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Trane VariTrac Dampers Catalogue

1. S Rion TB1 1 24VAC pote oes ence 7 0 COMMON TB4 1 BIP R he Geeta ee GR NC TB p 24VAC G BK RETUR ______ 781 2 GND W NOT CONNECTED w OPTIONAL FIELD INSTALLED OCCUPANCY SENSOR CAMPER Tos SE STG TER STAGE CONTACTOR S WIRING 187879 24vac 12VA HOT MAXICOIL pet oe 1 OPTIONAL FIELD INSTALLED li eccl ELECTRIC HEATER ACT IGNDI20V Jb bb 3l 2n T tow __ HOT prop water gt gt gug BK CLOSE _ VALV r 2 R OPEN 24VAC B Toso 8 12 VA ADDRESS wre mes SWITCH D D C U CM J3 T F4 T4 CONTROL BOARD 18 7 o4 ON OFF be 371 TOJ 4 WATER VALVE aan ana sisi GRN ZAMEN sob gt DIGITAL ac PUY PUB BUPU o fel 12 VA MAX Q ZONE GND SET D L INSTALLED DIGITAL ZONE SENSOR OPTIONAL FIELD INSTALLED 77 V ime ON OFF WATER VALVE TH 4 L4 TES ome AL 554 D D C U CM I CONTROL BOAR
2. Wiring Actuator CCP Black CW Clase White COM Com CCW Open Standard Dims Damper Sizes Size W H i 14 00 12 007 Ge x 14 1616 16 00 16 00 2020 20 00 20 00 3020 20 x 305 30 00 20 00 DAMPER FRAME DATA 16 REF Actuator Frame 18 gauge Galvanized Steel Blades B gauge Galvanized Steel All blades are 4 or 5 nominal width Shroud 2e gauge Galvanized Steel Linkage 14 gauge Galvanized Steel Zinc Plated Damper Shaft 172 Dio Steel Zinc Plated Bearings Self lubrica ting Nylon Cable 10 00 Ft 3m gt Plenum Rated e TRANE Dimensions and Weights VAV PRC003 EN 47 e TRANE Dimensions and Weights Figure 42 Occupancy sensor L CO2 sensor dimensions R Top and digital zone sensor R Bottom 4 1 44 4 25 73 55 2 90 27 82 1 08 3 60 Front View 120 41 4 74 2 50 Side View 1 90 gt 48 VAV PRC003 EN Glossary Back Draft Damper A one way airflow damper in a parallel fan powered unit prevents primary flow from exiting the plenem inlet Binary Input A two position signal indicating on off status Binary Output A control output that is either on or off Built In Time Clock The occupancy timer included in the CCP op
3. 37 Nr 39 Dimensions and Weights 43 deuda casa A ame Gade sam cu Hu a 49 3 S Features and Benefits Figure 3 VariTrac changeover bypass VAV system components VariTrac Central Control Panel with touchscreen HVAC Unit IE interface P Bypass Damper Am Communicating Bypass Controller lt LJ li Wireless Zone Sensor Zone Sensor VariTrac Central Control Panel CCP Communicating Bypass Controller The is the system level controller which A single enclosure with duct coordinates and monitors VariTrac system a temperature sensor static operation including HVAC system supply i pressure sensor and By pressure and airflow heating cooling yt 2 communicating controller UCM mode supply air temperature all zone which easily mounts on the temperatures and setpoints fan mode supply ductwork The UCM economizer position when paired with CO2 provides power to drive the bypass damper actuator demand controlled ventilation time of day scheduling zone grouping logic system override mode after hours operation and much more Zone Sensor Zone sensors sometimes referred to as thermostats measure space temperature and report it to the zone damper controller UCM Five models are available to satisfy varied aesthetic and 8 application preferences
4. Involves engineer s and contractors Step 3 Determine Comfort Zones Involves engineers contractors and building owner Step 7 Air Diffuser Selection and Placement Step 4 Size Heating Involves engineer s and contractors Cooling Equipment Involves engineer s and contractors VAV PRC003 EN S TRANE Application Considerations Step 1 Define occupant comfort needs The design process begins by considering the needs of building occupants and intended building use What is the intended use of the building Is the building usage primarily office space Is there a manufacturing operation Are there areas that have special requirements such as computer or electronic rooms video television production training facilities etc What physical activity level is expected of the occupants Seated occupants require different indoor temperatures for comfort than continuously moving occupants An example may be a building with a mix of office space and light assembly or manufacturing Where will the occupants be located and at what times Pay particular attention to areas with intermittent use such as conference training and lunchrooms How are the occupants expected to dress Give consideration to how the building occupants will dress Will they dress in traditional business attire such as long sleeved shirts or blouses ties and jackets Or will they dress in cooler casual attire such as golf shirts light slack
5. When selecting the heating and cooling unit for a thermal zone load diversity within the zone should be considered to minimize equipment size and therefore reduce system first cost and operating expense Load diversity is defined as the ratio of the instantaneous peak loads block load to the sum of the peak loads within the thermal zone In recognizing load diversity the designer acknowledges that all areas of the thermal zone will not require maximum cooling or heating at the same time 17 e TRANE Application Considerations While using diversity may reduce the size of the HVAC unit the zone ductwork dampers and diffusers must be sized for the individual zone peak loads The main trunk duct may be sized based on the HVAC unit airflow Calculating thermal zone diversity 1 Determine the instantaneous peak or block load for the thermal zone This information is output from load analysis software such as Trane TRACE or manually calculated Calculate the sum of the peak loads for each of the comfort zones within the thermal zone The diversity factor is then calculated by dividing the instantaneous peak load value by the sum of the peak loads Diversity Factor Instavt Peak Load Sum of Peaks The heating and cooling equipment will never be called upon to provide more capacity than was determined by the instantaneous peak load value Consequently the equipment capacity can be reduced by the diversity factor Fi
6. 1 represents NC levels below NC 15 2 NC Values are calculated using modeling assumptions based on AHRI 885 98 02 Addendum 3 Data at 1 5 inlet pressure constitute AHRI 880 2011 Standard Rating Conditions 4 Where APs is the inlet static pressure minus discharge static 5 Data at 0 5 1 0 2 0 and 3 0 are application ratings These ratings are outside the scope of the certification program 42 VAV PRC003 EN Dimensions and Weights Figure 37 Central control panel dimensions Top view 10 25 in 2 75 in 26 04 cm 6 99 cm 8 75 in 22 38 cm Front view Side view Bottom view Note Central contro panel weight is 2 5 Ibs 43 e TRANE Dimensions and Weights Figure 38 Communicating bypass control dimensions 4 63 4 gt lt M 5 p 3 3 8 1 i o 45 16 37 8 J L o 0300 9 1 00 lt gt 1 00 lt gt 1 Back View 7 8 knockout 1 2 conduit Customer entry Notes Weight 3 1 4 Ibs Operating Temp 32 to 140 Humidity Mounting Method 44 41 4 Mounting holes gt Side View 5 to 95 non condensing Metal screws Duct Static Pressure Sensor Duct Temp Sensor i ka 1 15 16
7. 4 VAV PRC003 EN HVAC Unit Overview VAV PRC003 EN VariTrac changeover bypass systems operate with Trane and non Trane products including split systems packaged rooftop units and water source heat pumps These systems are generically referred to as HVAC heating ventilating and air conditioning units When combined with a Trane packaged rooftop with ReliaTel controller wiring installation and system startup efficiency is maximized by connecting with a simple twisted shielded wire pair S TRANE Features and Benefits Bypass Damper with Wire and Quick Connect A round or rectangular damper ducted between the HVAC supply and return ducts It is easily connected via a quick connector which provides quick and consistent field wiring The bypass damper is modulated by the CCP to maintain required system static pressure Changeover bypass VAV is a comfort system developed for light commercial applications A changeover bypass VAV system responds to changing cooling or heating requirements by varying the quantity or volume of air delivered to each zone Each zone has a thermostat for individual comfort control An HVAC unit delivers a constant volume of air to the system As the volume of air required by the zone changes excess supply air is directed to the return duct via a bypass duct and damper See Figure 3 p 4 for typical system components A changeover bypass VAV system
8. 93 C 5 95 relative humidity non condensing Control Enclosure NEMA 1 metal enclosure plenum rated Communication link wiring must be Level 4 22 AWG twisted shielded pair wire with stranded tinned copper Communication Link Wiring conductors Maximum total wire is 3 500 ft 1066 8 m Wire must meet Trane specifications Table 9 Communicating bypass control assembly specifications Power Requirements 20 30 Vac 60Hz single phase 15 VA minimum Class 2 transformer required Operating Environment 32 120 F 0 49 C 10 90 relative humidity non condensing Storage Environment 50 200 F 46 93 C 5 95 relative humidity non condensing Control Enclosure NEMA 1 metal enclosure plenum rated Communication link wiring must be Level 4 22 AWG twisted shielded pair wire with stranded tinned copper Communication Link Wiring conductors Maximum total wire is 3 500 ft 1066 8 m Wire must meet Trane specifications VAV PRC003 EN 37 e TRANE Specifications 38 Table 10 Zone occupancy sensor specifications Power Supply 24 Vac or 24 Vdc 10 Maximum VA Load 0 88 VA 24 Vac 0 722 VA 24 Vdc Isolated Relay Rating 1 A 24 Vac or 24 Vdc Operating Temperature 32 131 F 0 55 C Storage Temperature 22 176 F 30 80 C Humidity Range 0 95 non condensing Effective Coverage Area Effective Coverage Radius 1200 sq ft 365 8 m 22 ft 6
9. T A re an 8 28 A 8 Comm4 UCM Comm4 UCM e Comm4 Comm4 link link Splice Tracker Comm5 UCM A JA A Comms link link B B o E Splice N Legend Figure Notes Transformer Figure note Termination resistor Shield termination Contact points Earth ground A NS _ Twisted pair shielded wire 7 per Trane specifications Shield ground 1 All customer wiring must be in accordance with national state and local electrical codes 2 Trane recommends a dedicated transformer for 24 Vac power 3 Do not apply voltage to the priority shutdown and occupancy inputs 4 Example of Comm5 communication link wiring See product specific literature for Comm5 wire connection details 31 e TRANE Electrical Data and Connections Figure 30 Relay board wiring Relay Board TB2 24 VAC CLASS 2 COOL UNIT 24 VAC CLASS 2 HEAT UNIT SUPPLY FAN 2 HEAT 2COOL HEAT PUMP ix COOL 1 COMP 1 5 COOL 2 COMP 2 6 1 AUX HEAT ele HEAT 2 REV VALVE SPARE OUTSIDE AIR HEAT COOL 2 OR ICS E NOT USED 15 Figure 31 Typical relay board wiring Relay Board TB2 HVAC Unit 24V Terminal Strip Y2 W2 0 1 32 VAV PRC003 EN e TRANE Electrical Data and Connections Figu
10. lt 4 3 5 16 gt VAV PRC003 EN e TRANE Dimensions and Weights Figure 39 Round zone and bypass damper dimensions Pd 14 11 16 9 5 8 CONTROLS AREA 4 15 16 B AIRFLOW 17 A LP E Size CFM 5875 131875 ams e rarer e e noo rre 21625 aee 13 ws Lie sas 25667 2000 45 e TRANE Dimensions and Weights Figure 40 Rectangular zone damper dimensions Sica Optional Duct Temp Sensor Standard Dims Damper Sizes Size W H 0812 2 00 8 00 0814 4 00 8 00 0816 6 00 8 00 1016 6 00 10 00 1020 20 00 10 00 1418 8 00 14 00 DAMPER FRAME DATA Frame 8 gouge Galvanized Steel Blades 8 gouge Galvanized Steel All klades are 4 or 5 nominal width Shroud 2e gauge Galvanized Steel Linkage 4 gauge Galvanized Steel Zinc Plated Damper Shaft Dia Steel Zinc Platec Bearings Self Lubricating Ny on VAV PRC003 EN Figure 41 Rectangular bypass damper dimensions I aes 1 00 4 171 pei m 3 42 ACTUATOR DIMENSIONS
