Humidity Alert with Automatic Dehumidifier

Medium 30 min

High humidity in basements or bathrooms can lead to mold, musty smells, and expensive repairs. This guide shows you how to monitor humidity, get alerts when it’s too high, and automatically control a dehumidifier.

Why Monitor Humidity?

Problem	Consequence	Solution
Mold growth	Health hazard, expensive to remove	Keep humidity below 60%
Musty smell	Unpleasant, spreads	Dehumidify regularly
Moisture damage	Damaged furniture, walls	Early alert + action
Condensation	Rust on metal, damaged electronics	Constant monitoring

Recommended humidity levels

• Basement: Below 60% (ideal 50-55%)
• Bathroom: Below 70% (briefly after shower is OK)
• Living areas: 40-60%

What You Need

Minimum setup

Component	Examples	Price approx.
Humidity sensor	Aqara, SONOFF, Xiaomi	€10-25

Extended setup (recommended)

Component	Examples	Price approx.
Humidity sensor	Aqara WSDCGQ11LM, SONOFF SNZB-02	€10-25
Smart dehumidifier	Tuya WiFi dehumidifier	€80-200
Smart plug with power monitoring	Shelly Plug S, NOUS A1T	€15-30

Tuya dehumidifier recommendation

Tuya-based dehumidifiers can be integrated directly into Home Assistant via the Local Tuya integration - no cloud required! They often have a built-in humidity sensor, but a separate sensor provides more accurate readings.

Setup

Step 1: Add humidity sensor

1. Connect your Zigbee sensor via Zigbee2MQTT or ZHA
2. Verify the sensor reports in Home Assistant
3. Find the entity_id (e.g., sensor.basement_humidity)
4. Check that the value updates regularly

Test your sensor:

# Go to Developer Tools → States
# Search for "humidity"
# Your sensor should show a value between 30-80%

Step 2: Create Helper for status tracking

1. Go to Settings → Devices & Services → Helpers
2. Click Create helper → Dropdown
3. Name: “Basement Humidity Status”
4. Options: normal, high, critical, dehumidifier_active

Automations

Basic: Alert on high humidity

automation:
  - alias: "Alert on high basement humidity"
    description: "Send notification when humidity is above 65% for 1 hour"
    mode: single
    trigger:
      - platform: numeric_state
        entity_id: sensor.basement_humidity
        above: 65
        for:
          hours: 1
    action:
      - service: notify.mobile_app_your_phone
        data:
          title: "💧 High humidity in basement"
          message: >
            Humidity: {{ states("sensor.basement_humidity") }}%.
            Turn on dehumidifier!
          data:
            tag: "humidity_basement"
            persistent: true

Advanced: Automatic dehumidifier control

Turn on the dehumidifier automatically when humidity is too high, turn off when normal:

automation:
  # Turn on dehumidifier when humidity is high
  - alias: "Basement: Turn on dehumidifier on high humidity"
    description: "Start dehumidifier when humidity above 60% for 30 min"
    mode: single
    trigger:
      - platform: numeric_state
        entity_id: sensor.basement_humidity
        above: 60
        for:
          minutes: 30
    condition:
      - condition: state
        entity_id: humidifier.dehumidifier_basement
        state: "off"
    action:
      - service: humidifier.turn_on
        target:
          entity_id: humidifier.dehumidifier_basement
      - service: notify.mobile_app_your_phone
        data:
          title: "💨 Dehumidifier turned on"
          message: >
            Humidity: {{ states("sensor.basement_humidity") }}%
            Dehumidifier started automatically.

