
Setting up humidity control on your Nest thermostat is a straightforward process that can be completed in a few steps. You'll need to ensure your thermostat is connected to the internet and has the latest software updates.
The Nest thermostat's built-in humidity sensor measures the air's relative humidity levels. This sensor is usually located on the back or side of the thermostat.
To enable humidity control, navigate to your thermostat's settings and look for the "Humidity" or "Dehumidify" option. This is usually located under the "Temperature" or "Comfort" settings.
The Nest thermostat can automatically adjust the temperature and humidity levels to maintain a comfortable indoor climate. This can be especially useful during humid summer months or dry winter months.
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Understanding Nest Thermostat Humidity Control
The Nest thermostat's humidity control feature is a game-changer for many homeowners. It allows you to customize your humidification preferences and maintain a comfortable humidity level in your home.
To enable or disable Cool to Dry, a feature that cools your home to 3°F below your set temperature when you're home, you'll need to access the Quick View menu on your thermostat. This involves pressing the ring, selecting Settings, and then opening Nest Sense.
By default, your humidifier and dehumidifier are enabled, but you can customize your humidification preferences through the Google Home app. This is a great way to tailor your humidification settings to your specific needs.
If you have a bypass flow through humidifier, you can bypass the sail switch or pressure switch, humidistat, and 120/24V plug-in transformer. The Nest thermostat has a setting that requires both heat and humidity before it activates the humidifier, making these switches redundant.
The thermostat's black wire connects to the Nest's * connector, controlling the operation of the humidifier. When there is a call for heat and humidity, the Nest closes its * "switch" and applies 24VAC to the humidifier solenoid.
You can set the minimum humidity the Nest should maintain by turning the dial on your thermostat. An empty drop indicates 0% relative humidity, while three fully shaded drops indicate 100% humidity.
Here are the different humidity levels you can set on your Nest thermostat:
The Cool to Dry setting cools to 3 degrees F (-16.1 C) lower than your scheduled temperatures or 5 degrees F (-15 C) lower than your Eco temperature settings when high humidity is detected in your home. This helps to remove excess moisture from the air, making your home feel more comfortable.
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Configuring Dehumidification
Your air conditioner doesn't have a dehumidification mode, so you'll need to explore other options. To control humidity, you can customize your humidification preferences through the Google Home app.
To check if your thermostat has a dehumidification mode, follow these steps: check the thermostat's star terminal or AQ+ terminal (depending on your thermostat and system) to see if it's enabled. If not, you can try customizing your humidification preferences through the Google Home app.
You can also check the relay orientation when the dehumidifier is active. Most dehumidifiers are active when the relay is closed, but you can change this setting if needed. To do so, open the Home app, tap Favorites or Devices, and then tap your thermostat SettingsThermostatHumidity.
To turn on the Cool to Dry setting, follow these steps: open the app, tap on the Settings icon, choose Equipment > Dehumidifier, and toggle the Dehumidifier switch to on. You can also adjust the sliding switch to your desired humidity levels.
For your interest: How to Control the Humidity in Your House
Keep in mind that having the Cool to Dry setting on all the time may raise your electricity bill, as your AC unit will work more than usual. However, if you hate humidity, it may be worth it.
Here's a summary of the steps to turn on the Cool to Dry setting:
- Open the app
- Tap on the Settings icon
- Choose Equipment > Dehumidifier
- Toggle the Dehumidifier switch to on
- Adjust the sliding switch to your desired humidity levels
Advanced Features
The Nest thermostat's advanced features make it a game-changer for humidity control.
The Nest thermostat can learn your schedule and preferences to optimize humidity levels when you're not home.
It can also detect humidity levels in your home and automatically adjust the temperature to maintain a comfortable humidity level.
With the Nest thermostat, you can set a humidity target and it will work to maintain that level, even when you're not home.
The Nest thermostat can also detect when you're away and adjust the humidity levels to prevent mold and mildew growth.
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Humidifier Settings
The Nest thermostat offers a range of humidifier settings to help you control the humidity levels in your home.
You can customize your humidification preferences through the Google Home app, which is a great starting point for getting the right settings for your home.
To set an exact humidity percentage, you'll need a standalone dehumidifier set up in your thermostat, but this might not always reach your target humidity level.
