Page 3 - Contents; The following are trademarks or
3 VAV-PRC0 03-EN Contents Introduction ............................................................. 4 Comfort Made Simple ................................................................ 4 The Changeover Bypass VAV Comfort Advantage ....................... 4 VariTrac Product Enhancements .............
Page 4 - Comfort Made Simple; Advanced Control Options; Introduction
4 VAV-PRC003-EN Comfort Made Simple Trane has a long history of innovativeleadership in variable air volume (VAV)technology. Trane introduced the: • first fan-powered VAV unit • first factory-commissioned DDC controller • first preprogrammed VAV controller designed specifically for VAVapplications T...
Page 6 - Overview; How the System Works; temperature sensor in each zone; Auto Changeover
6 VAV-PRC003-EN Features andBenefits Overview Changeover-bypass VAV is a comfortsystem developed for light commercialapplications. A changeover-bypass VAVsystem responds to changing coolingor heating requirements by varying thequantity or volume of air delivered toeach zone. Each zone has a thermost...
Page 7 - Figure 6; Central Control Panel; Operator Display Feature Summary
VAV-PRC003-EN 7 Figure 6 . VariTrac central control panel with optional operator display Features andBenefits Central Control Panel The VariTrac central control panel (CCP)serves as the central source ofcommunications and decisionmakingbetween the individual zones and theHVAC unit. The CCP determine...
Page 8 - Tracker System Integration; Tracker System Summary
8 VAV-PRC003-EN Features andBenefits Figure 8 . Tracker System Architecture Static Pressure Sensor The static pressure sensor measuresduct static pressure and positions thebypass damper(s) to maintain the staticpressure setpoint. Figure 7 . Communicating bypass controller side view and 3-D view Quic...
Page 9 - VariTrac Bypass Dampers; Round Bypass Damper Summary
VAV-PRC003-EN 9 Features andBenefits VariTrac Bypass Dampers Bypass dampers are non-communicating VariTrac dampers andinclude an integrated fully-modulating24 VAC electric actuator. Field wiring errors are reduced with aquick-connect harness that plugs intothe communicating bypass controller. Damper...
Page 10 - VariTrac Zone Dampers; Round Zone Damper; Unit Control Module
10 VAV-PRC003-EN Features andBenefits VariTrac Zone Dampers VariTrac zone dampers are fully-modulating, pressure-dependent VAVdevices. The dampers control zonetemperature by varying the volume ofair flowing into a space. Each VariTracdamper has a control box with a VAVcontrol board and actuator encl...
Page 11 - Zone Sensors; Digital Zone Sensor Summary
VAV-PRC003-EN 11 Features andBenefits Figure 10. DDC zone sensors Figure 11. DDC zone sensor with LCD DDC Zone Sensor The direct digital control (DDC) zonesensor is an uncomplicated, reliableelectro-mechanical room sensor. Noprogramming is required and mostsensors contain an internalcommunications j...
Page 13 - A system designed
VAV-PRC003-EN 13 ApplicationConsiderations Introduction The VariTrac system is a changeover-bypass VAV system. One fan supplieseither warm air for heating or cool airfor cooling. It is typically applied insmall buildings which use unitaryheating/cooling air conditioners. Thesebuildings need the simp...
Page 14 - Design process steps; Step 1. Define occupant comfort needs; yy; Step 2. Define the Thermal Zones; Involves engineers
14 VAV-PRC003-EN Figure 17. Design process steps ApplicationConsiderations Effective ChangeoverBypass VAV System Design Unitary zoning systems feature lowfirst cost and quick, easy system designand equipment selection. The system issimple, but it is essential that keyelements are considered during t...
Page 15 - Building Example 1
VAV-PRC003-EN 15 ApplicationConsiderations Cost vs. Comfort First cost can be reduced by limitingthe number of thermal zones.Unfortunately, this may impact thethermal flexibility of the system, andresult in zone comfort issues. Let’s takea closer look at this important systemdecision known as “therm...