11. Allows the CCP and Trane rooftop controller to One per controlled Trane rooftop interface communicate with each other via simple twisted with ReliaTel controller shielded wire pair Optional relay board Provides 24V control of any non communicating One per controlled non HVAC unit communicating HVAC unit Figure 28 Typical components in a changeover bypass VAV system H VAV PRC003 EN 29 TRANE Model Number Descriptions Digit 1 2 3 4 Product Type VADB VariTrac Air Damper VARA Rectangular Air Damper Digit 5 6 VariTrac Damper Size 06 6 Damper 08 8 Damper 10 10 Damper 12 12 Damper 14 14 Damper 16 16 Damper 1R 14x12 Bypass Damper 2R 16x 16 Bypass Damper 20x 20 Bypass Damper 4R 30 20 Bypass Damper 5R 8 12 Zone Damper 6R 8 14 Zone Damper 7R 8x16 Zone Damper 8R 10x 16 Zone Damper 9R 10x 20 Zone Damper 14x 18 Zone Damper Digit 7 Controls all factory downloaded and verified Bypass with Actuator Damper only Control Changeover Damper Plus Up to Stages of Electric Damper Plus 1 Stage Normally Closed Hot Water Not Used No Controls Actuator Only H Residential J Not Used Digit 8 9 10 11 00A0 Design Sequence VADB Only Design Sequence VARA only Digit 12 Special Options S Special Digit 13 Transformer 0 NO TRANSFORMER 1 3120 24 VOLT 2 2
12. Tracker System Integration VAV PRC003 EN The VariTrac system can be fully integrated with the new family of Tracker building controls A Tracker building management system can manage multiple VariTrac systems from a single control point Tracker System Summary e Controls up to 10 VariTrac systems from a single Tracker panel for easy building operation e TRANE Features and Benefits LCD touch screen operator display or Tracker PC software interface provides single point building management by a local operator 365 day scheduling function and the flexibility of up to 10 schedules Assign all systems to a single schedule if desired for simplified schedule changes Exception scheduling feature for easy management of vacations and holidays Automatically adjusts for daylight savings time and leap year Remote communications capability via modem for system programming and control Figure 7 Tracker system architecture 5 Up to 24 1 VariTac or e VariTrane Dampers VariTrac Bypass Dampers Bypass dampers are non communicating VariTrac dampers and include an integrated fully modulating 24 VAC electric actuator Field wiring errors are reduced with a quick connect harness that plugs into the communicating bypass controller Dampers are nominally rated up to 1800 2400 fpm at 1 75 of static pressure depending on size For damper performance information see Table 2 p 27 Tabl
13. 1415 2211 3316 1000 1161 1769 2763 4145 1200 1393 2122 3316 4974 1400 1625 2476 3869 5803 1600 1857 2830 4421 6632 1800 a 2089 3183 4974 7461 2000 a 2321 3537 5527 8290 Blades 2 3 3 3 Ship Wt 16 Ibs 21 Ibs 29 Ibs 40 Ibs a Recommended velocity for bypass damper is between 1600 and 2000 fpm 28 VAV PRC003 EN S TRANE Selection Procedures Figure 27 Typical VariTrac changeover bypass VAV system components Device Name Function in System Number Required A Central control panel Controls the HVAC system and provides local One per HVAC unit VariTrac system w optional operator display operator interface thermal zone B Communicating bypass Sends supply duct temperature and pressure to One per VariTrac system controller the central control panel Bypass damper s Supply air duct volume control to maintain One or two per system as needed to appropriate static pressure in the duct bypass from supply to return airstream VariTrac dampers Varies air volume to the space to control comfort One per comfort zone Zone sensors Sends space temperature and setpoint One per comfort zone DDC sensor information to the zone damper controller w LCD requires 4 VA CCP power supply 24V power for the central control panel The CCP must have a dedicated 24V power supply Zone damper power supply s 24V power for the zone dampers Power supplies may be shared each zone requires 10VA plus the load of optional outputs Trane rooftop communications
14. 59 60 58171 70 64 62 64 63 1600 755 64 58 58 53 51 46 68 62 62 57 56 53 73 67 68 62 62 60 76 71 72 65 66 64 A 2100 991 67 60 61 56 54 49 72 65 65 60 59 55 75 68 68 63 62 59 77 70 70 65 64 62 80 73 76 68 67 66 3000 1416 72 64 66 62 59 55 77 69 70 65 63 59 83 75 75 69 67 65186 77 78 72 71 69 1400 661 64 58 55 53 52 48 67 64 60 58 58 56 72 70 67 63 64 63174 73 71 67 68 67 2100 991 66 61 58 55 55 51 70 67 64 60 60 59 74 71 70 66 66 65176 75 73 70 69 68 2800 1321 69 63 61 58 57 54 73 69 66 63 62 61 76 71 70 66 65 64 78 73 72 68 67 66 80 76 76 72 71 70 4000 1888 73 68 67 64 62 58178 72 70 66 65 62 83 77 74 71 70 68186 79 78 75 73 72 Notes 1 All data are measured in accordance with Industry Standard AHRI 880 2011 2 All sound power levels dB re 10 12 Watts 3 Data in this column constitute AHRI 880 2011 Standard Rating Conditions 4 Where APs is the inlet static pressure minus discharge static 5 Application ratings are outside the scope of the certification program 40 VAV PRC003 EN S TRANE Acoustics Table 16 Radiated sound power 9 1 2 4 Inlet 0 5 Inlet Pressure 1 0 Inlet Pressure 1 5 Inlet Pressure 2 0 Inlet Pressure 3 0 Inlet Pressure Size APs5 APs5 APs3 APs5 APs5 1 5 2 3 4 5 6 7 2 3 45 672 3 45 67 2 34 5672 3 45 6 7 80 38 40 43 47 45 45 43 41 46 50 49 50 49 42 52 57 51 54 55 42 55 61 55 57 58 120 57 43 44 48 48 46 43143 49 53 51 51 50 43 52
15. 7 m Housing Material ABS plastic Table 11 Digital zone sensor specifications Thermistor Resistance Rating 10kW at 77 25 C Accuracy at 77 F 25 C Setpoint Resistance Rating 0 4 F 0 2 C 500 Ohms at 70 F 21 2 F Display Zone Temperature Range 40 99 F 10 to 35 C Display Setpoint Range 50 90 F 10 to 32 C Operating Temperature 0 120 F 18 to 49 C Storage Temperature 20 130 F 29 to 54 C Humidity Range 5 95 non condensing Power Supply 24 VAC Maximum VA Load 4 Housing Material Rigid vinyl Table 12 CO2 sensor specifications Dimensions Duct 3 1 8 x 3 1 8 x 7 3 4 Wall 4 1 4 x 3 1 8 x 1 7 16 Operating Temperature 23 113 F 5 45 C 59 95 F 15 35 C Accuracy at 77 F 25 C lt 30 ppm 2 3 of reading lt 40 ppm CO2 3 of reading Measuring Range 0 2000 parts per million ppm Recommended Calibration Interval 5 years Response Time 1 minute 0 63 Storage Temperature 4 158 F 20 70 C Humidity Range 0 to 85 relative humidity RH Output Signal jumper selectable 4 20 mA 0 20 mA 0 10 VDC Resolution of Analog Outputs 10 ppm CO2 Power Supply Nominal 24 VAC Power Consumption 5 VA Housing Material ABS plastic VAV PRC003 EN Acoustics VAV PRC003 EN TRANE Acoustic
16. Operator Display Feature Summary e Backlit LCD touch screen display for easy operator interface e Combination of icon and menu based navigation provides intuitive operation e Provides a level of control for the daily operator and a second level for commissioning and service e Three levels of security are available to protect system settings e Seven day time clock for stand alone time of day scheduling Communicating Bypass Controller The communicating bypass controller is a single control enclosure with the following integrated devices included e Integrated UCM board e Static pressure sensor and e Discharge air temperature sensor The communicating bypass controller directly controls the bypass damper and communicates duct conditions to the central control panel via a simple twisted shielded wire pair Quick Connect Minimizes field wiring labor and assures wiring consistency Duct Temperature Sensor The supply air temperature sensor allows the CCP to control heating and cooling stages to maintain the supply air temperature Supply air temperature setpoints can be edited through the operator display or PC software Static Pressure Sensor The static pressure sensor measures duct static pressure and positions the bypass damper s to maintain the static pressure setpoint Figure 6 Communicating bypass controller side L and 3D R views Duct Temperature Sensor Static Pressure Sensor Quick Connect
17. The VAV system then changes the zone from occupied standby mode to occupied mode Occupancy Zone Sensor Summary e Compatible with VariTrane VAV and VariTrac controllers e Used with zone damper UCM for controlling the occupied standby function e Ceiling mount PIR occupancy sensor detects motion over an adjustable range up to 360 degrees e Single detector covers up to 1200 square feet For areas larger than 1200 square feet multiple sensors can be wired in parallel e Adjustable time delay avoids nuisance change of state on loss of detection 11 e TRANE Features and Benefits Adjustable sensitivity SPDT isolated contacts connect to UCM input Auxiliary Temperature Sensor 12 Figure 12 Auxiliary temperature sensor The auxiliary temperature sensor is used with any UCM M damper control The sensor allows the operator to monitor duct temperature or air temperature leaving a reheat device the zone damper This sensor is used for automatic changeover of a UCM damper when not using CCP The auxiliary temperature sensor is ideal for remote monitoring and diagnostics from the Te operator display Installed Temperature Sensor Thermistor sensing element 10 000 Ohms 77 F Wiring connection 2 feet 18 awg Sleeving for wire leads is acrylic 5 awg grade C rated 155C VAV PRC003 EN TRANE Application Considerations Introduction The VariTrac system is a changeover bypass VAV system One fan su
18. dR 48 vs ane EE I e IRL pee BEREE EIE bis L IWS up 33 e TRANE Electrical Data and Connections Figure 33 Communicating bypass controller wiring CW CLOSE CCW OPEN TO NEC CLASS 2 COM HOT 24V TRANSFORMER LOAD 8 VA ACTUATOR WITHOUT ACTUATOR ACTUATOR W HOT SPARE BK OPEN CONNECTOR R CLOSE STATIC PRESSURE PORT GND 24V FEMALE PLUG END x OF BYPASS SENSOR CABLE ADDRESS N X MALE PLUG END SWITCH D D CAU C M E N LOCATED ON DDC UCM CONTROL BOARD x CONTROL BOARD PRESSURE TRANSDUCER D D C U C M 7 CONTROLBOARD AIR SUPPLY TEMP SENSOR i ET Of COMMUNICATING SENSOR BYPASS SS CONTROL BOX 22 SS SHIELDED TWISTED PAIR COMMUNICATIONS WIRING OUT OUT 34 VAV PRC003 EN S TRANE Electrical Data and Connections Figure 34 UCM wiring 24 VAC 60 HZ lt 8 CLASS 2 CONTROL CIRCUIT
19. environment Each thermal zone is conditioned by a single heating and or cooling unit The load of the thermal zone determines the size of the heating and cooling unit Cost vs Comfort First cost can be reduced by limiting the number of thermal zones Unfortunately this may impact the thermal flexibility of the system and result in zone comfort issues Let s take a closer look at this important system decision known as thermal zoning Characteristics of a building which can influence thermal load are Orientation of the building North South East West e Amount and thermal resistance R value of glass walls skylights etc e Expected occupancy within the area 15 e TRANE Application Considerations e Interior partitions and doors e Varying loads from equipment or processes Let s examine a few building examples and discuss the zoning criteria of each Building Example 1 See Figure 15 p 16 Consider an existing single story office building which is small poorly insulated with many large windows and few interior partitions On a clear cool spring day the entire building is cool in the morning so heating is required By afternoon however the south side of the building being influenced by the solar load is warm and requires cooling The north side remains shaded and continues to require heating This situation results in a simultaneous requirement for heating and cooling for extended periods Due to the varying
