The 75F system comes with a feature called Epidemic Mode which includes toggles for "Smart Pre Purge", "Smart Post Purge", and "Enhanced Ventilation". This feature is only available at the CCU level and is not available for terminal devices such as Hyperstat.
The Pre-Purge and Post-Purge toggles when enabled will conduct a 2-hour purge cycle before the schedule starts and after the schedule ends. During the 2-hour purge period, the economizer will open to 100% and the fan will activate in an attempt to turn over the air supply in the space. When the Enhanced Ventilation toggle is enabled, the system will lock the economizer minimum position at 50% during occupied hours and will keep the fan running to enforce a constant ventilation mode.