Manuals / Trane / Household Appliance / Air Conditioner

Trane TRG-TRC014-EN manual

Models: TRG-TRC014-EN

1 93

Page 5

iv	TRG-TRC014-EN

Page 5

Image 5

Contents

TRG-TRC014-EN Air Conditioning Clinic VAV SystemsOne of the Systems Series One of the Systems Series VAV SystemsA publication of The Trane Company A Trane Air Conditioning Clinic PrefaceVAV Systems period one What Is Variable Air Volume? Contentsperiod two Components of a VAV SystemTRG-TRC014-EN What Is Variable Air Volume? What Is Variable Air Volume?Constant-Volume Variable-TemperatureSystem period oneWhat Is Variable Air Volume? Constant Volume-FullLoadperiod one period one Constant Volume-PartLoadWhat Is Variable Air Volume? What Is Variable Air Volume? Constant Volume-MultipleSpacesConstant Volume-MultipleSpaces period oneperiod one Terminal Reheat SystemWhat Is Variable Air Volume? VAV-FullLoad Variable-Air-VolumeVAV SystemWhat Is Variable Air Volume? period oneVAV-PartLoad Why VAV? Energy SavingsWhat Is Variable Air Volume? Why VAV?What Is Variable Air Volume? Why VAV? Comfortperiod one quiteperiod one System ComparisonWhat Is Variable Air Volume? Variable Thermal Load Profiles VAV Building CharacteristicsWhat Is Variable Air Volume? period oneCommon Return Air Path Independent Space ControlWhat Is Variable Air Volume? period oneComponents of a VAV System period twoComponents of a VAV System period twoComponents of a VAV System period twoVAV Terminal Units Components of a VAV System Single Duct, Cooling Onlyperiod two Single Duct, Cooling Onlyperiod two Space Heating with a VAV SystemComponents of a VAV System primary air VAV ReheatComponents of a VAV System period twoComponents of a VAV System Fan-PoweredTerminal Unitsperiod two parallelplenum air Parallel, Fan-PoweredParallel, Fan-Powered Components of a VAV Systemperiod two Series, Fan-PoweredComponents of a VAV System Series, Fan-Powered Parallel Versus Series Fan-PoweredComponents of a VAV System period twoperiod two Single-DuctVAV SystemsComponents of a VAV System Components of a VAV System Dual-Ductperiod two warm primary air cool primary air supply airwarm Variable Air Volume to the Spacecool Components of a VAV SystemSingle-Fan, Dual-DuctVAV System Constant Air Volume to the SpaceComponents of a VAV System period twoperiod two Two-Fan, Dual-DuctVAV SystemComponents of a VAV System Upstream Pressure Affects Airflow VAV Terminal Unit ControlsComponents of a VAV System period twoPressure-IndependentControl Pressure-DependentControlComponents of a VAV System period twoTerminal-UnitControl Technologies Primary Airflow MeasurementComponents of a VAV System period twoperiod two Pneumatic ControlComponents of a VAV System period two Electronic ControlComponents of a VAV System period two Direct Digital Control DDCComponents of a VAV System period two Components of a VAV SystemDirect Digital Control DDC Electronic pressure transducer provides pressure-independentcontrolComponents of a VAV System Diffusersperiod two DiffusersComponents of a VAV System Linear Slot Diffuserperiod two Coandaperiod two Ceiling-DiffuserCompatibilityComponents of a VAV System period two Components of a VAV SystemCeiling-DiffuserCompatibility cross TComponents of a VAV System Supply Duct Systemperiod two Supply Duct SystemComponents of a VAV System Duct Designperiod two Equal friction methodperiod two Duct Design RecommendationsComponents of a VAV System System Configurations System Configurationsperiod three period threePerimeter Spaces period threeSystem Configurations Perimeter SpacesSystem Configurations Baseboard Perimeter Heatingperiod three heat loss 450 Btu/hr/ftperiod three Overhead Supply Perimeter HeatingSystem Configurations period three System ConfigurationsVAV Reheat heat loss 250 Btu/hr/ftDual-DuctVAV Fan-PoweredVAVSystem Configurations period threeInterior Spaces, Reheat Required Interior SpacesSystem Configurations period threeChangeover/Bypass VAV System Small BuildingsSystem Configurations period threeSystem Configurations System-LevelControl Modesperiod three System-LevelControl Modesperiod three Occupied ModeSystem Configurations period three Unoccupied ModeSystem Configurations period three Morning Warm-up/Cool-downModeSystem Configurations Fan Modulation period fourFan Modulation period fourFan Modulation period fourSystem Resistance Curve Riding the Fan Curve Operating PointFan Modulation period fourperiod four Forward-CurvedCentrifugal FanFan Modulation Fan Modulation Fan Modulation Curveperiod four Fan Modulation CurveVAV Fan Modulation Fan Control LoopFan Modulation period fourDischarge Dampers Fan Modulation MethodsFan Modulation period fourperiod four Fan ModulationDischarge Dampers As the VAV terminal units modulate shut, the system resistance curve shifts upwards. The fan begins to “ride up” the constant-speedperformance curve, from the design operating point A, trying to reach the balance point with this new system resistance curve. As a result, the fan delivers a lower airflow at a higher static pressureFan Modulation Inlet Vanesperiod four Inlet VanesFan Modulation Fan-SpeedControlperiod four Fan-SpeedControlFan Modulation Variable-PitchBlade Controlperiod four Variable-PitchBlade Controlperiod four Fan Modulation ComparisonsFan Modulation Fan Outlet Static-PressureControl Controlling System Static PressureFan Modulation period fourFan Modulation Supply Duct Static-PressureControlperiod four sensor located 2/3 down supply ductFan Modulation Optimized Static-PressureControlperiod four sensor locatedperiod four Part-LoadComparisonFan Modulation Application Considerations period fiveperiod five Application ConsiderationsApplication Considerations period fiveSystem-LevelVentilation Application Considerations Ventilation Resetperiod five outdoor airflowMeasures to Prevent Coil Freeze-Up Freeze Protection for CoilsApplication Considerations period fiveApplication Considerations Part-LoadSpace Humidity Controlperiod five Part-LoadSpace Humidity Controlperiod five Part-LoadSupply Air TemperingApplication Considerations Direct Pressurization Control Building Pressure ControlApplication Considerations period fiveA sensitive static-pressurecontroller directly compares the variations between the space static pressure and the outdoor reference static pressure. The controller modulates the capacity of a central relief fan to maintain a fixed static-pressuredifference, usually a slightly positive building pressure. The space static-pressuresensor is typically located in the lobby or near the main entrance Application Considerationsperiod five Review period sixReview period sixReview-PeriodTwo period sixfan-poweredVAV terminal unit ReviewReview-PeriodFour Review-PeriodThreeReview period sixReview Review-PeriodFiveperiod six System-levelventilationTRG-TRC014-EN Reviewperiod six Questions for Period QuizQuestions for Period Questions for PeriodQuestions for Period 11What method of static-pressurecontrol provides the greatest power- savings potential for a VAV system?Quiz TRG-TRC014-EN Answers Glossary Glossary parallel fan-poweredterminal unit A fan-poweredVAV terminal unitsupply air Conditioned air delivered to a space GlossaryAn American Standard Company The Trane Company