If you have a humidifier or dehumidifier system, you can adjust your desired humidity level through the Google Home app. You can use Smart Humidity, Cool to Dry, and Quiet Time schedule to keep your home comfortable. To support both your humidifier and dehumidifier, the Nest Learning Thermostat (4th gen) has extra terminals.
Your air conditioner or heat pump can help reduce excessive humidity in your home. For more information, refer to Learn about Cool to Dry.
Turn humidification and dehumidification on or off
Tip: This feature is only available if you have a humidifier or dehumidifier setup on your Nest Learning Thermostat 4th gen.
By default, your humidifier and dehumidifier are enabled. You can customize your humidification preferences through the Google Home app.
- Open the Google Home app
.
- Tap Home
Climate
- Tap Settings
- Turn Enable humidifier or Enable dehumidifier on or off.
- Adjust your preferred humidity level.
Climate 
Learn about Smart Humidity
Automatic adjustments to your humidifier setpoint are made based on current indoor temperature and outdoor weather conditions. This helps to reduce condensation on windows or walls during cold weather. It also helps in reducing possible mold and mildew growth and air quality degradation. For example, when the outdoor temperature drops below 40°F (4.44°C), Smart Humidity reduces the humidity target.
Tip: By default, Smart Humidity is enabled. Smart Humidity doesn’t apply to Dehumidification.
You may choose from 3 condensation avoidance levels: low, medium, or high. You need to try the settings until you find the best one for your home.
Here are some humidity levels that Smart Humidity will recommend for a home with an indoor temperature of 68°F based on outdoor temperature:
| Outdoor Temperature | High | Medium | Low |
|---|---|---|---|
| 40°F | 50% | 55% | 60% |
| 30°F | 40% | 45% | 60% |
| 20°F | 30% | 35% | 50% |
| 10°F | 20% | 30% | 45% |
| 0°F | 15% | 25% | 40% |
| -10°F | 15% | 20% | 35% |
| -20°F | 15% | 15% | 30% |
If the humidity target you set is above the recommended one, the Smart Humidity feature automatically reduces the humidity target.
Turn Smart Humidity on or off
- Open the Google Home app
- Tap Home
- Tap Settings
- Turn Smart Humidity on or off.
Set up Quiet Time
Humidifier and dehumidifier systems can be noisy. You can set a Quiet Time schedule during times when you don't want the system to interrupt your sleep.
Tip: Quiet Time only affects humidification or dehumidification. It doesn't impact fans used during heating and cooling.
- Open the Google Home app
- Tap Home
- Tap Settings
- Turn on Quiet Time.
- Adjust the times Quiet Time should turn on and off.
- Tap Save.
Manage system configuration settings
Customize other settings for your humidifiers and dehumidifiers such as A/C or heat integration, relay orientation, and fan activation.
Humidifiers that are heat integrated can add moisture to the air while also warming it up.
- Open the Google Home app
- Tap Home
- Tap Settings
- Tap System configuration.
- In the "A/C integration" section, choose whether your system is Standalone or AC integrated.
Most dehumidifiers are active when relay is closed, but if you need to change this setting:
- Open the Google Home app
- Tap Home
- Tap Settings
- Tap System configuration.
- In the "Relay orientation when dehumidifier is active" section, select whether your dehumidifier is active when the relay is Open or Closed.
Some humidifier or dehumidifier systems require a fan to push air in or out.
- Open the Google Home app
- Tap Home
- Tap Settings
- Tap System configuration.
- In the Fan activation section under “Humidifier or Dehumidifier,” choose to Activate or Don’t activate the fan when the system is on.