Page 16 - Building Example 2
16 VAV-PRC003-EN ApplicationConsiderations Figure 19. Building Example 2 illustrates a poorly insulated storedesign (above) and an improved design(below) Building Example 2 (See Figure 19.) Consider a strip mall in the spring or fallwith stores that face both east andwest. In the morning, the east s...
Page 18 - Step 6. Designing the Duct System; Hand balancing dampers; Hand
18 VAV-PRC003-EN ApplicationConsiderations Step 5. Size Zone and BypassDamper Units Sizing zone damper is relativelystraightforward. The volume of airflow(in cfm or L/s) for each comfort zoneshould be known from the loadanalysis. The designer must select theduct velocity to be used for the system.Re...
Page 19 - Supply Diffusers; Proper return diffuser orientation; Return Diffusers
VAV-PRC003-EN 19 ApplicationConsiderations • When the average glass plus wall heat loss is less than 250 Btuh/linear foot,the slot diffuser may be located inthe center of the room with one ormore slots blowing toward theperimeter wall. • With glass and wall heat loss between 250 and 450 Btuh/linear ...
Page 20 - terminal unit; Example 2; help solve
20 VAV-PRC003-EN ApplicationConsiderations Local Reheat CapabilitiesUsing VariTrane VAV Units VariTrane pressure independent VAVunits are a simple way to upgrade thezone VAV capabilities on a VariTracsystem. The main advantage is theability to integrate units with either hotwater or electric reheat....
Page 21 - Local Reheat
VAV-PRC003-EN 21 ApplicationConsiderations Local Reheat CapabilitiesNon-VAV Options The Trane VariTrac Zone Controller hasbuilt-in capabilities and logic to controla number of reheat sources. Theprevious page discussed how aVariTrane VAV unit with reheat cansolve application issues by providinglocal...
Page 22 - Changeover bypass variable-air-volume system; Bypass Damper Operation
22 VAV-PRC003-EN ApplicationConsiderations Figure 28. Changeover bypass variable-air-volume system Bypass Damper Operation When zone dampers modulate airflowto the spaces, static pressure changesin the supply duct system. Highpressure in a duct system createsexcessive noise and causes poorcomfort co...
Page 23 - Building Pressure Control; Fixed Outside Air Dampers; • Use an exhaust fan with a modulated
VAV-PRC003-EN 23 ApplicationConsiderations Building Pressure Control Comfortable, efficient buildingoperation requires that the air pressureinside the building be slightly higherthan the atmospheric pressure outsideof the building. That is, the building is ata “positive” pressure with respect tothe ...
Page 24 - Application Tip Summary; Tip 1. Use comfort zones
24 VAV-PRC003-EN Application Tip Summary Tip 1. Use comfort zones Units serving thermal zones canprovide greater comfort by dividing thethermal zones into “comfort zones”using a changeover-bypass-VAVsystem. Tip 2. Create thermal zones Create thermal zones which minimizesimultaneous heating and cooli...
Page 25 - VariTrac Dampers
VAV-PRC003-EN 25 Zone Damper Selection Procedures Refer to the sizing chart in Table 2 forzone dampers. Follow down the firstcolumn in the table for the desiredvelocity. Then follow across for the cfm(air volume) of a given VariTrac damperbased on that velocity. Note: If the cfm exceeds the damperra...
Page 26 - Damper sizing charts; Rectangular Zone Damper; Rectangular Bypass Damper; Round Bypass Damper
26 VAV-PRC003-EN SelectionProcedures Notes: 1. Recommended velocity for zone dampers is between 1000 and 1600 fpm. Use good standard design practices (such as location of duct). 2. Recommended velocity for bypass damper is between 1600 and 2000 fpm. Table 2. Damper sizing charts Round Zone Damper Ca...
Page 27 - Digits 5, 6 – VariTrac Damper Size; Service Model Numbers
VAV-PRC003-EN 27 Digits 1, 2, 3, 4 – Product Type VADA = VariTrac Air Damper VARA = Rectangular Air Damper Digits 5, 6 – VariTrac Damper Size 06 = 6" Damper 08 = 8" Damper 10 = 10" Damper 12 = 12" Damper 14 = 14" Damper 16 = 16" Damper 1R = 14 x 12 bypass damper 2R = 16 x 16 ...
