Occupied Zone Sequencing (UV Cycle 3) v51 - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 15.0

Controller Tool Help

Johnson Controls
Product name
Controller Configuration Tool
Document type
User Guide
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Revision date
Important: As of Release 5.1, the Occupied Sequencing (UV Cycle 3) v51 module replaces the Occupied Sequencing (UV Cycle 3) module.

This module generates the appropriate temperature control state for a Unit Ventilator ASHRAE Cycle 3 zone control application. This module accepts the temperature and setpoint inputs as well as the heating, cooling, and damper control statuses. The module outputs the current state as calculated by the ZN-T Sequencing Finite State Machine. For information on how the FSM determines the state, see FSM (Occupied Zone Sequencing [UV Cycle 3] v51).

In ASHRAE Cycle 3, a mixed air sensor controls the mixed air temperature. During the heating, ventilating, and cooling states, Cycle 3 supplies a variable amount of outside air as required to maintain a fixed temperature (typically 55˚F) entering the heating coil. As the zone temperature rises into the range of the heating setpoint, ventilation dampers control the air temperature entering the heating coil at the mixed air setpoint. Zone temperature is controlled by positioning the heating valve as required. The zone sensor directly controls the heating element without low limit interference.

Note: The mixed air temperature is read and used for control of the damper within the UV Cycle 3 Damper Output module; it is not an input in this module.

This module also provides a quick transition from heating to cooling mode during major changes to space load conditions or setpoints (for example, a large group of people enter a space, or a schedule changes from unoccupied to occupied mode).