20. space An airflow measuring device in the VAV terminal unit makes this possible The position of the modulating device is not directly controlled and is a by product of regulating the airflow through the unit Because the airflow delivered to the space is directly controlled it is independent of inlet static pressure Local Reheat Capabilities Using VariTrane VAV Units VariTrane pressure independent VAV units a simple way to upgrade the zone VAV capabilities on a VariTrac system The main advantage is the ability to integrate units with either hot water or electric reheat Here are application examples where VAV units may enhance your design Example 1 Series fan powered VAV units work well in conference rooms and training rooms Series fan powered units supply constant air volume to the space This provides excellent air movement in the space regardless of the internal load requirements Hot water or electric heat are integral to the unit and optionally available to temper the air at partial load conditions Example 2 Parallel fan powered units with local heat applied help solve problems in difficult areas to control like lobbies and vestibules The parallel fan provides local heat to an individual zone without relying on the main HVAC unit s heat or supply fan This allows greater flexibility for mixing zones on a VariTrac system 21 e TRANE Application Considerations VariTrane units with integra
21. zone duct temperature sensor is used for stand alone control In addition when controlling duct mounted electric reheat coils cooling minimum airflow should meet the heating unit manufacturer s guidelines See Application Considerations Maximum System Effectiveness for more details Bypass Damper Selection Procedures To determine the cfm capacity required for a bypass damper calculate 80 percent of the cfm capacity of the heating cooling unit Example If the rooftop capacity is 1200 cfm the bypass damper should be sized for 1200 x 8 960 cfm To determine the size of the damper locate the recommended velocity and cfm for the bypass damper Since a 10 round bypass damper at 1800 fpm provides 980 cfm a 10 damper at 960 cfm would be slightly less than 1800 fpm but still within the 1600 to 2000 fpm recommended velocity A 10 bypass damper is selected Damper Sizing Charts VAV PRC003 EN Table 2 Round zone damper capacity cfm dimensions and weights Size Velocity fpm 6 8 10 12 14 16 600 113 203 319 461 630 825 800 151 271 425 615 840 1100 1000 188 338 532 769 1050 1375 1200 226 406 638 923 1260 1649 1400 264 474 745 1077 1470 1924 1600 301 541 851 1231 1680 2199 Length 17 17 17 17 17 17 Ship Wt 19 Ibs 21 Ibs 22 Ibs 23 Ibs 25 Ibs 27 Ibs a Recommended velocity for zone dampers is between 1000 and 1600 fpm Use good standard desig
22. 08 24 VOLT 3 240 24 VOLT 50VA 4 277 24 VOLT 5 480 24 VOLT 50VA 6 347 24 VOLT 7 575 24 VOLT 50VA 8 380 24 VOLT 50VA Digit 14 Disconnect Switch 0 None W With Switch Digit 15 Power Fuse 0 None W With Fuse igit 16 Wireless Sensor None Factory Installation of Wireless Receiver 72006 5 Digit 17 Duct Temp Sensor 0 None With Sensor Digit 18 Zone Sensor None DDC Sensor Only DDC Sensor Nsb Comm Jack How ow Jack Digital Display Zone Sensor Wireless DDC Sensor Ext Adj On Cancel Deg F Wireless DDC Sensor Ext Adj On Cancel Deg C Not Used Not Used Wireless Digital Display Zone Sensor Digit 19 Water Valve None Proportional HW Valve 0 7 Cv Proportional HW Valve 2 2 Cv Proportional HW Valve 3 8 Cv Proportional HW Valve 6 6 Cv 2 position HW Valve 4 0 Cv 2 position HW Valve 5 0 Cv 2 position HW Valve 8 0 Cv mm cr DDC Sensor Ext Adj Comm Jack DDC Sensor Ext Adj Nsb Comm VAV PRC003 EN Electrical Data and Connections Figure 29 Central control panel field wiring TRANE Termination Board TB2 Line voltage 24 Vac 5 A N 2 m Ex E t
23. 56150 54 59 59 61 61 1400 661 44 49 51 49 47 43 48 51 54 53 52 48 51 54 57 57 57 56153 56 60 59 60 60 800 378 40 46 47 47 45 40140 48 50 50 50 48 41 48 53 56 55 54 41 48 53 55 58 57 1200 566 41 47 47 47 44 39143 50 52 51 51 47 44 52 57 56 57 56 45 52 57 58 59 58 is 1600 755 42 49 48 48 46 41144 51 51 51 50 46 45 53 54 53 52 50 47 54 56 55 55 53 49 57 60 60 60 59 2000 944 44 49 50 51 48 43 46 53 53 53 52 48 50 55 56 56 56 54151 58 60 59 59 58 1100 519 39 46 50 46 43 38 40 48 53 49 47 45 41 48 54 52 51 50 43 51 56 53 52 53 1600 755 40 47 51 47 44 40142 51 55 51 49 47 44 52 57 55 53 53 47 54 58 55 54 56 14 2100 991 43 49 50 47 45 41 45 52 55 51 50 48 47 55 58 55 53 52 47 56 60 56 55 54 50 57 62 58 56 57 3000 1416 47 55 55 50 46 43 50 58 59 53 50 48 54 60 61 56 55 54154 61 65 61 60 60 1400 661 42 48 51 50 48 44143 51 54 54 53 51 43 52 56 59 58 57144 52 58 60 61 60 2100 991 43 49 51 50 49 45 45 52 55 55 55 53 46 54 59 61 61 60148 56 60 62 63 63 5 2800 1321 46 51 53 52 49 46 48 55 56 56 55 54 50 57 59 59 59 58 50 57 61 61 62 61 52 58 63 64 64 64 4000 1888 49 56 55 55 54 51151 56 58 57 57 54 54 61 63 62 62 62155 62 65 66 65 65 Notes 1 All data are measured in accordance with Industry Standard AHRI 880 2011 2 All sound power levels dB 10 12 Watts 3 Data in this column constitute AHRI 880 2011 Standard Rating Conditions 4 Where APs is the inlet static pressure minus discharge static 5 Application ratings are outside the scope of the cer
24. 57 54 57 56 43 55 61 56 58 60 150 71 44 45 48 48 47 44145 49 53 52 52 50 45 52 59 56 56 54145 53 58 57 58 57145 56 61 57 59 61 225 106 45 48 49 50 50 46 48 52 54 53 54 51 49 56 59 58 59 59 49 58 63 61 62 63 130 61 39 41 45 43 41 37139 43 49 50 49 46 39 45 51 53 54 53141 46 53 55 57 57 200 94 40 41 43 42 39 36 41 45 49 50 49 47 41 48 53 54 56 55 42 48 54 56 58 58 gt 250 118 40 41 43 42 39 36 43 45 49 49 48 46 44 48 51 52 53 52 44 49 53 54 56 56 44 50 55 56 58 59 350 165 39 43 47 47 44 40 43 47 49 49 47 46 48 52 53 54 55 54 48 54 56 57 58 58 200 94 41 45 45 42 40 37 41 46 49 49 49 46 41 49 52 52 55 55 42 51 55 55 57 58 300 142 40 44 45 45 43 41 43 48 49 48 48 47 43 51 54 54 56 55 43 53 56 56 58 59 400 189 40 47 48 48 47 45141 49 50 50 50 48145 51 52 52 53 51148 53 54 53 54 54148 55 57 55 57 58 500 236 41 50 51 51 50 47 43 51 52 52 53 51 46 53 54 54 56 55 51 57 58 56 57 58 350 165 39 43 48 46 44 39 40 45 50 50 50 46 41 47 52 52 54 53 42 49 55 54 56 56 520 245 40 45 47 46 44 39 43 48 52 51 50 48 44 50 55 55 57 55 45 52 56 57 60 59 700 330 41 46 48 47 45 41 47 51 53 51 50 48 47 53 55 54 54 52 48 54 57 56 57 55 49 56 59 59 61 60 900 425 44 49 50 50 48 46145 51 54 52 51 49 50 56 58 57 57 55152 57 61 59 59 59 550 260 39 42 47 46 45 40 42 45 50 51 51 48 45 49 53 54 56 55 45 50 53 55 58 59 820 387 41 45 48 47 45 40144 47 52 52 51 49 47 51 56 57 58 57148 52 57 58 60 61 m 1100 519 43 47 49 48 45 41 47 50 53 52 51 48149 52 56 55 55 53 49 53 57 56 57
25. 61 56 51 51 81 75 70 63 58 59181 78 75 68 63 63 200 94 66 61 54 50 47 43 69 65 60 56 54 51 70 68 66 61 60 58171 70 68 64 65 63 300 142 68 63 57 54 50 46 72 69 64 58 55 53 76 73 69 63 62 60176 74 72 67 66 64 8 400 189 69 64 59 56 51 48174 70 66 60 57 56176 74 69 63 60 59179 76 72 66 63 62180 77 75 69 67 66 500 236 71 66 62 59 55 52 75 71 67 63 59 57 80 77 74 68 64 64 82 79 77 71 68 67 350 165 66 58 52 49 47 41 70 62 56 54 52 49 74 65 61 59 59 56175 67 63 61 62 61 520 245 67 62 55 53 50 45 73 68 60 57 55 52 76 73 65 62 61 59178 75 67 64 65 63 3 700 330 71 64 58 56 53 49 75 70 65 60 58 57 78 74 68 63 61 59 80 76 69 65 63 61 81 79 72 68 67 66 900 425 73 64 61 60 56 52178 70 68 63 60 60 82 76 74 68 65 64 84 79 78 71 68 67 550 260 61 55 51 47 45 41 67 59 55 54 53 50 70 65 59 58 59 58 73 68 62 61 64 63 820 387 66 59 55 50 49 45172 63 59 55 56 53 76 68 64 61 62 61178 71 67 64 65 65 B 1100 519 71 62 59 53 53 48176 67 63 57 58 56179 70 65 60 61 60180 72 67 63 63 63183 75 71 66 66 67 1400 661 73 65 62 58 56 52 79 71 66 61 60 58 84 76 70 64 64 64 86 78 73 68 68 68 800 378 60 53 52 50 49 43164 58 56 55 55 52 69 65 60 60 61 58 71 70 64 63 65 63 1200 566 64 57 55 52 53 46 69 62 60 57 58 54 74 67 66 63 64 61176 72 69 66 67 65 1600 755 68 60 59 55 56 50 74 65 63 59 61 56176 69 66 62 63 60 78 70 68 65 66 63 80 74 72 69 70 67 2000 944 71 63 62 60 58 53 77 69 66 63 63 58 82 73 71 67 68 64 83 76 74 71 71 68 1100 519 60 54 53 50 48 43 64 59 57 55 53 50 69 66 62
26. D Digital Sensor Board TB1 1 24 1 5 B AGT GND 24V TB2 1 Digital Sensor Temperature ADDRESS Terminal Connection Chart SWITCH D D CAU C M 8 Field Wire Sensor UCM Color Code Signal Common 48688 CONTROL BOARD amp TB1 1 TB1 1 m ues See Setpoint 5 TB1 2 TB1 2 ala via aja v em 33 133 BIB BIB TB2 1 TB3 1 zone cnp set adoz Tenn TB2 2 TB3 2 TB3 1 AN TB2 3 TB3 3 High 2 TB3 1 TB2 5 Zh Communications i TB3 2 TB2 6 eo Figure 36 DDC zone sensor wiring qp 3 alla m GND 24V ADDRESS is SWITCH D D C U C M CONTROL BOARD B 5 e t te f t t a gO UE GN
27. D sit adoz A Night Setback 1 1 Override Opti verride Option Sensor Temperature Optional 2 Field Mounted Mechanical Sensor Aux Temp Sensor Terminal Connection Chart Signal Common RR o AERIAL 2 99H 3 Sensor UCM gus cose Adjustable Warmer TB1 1 TB3 4 Setpoint option cooler 8900 __ A Comm 1 E D TB1 2 TB3 2 Communications Optional Figure Notes Communications 1 High 5 TB1 4 TB2 5 Jacl 2 ee must be spliced with other TB1 5 TB2 6 communicator Optional communication link shields 36 Shield must be cut back and taped at sensor VAV PRC003 EN TRANE Specifications Table 6 Zone sensor options Zone Sensor Options Number of Required Wires Sensor only no communications jack available 2 Sensor with adjustable setpoint 3 Sensor with night setback override and cancel buttons 2 Sensor with adjustable setpoint and night setback override and cancel buttons 3 Sensor with digital display and adjustable setpoint and night setback override and cancel buttons 5 b a Most sensors have a communication jack available as an option If these jacks are used they must be wired to the UCM using an approved two conductor shielded cable The communication jacks do not need to be wired for the system to operate properly b Three wires are required for sensor connections Two wires are req
28. D 00006 5 4 3 2 1 SHIELDED TWISTED PAIR COMMUNICATIONS WIRING OPTIONAL FIELD 1835 q m TB3 6 INSTALLED DIGITAL ZONE SENSOR coe Factory Wiring Field Wiring m RO SS _____ Optional or Alternate Wiring 3 AUX TEMP SENSOR 2 14 quick connect required for all field connection lt 3 Zone sensor terminals 4 and 5 require shielded twisted pair wiring for communications jack equipped zone sensor options A lt 4 No additional wiring required for night setback override on cancel lt 5 The optional binary input connects between TB4 1 BIP and 24VAC HOT from transformer The binary input can be reconfigured as an occupancy input via the communications interface a lt 6 As shipped the aux input is configured as an AUX input The AUX input can be reconfigured as a CO2 sensor input via the communications interface T S terminal not to be used with this applications 8 If unit mounted transformer is not provided polarity from unit to unit must be maintained to prevent permanent damage control board If one leg of 24VAC supply is grounded then ground leg must be connected to TB1 2 5 9 Shields of communication wiring should be tied together and insulated 35 e TRANE Electrical Data and Connections Figure 35 DDC zone sensor with LC
