Trane N512 manual Ashrae Cycle 1 conformance, Ashrae Cycle 2 conformance, Economizing free cooling

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Modulating outdoor/return air dampers

ASHRAE Cycle 1 conformance

Tracer ZN521 applications with an outside air damper support ASHRAE Cycle 1 conformance. ASHRAE Cycle 1 operation admits 100% outdoor air at all times except during a warm-up cycle. A tri-state modulating damper actuator is required for this operation. For Tracer ZN521 ASHRAE Cycle 1 conformance, configure the minimum position of the economizer setpoint to 100% open during occupied periods. If the zone temperature drops 3°F (1.7°C) below the active zone temperature set- point, the Tracer ZN521 closes the outdoor air damper regardless of the minimum position setpoint.

ASHRAE Cycle 2 conformance

Tracer ZN521 controller applications with modulating outside air damper support ASHRAE Cycle 2 conformance. ASHRAE Cycle 2 operation allows the modulating outdoor air damper to completely close when the zone temperature drops 3°F (1.7°C) or more below the active zone temper- ature setpoint. If the zone temperature rises to within 2°F (1.2°C) of the active setpoint, the damper opens to the occupied or occupied standby minimum damper positions. If the zone temperature is between 2°F and 3°F (1.2°C and 1.7°C) below the active zone temperature setpoint, the damper modulates between the minimum position and closed.

If the discharge air temperature is between the discharge air tempera- ture low limit and the discharge air temperature low setpoint, the damper modulates between the minimum position and closed. If this situ- ation is concurrent with ASHRAE Cycle 2 operation, the lesser of the two setpoints will determine the actual damper position.

Economizing (free cooling)

Cooling with outdoor air, when the temperature is low enough to make this possible, is referred to as economizing or free cooling. Tracer ZN521 controller applications with modulating outside air damper support econ- omizing. The modulating outdoor air damper provides the first source of cooling for the Tracer ZN521. The controller initiates economizing if the outdoor air temperature is below the economizer enable point (config- urable using the Rover service tool). If economizing is initiated, the con- troller modulates the outdoor air damper (between the active minimum damper position and 100%) to control the amount of outdoor air cooling capacity. When the outdoor air temperature rises 5°F (2.8°C) above the economizer enable point, the controller disables economizing and moves the outdoor air damper back to its predetermined minimum position based on the current occupancy mode or communicated minimum outdoor air damper position. If an outdoor air temperature value is not present, economizing is disabled.

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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 specificationsStorage environment DimensionsClearances Plastic-cover model dimensions and clearances Additional components Agency listing/complianceCO2 sensor Tracer zone temperature sensor optionsDamper actuators Zone humidity 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 recommendationsHeatElectric Typical applications for the Tracer ZN521 zone controllerApplication SpeedfanMultiple Dehumidification ControlValve EconomizingBinary inputs BI1 Low-coil-temperature detectionBinary inputs BI2 Condensate overflowBI4 Fan status BI3 Occupancy or generic binary inputAnalog inputs ZN Zone temperatureAnalog inputs GND Ground terminalsAI1 Entering water temperature FAN Fan mode inputSET Local setpoint AI3 Outdoor air temperature or generic temperature AI2 Discharge air temperatureConfiguration Measurement range AI4 configuration options and associated measurement rangesAI4 Universal 4-20 mA AI4 terminal wiring CO2 measurement Binary output Functions Binary outputsGeneric binary output Binary output functionsFunction Input source For more information See Wiring requirements and optionsOverriding binary outputs Required controller inputs for proper operationTwo-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 sequenceOccupancy modes Occupied modeUnoccupied mode Occupied standby modeTimed override control Occupied bypass modeCascade zone control Zone temperature controlSimplified zone control Morning cool-down Heating or cooling modeDischarge air tempering Morning warm-upFan operation Entering water temperature sampling functionExhaust control Exhaust controlValve control options Valve operationModulating valve operation Modulating valve calibrationTwo-pipe operation Modulating outdoor/return air dampersTwo-position valve operation Isolation-valve operationModulating outdoor air damper position Ashrae Cycle 2 conformance Ashrae Cycle 1 conformanceEconomizing free cooling Face-and-bypass, isolation-valve operation Two-position control of a modulating outdoor air damperFace-and-bypass damper operation DX cooling operationBaseboard heat operation Electric heat operationDehumidification Unit protection strategies Peer-to-peer communicationCondensate overflow Smart resetLow-coil-temperature protection Fan off delayFreeze protection discharge air temperature low limit Filter-maintenance timerFreeze avoidance 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 ResultLED activity Explanation Service pin buttonRed LED Service indicator Interpreting LEDsYellow LED Communications indicator Green LED Status indicatorTypes of diagnostics DiagnosticsFan unaffected Table of diagnosticsDiagnostics Diagnostic Probable cause Consequences TypePosition 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
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