Trane ZN.520 manual Entering Water Temperature Sampling, Modulating Outdoor Air Operation

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Unit Operation

Figure 19: Vertical unit with face-and- bypass damper operations

Upon power-up, the controller cal-

controller for standalone applica- tions.

When a unit uses 2-way modulat- ing valves, it is possible for the wa- ter near the entering water temperature sensor to migrate to- wards ambient temperature. The Tracer ZN.520 controller has a wa- ter sampling feature for these ap- plications. When the sensed water temperature is not sufficient for the requested heat/cool mode (5°F above the zone temperature for heating or 5°F below the zone temperature for cooling), the con- troller drives the valve fully open. The controller then monitors the water temperature until the appro- priate temperature is sensed or until the three minute time limit expires. If the water temperature is acceptable for the requested ca- pacity, the unit continues normal operation. If the three minute tim- er expires and the water tempera- ture is still unsuitable, the unit closes the valve and waits one hour before invoking the sampling feature again.

Table 22: Water assumption chart

point. Default minimum damper positions are provided and can be changed for occupied and occu- pied standby modes, or for low speed operation. The controller can also receive a communicated outdoor air damper minimum po- sition from Tracer Summit. A com- municated minimum position from Tracer Summit has priority over all configured setpoints.

During the OCCUPIED mode the outdoor air damper will always be controlled to the effective mini- mum position unless ASHRAE Cy- cle I, ASHRAE Cycle II, or economizing modes are active.

ibrates the face-and-bypass damp- er to the full bypass position by overdriving the damper actuator. During normal operation, whenev- er the Tracer ZN.520 controller generates a face-and-bypass damper position request of zero or 100%, the unit calibrates the actu- ator by overdriving the damper ac- tuator 135%.

Unit Configuration

2-pipe Heating valve

2-pipe cooling valve

2-pipe H/C valve with auto changeover enabled

2-pipe H/C valve with auto changeover disabled

Temperature Assumed1

Hot

Cold

Hot

Cold

Figure 20: OA/RA actuator mounting for the vertical unit ventilator

Entering Water

Temperature

Sampling

Units with 4-pipe changeover and 2-pipe changeover require an en- tering water temperature to deter- mine if the appropriate water temperature is present for the re- quested mode (heating or cool- ing). This temperature may be communicated in an ICS system or hardwired to the Tracer ZN.520

1.Assumption based on absence of a valid entering water temperature

Modulating Outdoor Air Operation

The Tracer ZN.520 controller oper- ates a modulating (3-wire floating) outdoor air damper actuator ac- cording to the effective occupan- cy, outdoor air temperature, space temperature, effective setpoint, discharge air temperature, and discharge air temperature set-

Figure 21: Figure 2: OA/RA actuator mounting for the horizontal unit ventilator

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 boardService Controller FeaturesTypical Components Peer-to-Peer Communications Communication ConfigurationsIntegrated Comfort System Communication Interface Stand-AloneInteroperability 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 LimitsPower-Up Control Wait Occupied Bypass TimerMaintenance Timers Unit Identification Tag Location IdentifierWinking 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 stay closed Probable cause Possible Explanation ValvesValves stay open Probable cause Possible Explanation Outside Air Damper DX/Electric HeatOutdoor 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