29. ample is the foyer or reception area of an office building These areas often have wide variations in thermal load because of glass relative to other areas of the building and frequently opened exterior doors Another example is an interior storage room with the need for ventilation but little or no heating or cooling These zones can significantly influence efficient operation and comfort levels throughout the building Preferably areas such as these are designed as separate thermal zones with dedicated HVAC units However this may be impractical or costly Instead use fan powered variable volume terminal units or units with local reheat Effective Changeover Bypass VAV System Design 14 Unitary zoning systems feature low first cost and quick easy system design and equipment selection The system is simple but it is essential that key elements are considered during the design process This section offers a system design sequence and discusses application considerations that when followed help avoid system control and operational instabilities Suggested design steps for unitary zoning systems are summarized in Figure 14 p 14 Figure 14 Suggested design steps Step 1 Define Occupant Comfort Needs Involves architect engineer s and building owner Step 5 Size Zone and Bypass Damper Units Step 2 Define Thermal Zones Involves engineer s and contractors Involves engineers and contractors Step 6 Design the Duct system
30. ancing dampers in the branches will also ensure that airflow is appropriately distributed to each diffuser See Figure 18 p 19 The overall effect is improved acoustical and system performance Step 7 Air Diffuser Selection and Placement 20 Supply Diffusers Many types of supply air diffusers are used in variable air volume systems Performance and ultimately space comfort can vary greatly depending on the diffuser selected Although constant volume diffusers will provide air to the space at full cfm as air volume delivered to the space decreases so does performance Linear slot diffusers are recommended for most VAV systems Linear supply air slot diffusers are designed to properly mix variable air delivery of both heated and cooled air Linear slot diffusers supply conditioned air which hugs the ceiling rather than dumps air downward on the occupants This airflow characteristic is known as the coanda effect The throw and aspiration characteristics of slot diffusers help to evenly distribute the air throughout the room or space Locate linear slot diffusers in the center of the room with the discharge air pattern perpendicular to a perimeter wall To maximize diffuser performance placement in which air discharge patterns converge at right angles should be avoided See Diffuser section of the VariTrane catalog VAV PRCOO8 EN for additional diffuser placement and performance recommendations The throw characteristics
31. changeover bypass VAV system VariTrane The Trane pressure independent VAV box VAV Box The damper or air valve plus associated controller that controls the zone air volume in a VAV system Also see Variable air volume Ventilation Air The outdoor air drawn into the HVAC unit to provide fresh air to the space Also see Outdoor air OA Voting See Polling 2 Zone Sensor The device that measures a variable usually temperature in a space and sends it to a controller Commonly referred to as a thermostat 51 ex TRANE Trane optimizes the performance of homes and buildings around the world A business of Ingersoll Rand the leader in creating and sustaining safe comfortable and energy efficient environments Trane offers a broad portfolio of advanced controls and HVAC systems comprehensive building services and parts For more information visit www Trane com Trane has a policy of continuous product and product data improvement and reserves the right to change design and specifications without notice 2012 Trane All rights reserved VAV PRCOOS EN 13 2012 We are committed to using environmentally IR Ingersoll Rand Supersedes VAV PRCOO3 EN 31 Jan 2012 conscious print practices that reduce waste
32. combines the comfort benefits of VAV with the cost effectiveness and simplicity of packaged constant volume unitary equipment How the System Works A changeover bypass VAV system commonly consists of an HVAC unit with a constant volume supply fan and direct expansion DX cooling This combined system has the ability to change to the heating mode or cooling mode depending on individual zone comfort requirements A heating coil or a gas fired heater and an outside air damper are possible options A temperature sensor in each zone communicates information to an electronic controller on the VAV terminal unit The controller then modulates the zone damper open or closed supplying heating or cooling air to the zone The HVAC unit delivers a constant volume of supply air to the system In order to maintain duct static pressure a bypass duct and damper are required to bypass detour air not required in the zones The VAV terminal unit controller communicates zone temperature information to a central control panel CCP The CCP also gathers information from the system including duct static pressure and supply air temperature The CCP determines zone heating or cooling needs using voting or polling logic then requests heating or cooling from the HVAC unit The CCP directs the HVAC unit to provide ventilation air to high occupancy areas demand control ventilation or free cooling when the outside air temperature falls below the temperature
33. e 3 p 28 Table 4 p 28 and Table 5 p 28 Round Bypass Damper Summary Round bypass dampers are available with inlet diameters 6 8 10 12 14 amp 16 inches Heavy gage galvanized steel cylinder with rolled bead for high structural integrity and positive shut off Sandwich damper blade with elastomeric seal provides quiet operation and tight shutoff for low leakage Factory installed direct coupled fully modulating 24 VAC actuator VAV PRC003 EN e TRANE Features and Benefits Rated up to 2400 fpm at 1 75 of static pressure Rectangular Bypass Damper Summary Rectangular bypass dampers are available in sizes 14 x 12 16 x 16 20 x 20 and 30 x 20 inches Formed heavy gage galvanized steel frame mechanically joined with linkage concealed in the side channel Air leakage is minimized with an opposed blade design Damper casing is 16 inches long and constructed of heavy gage galvanized sheet metal with slip and drive connections on the inlet and outlet for easy installation Blades are either four inch or five inch nominal widths depending on height of damper constructed of 18 gage galvanized steel A blade rotation stop feature prevents over rotation of the blades in the fully open position Factory installed direct coupled fully modulating 24 VAC actuator Rated up to 3000 fpm at 2 of static pressure Vari Trac Zone Dampers VAV PRC003 EN VariTrac zone dampers are fully modulating pressure depende
34. e TRANE Product Catalog Tracker System CB VariTrac Changeover Bypass VAV VariTrac Central Control E Panel with touchscreen HVAC Unit El interface Bypass Damper p 249 Communicating Bypass Controller um Gy 4 Wireless Receiver C Zone Sensor March 2012 VAV PRC003 EN S TRANE Introduction Comfort Made Simple Trane has a long history of innovative leadership in variable air volume VAV technology Trane introduced the 1 First fan powered VAV unit 2 First factory commissioned DDC controller and 3 First preprogrammed VAV controller designed specifically for VAV applications Trane is now the leading manufacturer of VAV terminal units and VAV related products in the world The introduction of VariTrac in 1989 brought VAV controls expertise into the changeover bypass zoning market Trane is committed to continuous product improvement and now introduces a new generation of VariTrac controls This latest generation retains the functionality of the original VariTrac system with exciting new enhancements utilizing the best of today s technology The Changeover Bypass VAV Comfort Advantage Figure 1 VariTrac Packaged unitary systems offer a popular and cost effective method of supplying conditioned air to light commercial buildings These systems commonly have a constant volume fan with a fixed outside air damper and a single thermostat Whi
35. ed into comfort zones Choosing the number and location of thermal and comfort zones is critical in planning an effective system Some things to consider in the design process include Geographic location e Orientation of the building to the sun e Prevailing winds e Wall construction glass insulation building materials 13 e TRANE Application Considerations e Building layout design occupancy and occupancy pattern throughout the day and year e Activities in each zone Zoned unitary systems such as changeover bypass VAV divide thermal zones into smaller comfort zones Each comfort zone has a damper and zone sensor that controls the amount of heated or cooled air delivered to the zone A central system controller monitors the status of each zone damper and zone sensor The controller then makes the decision to heat or cool for the HVAC unit Individual comfort zones served by a common HVAC unit part of the same thermal zone can require heating and cooling at the same time In a changeover bypass VAV system the unit alternately provides warm and cool air in an attempt to satisfy the needs of all comfort zones This is effective if the simultaneous calls for heating and cooling exist for short time periods only Wide temperature variations may occur if some comfort zones need heating for extended periods of time while others need cooling Some comfort zones require special consideration because of their use or location An ex
36. erator display Bypass Damper The motorized damper ducted between the system supply and return ducts used to control static pressure in changeover bypass VAV systems Central Control Panel CCP The system level control device in a Trane changeover bypass or delivered VAV system that gathers data from zone controllers and operates the HVAC unit to maintain the correct air flow and temperature Changeover Bypass VAV A control that provides variable air volume functionality to a constant volume air handling system CO2 Sensor An analog sensor that detects and measures carbon dioxide sensor to determine occupancy level Commissioning The process of starting up and verifying correct operation of a building system Conditioned Air Air that is heated cooled humidified or dehumidified to maintain comfort in an interior space Constant Volume An air distribution system that varies the temperature of a fixed volume of air to maintain space comfort D Direct Expansion DX When the refrigerant in the system is either condensed or evaporated directly by the medium being heated or cooled VAV PRC003 EN e TRANE Delivered VAV A self configuring system providing true pressure independent VAV control to smaller building applications Delivered VAV requires a CCP with operator display a Commercial Voyager VAV rooftop unit and VariTrane VAV boxes Demand Control Ventilation A method of maintaining indoor air qualit
