Learn more about Cool to Dry

With Cool to Dry, the Google Nest thermostat can use your air conditioner (AC) or heat pump to help reduce excessive humidity, and help maintain a healthier environment in your home. If your AC unit has a special dehumidification mode, your Nest thermostat can do even more to help reduce your home’s humidity.

Excessive moisture in the air can allow mold to grow inside your home, especially if you live in a humid area. With Cool to Dry, the Nest thermostat uses your air conditioner (AC) or heat pump to help reduce excess humidity in your home.

Note: The Cool to Dry setting will not be available if you don’t have a heat pump or AC unit, since Cool to Dry needs one of these systems to work. You also won’t see Cool to Dry if you have a standalone dehumidifier installed with your Nest thermostat. To learn more about how your Nest thermostat will work with standalone dehumidifiers follow this link:

Learn more about Nest thermostats and whole-home humidifier or dehumidifiers >

Cool to Dry can be used with any AC or heat pump, but works differently depending on whether or not your system has its own dehumidification mode.

How to tell if your system has a dehumidification mode >

Once you know if your system has a dehumidification mode or not, follow one of the links below for more information on how Cool to Dry will work in your home.

Cool to Dry and systems that don't have dehumidification mode

If you don’t have a dehumidification mode on your AC unit you can still use Cool to Dry to help lower your home’s humidity.

Since your AC converts hot humid air into cold dry air. Cool to Dry takes advantage of this and cycles the AC on and off to lower the humidity without the help of a dehumidifier.

When the Nest thermostat senses very high humidity, Cool to Dry automatically turns on the AC. This can cause Cool to Dry to cool beyond the temperatures you’ve set, up to 3°F lower than your scheduled temperature or 5°F lower than your Eco Temperatures.

What happens when Cool to Dry runs

When Cool to Dry turns on you’ll see it on the Nest
thermostat and with the Nest app.

While you’re home, Cool to Dry will turn on the AC if
humidity levels rise above 70% and your cooling isn’t
already on

If you’re away, and your thermostat is set to Eco
Temperatures without interruption for three days, Cool
to Dry will turn on the AC if humidity rises above 65%.

thermostat cool to dry

Important: Because you’re using Cool to Dry with an AC unit that does not have its own dehumidification mode, you will only be able to turn Cool to Dry on or off. You will not be able to adjust the humidity levels. Cool to Dry will use the percentages above.

Cool to Dry may not always be able to lower the humidity in your home, since Cool to Dry will only cool your home a few degrees lower than your set temperature. In addition Cool to Dry will not cool your home below 75°F while you’re away or 80°F while you’re home, even if your humidity is still high.

If Cool to Dry senses that the humidity isn’t dropping over time, it’ll shut off the AC and return to your regular cooling schedule to avoid wasting energy. Below you can see how Cool to Dry can help keep humidity at healthy levels by periodically turning on the AC.

cool to dry chart

Without Cool to Dry in a humid climate
While you’re away humidity levels continue to rise into the High Humidity range when the AC is off. This may allow mold to grow inside your home.

cool to dry chart

With Cool to Dry in a humid climate
While you’re away your Nest thermostat cycles your AC to keep humidity levels below 65%.

Cool to Dry without a dehumidification mode can be expensive

Using Cool to Dry with an air conditioner that doesn’t have its own dehumidification mode can use your AC more than you would otherwise, which can be expensive. AC units with their own dehumidification mode will be more efficient at reducing the humidity in your home. If your AC doesn’t have its own dehumidification mode you should only use Cool to Dry if you live in a very humid climate.

If you do live in a very humid climate, you may already be using your air conditioner to lower the humidity in your home. This can lead to running your AC non-stop while you’re home and while you’re away. In this case Cool to Dry can help save money. Instead of keeping the AC on all the time, Cool to Dry will cycle your AC on and off while you’re away, only when your humidity levels rise.

Cool to Dry and systems that do have dehumidification mode

All air conditioner units help dehumidify your home during normal operation. Your air conditioner cools air by passing it over refrigerated coils, and these coils take some of the moisture out of the air and condense it into water. In other words your AC takes hot humid air in and cold dry air comes out. When your Nest thermostat is controlling an AC with dehumidification mode, Cool to Dry will work more efficiently to lower your home’s humidity.

