American Standard UV05 manual Outdoor Air Damper Operation

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Description of Operation

Unoccupied Operation

During unoccupied mode, the IA fan typically remains off and cycles with calls for heating and cooling.

Cycle Fan

The UVC is provided with a Fan Cycling Configuration variable that can be used to force the IA fan to cycle with calls for heating and cooling during the occupied, standby, and bypass occupancy modes. When the fan is off, the OA damper is closed. McQuay recommends using this feature only when it is acceptable that normal ventilation is not required.

When the IA fan is set to cycle, the UVC is configured to continue fan operation for a time period after heating or cooling is complete.

Off Delay

When the UVC is placed into off mode or shutdown mode, the UVC is configured to continue fan operation for a short time period and then shutdown.

Outdoor Air Damper Operation

The UVC is configured for an OA damper operated by a floating-point actuator. The OA damper actuator contains a spring that ensures the OA damper is closed upon loss of power. The floating-point actuator is driven by the UVC using two binary (Triac) outputs. The OA damper typically is open to the current minimum position during the occupied and bypass occupancy modes and closed during the unoccupied and standby occupancy modes.

A Triac output is best tested under load using a 24 V relay for verification. To verify:

1Put a relay across the Triac outputs.

2Cycle the power.

3Verify the relay’s closed contacts during calibration.

Minimum Position

The UVC is configured to maintain three OA damper minimum positions based on the operation of the IAF fan. This allows each unit to be field configured to provide the amount of fresh air required to the space at each of the three IA fan speeds.

Table 17: Default OA damper minimum positions

IAF speed

Without CO2

With CO2

High

20%

5%

Medium

25%

5%

Low

30%

5%

Note – If the CO2 Demand Controlled Ventilation (DCV) option is used, the UVC only uses the IA fan high speed OA damper minimum position regardless of fan speed. The DCV function adjusts the OA damper above this minimum as needed to maintain CO2 set point.

Economizer Operation

The economizer function is used by the UVC to determine if the OA is adequate for economizer (primary) cooling. When both the economizer and mechanical cooling are available, the economizer is used as primary cooling and the UVC adds mechanical cooling only if the economizer is not adequate to meet the current cooling load (e.g., the OA damper reaches 100% and cooling is still required).

The UVC supports three economizer functions:

•Basic (default)—Temperature Comparison Economizer

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McQuay OM 751

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Contents Date November DX Cooling Only Software Model UV05Group Applied Systems UVC Configuration Parameters IntroductionGetting Started Description of OperationDescription Manual # Model-specific unit ventilator installation literatureAccessory-specific installation literature Extreme temperature can damage system components Software program literatureDescription Acronym Abr Acronyms/AbbreviationsAcronyms and abbreviations OCS Using the Keypad/Display Display FormatKeypad Functions Security LevelsMode Key ON/STOP Key and LEDFAN Key Arrow KeysUsing the Keypad/Display Viewing Actual Indoor Air Temperature IATMenu Reference Changing Set PointsAbr Description Default RW1Chlo Description of Operation State ProgrammingComplete UVC-state diagram UVC Unit ModesOFF Mode State UVC state names and numbersNormal UVC modes State names DecimalNight Purge Mode State Fan Only Mode State aCant Heat State State D Emergency Heat Mode Super StateFull Heat State State Heat State State Auto ModeHeat Mode Super State Cant Heat State State B Cool Mode Super StateLow Limit State State E Cool mode super state diagram Econ State StateEcon Mech State State Mech State StateSpecial Purpose Unit Modes Discharge Air DA Heat State StateLow Limit State State F Cant Cool State State CPressurize Mode Depressurize ModePurge Mode Shutdown ModeUnit Mode Priority Special purpose UVC unit mode priorityNormal UVC mode priority Priority resultOccupied Mode Unoccupied ModeStandby Mode Occupancy mode priorityAdditional Occupancy Features Space Temperature Set Points Networked Space Temperature Sensor CapabilityNetworked Set Point Capability Networked Set Point Offset CapabilityRemote Wall-Mounted Sensor with +/-3F Adjustment optional Effective Set Point CalculationsEffective set point calculations Set point calculation examplesExample a Example B Given Discharge Air Temperature Control Proportional Integral PI Control LoopsPI loop list PI loopsPI Control Parameters Proportional BandOccupied, Standby, and Bypass Operation Indoor Air Fan OperationIntegral Time Outdoor Air Damper Operation OA temp sensor Space humidity Economizer enableEconomizer Networked Space Humidity Sensor Capability Networked Outdoor Humidity Sensor CapabilityCO2 Demand Controlled Ventilation optional Networked Space CO2 Sensor CapabilityCompressor Operation Ashrae CycleCompressor Envelope Compressor Cooling LockoutCompressor Minimum On and Off Timers Compressor Start DelayFloating-Point Actuator Auto-Zero, Overdrive and Sync Outdoor Air Fan OperationUnoccupied Input Signal Remote Shutdown Input SignalVentilation Lockout Input Signal External Binary InputsExhaust Interlock Input Signal Lights On/Off SignalFault Signal External Binary OutputsExhaust Fan ON/OFF Signal Auxiliary Heat SignalAuxiliary heat start/stop calculation Start/Stop CalculationInputs and outputs, software model 05-DX cooling only Expansion boardPriority Fault description Reset Keypad Alarm and Fault MonitoringAlarm and fault code summary DX Pressure Fault F1 Compressor Envelope Fault F2Space Temp Sensor Failure F0 Discharge Air DX Cooling Low Limit Indication F3Condensate Overflow Indication optional F4 Space Coil DX Temp Sensor Failure F5Outdoor Temp Sensor Failure F6 Discharge Air Temp Sensor Failure F7Troubleshooting Temperature Sensors Troubleshooting Humidity Sensors Temperature versus resistanceTroubleshooting Carbon Dioxide CO2 Sensors Humidity versus voltageCO2 versus voltage table RH % VDC mVUVC configuration parameters OM Configuration Parameter Name Abr Default LUI MenuAbr Default LUI Menu OAD Stroke Time Warranty
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