Trane ZN.520 manual Unit Operation, Heating And Cooling Changeover Logic, Power-Up, Occupancy

Page 36

Unit Operation

Power-Up

When 24 VAC is initially applied to the controller, the following se- quence of events occurs:

qGreen status LED turns ON .

qAll outputs are controlled OFF.

qThe controller reads input values to determine initial values.

qRandom-start timer expires (5 to 30 seconds).

qWhen POWER-UP CONTROL WAIT

is enabled, the controller waits 0-120 seconds (depending on configuration) to allow ample time for communicated control data to input. If the controller does not receive communi- cated information, standalone control is assumed.

qAll modulating valves and dampers calibrate closed.

qNORMAL operation begins.

Occupancy

The valid occupancy modes for the Tracer ZN.520 controller are:

qOCCUPIED - Normal operating mode for occupied spaces or daytime operation.

qUNOCCUPIED - Normal

operating mode for unoccupied spaces or nighttime operation.

qOCCUPIED STANDBY - Mode

used to reduce the heating and cooling demands, while providing ventilation, during the occupied hours when the space is vacant or unoccupied.

qOCCUPIED BYPASS -Used to

temporarily place the unit into the occupied operation.

The occupancy mode can be hard- wired to the controller via the oc- cupancy binary input or communicated to the controller.

OCCUPIED mode

When the controller is in the OCCU- PIED mode, the unit attempts to maintain the space temperature at the active occupied heating or cooling setpoint.

OCCUPIED mode is the default mode of the Tracer ZN.520 control- ler.

UNOCCUPIED mode

When the controller is in the UN- OCCUPIED mode, the unit attempts to maintain space temperature at the stored unoccupied heating or cooling setpoint (i.e., config- urable through Tracer Summit or the Rover service tool) regardless of the presence of a hardwired or communicated setpoint. When the space temperature exceeds the stored unoccupied setpoint, the controller brings on 100% of the primary heating or cooling ca- pacity.

The UNOCCUPIED mode can be ini- tiated through a hardwired signal to the occupancy binary input or by a communicated request.

OCCUPIED STANDBY mode

The OCCUPIED STANDBY mode al-

lows the unit to operate at a heat- ing or cooling setpoint between the occupied and unoccupied set- points to help maintain the envi- ronment while decreasing energy consumption.

This mode decreases the ventila- tion for heating or cooling during brief periods of vacancy in the space. Unit operation in this mode is similar to the occupied mode ex- cept for the different heating and cooling setpoints and a different outside air damper position.

The OCCUPIED STANDBY mode is

initiated only when occupancy is communicated to the Tracer ZN.520 controller and the hard- wired signal to the occupancy in- put is calling for unoccupied operation.

OCCUPIED BYPASS mode

The OCCUPIED BYPASS mode is

used to transition the unit from the

UNOCCUPIED mode to the OCCU-

PIED mode for a period of time from 0 to 4 hours (configurable through Rover. Default=RUN). The controller can be placed in OCCU- PIED BYPASS mode by either com- municating an occupancy request of BYPASS or by using the TIMED OVERRIDE (i.e., ON) button on the Trane zone sensor.

ON and CANCEL Buttons

Some Trane zone sensors have ON and CANCEL buttons for timed over- ride operation. Pressing the ON button on the zone sensor when the unit is in the UNOCCUPIED mode initiates the OCCUPIED BY- PASS mode and initializes the by- pass timer. The CANCEL button is used to send the unit back into UN- OCCUPIED mode before the bypass timer has expired.

The ON button may also be used for the unit identification or the

“WINK” feature. (See “Winking” on page38.for more information.) When the Tracer ZN.520 controller is connected to a Tracer Summit system or the Rover service tool, the ON button may be used in place of the service pin for easy unit identification.