37. ertification Program Some general ideas to minimize acoustical issues e Pay close attention to location of the HVAC unit This will typically set the overall acoustical quality of your job e Locate VariTrac dampers outside the occupied space e Internally lined ductwork can be used to reduce the discharge sound generated by the HVAC unit e Install flex duct with minimal sagging and turns e Locate balancing dampers as far from the diffuser as possible to limit airborne noise 39 e TRANE Acoustics Table 15 Discharge sound power 48 124 Inlet 0 5 Inlet Pressure 1 0 Inlet Pressure 1 5 Inlet Pressure 2 0 Inlet Pressure 3 0 Inlet Pressure Size APs5 APs5 APs3 APs5 APs5 1 5 2 3 4 5 6 712 3 4 5 6 712 3 4 5 6 712 3 4 5 6 712 3 4 5 6 7 80 38 166 61 54 48 43 36167 65 61 54 49 45 68 67 66 60 56 54168 69 68 63 60 58 120 57 69 66 57 51 44 38173 70 63 57 51 47 73 73 70 64 58 56173 74 73 67 63 61 150 71 70 69 58 52 45 39 76 74 65 59 52 48 77 76 69 62 56 53 77 77 72 65 60 57 76 78 75 69 64 62 225 106 69 68 61 56 49 45 76 77 68 61 55 50 81 83 76 68 62 59183 86 79 72 67 64 130 61 64 58 52 47 43 39166 64 58 54 50 47 66 70 65 59 57 55167 68 67 61 61 60 200 94 66 58 52 48 44 41 71 66 60 55 50 50 72 72 69 60 58 57 73 74 74 64 62 62 250 118 65 58 52 49 44 41 73 67 61 55 50 50 76 70 66 59 55 55 77 72 70 62 58 58 76 74 75 66 63 63 350 165 65 58 53 48 44 41 74 66
38. g Store Store Step 3 Define the Comfort Zones A primary criteria for defining a thermal zone is that it will not require simultaneous heating and cooling An HVAC unit with one fan is limited to supplying either heating or cooling Most applications with larger thermal zones however will have varying thermal needs throughout the zone These small variations can easily be addressed by properly defining comfort zones A comfort zone is an area within a thermal zone that is controlled by a zone damper The amount of conditioned heated or cooled air entering the space varies This is in response to a space thermostat ASHRAE Standard 55 recommends limiting indoor temperature variations Temperature variations of less than 2 F in 15 minutes or 4 F in an hour Deviations from this recommendation will cause discomfort in 80 percent of the occupants Zoning systems can greatly reduce temperature variations caused by shifting occupancy and solar load conditions in large thermal zones Step 4 Sizing HVAC Equipment VAV PRC003 EN Once the building heating and cooling loads are known and the thermal zones have been determined the heating and cooling equipment can be selected Each thermal zone requires a separate heating and cooling unit As discussed earlier unitary zoning systems typically use packaged DX rooftop units or DX split systems These systems are offered as heating and cooling units or heat pumps
39. gure 17 Diversity example Building Perimeter North Zone Glass Windows Interior Zone South Zone Table 1 Diversity example Wedge Zone East Zone Zone Time Peak Load Interior 3 p m in mid July 7 5 tons North 5 p m in mid July 3 0 tons East 9 a m in June 2 5 tons South 4 p m in November 4 0 tons West 5 p m in September 2 5 tons Sum of Peak Loads 19 5 tons a The sum of blocks loads 17 5 tons and occurs at 5 p m in mid July Diversity 19 5 18 17 5 90 percent VAV PRC003 EN e TRANE Application Considerations Step 5 Size Zone and Bypass Damper Units Sizing zone damper is relatively straightforward The volume of airflow in cfm or L s for each comfort zone should be known from the load analysis The designer must select the duct velocity to be used for the system Recommended zone damper velocities are 1000 to 1600 feet per minute fom when applied at the branch level Sizing dampers in this range will minimize damper cost reduce the risk of excessive noise and ensure adequate zone modulation temperature control Dampers located immediately adjacent to the zone or diffuser may need to be sized at a lower velocity to avoid sound and airflow delivery issues Bypass dampers are typically sized for 80 percent of HVAC unit airflow Recommended velocities are 1600 to 2000 fpm Bypass dampers should be located as close to the HVAC unit as possible See Bypass Damper Opera
40. her modulating or two position control See trane com for a full line of duct mounted water coils Figure 23 Trane hydronic wall fin This is ideal for spaces with large windows or perimeter heat losses which exceed 450 Btuh per linear foot Trane wallfin is available with various grilles and paint options and can be pedestal or wall mounted Figure 24 Trane electric wall fin Bypass Damper Operation When zone dampers modulate airflow to the spaces static pressure changes in the supply duct system High pressure in a duct system creates excessive noise and causes poor comfort control Low pressure results in insufficient airflow to the spaces The HVAC unit in a changeover bypass system is constant volume and does not modulate supply airflow Changeover bypass VAV systems support variable air volume operation in the zones by using a bypass duct with a motorized damper and a pressure sensing device As duct pressure rises above the static pressure setpoint the bypass damper begins to open Conversely when static pressure falls below the static pressure setpoint the bypass damper begins to close until the static pressure setpoint is reached The optimal static pressure setpoint is automatically determined upon system calibration 23 e TRANE Application Considerations Proper operation requires consideration of all aspects of bypass design and location The bypass dampers and ductwork should be si
41. icon driven design Advanced Control Options Some VariTrac intelligent system control features are listed below e COz based demand control ventilation resets the position of the HVAC unit ventilation air damper when zone CO levels rise e Zone based HVAC unit control operates heating and cooling only when zone demand exists e Discharge air control to avoid extreme supply air conditions and maximize equipment life and occupant comfort e Asimplified system balancing process is available via PC software or the touch screen interface Global zone temperature setpoint limits simplify startup commissioning and operator control Trademarks Trane VariTrac and the Trane logo are trademarks of Trane in the United States and other countries All trademarks referenced in this document are the trademarks of their respective owners LISTED 2012 Trane All rights reserved VAV PRC003 EN Table of Contents VAV PRC003 EN IN FORUCION earam ae 2 Features and Benefits 4 Application Considerations 2 13 Selection 27 Model Number Descriptions 30 Electrical Data and Connections 31
42. l electric or hot water heat are available as e Single duct e Parallel fan powered e Series fan powered Figure 20 Single duct VAV unit available with integral electric or hot water heat Figure 21 Series fan powered VAV terminal unit Figure 22 Parallel fan powered VAV terminal unit Local Reheat Capabilities Non VAV Options Local Reheat 22 The Trane VariTrac Zone Controller has built in capabilities and logic to control a number of reheat sources The previous pages discussed how a VariTrane VAV unit with reheat can solve application issues by providing local reheat Let s investigate a few other alternatives which will provide local reheat and result in exceptional zone temperature control VAV PRC003 EN S TRANE Application Considerations Local reheat is particularly important when an HVAC unit is in cooling mode Cold air is delivered to all zones whether it is needed or not Setting the minimum cooling position to zero may not be practical based on ventilation and or general airflow requirements In this case local reheat options which can be controlled by the standard VariTrac zone controller include e Hydronic wall fin or convector unit with either modulating or two position control See trane com for a full line of wall fin and convector products e Electric wall fin with multi stage control Duct mounted electric heater with multi stage control e Duct mounted hot water coil with eit
43. le a constant volume system may meet the overall thermal requirements of the space only a single thermostat is available This system may be insufficient in multiple space applications with independent thermal load requirements Changeover bypass systems use the practicality and cost effectiveness of constant volume unitary components like packaged rooftop units split systems or water source heat pumps and simply add dampers and a central control panel to coordinate the components This allows up to 24 individual sensors thermostats for independent temperature control a Maximizes system efficiency and reliability by coordinating the components of the changeover bypass system VariTrac Product Enhancements Figure 2 VariTrac CCP with optional touch screen interface Selected enhancements of the new VariTrac product are as follows 1 A new central control panel CCP with improved system temperature and pressure control functions 2 An optional touch screen operator display for the CCP with built in time clock for easier system setup and control E 3 Acommunicating bypass controller allows duct pressure and duct temperature to communicate to the system via a twisted shielded wire pair thus eliminating costly home run wiring 4 The BE next generation UCM zone controller allows CO2 and occupancy sensor inputs and 5 A digital display zone sensor for simplified occupant control a Simplifies system operation with intuitive
44. loads throughout the building controlling the building as a single thermal zone with a single HVAC unit cannot satisfy the comfort needs of all areas It also is not a good candidate for a zoning system because of the simultaneous need for heating and cooling A similar building with good insulation and fewer shaded windows on the other hand may be a good candidate for a single thermal zone with individual comfort zones The reduction in wall glass reduces the solar effect on the building resulting in all areas of the building having similar load profiles throughout the day In this case the building has a single thermal zone and is a good candidate for one HVAC unit Individual comfort zones zone dampers will be needed to assure comfortable conditions throughout the zone Figure 15 Building Example 1 illustrates a small poorly insulated office on the left and improved design on the right Restroom Restroom Mens Womens Restroom Restroom QW windows with no shading 16 Thermostat Glass windows with no shading Thermostat Poor Design Elements One thermostat for space Improved Design Elements Multiple zone thermostats Thermostat Minimal wall insulation Shaded windows Insulated walls Thermostat ae Shaded Minimal wall Windows insulation B Insulated Building Example 2 See Figure 16 p 17 Consider a strip mall in the spring or fall with stores that face both east a
