Trane CNT-SVX07C-EN, N512 Modulating outdoor/return air dampers, Two-position valve operation

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Modulating outdoor/return air dampers

Two-position valve operation

The Tracer ZN521 supports two-position valves with a single binary out- put for each valve. Controllers used for two-pipe applications support heating, cooling, or heat/cool changeover with a single valve/coil. Control- ler used for four-pipe applications support cooling or heat/cool changeover with a main valve/coil, and heating only with an auxiliary valve/coil.

Isolation-valve operation

See “Face-and-bypass damper operation” on page 46.

Two-pipe operation

For two-pipe applications, the Tracer ZN521 can be configured as heating only, cooling only, or heat/cool changeover. The coil can be used as the pri- mary heating source and/or the primary cooling source. If present, an electric heating element can be used only as the primary heating source (instead of hydronic or steam heating). A changeover unit requires a valid entering water temperature value—either communicated or hard-wired— to operate properly (see “AI1: Entering water temperature” on page 17 and “Entering water temperature sampling function” on page 40).

Four-pipe operation

For four-pipe applications, the Tracer ZN521 can be configured as heat/ cool or heat/cool changeover. The main coil can be used as the primary cooling source or the primary heating/cooling source. The auxiliary coil can be used only as the primary heating source, not as a second stage of heating. During normal operation, the controller never uses the main coil and auxiliary coil simultaneously. A changeover unit requires a valid entering water temperature value—either communicated or hard-wired— to operate properly (see“AI1: Entering water temperature” on page 17 and “Entering water temperature sampling function” on page 40). Elec- tric heat control is not available on four-pipe applications.

Modulating outdoor/return air dampers

The Tracer ZN521 operates the modulating outdoor/return air dampers according to the following factors:

Occupancy mode

Outdoor air temperature (communicated or hard-wired sensor)

Zone temperature

Setpoint

Discharge air temperature

Discharge air temperature setpoint

The minimum position for an outdoor air damper is configurable using the Rover service tool for occupied and occupied standby modes and for

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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/complianceDamper actuators Tracer zone temperature sensor optionsZone humidity sensor CO2 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 recommendationsApplication SpeedfanMultiple Dehumidification Typical applications for the Tracer ZN521 zone controllerControlValve Economizing HeatElectricBinary inputs BI1 Low-coil-temperature detectionBI2 Condensate overflow Binary inputsBI4 Fan status BI3 Occupancy or generic binary inputAnalog inputs ZN Zone temperatureGND Ground terminals Analog inputsSET 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 Generic binary output Binary outputsBinary output functions Binary output FunctionsOverriding binary outputs Wiring requirements and optionsRequired 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 Random start Power-up sequenceUnoccupied mode Occupied modeOccupied standby mode Occupancy modesTimed override control Occupied bypass modeSimplified zone control Zone temperature controlCascade zone control Discharge air tempering Heating or cooling modeMorning warm-up Morning cool-downFan operation Entering water temperature sampling functionExhaust control Exhaust controlModulating valve operation Valve operationModulating valve calibration Valve control optionsTwo-position valve operation Modulating outdoor/return air dampersIsolation-valve operation Two-pipe operationModulating outdoor air damper position Economizing free cooling Ashrae Cycle 1 conformanceAshrae Cycle 2 conformance Face-and-bypass damper operation Two-position control of a modulating outdoor air damperDX cooling operation Face-and-bypass, isolation-valve operationDehumidification Electric heat operationBaseboard heat operation Unit protection strategies Peer-to-peer communicationLow-coil-temperature protection Smart resetFan off delay Condensate overflowFreeze 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 ResultRed LED Service indicator Service pin buttonInterpreting LEDs LED activity ExplanationYellow LED Communications indicator Green LED Status indicatorTypes of diagnostics DiagnosticsDiagnostics Table of diagnosticsDiagnostic Probable cause Consequences Type Fan unaffectedPosition 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