Google Nest Learning Thermostat 4th Gen Installation And Configuration Manual page 15

Key Features and Functionality
Fan and Ventilation Control
The Nest Learning Thermostat (4th gen) can control the HVAC system fan if there is a wire allowing
independent control. The fan can be scheduled to run for 15-60 minutes each hour every day. It can also
be manually engaged for a set amount of time. If there is a multi-speed fan, the user will be prompted to
choose a fan speed when manually activating the fan.
If there is a ventilation system configured on the thermostat, the user will be able to manually activate it
with a timer alone or with the system fan. If the ventilation system requires the fan to be activated, the
user will only be shown the option to activate the fan or the fan+ventilation.
When ventilation is enabled, the user will need to set the "Required daily ventilation" from 2-24 hours.
The default for "required daily ventilation" is 18 hours.
Smart Ventilation
The Smart Ventilation feature uses the outdoor temperature, air quality, and user behavior to determine
how much ventilation to use and when it should be used. For example, this feature may not run the
ventilation system if the outdoor air quality is poor. It can also take outdoor temperatures into account
and bring in outdoor air that is warmer or cooler than indoors as necessary rather than running the
heating or cooling system. When enabled, this feature will activate a ventilation system at varying times
throughout the day while still meeting the "Required Daily Ventilation" threshold set by the user.
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