45. n practices such as location of duct 27 e TRANE Selection Procedures Table 3 Rectangular zone damper capacity cfm dimensions blades and weights Velocity Size fpm 8x12 8x14 8x16 10 x 16 10 x 20 14x18 600 398 464 531 663 829 1045 800 531 619 707 884 1105 1393 1000 663 774 884 1105 1382 1741 1200 796 928 1061 1326 1658 2089 1400 928 1083 1238 1547 1934 2437 1600 1061 1238 1415 1769 2211 2785 Blades 2 2 2 3 3 4 Ship Wt 8 Ibs 10 Ibs 12 Ibs 14 Ibs 16 Ibs 18 165 a Recommended velocity for zone dampers is between 1000 and 1600 fpm Use good standard design practices such as location of duct Table 4 Round bypass damper capacity cfm dimensions and weights Size Velocity fpm 6 8 10 12 14 16 600 113 203 319 461 630 825 800 151 271 425 615 840 1100 1000 188 338 532 769 1050 1375 1200 226 406 638 923 1260 1649 1400 264 474 745 1077 1470 1924 16006 301 541 851 1231 1680 2199 1800 a 339 609 957 1384 1890 2474 2000 a 377 676 1064 1538 2100 2749 length 17 174 17 17 17 17 Ship Wt 17 165 19 Ibs 20 Ibs 21 165 23 Ibs 25 Ibs a Recommended velocity for bypass damper is between 1600 and 2000 fpm Table 5 Rectangular bypass damper capacity cfm dimensions blades and weights Size Velocity fpm 14x12 16x 16 20 x 20 30 x 20 600 696 1061 1658 2487 800 928
46. nd west In the morning the east side of the building gets full sun and warms up while the west side is shaded and requires heating In the afternoon the east side of the building may need heat and the west side cooling Because ofthe thermal load variation throughoutthe day this building will not remain comfortable if designed with a single heating and cooling unit On the other hand comfort in this building could be improved by dividing the building into two thermal zones two HVAC units one serving the east exposure and the other serving the west Even with the two systems individual occupant comfort is not necessarily assured Interior partitioning varying schedules and number of occupants within the thermal zone will drive differing amounts of heating and cooling The issues related to comfort zoning are addressed in the next section VAV PRC003 EN e TRANE Application Considerations Figure 16 Building Example 2 illustrates a poorly insulated store design L and an improved design R Outside Doors i Jewelry Outside Jewelry 7 Doors Store Store E Poor Design Elements One thermostat for entire space One HVAC unit Improved Design Elements Two thermal zones Two HVAC units __ ________ a N i Electronics Store Electronics k Pharmacy Store Pharmacy B Store 4 y Clothing Store ni Clothin
47. nt VAV boxes Pressure Independent VAV Control A VAN unit with airflow quantity independent of duct static pressure Actual airflow to the space is measured and controlled by an airflow sensor in the pressure independent VAV box Priority Shutdown An immediate shutdown of the fan and heating or cooling stages in a VariTrac changeover bypass or Delivered VAV system caused by either the loss of critical system information or an external priority shutdown input Pulse Width Modulating Reheat Reheat that operates duct mounted electric coils on a 0 10096 duty cycle in response to increased space heating demand Reheat Device A source of heat located downstream from a control device such as a VAV box to add heat to air entering a space to provide occupant comfort ReliaTel RTRM The latest generation Trane factory mounted unitary controller Return Air RA Air returned to the air handler from the conditioned space to be reconditioned 5 Setpoint The desired room temperature to be achieved and maintained by an HVAC system Setpoint Limit An electronic or manual constraint imposed on a setpoint to prevent misadjustment VAV PRC003 EN SPDT A relay with of one set of normally open normally closed contacts Staged Electric Reheat Reheat that operates one or more duct mounted electric coils in a series in response to increased space heating demand Staged or Perimeter Hot Water Reheat Reheat that operates duc
48. nt VAV devices The dampers control zone temperature by varying the volume of air flowing into a space Each VariTrac damper has a control box with a VAV control board and actuator enclosed The dampers are designed to operate in static pressures up to 1 75 in wg Figure 8 VariTrac rectangular L and round zone R dampers with UCMs Round Zone Damper Round dampers are available in 6 8 10 12 14 and 16 inch diameters Heavy gage galvanized steel cylinder with rolled bead for high structural integrity and positive shut off Sandwich damper blade with elastomeric seal provides quiet operation and tight shutoff 90 blade rotation for a wide control range and stable operation Rated up to 2000 fpm at 1 75 of static pressure Rectangular Zone Damper Rectangular dampers are available in sizes 8 x 12 8 x 14 8 x 16 10 x 16 10 x 20 and 14 x 18 inches Heavy gage G60 galvanized steel frame assembled by a mechanical joining process Single ply heavy gage G60 galvanized steel blades Linkage uses glass fiber filled nylon crank bearings connected by a metal drive link Factory installed 24 VAC direct coupled actuator Rated up to 2400 fpm at 2 of static pressure e TRANE Features and Benefits Unit Control Module A unit control module UCM is the individual zone controller for the VariTrac air damper and is mounted on each zone damper The unit controller continually monitors the zone temperature to maintain space tempe
49. of diffusers is well documented Slot diffusers should be positioned so that the velocity of the air striking an obstruction such as a wall or column is 75 feet per minute fpm or less If airstreams from two diffusers collide the collision velocity should not exceed 150 fpm Higher collision velocities result in uncomfortable drafts in the lower levels of the room In heating applications linear slot diffusers must be placed to offset heat loss and prevent downdraft problems along perimeter walls The following techniques have been proven by test and experience e When the average glass plus wall heat loss is less than 250 Btuh linear foot the slot diffuser may be located in the center of the room with one or more slots blowing toward the perimeter wall e With glass and wall heat loss between 250 and 450 Btuh linear foot diffusers should be positioned to blow toward the window and the perimeter wall with a collision velocity of 75 to 150 fpm If using a continuous glass design position diffusers every four feet e If heat loss exceeds 450 Btuh linear foot radiation or floor mounted heated air will be required to offset the high wall heat loss Return Diffusers Slot style return diffusers offer some acoustical advantages over perforated grille styles Perforated drop in grilles typically offer little attenuation effect and thus allow sound in the plenum to break out into the occupied space This 1 a problem in areas near the unitary hea
50. ommunications jack is provided for Trane portable edit terminal devices e Nonvolatile memory stores last programmed setpoints e For field balancing maximum and minimum airflow or position can be overridden from the sensor 10 VAV PRC003 EN CO2 Sensor e TRANE Features and Benefits Figure 10 Duct mounted CO2 sensor L and wall mounted CO2 sensor R Wall and duct mounted carbon dioxide CO2 sensors are designed for demand controlled ventilation zone applications The sensor is compatible with VariTrane VAV and VariTrac controllers The Trane CO2 sensors measure carbon dioxide in parts per million ppm in occupied building spaces Carbon dioxide measurements are used to identify under ventilated building zones Outdoor airflow increases beyond design ventilation rates if the CO2 exceeds specified levels CO2 Zone Sensor Summary e Use with the UCM CO2 input for demand control ventilation e Silicone based NDIR sensor technology for long term stability e Measurement range of 2000 ppm CO2 input with an output of 0 10 Vdc e Wall mount transmitter is compact and aesthetic in appearance e Optional zone return duct mount transmitter is available Zone Occupancy Sensor VAV PRC003 EN Figure 11 Zone occupancy sensor The energy saving zone occupancy sensor is ideal for zones having intermittent use during the occupied mode The sensor sends a signal to the VAV controller upon detection of movement in the coverage area
51. pace than is supplied Non Volatile Memory System memory that retains programming with no battery or capacitor back up required Normally Closed NC Electrical contacts that are closed current flows in the de energized condition Normally Ppen NO Electrical contacts that are open no current flows in the de energized condition A binary sensor that transmits a signal upon detection of movement in the coverage area Outdoor Air OA This is fresh air drawn in to provide space ventilation Also see Ventilation air Outdoor Air Damper The damper that draws fresh air into the air handling system for ventilation Also referred to as the ventilation or fresh air damper Override A manual or automatic action taken to bypass normal operation Packaged Unitary System An air handling system with all the major components contained in a single cabinet or installed in a single location PIR Passive infrared sensing technology used in occupancy and motion detection sensors 50 Polling The method a VariTrac CCP uses to determine the need for heating or cooling from the air handling system by examining the zone requirements Positive Pressure The condition that exists when more air is supplied to a space than is exhausted Pressure Dependent VAV Control A VAN unit with airflow quantity dependent upon static pressure There is no zone flow sensor in pressure depende
52. pplies either warm air for heating or cool air for cooling It is typically applied in small buildings which use unitary heating cooling air conditioners These buildings need the simplicity and low cost of unitary equipment but more than one comfort control zone one zone temperature sensor for each air conditioner When is VariTrac a good HVAC system choice To help answer this question several important application concepts and considerations are discussed below Figure 13 System design affects occupancy comfort Least Single Zone Building One thermal and one comfort zone Thermal Zoned Building Multiple thermal zones each with one comfort zone Thermal and Comfort Zoned Building Multiple thermal zones each with multiple Most comfort zones Energy Savings Comfort Flexibility Zoning Considerations VAV PRC003 EN Consider the following two questions when evaluating your HVAC system design Will the building occupants be comfortable A system designed with a single zone HVAC unit and one zone sensor provides comfort to occupants near the zone sensor However occupants in perimeter areas or interior rooms may be too hot or too cold Will comfort be consistent from room to room and area by area A building is normally divided into thermal zones for increased comfort control and energy savings Each thermal zone should have a dedicated HVAC unit For optimum comfort each thermal zone should be further divid
