Trane RT-PRC031-EN User Manual

Rooftop Air Handlers

IntelliPak™ II Air Handlers

Casing A-C, 16000-45000 CFM—60 Hz

November 2007 RT-PRC031-EN

Introduction

IntelliPak™ II Rooftop Air Handlers Designed For Today, Tomorrow and Beyond

Built on the legacy of Trane's industry leading IntelliPak, the IntelliPak II Air Handler platform is designed for the future. Expanded features and benefits, controls enhancements and world class energy efficiencies make the IntelliPak II the right choice for demanding applications today, and tomorrow.

Trane's Unit Control Module (UCM), an innovative, modular microprocessor control design, coordinates the actions of the IntelliPak II Air Handler for reliable and efficient operation and allows for standalone operation of the unit.

Access to the unit controls, via a Human Interface Panel, provides a high degree of control, superior monitoring capability, and unmatched diagnostic information.

Optionally, for centralized building control on-site, or from a remote location, IntelliPak II can be configured for direct communication with a Trane Tracer™ or a 3rd party building management system using LonTalk®. With either of these systems, the IntelliPak II operating status data and control adjustment features can be conveniently monitored from a central location.

The IntelliPak II has the technology and flexibility to bring total comfort to every building space.

Table of Contents

Features and Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Controls

Variable Air Volume (VAV) Only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Controls Constant Volume (CV) Only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Controls VAV and CV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Applications Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Selection Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Model Number Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

General Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Performance Adjustment Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Performance Data—Chilled Water Coil Capacities . . . . . . . . . . . . . . . . . . . . . . . . .38

Performance Data — Supply Fan without Inlet Guide Vanes (with or without Variable

Frequency Drive) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Performance Data — Supply Fan with Inlet Guide Vanes . . . . . . . . . . . . . . . . . . .51

Performance Data—Exhaust Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60

Performance Data—Return Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

Performance Data—Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Performance Data—Component Static Pressure Drops/Fan Drive Selections . . .72

Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76

Dimensional Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79

Weights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91

Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94

Mechanical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

RT-PRC031-EN 3

Features and Benefits

Standard Features

• 16000-45000 CFM (Casings A, B, C) industrial/ commercial Rooftop Air Handlers

• ASHRAE 90.1 - 2010 Efficiency Compliant

• IBC (International Building Code) Seismic compliance

• UL and CSA approval on standard options

Controls

• Fully integrated, factory installed/commissioned microelectronic controls

• Unit mounted Human Interface Panel with a 2 line x 40 character English display and a 16 function keypad that includes Custom, Diagnostics, and Service Test mode menu keys.

• CV or VAV control

• Daytime Warm-up (Occupied mode) on VAV models and Morning Warm-up operation on all units with heating options

• Freeze Stat coil frost protection on chilled water coil

• Supply air static overpressurization protection on units with inlet guide vanes and VFD's.

• Supply airflow proving

• Exhaust/return airflow proving on units with exhaust or return fan options

• Supply air tempering control

• Supply air heating control on VAV units with heat: modulating gas, electric, steam and hot water

• Emergency stop input

• Mappable sensors and setpoint sources

• Occupied/Unoccupied switching

• Timed override activation

Cabinet

• Solid double wall construction with foam injected insulation

Figure 1. Solid Double Wall

• Single point latching, hinged access doors on control panel, filter, supply and exhaust/return fan section as well as gas heat section

Figure 2. Latching Access Door

• Flexible downflow and horizontal discharge/return paths

• Double sloped galvanized drain pans

• Extended casing, cooling only models

• Pitched roof

• Heavy-gauge, continuous construction base rails

• Meets salt spray testing in accordance to ASTM B117 Standard

Mechanical

• Airfoil supply fan—standard CFM

• Stainless steel flue stack on gas heat units

• Two-inch spring fan isolation standard

Figure 3. Spring Isolation

• Two-inch high efficiency throwaway filters Optional Features

4 RT-PRC031-EN

Features and Benefits

Optional Features

Controls

• Demand control ventilation (energy saving CO control)

• Twinning of up to four units for applications on common supply and return ducts

• Variable frequency drive (VFD) control of supply/exhaust/return fan motor

Figure 4. Variable Frequency Drive

• Inlet guide vanes on airfoil supply fans (VAV only)

• Choose from three economizer control options: comparative enthalpy, reference enthalpy, dry bulb control

• LonTalk® Communication Interface module

• Generic BAS interfaces—0-5 VDC, and 0-10 VDC

• Remote Human Interface Panel (controls up to 4 units)

• Five ventilation override sequences

• High duct temperature thermostats

Chilled Water Cooling

• 2 to 8 row 5/8” OD chilled water coils

• 80, 108, 144, and 168 fin spacing options

• Galvanized steel coil casing

• Header drain and vent connections

• Fully drainable coils

economizer

•1.5”, 2.0”, 2.5”, or 3.0” water modulating valve with actuator and linkage

• External piping enclosure

Cabinet

• Blank Section Options

– Four foot blank—cooling only

– Eight foot blank—cooling and

heating

• Single Point access doors on both sides of the unit

• Belt guards for supply and exhaust/return fans

• Burglar Bars on select configured units

Mechanical

• Airfoil plenum return fan— standard CFM

• Modulating plenum return fan with Statitrac™ direct space sensing building pressurization control

• Forward curved exhaust fan— standard and low CFM

• 100 percent modulating exhaust

• 100 percent modulating exhaust with Statitrac™ direct space sensing building pressurization control

• Outside air CFM compensation on VAV units with IGV (or VFD) and economizer

• The Trane air quality (Traq™) fresh air measurement damper system

Figure 5. Traq Damper

• 0-100 percent modulating fresh air economizer

• 0-25 percent motorized fresh air damper

• Low and ultra low leak dampers

Filtration

• Pre-Evaporator Coil Filter Options

– Filter rack only (no filters)

– Two-inch Throwaway filters

– 90-95 percent bag filters

– 90-95 percent cartridge filters

• Final filters

– Bag filters

– Standard and high

temperature cartridge filters

– Standard and high

temperature HEPA filters

Heat Options

• Electric, gas, steam or hot water

• Gas heat options:

– 10:1 Modulating Gas Heat 850

MBH

– 20:1 Modulating Gas Heat

1100 and 1800 MBH

– 10 year limited warranty on

Modulating Gas Heat

Electrical

• Unit Withstand Rating of 65000 Amp (480V) and 25000 Amp (600V)

• High efficiency totally enclosed fan-cooled supply and exhaust/ return fan motors

• Standard efficiency supply and exhaust/return fan motors

• Marine lights in serviceable compartments

• Electrical convenience outlet

• Through the door non-fused disconnect with external handle

RT-PRC031-EN 5

Features and Benefits

Field Installed Accessories

• Roof curbs

• Wireless zone sensor

• Programmable sensors with night setback—CV and VAV

• Sensors without night setback— CV and VAV

• Remote zone sensors—used for remote sensing with remote panels

• ICS zone sensors used with Tracer™ system for zone control

• Outdoor temperature sensor for units without economizers

• Remote minimum position control for economizer

• Module kits available for field upgrade of controls

Features Summary

IntelliPak™ II air handler features make installation and servicing easy and operation extremely reliable.

Installation and Service

• Microprocessor unit controls coordinate the operation of the air handler with quality, industryaccepted components for service ease.

• Supply and return piping for the chilled water coil are easily accessed through the external piping enclosure

• Controls are factory installed/ commissioned for ease of start up

• Full unit points access—no field wiring of required points

• Modularity of unit control design

• Individual replaceable functional boards

• Unit mounted Human Interface Panel standard

– User-friendly keypad edit

parameters

– Dedicated Human Interface

access panel

– Start up adjustments

– Advanced diagnostics

• Unit mounted and remote interface panel key pads are identical

• Single twisted wire pair communication for ICS interface

• Sturdy, double wall, foam injected, hinged access doors with height adjustable single point latches on main compartments for service ease

• Main control box conveniently located on end of air handler for layout flexibility in tight spaces

• Built in optional features like high withstand rated breakers, belt guards and burglar bars contribute to safety

• Convenience outlet and marine lights for enhanced service capability

Figure 6. Convenience Outlet

• Unit mounted lifting lugs facilitate installation and can be used as unit tie-down points

Figure 7. Lifting Lugs

Reliability

• Advanced diagnostics

• Microprocessor controls

• Built-in safeties

• Modular control design

• UL/CSA approval as standard

• All supply, exhaust, and return fans are factory balanced

• Fully insulated floor, roof, panels, and gasketed interfaces reduce ambient air infiltration.

• Fixed-speed supply, exhaust/ return drives for smooth fan operation and belt durability.

• 200000 average life fan bearings enhance unit durability.

• Gas heater with free-floating stainless steel heat exchanger relieves the stresses of expansion and contraction. Stainless steel provides corrosion resistance through the entire material thickness.

• Factory-wired and commissioned controls assure efficient and reliable air handler operation.

• Roll-formed construction enhances cabinet integrity and assures a leak-proof casing.

• Trane industrial quality hot water, steam and chilled water coils are factory pressure and leak tested to ensure dependability

6 RT-PRC031-EN

Application Flexibility

• Chilled water or no cooling alternatives

• A variety of chilled water coil offerings to meet a diverse range of capacity requirements

• Multiple downflow and horizontal air path options

• An array of heating options are available, including Electric, Natural Gas, Steam and Hot Water. The Gas Heating option provides a choice of two-stage gas heat, as well as full modulating gas heat. Electric heating options provide four to six steps of capacity. Hot water and steam coils have two steaps of capacity.

• Indoor Air Quality (IAQ)

– Traq Damper System for

precise fresh air measurement

– Demand Control Ventilation

for CO

– Compensated outdoor air

control

– Statitrac™ direct space

building pressure control

– Multiple factory installed

filter types, pre evaporator and final filters

– Humidification control output

– Comparative enthalpy,

Reference enthalpy, or Dry bulb control for economizers

• Superior Building Automation interface through LonTalk

• Generic BAS interfaces

• Unit mounted or Remote Human Interface panels

– All parameters are editable

from the Human Interface Panel

• Five factory preset ventilation override sequences which can be redefined in the field

• Variable Frequency Drives (VFD) included With or Without Bypass Control for Supply and Exhaust/ Return Fans.

• CV controls stage heat based on space requirements.

economizer control

Features and Benefits

Figure 8. Trane Complete Comfort System

Integrated Comfort with Trane Tracer™ LCI

The Tracer Integrated Comfort™ System (ICS) improves job profit and increases job control by combining Trane rooftop air handler units with the Trane Tracer building management system. This integrated system provides total building comfort and control. Some of the primary motivations for building owners/managers in deciding to purchase a HVAC controls system are energy savings, cost control, and the convenience of facility automation.

Simplifying the Comfort System

Trane technology and innovation brings more capabilities, more flexibility, and offers equipment and systems that are easy to use, easy to

install, commission and service. The Tracer Integrated Comfort system saves time and money by simplifying system design and system installation.

When used with Trane DDC/VAV terminals (or VariTrane™), system balancing almost goes away because each VAV box is commissioned and tested before it leaves the factory.

All the status information and editing data from the air handler units, VAV terminals, lighting, exhaust and other auxiliary equipment is available from Tracer for facility control, monitoring and service support. Tracer, a family of building automation products from Trane, is designed with robust, application specific software

IntelliPak™ II Air Handler

RT-PRC031-EN 7

Features and Benefits

packages to minimize custom programming requirements and enable system setup and control through simple editing of parameters in the standard applications software.

When selecting an Integrated Comfort system for a facility, the accountability for equipment, automation and controls is Trane's, Trane's, and Trane's!

In addition to high quality, high performance, packaged air handler, Trane provides precise air delivery management with VariTrane VAV terminals.

Wireless zone sensors minimize the installation costs of the VariTrane terminals and the packaged air handler system in general.

The IntelliPak™ II air handler, as a part of an Integrated Comfort system, provides powerful maintenance monitoring, control and reporting capabilities. The Tracer places the air handler in the appropriate operating mode for: system on/off, night setback, demand limiting, setpoint adjustment based on outside parameters and much more.