Cool to Dry will only cool your home to 3°F below your current set temperature when you're home, so it may not always reach a specific humidity level before shutting off.
You can select from 0 to 3 shaded water drops on your thermostat as your target humidity level, which represents approximate humidity in your home. The empty water drop indicates that humidity control is turned off.
Selecting a low humidity level will make your system run more frequently to keep your humidity low, which may use more energy. Conversely, choosing a high humidity level will make your system run less often.
Here's a quick guide to the water drop settings on your thermostat:
App and Device Settings
To set humidity levels on your Nest thermostat, you can use the app or the device itself. To set an exact humidity percentage, you need a standalone dehumidifier set up in your thermostat.
The Nest thermostat app allows you to adjust humidity levels using a scrollbar, where fully left is 0% relative humidity and fully right is 100% relative humidity. This makes it easy to visualize and adjust your desired humidity level.
You can also adjust humidity levels on your thermostat device itself, selecting from 0 to 3 shaded water drops to represent approximate humidity in your home. Selecting a low humidity level may require your system to run more frequently, using more energy, while choosing a high humidity level should result in your system running less often.
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App Settings
Setting humidity from the Nest Thermostat App is a bit different from other settings. You can select a target humidity level using a scrollbar, with fully left representing 0% relative humidity and fully right representing 100% relative humidity.

If you want to turn humidity control off, you'll need to select the empty water drop. This is a convenient way to toggle humidity control on and off.
To set your target humidity level, you can select from 0 to 3 shaded water drops, which represent approximate humidity in your home. Keep in mind that selecting a low humidity level may require your system to run more frequently, which can use more energy.
On the other hand, choosing a high humidity level means your system should run less often, which can be more energy-efficient.
Quiet Time
Quiet Time is a feature that lets you set a schedule for when your humidifier and dehumidifier systems won't run, so you can sleep undisturbed.
This feature only affects humidification or dehumidification, so your fans will still be used during heating and cooling.
You can set Quiet Time to run during times when you don't want the system to interrupt your sleep, like late at night or early in the morning.
It's a thoughtful touch that can make a big difference in getting a good night's rest.
Tips and Considerations
Monitoring humidity levels is crucial for thermal comfort, and the ideal range is between 40-60%. This can vary depending on your location, with dry areas like Los Angeles requiring attention to low humidity levels.
A whole-home humidifier or dehumidifier may be necessary to manage humidity levels, especially if your HVAC system is not operating properly.
Energy Savings
You can save a significant amount of energy by controlling relative humidity. According to the U.S. Department of Energy’s Energy Saver Guide, turning the thermostat down 7 to 10F for 8 hours a day can save up to 10% per year on heating and cooling.
Decreasing the temperature by 5F/3C and controlling relative humidity can achieve an energy savings of 15%. This is because low relative humidity makes people uncomfortable, causing them to feel cooler, which can be mitigated by controlling humidity levels.
Controlling relative humidity can also help you achieve comfort levels, especially during the cold winter season when outdoor humidity levels are lower. By installing a humidifier and using a humidity & temperature smart sensor, you can monitor and trend your home's comfort levels.
For your interest: Indoor Temperature and Humidity
Tip 2: Monitor

Monitoring humidity levels is crucial for your thermal comfort. The ideal humidity level is between 40-60%.
A day with high humidity feels very different from a day with low humidity - think frizzy hair and sticky skin versus chapped lips and itchy skin.
Los Angeles can be extremely dry, while areas closer to the coast can be very humid. You should keep tabs on humidity levels.
The Nest Thermostat comes with a built-in humidity sensor to gauge the moisture content of the air inside your home.
Buildings in Cold Climates Require Additional Insulation
Buildings in cold climates require additional insulation. This is because the air in these regions has a lower water vapor content, which can lead to dryness and discomfort.
Heating cold air without additional humidification can reduce the relative humidity even further, making the air feel drier and more prone to moisture evaporation from surfaces and human bodies.
Condensation occurs when cold air comes into contact with cool surfaces, causing water vapor molecules to condense and reducing the air's relative humidity. This can lead to moisture-related issues if not addressed.
The air in cold climates can take on more water vapor when heated, but this can also lead to moisture evaporation from surfaces and human bodies, potentially causing dryness and discomfort.
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