Trane Tracer Unit Ventilator Valve Operation, Face-and-Bypass Damper Operation, Modulating Valves

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Unit Operation

seconds. This provides the ample torque required to start all fan mo- tors from the off position.

Exhaust fan/damper operation

This binary point is a shared point with medium fan speed. For this point to be used for exhaust con- trol, the controller must be config- ured for a 1- or 2-speed fan. The exhaust fan/damper is coordinated with the unit fan and outdoor damper operation. The exhaust output is energized only when the unit fan is operating and the out- door damper position is greater than or equal to the configurable exhaust enable point. The exhaust fan output is disabled when the outdoor air damper position drops 10% below the exhaust enable point. If the enable point is less than 10%, the unit turns on at the enable point and off at 0.

Valve Operation

Modulating Valves

The Tracer ZN.520 controller sup- ports one or two modulating valves for hydronic heating and cooling operation. The main valve/ coil is used for cooling only, heat/ cool changeover (2-pipe applica- tions), or cooling (4-pipe applica- tions). The auxiliary valve/coil provides heating in 4-pipe and heating only applications.

At power-up, the Tracer ZN.520 controller drives the modulating valves to the closed position. The controller calibrates to the full closed position by overdriving the actuator 135%. Whenever the con- troller requests a valve position of zero or 100%, the controller over- drives the actuator 135% regard- less of the current valve position.

Face-and-Bypass

Isolation Valves

Face-and-bypass units may use isolation valves to prevent unwant- ed water flow in the coil. This elim- inates problems such as radiant heat or excessive condensate in 2- pipe systems.

In 4-pipe applications, the isolation valves are used to prevent conflict- ing capacities within the unit.

Face-and-Bypass Damper Operation

Note: The Face-and-bypass actuator is located in the right- hand end pocket of the classroom unit ventilator.

The Tracer ZN.520 controller actu- ates a face-and- bypass damper to modulate a percentage of air to the face of the coil to maintain space comfort. When a requested capaci- ty is present, the unit modulates the damper to allow more air to the face of the coil. An averaging sen- sor is used on the discharge air to provide accurate capacity control.

Figure 18: Horizontal unit with face-and-bypass damper option.

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Contents Tracer ZN.520 for Classroom Unit Ventilator Installation Owner DiagnosticsInstallation of New Units Start-up ProceduresPower Up Sequence Tracer ZN.520 Overview General InformationGeneral Information Tracer ZN.520 unit controller circuit board Controller Circuit Board FeaturesController Features ServiceTypical Components Communication Configurations Peer-to-Peer CommunicationsIntegrated Comfort System Stand-Alone Communication InterfaceInteroperability Description End Device SpecificationsCharacteristic Standard End DevicesStandard End Devices Way Control Valve Time clock Zone sensor Dpdt Control Transformer Specifications Installation and WiringBinary Inputs Generic/baseboard Heat Binary Output Binary OutputsAnalog inputs Analog InputsMounting Vertical classroom unit ventilator end pocket Power WiringProper zone sensor placement Installing the Wall- Mounted Zone Sensor OptionalHumidity and CO2 Sensors Typical Wiring Diagram-Wall Mounted Zone Sensor Typical Wiring Diagram-Unit Mounted Zone Sensor Typical Wiring Diagram-Unit Input and output summary Input/Output SummaryInput/Output Summary Heating source ConfigurationConfigurable parameters Cooling sourceBinary Outputs1 Analog input summary Binary input summary ConfigurationBinary Inputs1 Analog Inputs1Default Fan ConfigurationEnd Device Configurations Fan configuration rangesDischarge Air Limits Setpoint defaults Default Valid rangeDischarge air limit ranges Default Valid range SetpointsOccupied Bypass Timer Power-Up Control WaitMaintenance Timers Location Identifier Unit Identification TagWinking Occupancy Power-UpUnit Operation Heating And Cooling Changeover LogicHeat/Cool Changeover logic Fan Operation Fan Off DelayCooling Operation Heating OperationModulating Valves Valve OperationFace-and-Bypass Damper Operation Exhaust fan/damper operationTemperature Assumed1 Entering Water Temperature SamplingWater assumption chart Unit ConfigurationBaseboard Heat Operation Economizer OperationDX Operation Electric Heat OperationOther Modes Filter Status/ Maintenance TimerOutput Overrides Fan StatusSimple data sharing application Data Sharing-LonWorksMore 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 Yellow Comm LED TroubleshootingRed Service LED Black Service Push ButtonExit6 Test ProcedureTroubleshooting Outdoor Air Temperature Failure Space Temperature FailureEntering Water Temperature Failure Discharge Air Temperature LimitDiagnostics Troubleshooting Translating Multiple Diagnostics Fans Rover service toolValves 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 Probable Cause Explanation Outdoor air damper stays openReplacing Circuit Boards Tracer ZN.520 Unit Controller ReplacementAppendix Hardwired Setpoint AdjustmentFan Switch Resistance Values Hardwired Thermistor ValuesFunction Appendix-Binary ConfigurationBinary Configuration Binary configuration details Binary input or outputUnit Operation Based On The Effective HEAT/COOL Output Heat/cool mode input NviHeatCoolEffective heat/ cool mode output nvoHeatCool Appendix-Unit OperationAppendix-Unit Operation Input/output listing1 Configuration properties1Appendix-Data Lists Data ListsSet the Program Setting the Time ClockAppendix-Timeclock Set the Time and DayOverride Program Manual Operation Review and Change ProgramsAppendix-Timeclock Appendix-Location Identifier Location Identifier Location Identifier Location Identifier Trane Company
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