Trane N512 manual Valve operation, Modulating valve operation, Modulating valve calibration

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Chapter 5 Sequence of operations

•The exhaust output is de-energized if the outdoor air damper position drops 10% below the Exhaust Fan/Damper Enable Setpoint.

•If the Exhaust Fan/Damper Enable Setpoint is less than 10%, the exhaust output is energized if the outdoor air damper position is at the setpoint and de-energized at 0.

Valve operation

The Tracer ZN521 zone controller supports one or two tri-state modulat- ing or two-position valves, depending on the application (see Table 8). The controller opens and closes the appropriate valve(s) to maintain the active zone temperature setpoint at the heating setpoint in heating mode or the cooling setpoint in cooling mode (see “Cascade zone control” on page 38). For face-and-bypass applications, one or two isolation valves are controlled.

Table 8. Valve control options

	Application	Tri-state	Two-position	Isolation
	Application	modulating	Two-position	(two-position)
		modulating		(two-position)

	Hydronic/steam fan coils and blower coils	×	×

	Unit ventilators with valve control	×

	Face-and-bypass unit ventilators			×

Modulating valve operation

The Tracer ZN521 supports tri-state modulating valve control. Two binary outputs control each valve: one to drive the valve open and one to drive the valve closed. The stroke time for each valve is configurable using the Rover service tool. The controller supports heating, cooling, or heat/cool changeover with a single valve/coil for two-pipe applications. The controller supports cooling or heat/cool changeover with the main valve/coil and heating only with the auxiliary valve/coil for four-pipe applications. The controller moves the modulating valve to the desired positions based on heating or cooling requirements.

Modulating valve calibration

Calibration of modulating valves is done automatically. During normal operation, the controller overdrives the actuator (135% of the stroke time) whenever a position of 0% or 100% is requested. as part of Tracer ZN521 normal operation. At power-up or after a power outage, the controller first drives all modulating valves (and dampers) to the closed position. The controller calibrates to the fully closed position by overdriving the actua- tor (135% of the stroke time). Then, the controller resumes normal operation.

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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 Overview and specifications Product descriptionStorage environment DimensionsClearances Plastic-cover model dimensions and clearances Agency listing/compliance Additional componentsTracer zone temperature sensor options Damper actuatorsZone humidity sensor CO2 sensorOverview and specifications Input/output terminal wiring AC-power wiringGeneral wiring information Communication-link wiring and addressing General wiring information Location recommendations Operating environment requirementsMounting recommendations Mounting the Tracer ZN521 zone controllerTypical applications for the Tracer ZN521 zone controller Application SpeedfanMultiple DehumidificationControlValve Economizing HeatElectricBI1 Low-coil-temperature detection Binary inputsBI2 Condensate overflow Binary inputsBI3 Occupancy or generic binary input BI4 Fan statusZN Zone temperature Analog inputsGND Ground terminals Analog inputsAI1 Entering water temperature FAN Fan mode inputSET Local setpoint AI2 Discharge air temperature AI3 Outdoor air temperature or generic temperatureConfiguration Measurement range AI4 configuration options and associated measurement rangesAI4 Universal 4-20 mA AI4 terminal wiring CO2 measurement Binary outputs Generic binary outputBinary output functions Binary output FunctionsWiring requirements and options Overriding binary outputsRequired controller inputs for proper operation Function Input source For more information SeeTwo-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 Power-up sequence Random startOccupied mode Unoccupied modeOccupied standby mode Occupancy modesOccupied bypass mode Timed override controlCascade zone control Zone temperature controlSimplified zone control Heating or cooling mode Discharge air temperingMorning warm-up Morning cool-downEntering water temperature sampling function Fan operationExhaust control Exhaust controlValve operation Modulating valve operationModulating valve calibration Valve control optionsModulating outdoor/return air dampers Two-position valve operationIsolation-valve operation Two-pipe operationModulating outdoor air damper position Ashrae Cycle 2 conformance Ashrae Cycle 1 conformanceEconomizing free cooling Two-position control of a modulating outdoor air damper Face-and-bypass damper operationDX cooling operation Face-and-bypass, isolation-valve operationBaseboard heat operation Electric heat operationDehumidification Peer-to-peer communication Unit protection strategiesSmart reset Low-coil-temperature protectionFan off delay Condensate overflowFreeze protection discharge air temperature low limit Filter-maintenance timerFreeze avoidance Test button Tracer ZN521 zone controller circuit boardManual output test For non OutputClose damper, air Outdoor Open damper, air Outdoor Step Result BOP1 BOP2 BOP3 BOP4 BOP5 BOP6 BOP7 BOP8 BOP9Service pin button Red LED Service indicatorInterpreting LEDs LED activity ExplanationGreen LED Status indicator Yellow LED Communications indicatorDiagnostics Types of diagnosticsTable of diagnostics DiagnosticsDiagnostic Probable cause Consequences Type Fan unaffectedValved unaffected PositionDamper unaffected Status indicators for operation and communication Fan does not energize Probable cause ExplanationTroubleshooting Valves remain closedValves remain open DX or electric heat does not energizeOutdoor air damper remains closed Outdoor air damper remains openOutdoor air damper remains open Troubleshooting Index NumericsIndex Index Index Page Trane