Does humidity sensor work well for shower exhaust fan?

Hardware
1

I currently have a Z-Wave motion dimmer mounted in the shower ceiling. Let’s not debate the safety aspects. I manually process the motion events using some hysteresis so that the motion is only triggered if you stick around long enough. The exhaust fan runs while there’s motion with a timed extension. This seems to work fine, but I wonder if the fan runs too much. Would a humidy sensor work better in this situation? I’m inclined to keep it simple.

2

Yes you can use a humidity sensor with a fan to keep things low. I currently use a switchbot hub2 as my temp and humidity sensor in the bathroom to turn on and off my dehumidifier and turn on my exhaust fan once it hits the threshold for it then its set to run for an hour.

alias: Bathroom Humidity Management
description: ""
triggers:
  - trigger: state
    entity_id:
      - sensor.hub_2_humisensor_humidity
    from: null
    to: null
    for:
      hours: 0
      minutes: 0
      seconds: 10
    id: Humidity
conditions: []
actions:
  - choose:
      - conditions:
          - condition: trigger
            id:
              - Humidity
          - condition: numeric_state
            entity_id: sensor.hub_2_humisensor_humidity
            above: 80
            below: 100
        sequence:
          - type: turn_on
            device_id:
            entity_id: 
            domain: light
        alias: Humidity 80-100%
      - conditions:
          - condition: trigger
            id:
              - Humidity
          - condition: numeric_state
            entity_id: sensor.hub_2_humisensor_humidity
            above: 60
            below: 70
        sequence:
          - action: switch.turn_on
            metadata: {}
            data: {}
            target:
              entity_id: switch.bathroom_power_strip_switch_2
        alias: Humidity 60-70%
      - conditions:
          - condition: trigger
            id:
              - Humidity
          - condition: numeric_state
            entity_id: sensor.hub_2_humisensor_humidity
            above: 40
            below: 60
        sequence:
          - type: turn_off
            device_id: 
            entity_id: 
            domain: light
          - action: switch.turn_off
            metadata: {}
            data: {}
            target:
              entity_id: switch.bathroom_power_strip_switch_2
        alias: Humidity 40-60%
mode: single


alias: Bathroom Fan Timer
description: ""
use_blueprint:
  path: flameeyes/bounce-switch-on-a-timer.yaml
  input:
    switch_entity: light.bathroom_switch
    timer_entity: timer.bathroom_exhaust_fan_timer
3

I have a Z-Wave multi-sensor above my shower which includes humidity.

Using this Blueprint, it works well to control the fan when I shower.

4

@sparkydave Yeah, I’m actually asking this question because I just got a deal on 6 of the multi-sensors. My question is not so much how to automate, but how much the humidity model differs from a simple timer? We live in Florida and the AC keeps the humidity at around 50%. Our shower routines are pretty consistent. Maybe I could just use the humidity sensor to calibrate my timer. There’s no sense running the fan if the humidity is not decreasing. How much of a delta do you see?

Bonus question: did you use the expensive Aeotec recessed mount? That would cost me more than the sensor.