Tracer® ZN.520
Occupied
When the controller is in the occupied mode, the unit attempts to maintain the space temperature at the active occupied heating or cooling setpoint, based on the measured space temperature, the discharge air temperature, the active setpoint, and the proportional/ integral control algorithm. The modulating control algorithm used when occupied or in occupied standby is described in the following sections. Additional information related to the handling of the control- ler setpoints can be found in the previous Setpoint operation section.
Unoccupied Mode
When the controller is in the unoccupied mode, the controller at- tempts to maintain the space temperature at the stored unoccupied heating or cooling setpoint, based on the measured space tempera- ture, the active setpoint and the control algorithm, regardless of the presence of a hardwired or communicated setpoint. Similar to other configuration properties of the controller, the locally stored unoccu- pied setpoints can be modified using Rover™ service tool.
In unoccupied mode, a simplified zone control algorithm is run. During the cooling mode, when the space temperature is above the cool setpoint, the primary cooling capacity operates at 100%. If more capacity is needed, the supplementary cooling capacity turns on (or opens to 100%). During the heating mode, when the space tempera- ture is below the heat setpoint, the primary heating capacity turns on. All capacity is turned off when the space temperature is between the unoccupied cooling and heating setpoints. Note that primary heating or cooling capacity is defined by unit type and whether heating or cooling is enabled or disabled. For example, if the economizer is enabled and possible, it will be the primary cooling capacity. If hydronic heating is possible, it will be the primary heating capacity.
Occupied Standby Mode
The controller can be placed into the occupied standby mode when a communicated occupancy request is combined with the local (hardwired) occupancy binary input signal. When the communicated occupancy request is unoccupied, the occupancy binary input (if present) does not affect the controller’s occupancy. When the communicated occupancy request is occupied, the controller uses the local occupancy binary input to switch between the occupied and occupied standby modes.
During occupied standby mode, the controller’s economizer damper position goes to the economizer standby minimum position. The economizer standby minimum position can be changed using Rover service tool.
In the occupied standby mode, the controller uses the occupied
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