Occupied Zone Sequencing (UV Cycle 2) 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
Document number
Revision date
Important: As of Release 5.1, the Occupied Sequencing (UV Cycle 2) v51 module replaces the Occupied Sequencing (UV Cycle 2) module.

This module generates the appropriate temperature control state for a Unit Ventilator ASHRAE Cycle 2 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 2] v51).

As the zone temperature rises to near the heating setpoint, ASHRAE Cycle 2 opens the outdoor air damper to the minimum position. A fixed minimum amount of outside air, normally 15 to 50%, is admitted during the heating and ventilating states. The percentage is gradually increased to 100%, if required, during the ventilating state. The heating valve and outside air dampers are operated in sequence as required to maintain zone temperature. Low discharge air temperature can override the zone temperature’s action on the heating valve to open the valve. Low discharge air temperature can also override the zone temperature’s action on the damper to close the damper to minimum. As the discharge temperature continues to drop, the heating output goes to 100% and the outside damper closes to prevent discharge air from dropping below a minimum temperature.

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).