53. pressurization bypass air may be forced out of the return duct Economizer Fan a Outdoor e Air Damper Return Damper gt Return Opening Application Tip Summary VAV PRC003 EN Tip 1 Use Comfort Zones Units serving thermal zones can provide greater comfort by dividing the thermal zones into comfort zones using a changeover bypass VAV system Tip 2 Create Thermal Zones Create thermal zones which minimize simultaneous heating and cooling requirements This will avoid unnecessary changeover of the system and maximize comfort As an example a computer room would be a poor candidate for one comfort zone of a changeover bypass VAV system because it will rarely if ever require heating 25 e TRANE Application Considerations 26 Tip 3 Use Local Heat Zones which vary thermally by requiring more heat than the other zones or require heat when the HVAC unit is in cooling mode should use local heat Local heat in the form of VariTrane VAV units with electric or hot water heat or wallfin or convectors or duct mounted coils The standard VariTrac controller is capable of controlling the heat based on zone temperature demands Tip 4 Place Dampers Properly The bypass damper should be ducted between the supply and the return of the unit as close to the unit as possible and should be sized to handle 80 of the total system CFM Tip 5 Control Building Pressure It may be necessary to
54. provide a modulating means to control building pressure especially when economizers or demand controlled ventilation are used in conjunction with changeover bypass VAV system Tip 6 Use Fan Powered VAV Boxes Consider using fan powered VAV boxes to provide local heat or to enhance comfort levels in some of your zones Conference rooms or zones with high wall heat loss are ideal for either series or parallel units VAV PRC003 EN TRANE Selection Procedures VariTrac Dampers VariTrac dampers are typically installed on VariTrac changeover bypass variable air volume VAV systems VariTrac is ideal when applied to buildings which use unitary HVAC units The damper units have controls which vary air volume and maintain appropriate duct static pressure in the system to make sure that all zones receive the right amount of airflow Trane offers four VariTrac dampers e Round zone dampers with DDC controls e Rectangular zone dampers with DDC controls e Round bypass dampers e Rectangular bypass dampers Zone Damper Selection Procedures Refer to the sizing chart in Table 2 p 27 and Table 3 p 28 for zone dampers Follow down the first column in the table for the desired velocity Then follow across for the cfm air volume of a given VariTrac damper based on that velocity Note If the cfm exceeds the damper range increase the damper size Minimum airflow damper position should be set to10 percent in heating or cooling when a
55. rature The UCM varies the damper position as needed to meet zone setpoints and communicates current space requirements and system operating modes to the CCP The UCM can also control local heat Local heat may be duct or space mounted and can be staged electric pulse width modulating electric and modulating or two position staged hot water Zone Sensors Figure 9 DDC zone sensor with LCD L and DDC zone sensors R e DDC Zone Sensor The direct digital control DDC zone sensor is an uncomplicated reliable electro mechanical room sensor No programming is required and most sensors contain an internal communications jack Models are available with combinations of features such as override on cancel buttons and space mounted setpoint Four sensor variations are available e Sensor only no communications jack e Sensor with override buttons e Sensor with temperature setpoint only e Sensor with temperature setpoint and override buttons DDC Zone Sensor with LCD The DDC zone sensor with LCD liquid crystal display or digital is compatible with VariTrane VAV and VariTrac controllers Digital Zone Sensor Summary e Displays setpoint adjustment and space temperature in F or C e Simple two button control of space setpoint Setpoint control and room temperature display can be optionally disabled e Includes button for timed override and a cancel feature for after hours system operation e An easily accessible c
56. re 32 UCM comm link wiring yul eui uo si jepio oads sesodind 4 si 1 WON 941 S JON pue Ino eq snw 5 v7 spjalys uoneorunuuoo 4 V puno 6 5 eue Jad papjalys pasm 281 peog ssed g 1osues 9 Ht 55 1 WON 9902 eit SSOIPPY WON 9102 Jeujo eg 5 SL 8 4 s v V pz EE R euoz Sich Bp T 6 8 Josua dey Aiddng i 9 G ab osaa NN loda dodo mopy sma ET a E RES EE 3 Oe Pe HOLIMS 18 Guvo8 TOHLNOS HOLIMS 58 GHVOH TOHLNOS HOLIMS T Wonvoaa Ss3uaav Wonvodd Ssaudav Wonvoada Ssauaav 2
57. s skirts or shorts Gather as much usage information as possible before designing a system This can be challenging particularly when finishing out tenant spaces However usage information is crucial to the selection of heating and cooling equipment building zoning and duct layout Several publications provide guidance for properly assessing indoor space comfort An example is ASHRAE American Society of Heating Refrigerating and Air Conditioning Engineers Standard 55 Thermal Environmental Conditions for Human Occupancy This standard specifies the combinations of indoor space environments and personal factors activity and clothing that will produce thermal environmental conditions acceptable to 80 percent or more of the occupants within a space Standard 55 addresses temperature thermal radiation humidity and air speed ASHRAE Standard 62 Ventilation for Acceptable Indoor Air Quality is another source for occupant comfort and safety issues regarding indoor air quality The standard recommends that relative humidity be maintained between 30 and 60 percent This maximizes comfort and reduces the potential for microbial growth Step 2 Define the Thermal Zones VAV PRC003 EN A thermal zone is an area with similar load profiles and occupant comfort requirements A thermal zone can be a single room an area a group of rooms or an entire building Defining the thermal zones within a building is crucial to designing a comfortable indoor
58. s are tricky to define for specific jobsites To provide an acoustical overview of a typical office system with mineral glass fiber dropped ceiling ARI standard 885 2008 has generated the transfer functions in Table 13 p 39 and Table 14 p 39 Sound power data was collected in accordance with ARI Standard 880 2011 Applying the transfer function for sound reduction due to office furnishings materials etc generated the NC data which follows This is a reference document only provided to address general acoustical issues What you will find is that the sound in the occupied spaces generated by the VariTrac dampers is minimal when compared to the main HVAC unit sound generation Table 13 AHRI 885 2008 discharge transfer function Octave Band 2 3 4 5 6 7 Medium Box lt 300 700 cfm 27 29 40 51 53 39 Large Box gt 700 cfm 29 30 41 51 52 39 a Add to terminal unit sound power to determine discharge sound pressure in the space Notes 1 All NC data are calculated in accordance with Industry Standard AHRI 885 2008 2 Application ratings are outside the scope of the Certification Program Table 14 AHRI 885 2008 radiated transfer function assumptions Octave Band 2 3 4 5 6 7 Type 2 Mineral Fiber Insulation 18 19 20 26 31 36 Notes 1 All NC data are calculated in accordance with Industry Standard AHRI 885 2008 2 Application ratings are outside the scope of the C
59. setpoint economizer control Auto Changeover Auto changeover refers to the ability of the system to automatically change between the heating and cooling modes In a changeover bypass VAV system the CCP determines whether the HVAC unit should heat or cool by polling the temperature of the individual zones It then compares the zone temperatures to the space temperature setpoints If the supply air does not meet the criteria for the heat or cool mode called for the CCP sends a signal to the HVAC unit to change the system to the opposite mode e TRANE Features and Benefits Central Control Panel The VariTrac central control panel CCP serves as the central source of communications and decisionmaking between the individual zones and the HVAC unit The CCP determines system heating and cooling modes and coordinates the system supply air temperature and static pressure to satisfy building thermal load conditions Inputs to the CCP include 24VAC power and communication wiring to the zone dampers and bypass control Binary inputs consist of priority shutdown and occupied unoccupied modes Heating cooling and the HVAC unit fan on split systems and non Trane HVAC units can be controlled through binary outputs on an accessory relay board If a Trane rooftop air conditioner with factory installed electronic controls is used the CCP can control heating cooling and the fan with a two wire communication link tied to an interface board moun
60. t mounted hot water or space mounted electric or hot water reheat coils in response to increased space heating demand Static Pressure The difference between the air pressure on the inside of the duct and outside of the duct Static pressure is an indicator of how much pressure the fans are creating and how effective they will be at distributing the supply air through the ducts Supply Air SA air which blows out of the air handler into the ducts See also Discharge air T Terminal Unit HVAC equipment that provides comfort directly to a space Thermal Requirements The heating or cooling load requirements for a specific area or space in a building Care must be taken to not control areas with different thermal requirements from one air handling system Touch Screen Operator Display The LCD panel mounted onto VariTrac CCP to allow direct user interface and time of day programming for the system U Unit Control Module UCM A Trane microelectronic circuit board that controls individual HVAC equipment May link to an Integrated Comfort System Unitary one or more factory made assemblies which normally include an evaporator or cooling coil an air moving device and a compressor and condenser combination VAV PRC003 EN S TRANE Glossary V Variable Air Volume VAV an air handling system that varies the volume amount of constant temperature air to a space to control comfort VariTrac The Trane
61. ted in the rooftop It can also display status information from the electronic controller in the rooftop See Figure 4 p 6 CCP Feature Summary e Communicates with up to 24 VAV unit control modules UCMs e Makes optimal heating and cooling decisions based on setpoint and temperature information received from individual zones e Automatically calibrates all dampers significantly reducing labor intensive and costly field calibration e Windows based PC software simplifies setup and control e Provides diagnostic information for all system components via the operator display or PC software e Provides status and diagnostic information for Trane HVAC units equipped with Trane ReliaTel or UCP electronic controls Figure 4 VariTrac central control panel L and a screen representation from the central control panel illustrating system status R Optional Operator Display Figure 5 VariTrac central control panel with optional operator display The optional operator display is a backlit liquid crystal display with touch screen programming capability The operator can access system and zone status through the display and perform basic setup of zone VAV UCMs and CCP system operating parameters The display allows an installer to commission a VariTrac system without using a PC The operator display has a seven day time clock for stand alone scheduling capability 6 VAV PRC003 EN e TRANE Features and Benefits
