Trane TRG-TRC014-EN manual Controlling System Static Pressure, Fan Outlet Static-Pressure Control

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period four

Fan Modulation

notes

Controlling System Static Pressure

Fan outlet static-pressure control

Supply duct static-pressure control

Optimized static-pressure control

Figure 90

System Static-Pressure Control

Each of these fan-capacity control methods requires a signal from a controller that monitors static pressure, using a sensor located somewhere in the supply- duct system. This controller compares the sensed pressure to a set point and modulates the fan capacity to maintain a set point at that sensor location.

There are three common methods for sensing and controlling system static pressure. They are: fan outlet static-pressure control, supply duct static- pressure control, and optimized static-pressure control.

Fan Outlet Static-Pressure Control

sensor located at fan outlet

static pressure sensor

VAV terminal units

supply fan

Figure 91

For the fan outlet static-pressure control method, the static pressure sensor is mounted near the outlet of the main supply fan. The controller is set to maintain the static pressure required at design flow.

The appeal of this method is that the sensor can be factory-installed and tested, resulting in greater reliability and no field installation cost. If fire dampers are

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Contents Air Conditioning Clinic VAV Systems One of the Systems Series Publication of The Trane Company VAV Systems PrefaceContents TRG-TRC014-EN Constant-Volume Variable-Temperature System What Is Variable Air Volume?Constant Volume-Full Load Constant × Supply Airflow Constant Volume-Part LoadFine Constant Volume-Multiple SpacesTerminal Reheat System VAV-Full Load Variable-Air-Volume VAV SystemWhy VAV? Energy Savings VAV-Part LoadReduced fan energy Reduced refrigeration energy Dedicated terminal units Dedicated thermostats Why VAV? ComfortVAV System ComparisonVariable Thermal Load Profiles VAV Building CharacteristicsCommon Return Air Path Independent Space ControlComponents of a VAV System Components of a VAV SystemVAV Terminal Units Air Heating coil Filter Mixing fanVAV Terminal Units Primary air ir Single Duct, Cooling OnlySpace Heating with a VAV System Primary air VAV ReheatSeries Fan-Powered Terminal UnitsParallel, Fan-Powered Series, Fan-Powered Parallel Versus Series Fan-Powered Single-Duct VAV Systems Dual-Duct Cool Primary air Variable Air Volume to the SpaceSingle-Fan, Dual-Duct VAV System Constant Air Volume to the SpaceTwo-Fan, Dual-Duct VAV System VAV Terminal Unit Controls Upstream Pressure Affects AirflowVAV Terminal Unit Controls Pressure-Independent Control Pressure-Dependent ControlTerminal-Unit Control Technologies Primary Airflow MeasurementPneumatic Control Electronic Control Direct Digital Control DDC Components of a VAV System Diffusers DiffusersEffect Linear Slot DiffuserCeiling-Diffuser Compatibility Components of a VAV System Supply Duct System Supply Duct SystemDuct Design Equal friction methodStatic regain method Duct Design Recommendations Perimeter P Versus Interior System ConfigurationsPerimeter Spaces Perimeter SpacesBaseboard Perimeter Heating Overhead Supply Perimeter Heating Heat loss 250 Btu/hr/ft Dual-Duct VAV Fan-Powered VAVInterior Spaces, Reheat Required Interior SpacesChangeover/Bypass VAV System Small BuildingsSystem-Level Control Modes Occupied mode Unoccupied mode Morning warm-up/cool-down modeOccupied Mode Unoccupied Mode Morning Warm-up/Cool-down Mode Fan Modulation Fan Performance CurveFan Performance Curve System Resistance Curve System Resistance CurveRiding the Fan Curve Operating PointForward-Curved Centrifugal Fan Fan Modulation Curve Fan Modulation CurveVAV Fan Modulation Fan Control LoopDischarge Dampers Fan Modulation MethodsStatic pressure Discharge damper SP loss Inlet Vanes 0 r p m Fan-Speed ControlVariable-Pitch Blade Control BI fan with Discharge Dampers Fan Modulation ComparisonsFan Outlet Static-Pressure Control Controlling System Static PressureSensor located Down supply duct Supply Duct Static-Pressure ControlAt fan outlet Optimized Static-Pressure ControlPart-Load Comparison Period five Application ConsiderationsSystem-Level Ventilation System-Level VentilationVentilation Reset Freeze Protection for Coils Measures to Prevent Coil Freeze-UpFreeze Protection for Coils Part-Load Space Humidity Control Part-Load Space Humidity ControlPart-Load Supply Air Tempering Building Pressure Control Direct Pressurization ControlBuilding Pressure Control Application Considerations Review-Period One ReviewReview-Period Two Review-Period Four Review-Period ThreeTrane Air Conditioning Manual Review-Period FiveReview Questions for Period QuizQuiz TRG-TRC014-EN Answers Glossary Glossary Glossary Trane Company

TRG-TRC014-EN specifications

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