Many different unit diagnostic conditions can be monitored through Tracer: sensor failures and loss of supply airflow. Further, the addition of Building Management Network software offers remote scanning, automatic receipt of alarms, and easy dial-up access to over 100 various Tracer sites across town or across the country.

IntelliPak™ II Air Handler monitoring points available through Tracer

• all active Air Handler diagnostics

• history of last 20 unit diagnostics

• all system setpoints

• system sensor inputs

• supply fan mode and status

• inlet guide vane position/VFD speed

• unit heat/cool mode

• exhaust/return fan status

• exhaust/return damper position

• economizer position, minimum position setpoint, economizing setpoint

• electric heat stage status

• ventilation override mode status

Tracer control points for IntelliPak II Air Handlers

• sensor calibration offsets cooling and heating setpoints

• zone setpoint offsets for use with demand limiting

• VAV discharge air setpoints

• supply air pressure setpoint

Figure 9. Tracer™

• space pressure setpoint

• zone and outdoor temperature values

• cooling and heating enable/ disable

• economizer enable/disable

• economizer setpoint

• economizer minimum position

• activation of ventilation override modes

• diagnostics reset

• unit priority shutdown

IntelliPak II Air Handler setup and configuration information through Tracer

• supply fan mode

• configuration of supply air reset

• ventilation override mode configuration

• default system setpoint values

Interoperability

Trane Tracer LonTalk Control Interface (LCI) for IntelliPak II offers a building automation control system with outstanding interoperability benefits.

LonTalk, which is an industry standard, is an open, secure and reliable network communication protocol for controls, created by Echelon Corporation and adopted by the LonMark Interoperability Association. It has been adopted by several standards, such as: EIA-709.1, the Electronic Industries Alliance (EIA) Control Network Protocol Specification and ANSI/ASHRAE 135, part of the American Society of Heating, Refrigeration, and Air Conditioning Engineer's BACnet control standard for buildings.

Interoperability allows application or project engineers to specify the best products of a given type, rather than one individual supplier's entire system. It reduces product training and installation costs by standardizing communications across products. Interoperable systems allow building managers to monitor and control IntelliPak II equipment with a Trane Tracer Summit or a 3rd party building automation system.

It enables integration with many different building controls such as access/intrusion monitoring, lighting, fire and smoke devices, energy management, and a wide variety of sensors (temperature, pressure, light, humidity, occupancy, CO air velocity). For more information on LonMark, visit www.lonmark.org or Echelon, www.echelon.com.

and

Optimum Building Comfort Control

The modular control design of the UCM allows for greater application flexibility. Customers can order exactly the options required for the job, rather than one large control package. Unit features are distributed among multiple field replaceable printed circuit boards. The Trane UCM can be setup to operate under one of three control applications:

1. standalone

8 RT-PRC031-EN

Features and Benefits

2. interface with Trane Tracer™ building management system

3. interface with a generic (nonTrane) building management system. All setup parameters are preset from the factory, requiring less start-up time during installation.

The unit mounted Human Interface and the Remote Human Interface Panels' functions are identical, with the exception of the Service mode which is not available on the Remote Human Interface Panel. This common interface feature requires less time for building maintenance personnel to learn to interact with the unit.

All air handler control parameters are adjustable and can be setup through the Remote Human Interface Panel such as, but not limited to: system on/off, demand limiting type, night setback setpoints, and many other setpoints. No potentiometers are required for setpoint adjustment, all adjustments are done through the Remote Human Interface keypad.

Up to 56 different air handler diagnostic points can be monitored through the human interfaces such as: sensor failures and loss of supply airflow. No special tools are required for servicing the unit. All diagnostic displays are available in clear English at the Remote Human Interface and will be held in memory, so that the operator/service person can diagnose the root cause of failures.

Figure 10. Statitrac

Statitrac™ Direct Space Building Pressurization Control

Trane Statitrac™ control is a highly accurate and efficient method of maintaining building pressure control with a large air handler.

Building space pressurization control is achieved with a 100 percent modulating exhaust system that features a single forward curved fan, with modulating discharge dampers that operates only when needed or a 100% modulating plenum return fan with airfoil wheel that operates continuously with the supply fan. Most of the operating hours of the 100 percent modulating exhaust system are at part load, resulting in energy savings.

Statitrac, with the 100 percent modulating exhaust system, provides comfort and economy for buildings with large air handler systems. Statitrac, with the 100% modulating plenum return fan provides comfort and space pressure control in more demanding applications with high return static pressure, and applications requiring duct returns.

Statitrac control with exhaust fan is simple! The space pressure control turns the exhaust fans on and off as required and modulates exhaust dampers, or VFD speed, to maintain space pressure within the space pressure deadband. Economizer and return air dampers are modulated based on ventilation control and economizer cooling request.

The unit mounted Human Interface Panel can be used to:

1. adjust space pressure setpoint

2. adjust space pressure deadband

3. measure and read building static pressure

The modulating exhaust system maintains the desired building pressure, while saving energy and keeping the building at the right pressure. Proper building pressurization eliminates annoying door whistling, doors standing open, and odors from other zones. The Statitrac™ direct space building control sequence will also be maintained when a variable frequency drive is used.

Statitrac Control with Plenum Return Fan is State of the Art!

Other manufacturers utilize a fan tracking control scheme whereby the return fan speed tracks the supply fan speed in a linear fashion. This scheme works well at minimum and maximum CFM airflow. However, due to the dissimilar performance characteristics of the supply and return fan, building pressure is difficult to control at points between minimum and maximum CFM airflow.

The Trane return fan/building pressurization control system eliminates the effects of dissimilar supply/return fan characteristics experienced in a linear tracking control system by modulating the exhaust dampers based on space pressure, the return/economizer dampers based on ventilation requirements, and the return fan speed based on return plenum static pressure. The supply fan, return fan, exhaust damper, and return/ economizer damper systems act independently from one another to maintain comfort and building pressure.

