Hi All,
What is concept of Night Vent control mentioned as following in equest

NOT-AVAILABLE When the main fans are scheduled off no other
fans can be on.

NIGHT-FAN When the main fans are scheduled off the
night fans always run to provide pressurization (e.g., for a fabric
roof system). You can also think of this as the main fans running but
at a reduced volume.

NIGHT-FAN+REVERT When the main fans are scheduled off the night
fans run unless any zone falls below its heating throttling range or
rises above its cooling throttling range, in which case the main fans
are turned on that hour.

WHEN-SCHEDULED When the main fans are scheduled off the night
ventilation fans will turn on if NIGHT-VENT-SCH is on and the outside
dry-bulb temperature is at least NIGHT-VENT-DT degrees below the
temperature in the control zone.

SCHEDULED+DEMAND The same as WHEN-SCHEDULED except that, in addition,
at least one conditioned zone in the system must be above the
VENT-TEMP-SCH value.

What is difference between main fans and night fans

Thanks
Sambhav