Product Catalog Tracker System — CB VariTrac™ — Changeover Bypass VAV VariTrac Central Control Panel with touchscreen interface HVAC Unit Bypass Damper Communicating Bypass Controller Wireless Receiver Wireless Zone Sensor March 2012 VariTrac Zone Damper Zone Sensor VAV-PRC003-EN
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.
Table of Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Features and Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Application Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Selection Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Model Number Descriptions .
Features and Benefits Figure 3.
Features and Benefits HVAC Unit 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.
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.
Features and Benefits Operator Display Feature Summary • Backlit LCD touch-screen display for easy operator interface. • Combination of icon- and menu-based navigation provides intuitive operation. • Provides a level of control for the daily operator, and a second level for commissioning and service. • Three levels of security are available to protect system settings. • Seven-day time clock for stand-alone, time-of-day scheduling.
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.
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.
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 temperature. 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.
Features and Benefits CO2 Sensor 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.
Features and Benefits • Adjustable sensitivity • SPDT isolated contacts connect to UCM input Auxiliary Temperature Sensor Figure 12. Auxiliary temperature sensor The auxiliary temperature sensor is used with any UCM damper control. The sensor allows the operator to monitor duct temperature or air temperature leaving a reheat device at the zone damper. This sensor is used for automatic changeover of a UCM damper when not using a CCP.
Application Considerations Introduction The VariTrac system is a changeover-bypass VAV system. One fan supplies 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.
Application Considerations • Building layout, design, occupancy and occupancy pattern throughout the day and year • 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.
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.
Application Considerations • Interior partitions and doors • 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.
Application Considerations Figure 16. Building Example 2 illustrates a poorly insulated store design (L) and an improved design (R) Outside Doors Outside Doors Coffee Shop Coffee Shop Jewelry Store Jewelry Store Improved Design Elements Poor Design Elements • Two thermal zones • Two HVAC units • One thermostat for entire space • One HVAC unit Electronics Store Pharmacy Electronics Store Pharmacy Toy Store Clothing Store Toy Store Clothing Store N N Step 3.
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. 2.
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 (fpm) when applied at the branch level.
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) balancing 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 Supply Diffusers Many types of supply air diffusers are used in variable air volume systems.
Application Considerations Figure 19. Proper return diffuser orientation 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.
Application Considerations VariTrane units with integral electric or hot water heat are available as: • Single-duct • Parallel fan-powered • 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 The Trane VariTrac Zone Controller has built-in capabilities and logic to control a number of reheat sources.
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: • Hydronic wall fin or convector unit with either modulating or two position control. (See trane.
Application Considerations Proper operation requires consideration of all aspects of bypass design and location. The bypass dampers and ductwork should be sized and located according to the following general recommendations: • Avoid turbulence by locating the bypass two to three equivalent duct diameters downstream of the HVAC unit discharge. • Locate the static pressure and supply air sensors in the main supply duct upstream of the bypass.
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.
Application Considerations 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.
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.
Selection Procedures Table 3.
Selection Procedures Figure 27.
Model Number Descriptions Digit 1, 2, 3, 4 — Product Type Digit 17 — Duct Temp Sensor VADB= VariTrac Air Damper VARA= Rectangular Air Damper 0 = W = Digit 5, 6 — VariTrac Damper Size Digit 18 — Zone Sensor 06 08 10 12 14 16 1R 2R 3R 4R 5R 6R 7R 8R 9R AR = = = = = = = = = = = = = = = = 6" Damper 8" Damper 10" Damper 12" Damper 14" Damper 16" Damper 14 x 12 Bypass Damper 16 x 16 Bypass Damper 20 x 20 Bypass Damper 30 x 20 Bypass Damper 8 x 12 Zone Damper 8 x 14 Zone Damper 8 x 16 Zone Damper 10 x 16 Z
Electrical Data and Connections Figure 29.
Electrical Data and Connections Figure 30. Relay board wiring Relay Board TB2 Rc Rh 2 G 3 Y1 4 5 COOL 2 COMP 2 6 HEAT 1 AUX HEAT 7 HEAT 2 REV VALVE NO AUX 8 NC W2/0 1 W1 Y2 TB1 10 9 24 VAC CLASS 2 COOL UNIT 24 VAC CLASS 2 HEAT UNIT SUPPLY FAN 2 HEAT/2COOL COOL 1 SPARE HEAT PUMP COMP 1 OUTSIDE AIR HEAT/COOL OR ICS NOT USED 11 12 13 14 15 Figure 31.