The return fan operates whenever the supply fan is in operation. The unit exhaust dampers are modulated in response to the space pressure signal to maintain space pressure within the space pressure deadband. The unit economizer and return air dampers are modulated based on ventilation control, minimum outside air economizer position, and economizer cooling request. The return fan speed is modulated based on a return duct static pressure deadband control. Using the unit mounted Human Interface Panel you can:

1. adjust space pressure setpoint

2. adjust space pressure deadband

3. measure and read building space pressure

4. measure and read return duct static pressure.

Proper building pressurization eliminates annoying door whistling, doors standing open, and odors from other zones.

RT-PRC031-EN 9

Supply Fans with Inlet Guide Van es

Trane airfoil fans with inlet guide vanes pre-rotate the air in the direction of the fan wheel, decreasing static pressure and horsepower, essentially unloading the fan wheel. The unloading characteristics result in superior part load performance.

Variable Frequency Drives (VFD)

Variable Frequency Drives are factory installed and tested to provide supply/exhaust/return fan motor speed modulation. VFD's, as compared to inlet guide vanes or discharge dampers, are quieter, more efficient, and may be eligible for utility rebates. The VFD's are available with or without a bypass option. Bypass control will simply provide full nominal airflow in the event of drive failure.

Features and Benefits

10 RT-PRC031-EN

Controls Variable Air Volume (VAV) Only

Figure 11. IntelliPak™ II Control Panel

VAV Units Only

Note: When noted in this sequence

“Human Interface Panel,” the reference is to both the unit mounted and remote mounted Human Interface Panel. All setpoint adjustments can be accomplished at the unit or Remote Human Interface Panel.

Supply Air Pressure Control

Inlet Guide Vanes Control

Inlet guide vanes are driven by a modulating 0-10 vdc signal from the Rooftop Module (RTM). A pressure transducer measures duct static pressure, and the inlet guide vanes are modulated to maintain the supply air static pressure within an adjustable user-defined range.

The range is determined by the supply air pressure setpoint and supply air pressure deadband, which are set through the Human Interface Panel or BAS/Network.

Inlet guide vane assemblies installed on the supply fan inlets regulate fan capacity and limit horsepower at lower system air requirements.

When in any position other than full open, the vanes pre-spin intake air in the same direction as supply fan rotation. As the vanes approach the full-closed position, the amount of “spin” induced by the vanes increases at the same time that intake airflow and fan horsepower diminish. The inlet guide vanes will close when the supply fan is shut down, except during night setback.

Variable Frequency Drive (VFD) Control

Variable frequency drives are driven by a modulating 0-10 vdc signal from the Rooftop Module (RTM). A pressure transducer measures duct static pressure, and the VFD is modulated to maintain the supply air static pressure within an adjustable user-defined range.

The range is determined by the supply air pressure setpoint and supply air pressure deadband, which are set through the Human Interface Panel or BAS/Network.

Variable frequency drives provide supply fan motor speed modulation. The drive will accelerate or decelerate as required to maintain the supply static pressure setpoint. When subjected to high ambient return conditions the VFD will reduce its output frequency to maintain operation.

Bypass control is offered to provide full nominal airflow in the event of drive failure.

Supply Air Static Pressure Limit

The opening of VAV terminals, and the amount of supply air provided by the inlet guide vanes, or variable frequency drive are coordinated during start up and transition to/from Occupied/Unoccupied modes to prevent over pressurization of the supply air ductwork.

However, if for any reason the supply air pressure exceeds the userdefined supply air static pressure limit that was set at the Human Interface Panel, the supply fan/VFD is shut down and the inlet guide vanes (if included) are closed.

The unit is then allowed to restart three times. If the over pressurization condition occurs on the third time, the unit is shut down and a manual reset diagnostic is set and displayed at the Human Interface Panel and BAS/Network.

Supply Air Temperature Controls

Cooling/Economizer

During Occupied cooling mode of operation, the economizer (if available) and cooling are used to control the supply air temperature. The supply air temperature setpoint and deadband are user-defined at the Human Interface Panel.

The supply air temperature setpoint may be user-defined from the BAS/ Network. If the conditions of the outside air is appropriate to use “free cooling,” the economizer will be used first to attempt to satisfy the supply air setpoint; then if required the hydronic valve will be modulated to maintain supply air temperature setpoint.

On units with economizer, a call for cooling will modulate the fresh air dampers open. The rate of economizer modulation is based on deviation of the supply air

RT-PRC031-EN 11

temperature from setpoint, i.e., the further away from setpoint, the faster the fresh air damper will open.

Note: The economizer is only

allowed to function freely if one of the following conditions is met. For dry bulb economizer control the ambient temperature must be below the dry bulb temperature control setting. For reference enthalpy economizer control, outdoor air enthalpy must be below the enthalpy control setting. For comparative enthalpy economizer control, outdoor air enthalpy must be below the enthalpy of the return air.

The outdoor air dampers may be set for a maximum of 25 percent outdoor air, through the unit mounted Human Interface Panel or a signal from the BAS/network, if the air handler is equipped with 0 to 25 percent motorized fresh air dampers.

A temperature sensor, located on the entering air side of the chilled water coil, will send a signal to the hydronic valve to drive it full open when a potential freeze condition is detected. The supply fan is then turned off and the fresh air damper is closed.

Heating

Modulating Gas

Upon a call for heating, the HEAT module closes the heating contacts, beginning the firing sequence. First, the heat exchanger combustion blower begins operation. Upon positive proving of combustion airflow, a 60 second pre-purge cycle is executed. Then the ignition sequence takes place.

If ignition is not proven, the safety control locks out and must be manually reset. As long as there is a call for heat, the safety control can be reset, which starts another purge cycle and try for ignition.

Once ignited, as additional heat is required, the combustion air damper opens, increasing the firing rate.

During heating operation, an electronic flame safety control provides continuous flame

Controls Variable Air Volume (VAV) Only

Supply Air

Temperature

Supply Air

Temperature

Setpoint

Cooling

Heating

Reset

Ending (Cooling) Beginning (Heating) Reset Temperature

Figure 12. Supply Air Temperature Reset

supervision. If combustion should become unstable for any reason,

heating will automatically shut down and be locked out until reset at the unit mounted Human Interface panel.

