Trane CNT-SVX07C-EN, Zone Controller, N512 manual Timed override control, Occupied bypass mode

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Timed override control

The fan will run as configured (continuous or cycling) for occupied mode. The controller always uses the stored default setpoint values (config- urable using the Rover service tool), regardless of hard-wired or commu- nicated setpoint values. In addition, the outdoor air damper uses the Economizer Occupied Standby Minimum Position setpoint to reduce the ventilation rate.

Occupied bypass mode

The controller is placed in occupied bypass mode when the controller is operating in the unoccupied mode and either the timed override ON but- ton on the Trane zone sensor is pressed or the controller receives a com- municated occupied bypass signal from a BAS. In occupied bypass mode, the controller maintains the zone temperature based on the occupied heating or cooling setpoints. The fan will run as configured (continuous or cycling). The outdoor air damper will close when the fan is off. The con- troller will remain in occupied bypass mode until either the CANCEL but- ton is pressed on the Trane zone sensor or the occupied bypass time (configurable using the Rover service tool) expires. The temperature set- points can be local (hard-wired), communicated, or stored default values (also configurable using the Rover service tool).

Timed override control

If the zone sensor has a timed override option (ON/CANCEL buttons), push- ing the ON button initiates a timed override on request. A timed override on request changes the occupancy mode from unoccupied mode to occu- pied bypass mode. In occupied bypass mode, the controller controls the zone temperature based on the occupied heating or cooling setpoints. The occupied bypass time, which resides in the Tracer ZN521 and defines the duration of the override, is configurable from 0 to 240 minutes (default value of 120 minutes). When the occupied bypass time expires, the unit transitions from occupied bypass mode to unoccupied mode. Pushing the CANCEL button cancels the timed override request. A timed override can- cel request will end the timed override before the occupied bypass time has expired and will transition the unit from occupied bypass mode to unoccupied mode.

If the controller is in any mode other than unoccupied when the ON but- ton is pressed, the controller still starts the occupied bypass timer with- out changing the mode to occupied bypass. If the controller is placed in unoccupied mode before the occupied bypass timer expires, the controller will be placed in occupied bypass mode and remain in that mode until either the CANCEL button is pressed on the Trane zone sensor or the occu- pied bypass time expires.

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Contents Installation and Operation Tracer ZN521 Zone Controller Page CNT-SVX07C-EN April CNT-SVX07C-EN Tracer ZN521 Zone Controller Installation and Operation CNT-SVX07C-EN Contents Sequence of operations Status indicators for operation and communication Troubleshooting Index Product description Overview and specificationsClearances DimensionsStorage environment Plastic-cover model dimensions and clearances Additional components Agency listing/complianceCO2 sensor Tracer zone temperature sensor optionsDamper actuators Zone humidity sensorOverview and specifications AC-power wiring Input/output terminal wiringGeneral wiring information Communication-link wiring and addressing General wiring information Operating environment requirements Location recommendationsMounting the Tracer ZN521 zone controller Mounting recommendationsHeatElectric Typical applications for the Tracer ZN521 zone controllerApplication SpeedfanMultiple Dehumidification ControlValve EconomizingBinary inputs BI1 Low-coil-temperature detectionBinary inputs BI2 Condensate overflowBI4 Fan status BI3 Occupancy or generic binary inputAnalog inputs ZN Zone temperatureAnalog inputs GND Ground terminalsSET Local setpoint FAN Fan mode inputAI1 Entering water temperature AI3 Outdoor air temperature or generic temperature AI2 Discharge air temperatureAI4 Universal 4-20 mA AI4 configuration options and associated measurement rangesConfiguration Measurement range AI4 terminal wiring CO2 measurement Binary output Functions Binary outputsGeneric binary output Binary output functionsFunction Input source For more information See Wiring requirements and optionsOverriding binary outputs Required controller inputs for proper operationTwo-pipe hydronic-cooling unit Two-pipe hydronic-heating unit Two-pipe hydronic heating/cooling unit with auto changeover Four-pipe hydronic heating/cooling unit Four-pipe heating/cooling unit with auto changeover Two-pipe heating unit with DX cooling Electric heat unit with DX cooling Electric heat unit Two-pipe heating unit with face-and-bypass damper Two-pipe heating/cooling unit with face-and-bypass damper Four-pipe heating/cooling unit with face-and-bypass damper Input/output functions and wiring for typical applications Random start Power-up sequenceOccupancy modes Occupied modeUnoccupied mode Occupied standby modeTimed override control Occupied bypass modeSimplified zone control Zone temperature controlCascade zone control Morning cool-down Heating or cooling modeDischarge air tempering Morning warm-upFan operation Entering water temperature sampling functionExhaust control Exhaust controlValve control options Valve operationModulating valve operation Modulating valve calibrationTwo-pipe operation Modulating outdoor/return air dampersTwo-position valve operation Isolation-valve operationModulating outdoor air damper position Economizing free cooling Ashrae Cycle 1 conformanceAshrae Cycle 2 conformance Face-and-bypass, isolation-valve operation Two-position control of a modulating outdoor air damperFace-and-bypass damper operation DX cooling operationDehumidification Electric heat operationBaseboard heat operation Unit protection strategies Peer-to-peer communicationCondensate overflow Smart resetLow-coil-temperature protection Fan off delayFreeze avoidance Filter-maintenance timerFreeze protection discharge air temperature low limit Tracer ZN521 zone controller circuit board Test buttonManual output test Output For nonClose damper, air Outdoor Open damper, air Outdoor BOP1 BOP2 BOP3 BOP4 BOP5 BOP6 BOP7 BOP8 BOP9 Step ResultLED activity Explanation Service pin buttonRed LED Service indicator Interpreting LEDsYellow LED Communications indicator Green LED Status indicatorTypes of diagnostics DiagnosticsFan unaffected Table of diagnosticsDiagnostics Diagnostic Probable cause Consequences TypePosition Valved unaffectedDamper unaffected Status indicators for operation and communication Probable cause Explanation Fan does not energizeValves remain closed TroubleshootingDX or electric heat does not energize Valves remain openOutdoor air damper remains open Outdoor air damper remains closedOutdoor air damper remains open Troubleshooting Numerics IndexIndex Index Index Page Trane