  # Turn off dehumidifier when humidity is normal
  - alias: "Basement: Turn off dehumidifier on normal humidity"
    description: "Stop dehumidifier when humidity below 50%"
    mode: single
    trigger:
      - platform: numeric_state
        entity_id: sensor.basement_humidity
        below: 50
        for:
          minutes: 15
    condition:
      - condition: state
        entity_id: humidifier.dehumidifier_basement
        state: "on"
    action:
      - service: humidifier.turn_off
        target:
          entity_id: humidifier.dehumidifier_basement
      - service: notify.mobile_app_your_phone
        data:
          title: "✅ Dehumidifier turned off"
          message: >
            Humidity normalized: {{ states("sensor.basement_humidity") }}%

Bonus: Track dehumidifier cycles

Keep track of how often the dehumidifier runs - useful for maintenance:

# Helpers (add via UI or configuration.yaml)
counter:
  basement_dehumidifier_cycles:
    name: "Basement Dehumidifier Cycles"
    icon: mdi:water-percent
    initial: 0
    step: 1

input_datetime:
  basement_dehumidifier_last_cycle:
    name: "Basement Dehumidifier Last Cycle"
    has_date: true
    has_time: true
    icon: mdi:clock-outline

automation:
  - alias: "Basement Dehumidifier Cycle Tracker"
    description: "Count dehumidifier cycles based on power consumption"
    mode: single
    trigger:
      - platform: numeric_state
        entity_id: sensor.dehumidifier_power
        above: 100
        for:
          seconds: 10
    action:
      - service: counter.increment
        target:
          entity_id: counter.basement_dehumidifier_cycles
      - service: input_datetime.set_datetime
        target:
          entity_id: input_datetime.basement_dehumidifier_last_cycle
        data:
          datetime: "{{ now().strftime('%Y-%m-%d %H:%M:%S') }}"

Tuya Dehumidifier Integration

Via Local Tuya (recommended)

1. Install Local Tuya via HACS
2. Find your dehumidifier’s Device ID and Local Key via Tuya IoT Platform
3. Add the device in Local Tuya
4. Select entity type: Humidifier (dehumidifier mode)

Local Tuya benefits

• No cloud dependency
• Faster response
• Works even when internet is down
• Privacy - data doesn’t leave your home

Dashboard Card

type: vertical-stack
cards:
  - type: entities
    title: "💧 Basement Humidity"
    entities:
      - entity: sensor.basement_humidity
        name: Current humidity
        icon: mdi:water-percent
      - entity: humidifier.dehumidifier_basement
        name: Dehumidifier
      - entity: counter.basement_dehumidifier_cycles
        name: Total cycles
      - entity: input_datetime.basement_dehumidifier_last_cycle
        name: Last cycle
        format: relative

  - type: history-graph
    title: "Humidity over time"
    hours_to_show: 168  # 1 week
    entities:
      - entity: sensor.basement_humidity
        name: Basement

Gauge Card

type: gauge
entity: sensor.basement_humidity
name: Basement Humidity
unit: "%"
min: 30
max: 80
severity:
  green: 40
  yellow: 55
  red: 65

Warning Levels

Configure different alerts based on severity:

Level	Humidity	Action
Normal	Below 55%	None
Elevated	55-65%	Log to history
High	65-75%	Notification + turn on dehumidifier
Critical	Above 75%	Repeated alarms + TTS

Troubleshooting

Sensor showing wrong value?

Calibrate your sensor by comparing with an accurate hygrometer. Most Zigbee sensors can be calibrated via Zigbee2MQTT.

Dehumidifier not responding?

1. Check that Local Tuya is correctly configured
2. Verify the dehumidifier is on WiFi
3. Test manually via Home Assistant UI
4. Check the log for errors

Too many notifications?

Use for: periods on triggers and tag: on notifications to avoid spam.

Tips for Lower Humidity

1. Ventilation - Open windows regularly
2. Heat source - Warm air holds less moisture
3. Avoid indoor drying - Dry clothes outside or in dryer
4. Check drains - Ensure floor drains work
5. Insulation - Avoid cold surfaces that cause condensation

Next Steps

🔋 Low Battery Alert

Get notified before your sensors run out of battery.

Low battery alert →

🌡️ Temperature Monitoring

Combine with temperature for better climate control.

Better Thermostat →