As the heating requirement is satisfied, the HEAT module will modulate the combustion air damper closed and the firing rate will lower to maintain the desired outlet temperature. When the requirement is fully satisfied, the heating contacts are opened, de-energizing the heat. The specific sequence of operation of the gas heat will depend on the size of the heat exchanger.

Electric Heating

The individual stages of electric heat will be sequenced on the zone demand. The number of available stages will depend on the unit size and heat capacity selected.

Hot Water or Steam

On units with hot water or steam heating, the supply air temperature can be controlled to a heating setpoint during the Occupied mode. The supply air temperature heating setpoint and deadband are userdefined at the Human Interface Panel. VAV Occupied heating on hot water and steam heat units is enabled by closing a field-supplied switch or contacts connected to an changeover input on the RTM.

Reset

Beginning (Cooling)

Ending (Heating)

Reset Temperature

Supply Air Setpoint Reset

Supply air setpoint reset can be used to adjust the supply air temperature setpoint on the basis of a zone temperature or on outdoor air temperature. Supply air setpoint reset adjustment is available from the Human Interface Panel for supply air heating and supply air cooling control.

Outdoor air cooling reset is sometimes used in applications where the outdoor temperature has a large effect on building load. When the outside air temperature is low and the building cooling load is low, the supply air setpoint can be raised, thereby preventing subcooling of critical zones. This reset can lower usage of primary cooling, thus savings in mechanical cooling kw, but an increase in supply fan kw may occur.

Outdoor air heating reset is the inverse of cooling, with the same principles applied.

For both outdoor air cooling reset and heating reset, there are three user-defined parameters that are adjustable through the Human Interface Panel.

– beginning reset temperature

– ending reset temperature

– amount of temperature reset

Zone reset is applied to the zone(s) in a building that tend to over cool or

Outdoor Air

Zone

Temperature

Amount of

Temperature

Reset

12 RT-PRC031-EN

Controls Variable Air Volume (VAV) Only

overheat. The supply air temperature setpoint is adjusted based on the temperature of the critical zone(s). This can have the effect of improving comfort and/or lowering energy usage. The user-defined parameters are the same as for outdoor air reset. See Figure 12, p. 12

Supply Air Tempering

Modulating gas, electric, hot water and steam heat units only—When supply air temperature falls below the supply air temperature deadband low end, the heat valve will be modulated to maintain the set minimum supply air temperature.

Zone Temperature Control

Unoccupied Zone Heating and Cooling

During Unoccupied mode, the unit is operated as a CV unit. Inlet guide vanes are driven full open, VFDs operate at 100%, and VAV boxes are driven full open. The unit controls zone temperature within the Unoccupied zone cooling and heating (heating units only) setpoints.

a. An optional temperature

sensor may be connected to the ventilation control module to enable it to control a field-installed pre-heater.

b. An optional CO

be connected to the ventilation control module to control fresh air based on CO

Demand Control

Ventilation (DCV).

sensor may

Outside Air CFM Compensation

As the supply fan (IGV or VFD) modulates, this function proportionally adjusts the economizer minimum position to compensate for the change in total airflow, in order to maintain a constant percent of outside air. The modified economizer minimum position is computed as a linear function, based on IGV or VFD position, given the two endpoints,

a. Minimum Position with IGV/

VFD @ 0%

b. Minimum Position with IGV/

VFD @ 100%

which are user adjustable at the Human Interface Panel.

Daytime warm-up

This feature is available on all types of heating units. During Occupied mode, if the zone temperature falls to a preset, user-defined zone low limit temperature setpoint, the unit is put into Unoccupied mode and Daytime Warm-up is initiated. The system changes over to CV heating (full unit airflow), the VAV boxes are fully opened and full heating capacity is provided until the Daytime Warm-up setpoint is reached. The unit is then returned to normal Occupied mode.

Fresh Air Measurement

Trane air quality (TRAQ™) fresh air measurement damper system utilizes velocity pressure sensing rings. Based on unit design CFM, the ventilation control module (VCM) monitors and controls the quantity of fresh outside air entering the unit. The outside airflow can be calibrated to accommodate for altitude.

RT-PRC031-EN 13

Controls Constant Volume (CV) Only

CV Units Only

Occupied Zone Temperature Control

Cooling/Economizer

During Occupied cooling mode, the economizer (if provided) and mechanical cooling are used to control zone temperature. The zone temperature cooling setpoint is userdefined at the Human Interface Panel or from the BAS/Network.

If the conditions of outside air is appropriate to use “free cooling”, the economizer will be used first to attempt to satisfy the cooling zone temperature setpoint; then if required the hydronic valve will be modulated to maintain supply air temperature setpoint.

On units with economizer, a call for cooling will modulate the fresh air dampers open. The rate of economizer modulation is based on deviation of the zone temperature from setpoint, i.e., the further away from setpoint, the faster the fresh air damper will open.

First stage of cooling will be allowed to start after the economizer reaches full open.

Note: The economizer is only

allowed to function freely if one of the following conditions is met: For dry bulb economizer control, the ambient temperature must be below the dry bulb temperature control setting. For reference enthalpy economizer control, outdoor air enthalpy must be below the enthalpy control setting. At outdoor air conditions above the enthalpy control setting, mechanical cooling only is used and the outdoor air dampers remain at minimum position. For comparative enthalpy economizer control, outdoor

air enthalpy must be below the enthalpy of the return air.

If the unit does not include an economizer, primary cooling only is used to satisfy cooling requirements.

Heating

Gas Heating: Two-Stage

Upon a call for heating, the HEAT module closes the first stage heating contacts beginning the firing sequence. First, the heat exchanger combustion blower begins operation. Upon positive proving of combustion airflow, a 60 second prepurge cycle is executed. Then the ignition sequence takes place.

As additional heat is required, the HEAT module will close the second stage heating contacts and depending on heat module size, will open either the second stage of the gas valve, or a second stage gas valve.

During heating operation, an electronic flame safety control provides continuous flame supervision. If combustion should become unstable for any reason, heating will automatically shut down. On the low heat and medium heat for all units, after a one minute delay, plus another 60 second prepurge cycle the ignition cycle begins.

