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Trane TRG-TRC014-EN manual Ceiling-DiffuserCompatibility, Components of a VAV System, period two

Models: TRG-TRC014-EN

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period two

Components of a VAV System

notes

Ceiling–Diffuser Compatibility

hanger wire

ceiling tile

cross T

structural T

Figure 50

Because variable-air-volume systems are installed in, and distribute air along the surfaces of, ceilings, it is essential that the diffusers be compatible with the ceiling design.

The T-bar ceiling is possibly the most popular design. It is constructed of a grid of inverted T-shaped members suspended by wires from the floor or roof structure above. Cross members added to the load bearing T-bars generate a symmetrical ceiling pattern. Finally, ceiling tiles are laid in place and supported by this grid.

TRG-TRC014-EN

Page 40

Image 40

Trane TRG-TRC014-EN manual Ceiling-DiffuserCompatibility, Components of a VAV System, period two

Contents

One of the Systems Series Air Conditioning Clinic VAV SystemsTRG-TRC014-EN A publication of The Trane Company VAV SystemsOne of the Systems Series VAV Systems PrefaceA Trane Air Conditioning Clinic Contents period one What Is Variable Air Volume?period two Components of a VAV SystemTRG-TRC014-EN What Is Variable Air Volume? What Is Variable Air Volume?Constant-Volume Variable-TemperatureSystem period oneperiod one Constant Volume-FullLoadWhat Is Variable Air Volume? What Is Variable Air Volume? Constant Volume-PartLoadperiod one Constant Volume-MultipleSpaces What Is Variable Air Volume?Constant Volume-MultipleSpaces period oneWhat Is Variable Air Volume? Terminal Reheat Systemperiod one Variable-Air-VolumeVAV System VAV-FullLoadWhat Is Variable Air Volume? period oneWhy VAV? Energy Savings VAV-PartLoadWhat Is Variable Air Volume? Why VAV?Why VAV? Comfort What Is Variable Air Volume?period one quiteWhat Is Variable Air Volume? System Comparisonperiod one VAV Building Characteristics Variable Thermal Load ProfilesWhat Is Variable Air Volume? period oneIndependent Space Control Common Return Air PathWhat Is Variable Air Volume? period oneperiod two Components of a VAV SystemComponents of a VAV System period twoVAV Terminal Units period twoComponents of a VAV System Single Duct, Cooling Only Components of a VAV Systemperiod two Single Duct, Cooling OnlyComponents of a VAV System Space Heating with a VAV Systemperiod two VAV Reheat primary airComponents of a VAV System period twoFan-PoweredTerminal Units Components of a VAV Systemperiod two parallelParallel, Fan-Powered plenum airParallel, Fan-Powered Components of a VAV SystemComponents of a VAV System Series, Fan-Poweredperiod two Parallel Versus Series Fan-Powered Series, Fan-PoweredComponents of a VAV System period twoComponents of a VAV System Single-DuctVAV Systemsperiod two Dual-Duct Components of a VAV Systemperiod two warm primary air cool primary air supply airVariable Air Volume to the Space warmcool Components of a VAV SystemConstant Air Volume to the Space Single-Fan, Dual-DuctVAV SystemComponents of a VAV System period twoComponents of a VAV System Two-Fan, Dual-DuctVAV Systemperiod two VAV Terminal Unit Controls Upstream Pressure Affects AirflowComponents of a VAV System period twoPressure-DependentControl Pressure-IndependentControlComponents of a VAV System period twoPrimary Airflow Measurement Terminal-UnitControl TechnologiesComponents of a VAV System period twoComponents of a VAV System Pneumatic Controlperiod two Components of a VAV System Electronic Controlperiod two Components of a VAV System Direct Digital Control DDCperiod two Components of a VAV System period twoDirect Digital Control DDC Electronic pressure transducer provides pressure-independentcontrolDiffusers Components of a VAV Systemperiod two DiffusersLinear Slot Diffuser Components of a VAV Systemperiod two CoandaComponents of a VAV System Ceiling-DiffuserCompatibilityperiod two Components of a VAV System period twoCeiling-DiffuserCompatibility cross TSupply Duct System Components of a VAV Systemperiod two Supply Duct SystemDuct Design Components of a VAV Systemperiod two Equal friction methodComponents of a VAV System Duct Design Recommendationsperiod two System Configurations System Configurationsperiod three period threeperiod three Perimeter SpacesSystem Configurations Perimeter SpacesBaseboard Perimeter Heating System Configurationsperiod three heat loss 450 Btu/hr/ftSystem Configurations Overhead Supply Perimeter Heatingperiod three System Configurations period threeVAV Reheat heat loss 250 Btu/hr/ftFan-PoweredVAV Dual-DuctVAVSystem Configurations period threeInterior Spaces Interior Spaces, Reheat RequiredSystem Configurations period threeSmall Buildings Changeover/Bypass VAV SystemSystem Configurations period threeSystem-LevelControl Modes System Configurationsperiod three System-LevelControl ModesSystem Configurations Occupied Modeperiod three System Configurations Unoccupied Modeperiod three System Configurations Morning Warm-up/Cool-downModeperiod three period four Fan ModulationFan Modulation period fourSystem Resistance Curve period fourFan Modulation Operating Point Riding the Fan CurveFan Modulation period fourFan Modulation Forward-CurvedCentrifugal Fanperiod four Fan Modulation Curve Fan Modulationperiod four Fan Modulation CurveFan Control Loop VAV Fan ModulationFan Modulation period fourFan Modulation Methods Discharge DampersFan Modulation period fourFan Modulation period fourDischarge 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 pressureInlet Vanes Fan Modulationperiod four Inlet VanesFan-SpeedControl Fan Modulationperiod four Fan-SpeedControlVariable-PitchBlade Control Fan Modulationperiod four Variable-PitchBlade ControlFan Modulation Fan Modulation Comparisonsperiod four Controlling System Static Pressure Fan Outlet Static-PressureControlFan Modulation period fourSupply Duct Static-PressureControl Fan Modulationperiod four sensor located 2/3 down supply ductOptimized Static-PressureControl Fan Modulationperiod four sensor locatedFan Modulation Part-LoadComparisonperiod four period five Application Considerationsperiod five Application ConsiderationsSystem-LevelVentilation period fiveApplication Considerations Ventilation Reset Application Considerationsperiod five outdoor airflowFreeze Protection for Coils Measures to Prevent Coil Freeze-UpApplication Considerations period fivePart-LoadSpace Humidity Control Application Considerationsperiod five Part-LoadSpace Humidity ControlApplication Considerations Part-LoadSupply Air Temperingperiod five Building Pressure Control Direct Pressurization ControlApplication Considerations period fiveperiod five Application ConsiderationsA 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 period six ReviewReview period sixperiod six Review-PeriodTwofan-poweredVAV terminal unit ReviewReview-PeriodThree Review-PeriodFourReview period sixReview-PeriodFive Reviewperiod six System-levelventilationperiod six ReviewTRG-TRC014-EN Quiz Questions for PeriodQuestions for Period Questions for PeriodQuiz 11What method of static-pressurecontrol provides the greatest power- savings potential for a VAV system?Questions for Period TRG-TRC014-EN Answers Glossary parallel fan-poweredterminal unit A fan-poweredVAV terminal unit GlossaryGlossary supply air Conditioned air delivered to a spaceThe Trane Company An American Standard Company