American Standard UV05 manual Indoor Air Fan Operation, Integral Time

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Description of Operation

In general, it is best to start with a relatively large proportional band setting (the factory default setting is best) and adjust to smaller values.

If you want the system to respond strongly to small changes in the space, adjust the proportional band to a higher setting.

If you want the system to react weakly to small changes in the space, adjust the proportional band to a higher setting.

Integral Time

The integral time, or integral action, causes the controlled output to change in proportion to time difference between the sensor value and set point. The difference over time between the actual value and set point forms an “area under the curve” (see Figure 22). The integral action works to reduce this “area under the curve” and to eliminate any natural system offset.

Figure 22: Integral time

Area Under The Curve	Too Small

The smaller the integral time, the faster the output ramps up or down with small changes in the space. The smaller the integral time, the quicker the system reacts to small changes in the space. If the Integral Time is set too small, long oscillations occur (see Figure 22).

In general, it is best to start with a relatively large integral time setting (the factory default setting is best) and adjust to smaller values. If you want the system respond strongly to small changes in the space, lower the integral time. If you want the system to react weakly to small changes in the space, adjust the integral time to a higher setting.

Indoor Air Fan Operation

The UVC supports a three-speed indoor air (IA) fan; low, medium, and high. The UVC calculates the effective fan speed and operation based on the unit mode, the occupancy mode, and the values of several network variables.

Auto Mode

The UVC is provided with a user selectable auto fan mode feature. When in auto fan mode, the UVC uses the space temperature PI loop to automatically adjust the fan speed as needed to maintain space temperature. This ensures that the UVC maintains the lowest and quietest fan speeds whenever possible. When in auto fan mode, a maximum of six fan speed changes per hour is allowed (by default). This prevents frequent automatic fan speed changes from disturbing room occupants.

Occupied, Standby, and Bypass Operation

During occupied standby and bypass modes, the IA fan, by default, remains On.

McQuay OM 751

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Contents Group Applied Systems DX Cooling Only Software Model UV05Date November Description of Operation UVC Configuration ParametersIntroduction Getting StartedAccessory-specific installation literature Model-specific unit ventilator installation literatureDescription Manual # Software program literature Extreme temperature can damage system componentsAcronyms and abbreviations Acronyms/AbbreviationsDescription Acronym Abr OCS Security Levels Using the Keypad/DisplayDisplay Format Keypad FunctionsArrow Keys Mode KeyON/STOP Key and LED FAN KeyChanging Set Points Using the Keypad/DisplayViewing Actual Indoor Air Temperature IAT Menu ReferenceRW1 Abr Description DefaultChlo State Programming Description of OperationUVC Unit Modes Complete UVC-state diagramDecimal OFF Mode StateUVC state names and numbers Normal UVC modes State namesFan Only Mode State a Night Purge Mode StateFull Heat State State Emergency Heat Mode Super StateCant Heat State State D Heat Mode Super State Auto ModeHeat State State Low Limit State State E Cool Mode Super StateCant Heat State State B Econ State State Cool mode super state diagramMech State State Econ Mech State StateCant Cool State State C Special Purpose Unit ModesDischarge Air DA Heat State State Low Limit State State FShutdown Mode Pressurize ModeDepressurize Mode Purge ModePriority result Unit Mode PrioritySpecial purpose UVC unit mode priority Normal UVC mode priorityOccupancy mode priority Occupied ModeUnoccupied Mode Standby ModeAdditional Occupancy Features Networked Set Point Offset Capability Space Temperature Set PointsNetworked Space Temperature Sensor Capability Networked Set Point CapabilityEffective Set Point Calculations Remote Wall-Mounted Sensor with +/-3F Adjustment optionalExample a Example B Given Set point calculation examplesEffective set point calculations PI loops Discharge Air Temperature ControlProportional Integral PI Control Loops PI loop listProportional Band PI Control ParametersIntegral Time Indoor Air Fan OperationOccupied, Standby, and Bypass Operation Outdoor Air Damper Operation Economizer Economizer enableOA temp sensor Space humidity Networked Space CO2 Sensor Capability Networked Space Humidity Sensor CapabilityNetworked Outdoor Humidity Sensor Capability CO2 Demand Controlled Ventilation optionalCompressor Cooling Lockout Compressor OperationAshrae Cycle Compressor EnvelopeOutdoor Air Fan Operation Compressor Minimum On and Off TimersCompressor Start Delay Floating-Point Actuator Auto-Zero, Overdrive and SyncExternal Binary Inputs Unoccupied Input SignalRemote Shutdown Input Signal Ventilation Lockout Input SignalExternal Binary Outputs Exhaust Interlock Input SignalLights On/Off Signal Fault SignalStart/Stop Calculation Exhaust Fan ON/OFF SignalAuxiliary Heat Signal Auxiliary heat start/stop calculationExpansion board Inputs and outputs, software model 05-DX cooling onlyAlarm and fault code summary Alarm and Fault MonitoringPriority Fault description Reset Keypad Discharge Air DX Cooling Low Limit Indication F3 DX Pressure Fault F1Compressor Envelope Fault F2 Space Temp Sensor Failure F0Discharge Air Temp Sensor Failure F7 Condensate Overflow Indication optional F4Space Coil DX Temp Sensor Failure F5 Outdoor Temp Sensor Failure F6Troubleshooting Temperature Sensors Temperature versus resistance Troubleshooting Humidity SensorsRH % VDC mV Troubleshooting Carbon Dioxide CO2 SensorsHumidity versus voltage CO2 versus voltage tableConfiguration Parameter Name Abr Default LUI Menu UVC configuration parameters OMAbr Default LUI Menu OAD Stroke Time Warranty