1 2 To Zone Dampers 3 through 24 J8 – J7 + + TB2–6 TB2–5 TB2–2 TB2–1 – Shielded ground Figure note = = S Twisted pair, shielded wire per Trane specifications ZONE GND SET A/CO2 GND TB3–5 = Legend YEL GRN 1 J3 J11 – – + 2 1 2 1 BIP TB4–1 GND 24V + – YEL GRN D.D.C.\U.C.M. CONTROL BOARD 1 J3 ZONE GND SET A/CO2 GND TB3–5 S – – + 2 Splice + ADDRESS SWITCH J11 ACT 1 BIP GND 24V + – YEL GRN D.D.C.\U.C.M.
Electrical Data and Connections Figure 33. Communicating bypass controller wiring CW CLOSE CCW OPEN COM TO NEC CLASS 2 24V TRANSFORMER LOAD 8 VA (WITHOUT ACTUATOR) HOT ACTUATOR { ACTUATOR W–HOT BK–OPEN R–CLOSE SPARE CONNECTOR 2.
Electrical Data and Connections Figure 34. UCM wiring 8. } 5. 24 VAC 60 HZ NEC CLASS–2 CONTROL CIRCUIT R (HOT) O (COMMON) GR (NC CONTACT) BK (RETURN) (TB1–1) 24VAC (TB4–1) BIP (TB1–1) 24VAC (TB1–2) GND Y NOT CONNECTED R G W W TO J11 3RD STG. TO J10 2ND STG. 1ST STG.
Electrical Data and Connections Figure 35. DDC zone sensor with LCD Digital Sensor Board TB1–1 24V –2 ACT BIP TB2–1 TB1–1 PRESS GND 1 Communications TB2–6 S TB3–6 TB3–5 TB3–3 ZONE GND SET A/CO2 TB3–1 TB2–5 TB3–2 GRN TB3–2 Communications + (High) –2 YEL TB3–1 TB3–3 TB2–5 TB2–3 – + – TB2–4 TB3–1 + TB2–3 TB3–1 TB3–2 – TB2–2 TB2–1 TB2–2 J3 1 + Setpoint TB1–2 TB1–2 GND 24V D.D.C.\U.C.M.
Specifications Table 6. Zone sensor options Zone Sensor Options Number of Required Wires(a) 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.
Specifications 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 1200 sq. ft (365.8 m) Effective Coverage Radius 22 ft (6.7 m) Housing Material ABS plastic Table 11.
Acoustics Acoustics 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.
Acoustics Table 15. Discharge sound power (dB)1,2,4 Inlet Size (in) Cfm 4 5 6 8 10 12 14 16 0.5” Inlet Pressure 1.0” Inlet Pressure 1.5” Inlet Pressure 2.0” Inlet Pressure 3.
Acoustics Table 16. Radiated sound power (dB)1,2,4 Inlet Size (in) Cfm 4 5 6 8 10 12 14 16 0.5” Inlet Pressure 1.0” Inlet Pressure 1.5” Inlet Pressure 2.0” Inlet Pressure 3.
Acoustics Table 17. Sound noise criteria (NC) - valve only Inlet Size (in) 4 5 6 8 10 12 14 16 Discharge1,2,4 Inlet Pressure CFM l/s 0.5” 1.0” 80 38 22 25 120 57 26 31 150 71 30 36 225 106 28 130 61 200 250 350 1.5” Radiated1,2,4 (Ps)3,5 Inlet Pressure (Ps)3,5 2.0” 3.0” 0.5” 1.
Dimensions and Weights Figure 37. Central control panel dimensions Top view 10.25 in. (26.04 cm) 2.75 in. (6.99 cm) 8.75 in. (22.38 cm) Front view Side view Bottom view Note: Central control panel weight is 2.5 lbs.
Dimensions and Weights Figure 38. Communicating bypass control dimensions Mounting holes See back view for dimensions 4 1/4" 6 3/4" 5" 3 3/8" Duct Static Pressure Sensor 4 5/16" 3 7/8" Duct Temp Sensor 0.300" Back View Notes: Weight Operating Temp Humidity Mounting Method 44 1 15/16" 1.00" 1.
Dimensions and Weights Figure 39.
Dimensions and Weights Figure 40.
Dimensions and Weights Figure 41.
Dimensions and Weights Figure 42. Occupancy sensor (L), CO2 sensor dimensions (R, Top), and digital zone sensor (R, Bottom) 3.125" 1.44" 4.25" (73,55 [2,90]) (27,52 [1,08]) 3.60" Front View (120,41 [4,74]) 2.50" Side View 1.
Glossary B 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 operator display. Bypass Damper The motorized damper ducted between the system supply and return ducts used to control static pressure in changeover bypass VAV systems.
Glossary L LCD Liquid crystal display. N NDIR Non-dispersive infrared technology. Negative Pressure The condition that exists when more air is exhausted from a space 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.
Glossary 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 duct-mounted hot water or spacemounted electric or hot water reheat coils in response to increased space heating demand.
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