Honeywell RTH4300B - Manual (Page 9)

RTH4300B Programmable Thermostat

About your new thermostat Select the fan setting
Set the FAN switch to Auto or On.
In “Auto” mode (the most commonly used
setting), the fan runs only when the heat-
ing or cooling system is on.
If set to “On,” the fan runs continuously.
Use this setting for improved air circula-
tion, or for more efficient air cleaning.
Set FAN switch to choose whether the fan
runs continuously or only as needed.