On all other heat sizes the heating section will be shutdown and locked out until manually reset at the ignition module and unit mounted Human Inferface Panel after the first shutdown due to flame instability.

As the heating requirement is satisfied, the HEAT module will open the second stage heating relay, deenergizing the second stage of heat. When the requirement is fully satisfied, the first stage contacts are opened, de-energizing the first stage of heat.

Gas Heating: Modulating Gas

Upon a call for heating, the HEAT module closes the heating contacts, beginning the firing sequence. First, the heat exchanger combustion blower begins operation. Upon positive proving of combustion airflow, a pre-purge cycle is executed. Then the ignition sequence takes place.

Once ignited, as additional heat is required, the combustion air damper opens, increasing the firing rate.

During heating operation, an electronic flame safety control provides continuous flame supervision. If combustion should become unstable for any reason, heating will automatically shut down and be blocked out until reset at the unit mounted Human Interface panel.

As the heating requirement is satisfied, the HEAT module will modulate the combustion air damper closed, and the firing rate will lower to maintain the desired outlet temperature. When the requirement is fully satisfied, the heating contacts are opened, deenergizing the heat. The specific sequence of operation of the gas heat will depend on the size of the heat exchanger.

14 RT-PRC031-EN

Controls Constant Volume (CV) Only

Electric Heating

The individual stages of electric heat will be sequenced on the zone demand. The number of available stages will depend on the unit size and heat capacity selected.

Hot Water or Steam Heating

Upon a call for heat, the UCM will send a varying voltage signal to the valve actuator. The valve will modulate to meet building demand as indicated by the voltage signal. When heating is satisfied, the valve will modulate closed. A temperature sensor is located on the coldest section of the coil. When it senses an impending freeze condition, a signal is sent to the hydronic valve to drive it full open. If the supply fan is on, or if the outside air damper is open when this freezing condition is sensed, the supply fan is turned off and the fresh air damper is closed.

Supply Air Tempering

For staged gas and electric heat units in the occupied Heating mode but not actively heating, if the supply air temperature drops to 10°F below the Occupied zone heating temperature setpoint, one stage of heat will be brought on to maintain a minimum supply air temperature. The heat stage is turned off if the supply air temperature rises to 10°F above the Occupied zone heating temperature setpoint.

On units with hot water or steam heating, if the supply air temperature drops below 48°F, the heating valve is modulated to maintain 50°F supply air temperature with a 4°F deadband.

Auto Changeover

When the System Mode is “Auto,” the mode will change to cooling or heating as necessary to satisfy the zone cooling and heating setpoints. The zone cooling and heating setpoints can be as close as 2°F apart.

Unoccupied Zone Temperature Control

Cooling and Heating

Cooling and/or heating modes can be selected to maintain Unoccupied zone temperature setpoints. For Unoccupied periods, heating, economizer operation or primary cooling operation can be selectively locked out at the Human Interface Panels.

RT-PRC031-EN 15

Controls VAV and CV

Common to VAV and CV Units

Space Pressure Control Statitrac™

A pressure transducer is used to measure and report direct space (building) static pressure. The userdefined control parameters used in this control scheme are space static pressure setpoint, space pressure deadband and exhaust enable point.

As the economizer opens, the building pressure rises and once above the exhaust enable point, enables the exhaust fan and dampers or exhaust VFD. The exhaust dampers or VFD then modulate to maintain space pressure within the deadband.

Morning Warm-up Options

This feature may be enabled on all types of factory installed heat units as well as cooling only units configured as “External Heat” (for example, VAV boxes with reheat).

At the conclusion of Unoccupied mode, while the economizer (if supplied) is kept closed, the selected zone is heated to the user-defined Morning Warm-up setpoint. The unit is then released to Occupied mode. There are two types of Morning Warm-up: full capacity or cycling capacity.

Full Capacity Morning Warm-up (MWU)

Full capacity Morning Warm-up uses full heating capacity, and heats the zone up as quickly as possible. Full heating capacity is provided until the Morning Warm-up setpoint is met. At this point, the unit is released to occupied mode.

Cycling Capacity Morning Warmup (MWU)

Cycling capacity Morning Warm-up provides a more gradual heating of the zone. Normal zone temperature control with varying capacity is used to raise the zone temperature to the

MWU zone temperature setpoint. This method of warm-up is used to overcome the “building sink” effect. Cycling capacity MWU will operate until the MWU setpoint is reached or for 60 minutes, then the unit switches to Occupied mode.

A control algorithm is used to increase or decrease the amount of heat in order to achieve the MWU zone temperature setpoint.

Note: When using the Morning

Warm-up option in a VAV heating/cooling air handler, airflow must be maintained through the air handler unit. This can be accomplished by electrically tying the VAV boxes to the VAV box output relay contacts on the Rooftop Module (RTM) or by using changeover thermostats. Either of these methods will assure adequate airflow through the unit and satisfactory heating of the building.

Emergency Override

When a LonTalk communication module is installed, the user can initiate from the Trane Tracer Summit or 3rd party BAS one of five (5) predefined, not available to configure, Emergency Override sequences. The Humidification output is deenergized for any Emergency Override sequence. Each Emergency Override sequence commands the unit operation as follows:

1. PRESSURIZE_EMERG:

– Supply Fan - On

– Supply Fan IGV / Supply Fan

VFD Open/Max (if so equipped)

– Exhaust Fan - Off; Exhaust

Dampers Closed (if so equipped)

– OA Dampers - Open; Return

Damper - Closed

– Heat - All heat stages off;

Mod Heat output at 0 vdc

– Occupied/Unoccupied/VAV

box output - Energized

– VOM Relay - Energized (if so

equipped)

– Preheat Output - Off

– Return Fan - Off; Exhaust

Dampers - Closed (if so equipped)

– Return VFD - Min (if so

equipped)

2. EMERG_DEPRESSURIZE:

– Supply Fan - Off

– Supply Fan IGV / Supply Fan

VFD - Closed/Min (if so equipped)

– Exhaust Fan - On; Exhaust

Dampers Open/Max (if so equipped)