AC units with a dehumidification mode are able to provide much more dehumidification than normal AC units by slowing down your fan speed. This slower fan speed allows for more dehumidification without overcooling the air in your home, but still requires your AC to be running.

How to change Cool to Dry humidity settings

You can set an approximate humidity level for your home on your Nest thermostat or with the Nest app. To set an exact humidity percentage for your Nest thermostat to try to maintain, your thermostat will have to be installed with a standalone dehumidifier.

Important: Cool to Dry will only cool 3°F below your current set temperature when you are home, or 5°F lower than your set temperature when you are away and your thermostat is set to Eco Temperatures. This means Cool to Dry may not always be able to reach a specific humidity level before it has to shut off.

Because Cool to Dry may not always reach your target humidity, you’ll only be able to set an approximate target humidity level. That’s why you won’t see a specific percentage in your humidity settings. Instead, you can select from zero to three shaded water drops on your thermostat as your target humidity level.

On the Nest thermostat

1. Press the ring to bring up the Quick View menu.
2. Select Settings.
3. Select Equipmentand thenContinue and then Continue.
4. Select Dehumidifier and then Set Humidity.

From here you can turn the ring to select the
approximate humidity level your Nest thermostat
should try to remain below. More water drops is a
higher humidity, fewer water drops is a lower humidity.

You can also select an empty water drop to turn your
humidity control off. If you select fewer water drops
your system may need to turn on more frequently to
keep your humidity low, and this may use more energy.

With the Nest app

1. On the Nest app home screen, select the thermostat you want to control.
2. Tap the Settings icon Nest settings icon.
3. Select Equipment and then Dehumidifier.
4. Slide the button to set the approximate humidity
level your Nest thermostat should try to remain below.
More water drops is a higher humidity, fewer water
drops is a lower humidity.

Tap the switch in the upper right to turn humidity
control on or off.

What happens when Cool to Dry runs

When Cool to Dry turns on, you’ll see it on the
Nest thermostat and with the Nest app.

Note: Cool to Dry will run your air conditioner in
dehumidification mode as needed to reach your
approximate humidity level. Because Cool to Dry uses
a lower fan speed it will give your AC a break after
every ten minutes of use to prevent your AC’s coils
from freezing while lowering the humidity in your
home.

thermostat cool to dry

 

If you’re home, having the AC on will usually keep humidity levels below your approximate humidity setting. If your humidity levels rise above your setting and the AC is not already running, Cool to Dry will turn on your AC in dehumidification mode to help lower the humidity.

Cool to Dry will turn on the AC in dehumidification mode if you’re away from home, your Nest thermostat is set to Eco Temperatures, and your humidity levels rise above your approximate set levels.

Turning Cool to Dry on or off

If your AC unit doesn’t have a dehumidification mode, Cool to Dry is turned off by default. If your AC unit does have its own dehumidification mode, Cool to Dry is turned on by default. You can turn Cool to Dry on or off on your thermostat or with the Nest app.

On your thermostat

1. Press the ring to bring up the Quick View menu.
2. Turn the ring to Settings and press to select.
3. Turn the ring to Nest Sense and press to select.
4. Choose Cool to Dry.
5. Choose YES to enable Cool to Dry or NO to disable it.

Nest thermostat cool to dry

With the Nest app

1. Open the Nest app and tap your thermostat.
2. Tap the Settings gear Nest settings icon in the top right.
3. Tap Nest Sense and then tap Cool to Dry.
4. You can turn Cool to Dry on or off here.

How to check the current humidity in your home

Press your thermostat’s ring to open the Quick View menu. Here you can see your home’s current humidity

Learn more about the Nest thermostat’s Quick View screen >

With the Nest app you can find the current humidity by tapping your Nest thermostat. Swipe to the left and right on the two dots at the bottom of the screen to toggle between showing current humidity and outside temperature.

Nest thermostat quick view

 

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