Occupied Zone Sequencing (UV Cycle W) 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 W) v51 module replaces the Occupied Sequencing (UV Cycle W) module.

This module generates the appropriate temperature control state for a Unit Ventilator ASHRAE Cycle W zone control application. The 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 W] v51).

ASHRAE Cycle W is the same as ASHRAE Cycle 2 with one exception: the discharge air low limit sensor controls only the outside and recirculated air dampers. The zone sensor directly controls heating without interference from the low limit. As the zone temperature rises to the normal operating temperature, the outside air damper is opened to minimum. A fixed minimum amount of outside air, normally 15 to 50%, is admitted during the heating and satisfied states. The percentage is gradually increased to 100%, if required, in the economizer and cooling states. The heating valve and outside air dampers are operated in sequence as required to maintain zone temperature. The discharge air sensor can override the zone sensor action on the damper to close the damper to minimum. As the discharge temperature continues to drop, the OA 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).