– OA Dampers - Closed; Return

Damper - Open

– Heat - All heat stages off;

Mod Heat output at 0 vdc

– Occupied/Unoccupied/VAV

box output - Energized

– VOM Relay - Energized (if so

equipped)

– Preheat Output - Off

– Return Fan - On; Exhaust

Dampers - Open (if so equipped)

– Return VFD - Max (if so

equipped)

3. EMERG_PURGE:

– Supply Fan - On

– Supply Fan IGV / Supply Fan

VFD - Open/Max (if so equipped)

– Exhaust Fan - On; Exhaust

Dampers Open (if so equipped)

– OA Dampers - Open; Return

Damper - Closed

– Heat - All heat stages off;

Mod Heat output at 0 vdc

– Occupied/Unoccupied/VAV

box output - Energized

– VOM Relay - Energized (if so

equipped)

– Preheat Output - Off

– Return Fan - On; Exhaust

Dampers - Open (if so equipped)

16 RT-PRC031-EN

Controls VAV and CV

– Return VFD - Max (if so

equipped)

4. EMERG_SHUTDOWN:

– Supply Fan - Off

– Supply Fan IGV / Supply Fan

VFD - Closed/Min (if so equipped)

– Exhaust Fan - Off; Exhaust

Dampers Closed (if so equipped)

– OA Dampers - Closed; Return

Damper - Open

– Heat - All heat stages off;

Mod Heat output at 0 vdc

– Occupied/Unoccupied/VAV

box output - Energized

– VOM Relay - Energized (if so

equipped)

– Preheat Output - Off

– Return Fan - Off; Exhaust

Dampers - Closed (if so equipped)

– Return VFD - Min (if so

equipped)

5. EMERG_FIRE - Input from fire pull box/system:

– Supply Fan - Off

– Supply Fan IGV / Supply Fan

VFD - Closed/Min (if so equipped)

– Exhaust Fan - Off; Exhaust

Dampers Closed (if so equipped)

– OA Dampers - Closed; Return

Damper - Open

– Heat - All heat stages off;

Mod Heat output at 0 vdc

– Occupied/Unoccupied/VAV

box output - Energized

– VOM Relay - Energized (if so

equipped)

– Preheat Output - Off

– Return Fan - Off; Exhaust

Dampers - Closed (if so equipped)

– Return VFD - Min (if so

equipped)

Ventilation Override Module (VOM)

The user can customize up to five (5) different override sequences for purposes of ventilation override control. If more than one VOM

sequence is being requested, the sequence with the highest priority is initiated first. Sequence hierarchy is the sequence “A” (UNIT OFF) is first, with sequence “E” (PURGE with Duct Pressure Control) last.

The factory default definitions for each mode are as follows:

1. UNIT OFF sequence “A”

When complete system shutdown is required the following sequence can be used.

– Supply Fan - Off

– Supply Fan IGV / Supply Fan

VFD - Closed/Min (if so equipped)

– Exhaust Fan - Off; Exhaust

Dampers Closed (if so equipped)

– OA Dampers - Closed; Return

Damper - Open

– Heat - All heat stages off;

Mod Heat output at 0 vdc

– Occupied/Unoccupied/VAV

box output - Deenergized

– VOM Relay - Energized

– Preheat Output - Off

– Return Fan - Off; Exhaust

Dampers - Closed (if so equipped)

– Return VFD - Min (if so

equipped)

– OA Bypass Dampers - Open

(if so equipped)

– Exhaust Bypass Dampers -

Open (if so equipped)

2. PRESSURIZE sequence “B”

Perhaps a positively pressurized space is desired instead of a negatively pressurized space. In this case, the supply fan should be turned on with inlet guide vanes open/VFD at 100% speed and exhaust fan should be turned off.

– Supply Fan - On

– Supply Fan IGV / Supply Fan

VFD - Max (if so equipped)

– Exhaust Fan - Off; Exhaust

Dampers Closed (if so equipped)

– OA Dampers - Open; Return

Damper - Closed

– Heat - All heat stages off;

Mod Heat output at 0 vdc

– Occupied/Unoccupied/VAV

box output - Energized

– VOM Relay - Energized

– Preheat Output - Off

– Return Fan - Off; Exhaust

Dampers - Closed (if so equipped)

– Return VFD - Min (if so

equipped)

– OA Bypass Dampers - Open

(if so equipped)

– Exhaust Bypass Dampers -

Open (if so equipped)

3. EXHAUST sequence “C”

With only the exhaust fans running (supply fan off), the space that is conditioned by the air handler would become negatively pressurized. This is desirable for clearing the area of smoke from the now-extinguished fire, possibly keeping smoke out of areas that were not damaged.

– Supply Fan - Off

– Supply Fan IGV / Supply Fan

VFD - Closed/Min (if so equipped)

– Exhaust Fan - On; Exhaust

Dampers Open (if so equipped)

– OA Dampers - Closed; Return

Damper - Open

– Heat - All heat stages off;

Mod Heat output at 0 vdc

– Occupied/Unoccupied/VAV

box output - Deenergized

– VOM Relay - Energized

– Preheat Output - Off

– Return Fan - On; Exhaust

Dampers - Open (if so equipped)

– Return VFD - Max (if so

equipped)

– OA Bypass Dampers - Open

(if so equipped)

– Exhaust Bypass Dampers -

Open (if so equipped)

4. PURGE sequence “D”

Possibly this sequence could be used for purging the air out of a building before coming out of Unoccupied mode of operation on VAV units or for the purging of smoke or stale air if required after a fire.

– Supply Fan - On

RT-PRC031-EN 17

Controls VAV and CV

– Supply Fan IGV/ Supply Fan

VFD - Max (if so equipped)

– Exhaust Fan - On; Exhaust

Dampers Open (if so equipped)

– OA Dampers - Open; Return

Damper - Closed

– Heat - All heat stages off;

Mod Heat output at 0 vdc

– Occupied/Unoccupied/VAV

box output - Energized

– VOM Relay - Energized

– Preheat Output - Off

– Return Fan - On; Exhaust

Dampers - Open (if so equipped)

– Return VFD - Max (if so

equipped)

– OA Bypass Dampers - Open

(if so equipped)

– Exhaust Bypass Dampers -

Open (if so equipped)

5. PURGE with duct pressure control sequence “E”

This sequence can be used when supply air control is required for smoke control.