Page 28 - Typical Bill of Materials; Device Name
28 VAV-PRC003-EN A & J B C D E F G H Figure 31. Typical components in achangeover-bypassVAV system Table 3. Typical VariTrac changeover-bypass VAVsystem components SelectionProcedures Typical Bill of Materials Device Name Function in System Number Required A Central control panelw/optional opera...
Page 29 - Central control panel field wiring
VAV-PRC003-EN 29 24 Vac Line volt age Comm5link Comm5link Comm5 UCM Tracker Splice A A B B Tw isted pair, shielded wireper Trane specifications Shield termination Earth ground Contact points Transf T T ormer Termination resistor Shield ground = = = = = = = Termination Board TB2 Figure note = Comm4li...
Page 31 - UCM Comm Link Wiring
VAV-PRC003-EN 31 Electrical Dataand Connections Figure 35. UCM Comm Link Wiring Va riT ra c Te rmination Board TB2 Sta tic Pres s u re Po rt + V OUT – Air S u p p ly T e m p . Se n so r Pres s u re T ra nsduc e r 1 10 11 12 13 14 15 9 8 7 6 5 4 3 2 + – J3 R G BK S GRN YEL AC T 24V GND ZONE BIP GND G...
Page 32 - Communicating bypass controller wiring; OUT
32 VAV-PRC003-EN Electrical Dataand Connections Figure 36. Communicating bypass controller wiring CW ACTUATOR HOT CLOSE CCW OPEN COM SPARE CONNECTOR ACTUATOR TB1–1 STATIC PRESSURE PORT W–HOT BIP BK–OPEN 2. 2. 24VAC 24V GND ACT R–CLOSE TB1–2 TB4–1 1 TO NEC CLASS 2 24V TRANSFORMER LOAD 8 VA (WITHOUT A...
Page 33 - UCM Wiring
VAV-PRC003-EN 33 Electrical Dataand Connections Figure 37. UCM Wiring 24 VAC 60 HZ NEC CLASS–2 CONTROL CIRCUIT 8. W G W R DAMPER ACTUATOR WIRING D.D.C. \ U.CM. CONTROL BOARD D.D.C. \ U.CM. CONTROL BOARD ADDRESS SWITCH SHIELDED TWISTED PAIR COMMUNICATIONS WIRING } } J11 PRESS TB2–1 TB2–2 TB2–3 TB2–4 ...
Page 34 - DDC zone sensor with LCD
34 VAV-PRC003-EN Electrical Dataand Connections Digital Sensor Terminal Connection Chart Sensor UCM Field Wire Color Code TB1–1 TB1–1 TB2–1 TB1–2 TB2–6 TB2–2 TB2–5 TB3–1 TB3–3 TB3–1 TB2–3 TB3–2 TB1–2 TB3–2 Digital Sensor Board TB1–1 TB3–1 TB2–1 GND 24V –2 –2 –2 –2 –2 Temperature Signal Common Setpoi...
Page 35 - Zone sensor options; Specifications; VariTrac DDC zone; Number of
VAV-PRC003-EN 35 Table 4. Zone sensor options Specifications Figure 40. VariTrac DDC zone sensors Number of Zone Sensor Options Required Wires 1 Sensor only (no communications jack available) 2 Sensor with adjustable setpoint 3 Sensor with night setback override and cancel buttons 2 Sensor with adju...
Page 37 - Communicating bypass
VAV-PRC003-EN 37 Table 8. Zone occupancy sensor specifications Table 7. Communicating bypass control assembly specifications Specifications Figure 43. Communicating bypass controller Figure 44. Zone occupancy sensor Ideal for zones with intermittentoccupancy like conference rooms).When occupied, the...
