto-on when humidity above a set point X
    • Auto-off when humidity returns below set point
    • (perhaps more feasible in changing indoor humidity: auto-on/off for a rapid deviation compared to a monitored background measurement like an hourly average?)
  • Humidistat for a humidifier
    • (e.g. plug in humidifier on a switched outlet)
    • Auto-on when humidity below a set point X
    • Auto-off when humidity returns above set point
1 Like

So are you suggesting a relative change over an absolute percentage of humidity? Interesting… And it could be specific to that switch/room…

There are a lot of exhaust fans that come with humidity sensors for the wall switch. I actually just bought some the other day. They are not smart, so this could be a benefit, but they do detect moisture and turn on for x time so not sure if smart switch would add any benefit other than retrofitting older setups. That said, people are more likely to do that then replace the current exhaust fan as its a pain in the butt to do. I did it to reduce the noise.

+1 to this. “Landlord Mode” is something I’d like to see. Many of the non-smart switches out there have a problem that you can either inadvertently disable them, or that they can be turned off by pressing the button. Ideally, the switch could be configured such that the button can only turn on the switch (optionally for some configurable number of minutes). Pressing the button again would only turn off the switch if there was no sensor event. The humidistat would also be able to turn on the fan. When the humidity sensor triggered the fan, it should be configurable such that the button will not turn off the fan.

this is a cool idea. I’d like to just see a shower fan with a humidity sensor that synced to smart things to track RH in the room.