Heating And Cooling Changeover Logic

The Tracer™ ZN.520 Unit Control- ler can receive communicated re- quests for heating or cooling operation. The communicated variable nviApplicMode is used to communicate the requests for the controller's operating mode based on the following values:

0 = Auto (mode determined by controller)

1 = Heat (uses heating setpoints)

2= Morning Warm-up

3= Cool (uses cooling setpoints)

UV-SVP01A-EN

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Contents Installation Owner Diagnostics Tracer ZN.520 for Classroom Unit VentilatorStart-up Procedures Installation of New UnitsPower Up Sequence General Information Tracer ZN.520 OverviewGeneral Information Controller Circuit Board Features Tracer ZN.520 unit controller circuit boardController Features ServiceTypical Components Communication Configurations Peer-to-Peer CommunicationsIntegrated Comfort System Stand-Alone Communication InterfaceInteroperability End Device Specifications CharacteristicStandard End Devices DescriptionStandard End Devices Way Control Valve Time clock Zone sensor Dpdt Control Transformer Installation and Wiring SpecificationsBinary Inputs Binary Outputs Generic/baseboard Heat Binary OutputAnalog Inputs Analog inputsMounting Vertical classroom unit ventilator end pocket Wiring PowerInstalling the Wall- Mounted Zone Sensor Optional Proper zone sensor placementHumidity and CO2 Sensors Typical Wiring Diagram-Wall Mounted Zone Sensor Typical Wiring Diagram-Unit Mounted Zone Sensor Typical Wiring Diagram-Unit Input/Output Summary Input and output summaryInput/Output Summary Configuration Configurable parametersCooling source Heating sourceBinary Outputs1 Binary input summary Configuration Binary Inputs1Analog Inputs1 Analog input summaryFan Configuration End Device ConfigurationsFan configuration ranges DefaultSetpoint defaults Default Valid range Discharge air limit ranges Default Valid rangeSetpoints Discharge Air LimitsOccupied Bypass Timer Power-Up Control WaitMaintenance Timers Location Identifier Unit Identification TagWinking Power-Up Unit OperationHeating And Cooling Changeover Logic OccupancyHeat/Cool Changeover logic Fan Off Delay Cooling OperationHeating Operation Fan OperationValve Operation Face-and-Bypass Damper OperationExhaust fan/damper operation Modulating ValvesEntering Water Temperature Sampling Water assumption chartUnit Configuration Temperature Assumed1Economizer Operation DX OperationElectric Heat Operation Baseboard Heat OperationFilter Status/ Maintenance Timer Output OverridesFan Status Other ModesData Sharing-LonWorks Simple data sharing applicationMore complex data sharing application Heating And Cooling Changeover Logic Heat/Cool Changeover logic Cooling Operation Valve Operation Entering Water Temperature Sampling Economizer Operation Output Overrides Data Sharing-LonWorks More complex data sharing application Troubleshooting Red Service LEDBlack Service Push Button Yellow Comm LEDTest Procedure Exit6Troubleshooting Space Temperature Failure Entering Water Temperature FailureDischarge Air Temperature Limit Outdoor Air Temperature FailureDiagnostics Troubleshooting Translating Multiple Diagnostics Rover service tool FansValves Valves stay closed Probable cause Possible ExplanationValves stay open Probable cause Possible Explanation DX/Electric Heat Outside Air DamperOutdoor air damper stays closed Probable cause Explanation Outdoor air damper stays open Probable Cause ExplanationTracer ZN.520 Unit Controller Replacement Replacing Circuit BoardsHardwired Setpoint Adjustment Fan Switch Resistance ValuesHardwired Thermistor Values AppendixAppendix-Binary Configuration Binary ConfigurationBinary configuration details Binary input or output FunctionHeat/cool mode input NviHeatCool Effective heat/ cool mode output nvoHeatCoolAppendix-Unit Operation Unit Operation Based On The Effective HEAT/COOL OutputAppendix-Unit Operation Configuration properties1 Appendix-Data ListsData Lists Input/output listing1Setting the Time Clock Appendix-TimeclockSet the Time and Day Set the ProgramReview and Change Programs Override Program Manual OperationAppendix-Timeclock Appendix-Location Identifier Location Identifier Location Identifier Location Identifier Trane Company
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