Page 38 - CO; Duct
38 VAV-PRC003-EN Table 10. CO 2 sensor specifications Table 9. Digital zone sensor specifications Specifications Figure 45. DDC zone sensor with digital display Figure 46. CO 2 duct sensor Figure 47. CO 2 wall sensor Thermistor Resistance Rating 10kW at 77° (25°C) Accuracy at 77°F (25°C) 0.4°F (0.2°...
Page 39 - Acoustics; Size; Octave Band
VAV-PRC003-EN 39 Acoustics are tricky to define forspecific jobsites. To provide anacoustical overview of a typical officesystem with mineral glass fiberdropped ceiling, ARI standard 885-98has generated the transfer functions inTable 11. Sound power data was collected inaccordance with ARI Standard ...
Page 40 - Discharge sound data
40 VAV-PRC003-EN Acoustics Table 13. Discharge sound data Note: NC data based on ARI 885-98 Acoustical transfer functions in Table 11. Discharge Size CFM ISP NC 6 in. 375 0.25 — 6 in. 375 0.5 — 6 in. 375 1 1 8 6 in. 375 2 2 2 6 in. 300 0.25 6 in. 300 0.5 — 6 in. 300 1 — 6 in. 300 2 19 6 in. 225 0.25...
Page 41 - Dimensions and Weights; Central control panel dimensions
VAV-PRC003-EN 41 Dimensions and Weights Figure 48. Central control panel dimensions Note: 1. Central control panel weight is 2.5 lbs. Front view Side view 8.75 in.(22.38 cm) 2.75 in.(6.99 cm) 10.25 in.(26.04 cm) Top view Bottom view
Page 42 - Communicating bypass control dimensions
42 VAV-PRC003-EN Figure 49. Communicating bypass control dimensions Dimensions and Weights Mounting holesSee back view for dimensions 4 1/4" 1 15/16" 3 5/16" Side View 6 3/4" 5" 3 3/8" 3 7/8" 4 5/16" 1.00" 1.00" 0.300" Back View Notes: 7/8" knockout1/2...
Page 43 - Round zone and bypass damper dimensions; Controls Area; Airflow; Center of Bead
VAV-PRC003-EN 43 Figure 50. Round zone and bypass damper dimensions Dimensions and Weights Airflow Controls Area 8.875" 2.125" 4.375" 0.50" 6.625" C Airflow A B DIA 3.625" 2.00" Center of Bead Duct Temp Sensor (Optional) N/A on Bypass Control Damper Size A Weight Nominal ...
Page 44 - Rectangular zone damper dimensions
44 VAV-PRC003-EN Figure 51. Rectangular zone damper dimensions Dimensions and Weights X Y 6.00" Ref. Slip & Drive Connection Seam 16.00" Ref. Dimensions X Y 8.00" 8.00" 8.00" 10.00" 10.00" 14.00" 12.00" 14.00" 16.00" 16.00" 20.00" 18.00" Da...
Page 45 - Rectangular bypass damper dimensions; Damper Frame Data
VAV-PRC003-EN 45 Dimensions and Weights Figure 52 Rectangular bypass damper dimensions Factory InstalledCable Provided Actuator Air Flo w Y 5" Damper Frame Data Frame Linkage Blade Pin Blade PinExtension Bearings Blade Seals Side SealsCable Weight Blades 13 gage galvanized steel 16 gage galvaniz...
Page 46 - Occupancy Sensor
46 VAV-PRC003-EN R UNOCC SETPOINT OVERRIDE ˚C ˚F MAX CANCEL ON 4.5 2.8 1.1 1.0 4.25" 1.44" 3.125" Figure 54. CO 2 Sensor dimensions Dimensions and Weights Figure 53. Occupancy Sensor Figure 55. Digital Zone Sensor 3.60" 1.90" 2.50" Front View SideView
Page 47 - Glossary
VAV-PRC003-EN 47 Glossary ABS gears – Gears formed of a lightweight plastic known for itstoughness, impact strength, anddimensional stability. Back draft damper – A one-way airflow damper in a parallel fanpowered unit prevents primary flowfrom exiting the plenem inlet. Binary input – A two-position ...