62. tification program VAV PRC003 EN 41 e TRANE Acoustics Table 17 Sound noise criteria NC valve only 1 2 4 Radiated1 2 4 Inlet Pressure 5 3 5 Inlet Pressure 5 3 5 in CFM 1 5 0 5 1 0 1 5 2 0 3 0 0 5 1 0 1 5 2 0 3 0 80 38 22 25 27 30 21 24 32 36 120 57 26 31 34 36 22 27 32 36 3 150 71 30 36 38 39 40 22 27 34 33 36 225 106 28 39 46 50 23 28 34 38 130 61 20 24 31 29 19 23 25 27 200 94 22 29 34 36 16 23 27 28 i 250 118 21 31 35 36 36 16 23 25 27 30 350 165 21 32 41 41 21 23 27 31 200 94 19 24 27 30 19 23 26 30 300 142 21 28 33 34 19 23 28 31 2 400 189 23 30 34 37 38 22 24 26 28 32 500 236 25 31 38 40 25 26 28 33 350 165 19 24 29 30 22 24 26 30 520 245 20 28 33 36 21 26 30 31 700 330 25 30 35 37 40 22 27 30 32 34 900 425 28 34 39 42 24 28 33 36 550 260 18 22 27 21 24 27 28 820 387 16 24 29 32 22 26 31 32 1100 519 23 29 33 34 38 23 27 31 32 34 1400 661 25 33 39 42 25 28 32 35 800 378 16 23 28 21 24 28 28 1200 566 20 26 31 21 26 32 32 1600 755 19 26 29 31 34 22 25 28 31 35 2000 944 22 30 37 38 24 27 31 35 1100 519 16 24 29 24 27 28 31 1600 755 19 25 30 25 30 32 33 2100 991 17 24 27 30 34 24 30 33 35 37 3000 1416 24 30 38 42 30 34 36 40 1400 661 21 28 32 25 28 32 33 2100 991 18 25 30 34 25 30 34 35 2800 1321 20 27 30 32 36 27 31 34 36 38 4000 1888 26 32 38 42 30 33 38 40 Notes
63. ting and cooling unit Improved ceiling aesthetics is also an advantage of slot return diffusers in jobs where slot supply diffusers are used Within the occupied space they blend with the slot supply diffusers A general rule of thumb is for the return air openings to equal the total area of the supply openings If the ceiling is nottight such as a drop in ceiling the return openings can be reduced by up to 5096 of the supply air openings To promote good air distribution return diffusers should be positioned to minimize supply air short circuiting to the return slot The returns should be either perpendicular to the supply airflow or parallel and offset from the supply diffusers VAV PRC003 EN S TRANE Application Considerations Figure 19 Proper return diffuser orientation PERPENDICULAR RETURN SLOT DIFFUSER Pressure Dependent vs Pressure Independent Pressure Dependent A pressure dependent VAV control sequence uses the space temperature sensor to directly control the position of the zone damper The actual airflow delivered to the space is a by product of this damper position and the static pressure in the duct upstream of the zone damper Ventilation air is a fixed damper position and must be measured and set during the commissioning process Pressure Independent A pressure independent VAV control scheme directly controls the actual volume of primary air that flows to the
64. tion for additional details Note VariTrac systems are designed for HVAC unit static pressures up to 1 75 w c Figure 18 Hand balancing dampers Hand Balancing Damper Step 6 Designing the Duct System VAV PRC003 EN Low pressure low velocity air distribution systems such as zoned unitary systems are usually designed using the equal friction method Although static regain is the duct design method of choice for medium and high velocity variable air volume systems the added complexity is difficult to justify with smaller unitary systems In addition the low operating velocity of most unitary systems makes the pressure available to regain small and inconsequential With the equal friction method ducts are sized for a constant pressure loss per given length of duct and fitting s Where low noise levels are especially critical the system velocity can be reduced by enlarging the entering and leaving ductwork damper unit or adding duct liner A characteristic of the equal friction method that must be considered however is that there is no natural provision for equalizing pressure drops in the branch sections This results in each branch duct and thus the damper units having different entering static pressure and airflow characteristics 19 e TRANE Application Considerations A robust system and zone unit controller like the Trane VariTrac system will compensate for system static changes The use of manual or hand bal
65. to the zones may decrease decreasing comfort Fixed Outside Air Dampers Achieving appropriate building pressure is simple in a system with a constant volume supply fan and fixed outdoor air damper To maintain a slightly positive building pressure size the exhaust fans to remove slightly less air than is introduced through the outdoor air damper Outside Economizer or Demand Controlled Ventilation Systems 24 If the system resets the quantity of outdoor air in response to occupancy demands demand controlled ventilation or uses an outdoor air economizer undesirable changes in building pressure may result As the quantity of outdoor air intake varies the system must exhaust a similar quantity of air to avoid over or under pressurizing the building When using an economizer in a changeover bypass VAV system under low cooling load conditions reduced airflow to the zones the bypass damper opens to maintain the static pressure setpoint VAV PRC003 EN e TRANE Application Considerations and airflow through the supply fan As the outside air damper opens to provide economizer cooling the return air damper closes In buildings with a ceiling plenum return the bypass air dumps into the ceiling plenum since it can no longer return to the fan The plenum pressure rises and plenum air enters the zones through the return air grilles In buildings that have a ducted return to the fan bypass air pressurizes the return air duct As the ret
66. uired for 24 Vac power connection Table 7 VariTrac control panel specifications Power Requirements 20 30 Vac 60 Hz single phase 30 VA minimum Class 2 transformer required Operating Environment 32 122 F 0 50 C 10 90 relative humidity non condensing Storage Environment 40 F 122 F 40 85 C 5 95 relative humidity non condensing Control Enclosure NEMA 1 resin enclosure plenum rated Mounting Mount directly on wall surface or mount on recessed 4 x 4 101 6 mm x 101 6 mm conduit box Weight 2 5 Ibs 1 13 kg Communication link wiring must be Level 4 22 AWG twisted shielded pair wire with stranded tinned copper conductors Maximum total wire length is 3 500 ft 1066 8 m Wire must meet Trane specifications Binary Input Voltage provided by VariTrac CCP 10 14 Vdc Current provided by VariTrac CCP 10 14 mA UL Approval The VariTrac Central Control Panel is UL approved Communication Link Wiring Upon a power loss all operator edited data stored in the VariTrac Central Control Panel is maintained Memory Backup permanently a Only dry contacts may be attached to binary inputs Table 8 UCM damper specifications Power Requirements 20 30 Vac 60Hz single phase 10 VA minimum plus load of optional heat outputs Class 2 transformer required Operating Environment 32 120 F 0 49 C 10 90 relative humidity non condensing Storage Environment 50 200 F 46
67. urn air duct pressure rises the air flows out of the building through the barometric relief damper in the rooftop unit Excess bypass air flows into the zones through the return air grilles Using the following suggestions will help maintain building pressurization control Use an exhaust fan with a modulated exhaust damper to remove air from the return air plenum or duct Energize the exhaust fan as the outside air damper opens beyond the minimum position Sense building static and maintain building air pressure at a slightly positive level by modulating the exhaust damper position Use an exhaust fan with no exhaust damper Energize the exhaust fan when the outdoor air damper opens beyond 25 percent to remove excess outside air from the building This method is used with some rooftop units and is effective affordable and easy to install Use a back draft damper to prevent airflow to the return air plenum or grilles When bypass airflow pressurizes the return duct the back draft damper closes Pressure in the HVAC unit return air inlet rises causing the rooftop barometric relief damper to open This method is less effective because the rooftop barometric relief damper is sized for a portion of the total airflow not 100 percent of airflow which may be seen in economizer mode As the economizer drives to the maximum position the building usually becomes over pressurized Figure 26 Changeover bypass with an economizer Without proper building
68. y through intelligent ventilation based on occupancy The quantity of ventilation is controlled based on indoor CC2 levels which correlate to occupancy levels Demand controlled ventilation saves money by reducing ventilation during periods of low occupancy Discharge Air DA Air discharged from the air handler into the ducts Discharge Air Control An air handling system that provides fixed temperature air either fixed or variable volume Other control devices vary the actual volume of air delivered to the space to maintain occupant comfort Economizer A damper arrangement and automatic control system that allows a heating ventilation and air conditioning HVAC system to supply up to 100 percent outside air to satisfy cooling demands even if additional mechanical cooling is required Exception Schedule A one time only time of day schedule in a system that is removed automatically after use F Free Cooling Outdoor air introduced to a system under correct conditions to provided cooling to a space Also see also Economizer HVAC Unit An air moving device that conditions air An HVAC unit may provide cooling or heating and cooling Typical HVAC units include packaged rooftop units split systems and water source heat pumps 49 e TRANE Glossary L LCD Liquid crystal display NDIR Non dispersive infrared technology Negative Pressure The condition that exists when more air is exhausted from a s
69. zed and located according to the following general recommendations e Avoid turbulence by locating the bypass two to three equivalent duct diameters downstream of the HVAC unit discharge e Locate the static pressure and supply air sensors in the main supply duct upstream of the bypass e Locate the bypass before the zone dampers as close to the HVAC unit as possible to avoid comfort or noise issues e Size the bypass damper to maintain the minimum required airflow through the HVAC unit usually 80 percent of the total design cfm e Provide adequate access for servicing the damper Figure 25 Changeover bypass variable air colume system Rooftop Micro Control Economizer Heating and Cooling Coils Static Pressure i and Supply Temperature Sensors Bypass Return Damper Supply 77 _ Air Duct Le Building Pressure Control Comfortable efficient building operation requires that the air pressure inside the building be slightly higher than the atmospheric pressure outside of the building That is the building is at a positive pressure with respect to the outside environment If the indoor pressure is too low negative the doors may be hard to open and cold air may leak in through construction cracks causing drafts and cold floors On the other hand if the indoor pressure is too high the doors may stand open and the supply air flow

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