– Supply Fan - On

– Supply Fan IGV / Supply Fan

VFD - (If so equipped) Controlled by Supply Air Pressure Control function; Supply Air Pressure High Limit disabled

– Exhaust Fan - On; Exhaust

Dampers Open (if so equipped)

– OA Dampers - Open; Return

Damper - Closed

– Heat - All heat stages off;

Mod Heat output at 0 vdc

– Occupied/Unoccupied/VAV

box output - Energized

– VOM Relay - Energized

– Preheat Output - Off

– Return Fan - On; Exhaust

Dampers - Open (if so equipped)

– Return VFD - Max (if so

equipped)

– OA Bypass Dampers - Open

(if so equipped)

– Exhaust Bypass Dampers -

Open (if so equipped)

Figure 13. Human Interface Panel (HI)

Human Interface Panel (HI)

The Human Interface (HI) Panel provides a 2 line X 40 character clear English liquid crystal display and a 16 button keypad for monitoring, setting, editing and controlling. The Human Interface Panel is mounted in the unit's main control panel and is accessible through an independent door. See Figure 13, p. 18

The optional remote mount version of the Human Interface (RHI) Panel has all the functions of the unit mount version except Service Mode. To use a RHI the unit must be equipped with an optional InterProcessor Communications Bridge (IPCB) module. The RHI can be located up to 1000 feet from the unit. A single RHI can be used to monitor and control up to four (4) air handlers, each containing an IPCB.

Human Interface Panel Main Menu

• STATUS - used to monitor all temperatures, pressures, humidities, setpoints, input and output status.

• CUSTOM - allows the user to create a custom status menu consisting of up to four (4) screens of the data available in the Status menu.

• SETPOINTS - used to review and/ or modify all the factory preset Default setpoints and setpoint source selections.

• DIAGNOSTICS - used to review active and historical lists of diagnostic conditions. Over one hundred different diagnostics can be read at the Human Interface Panel. The last 20 unique diagnostics can be held in an active history buffer log.

• SETUP - Control parameters, sensor source selections, function enable/disable, output definitions, and numerous other points can be edited in this menu. All points have factory preset values so unnecessary editing is kept to a minimum.

• CONFIGURATION - Preset with the proper configuration for the unit as it ships from the factory, this information would be edited only if certain features were physically added or deleted from the unit. For example, if a field supplied Ventilation Override Module was added to the unit in the field, the unit configuration would need to be edited to reflect that feature.

• SERVICE - used to selectively control outputs (for fans, damper position, etc.) for servicing or troubleshooting the unit. This menu is accessible only at the unit mounted Human Interface Panel.

Generic Building Automation System Module (GBAS 0-5 vdc)

The Generic Building Automation System Module (GBAS 0-5vdc) is used to provide broad control capabilities for building automation systems other than Trane's Tracer™ system. The following inputs and outputs are provided:

Analog Inputs - Four analog inputs, controlled via a field provided potentiometer or a 0-5 vdc signal, that can be configured to be any of the following:

1. Occupied Zone Cooling Setpoint (CV only)

2. Unoccupied Zone Cooling Setpoint (CV only)

3. Occupied Zone Heating Setpoint (CV only)

4. Unoccupied Zone Heating Setpoint (CV only)

5. Supply Air Cooling Setpoint (VAV only)

6. Supply Air Heating Setpoint (VAV only)

7. Space Static Pressure Setpoint

18 RT-PRC031-EN

Controls VAV and CV

8. Supply Air Static Pressure Setpoint

9. Minimum Outside Air Flow Setpoint

10. Morning Warm Up Setpoint

11. Economizer Dry Bulb Enable Setpoint

12. Supply Air Reheat Setpoint

13. Minimum Outside Air Position Setpoint

14. Occupied Dehumidification Setpoint

15. Unoccupied Dehumidification Setpoint

16. Occupied Humidification Setpoint

17. Unoccupied Humidification Setpoint

Binary Outputs - each of the five (5) relay outputs can be mapped to any/ all of the available diagnostics.

Binary Input - the single binary input can initiate or terminate the Demand Limit mode of operation via a field supplied switch or contact closure.

Generic Building Automation System Module (GBAS 0-10 vdc)

The Generic Building Automation System Module (GBAS 0-10vdc) is used to provide broad control capabilities for building automation systems other than Trane's Tracer™ system. The following inputs and outputs are provided:

Analog Inputs—Four analog inputs, controlled via a field provided potentiometer or a 0-10 vdc signal, that can be configured to be any of the following:

1. Occupied Zone Cooling Setpoint (CV only)

2. Unoccupied Zone Cooling Setpoint (CV only)

3. Occupied Zone Heating Setpoint (CV only)

4. Unoccupied Zone Heating Setpoint (CV only)

5. Supply Air Cooling Setpoint (VAV only)

6. Supply Air Heating Setpoint (VAV only)

7. Space Static Pressure Setpoint

8. Supply Air Static Pressure Setpoint

9. Minimum Outside Air Flow Setpoint

10. Morning Warm Up Setpoint

11. Economizer Dry Bulb Enable Setpoint

12. Supply Air Reheat Setpoint

13. Minimum Outside Air Position Setpoint

14. Occupied Dehumidification Setpoint

15. Unoccupied Dehumidification Setpoint

16. Occupied Humidification Setpoint

17. Unoccupied Humidification Setpoint

Analog Outputs—Four analog outputs that can be configured to be any of the following:

1. Outdoor Air Temperature

2. Zone Temperature

3. Supply Air Temperature (VAV only)

4. Supply Air Pressure (VAV only)

5. Space Pressure

6. Space Relative Humidity

7. Outdoor Air Relative Humidity

8. Space CO

9. Heat Staging (%)

10. Outdoor Air Damper Position

11. Outdoor Airflow

Binary Output - the single relay output can be mapped to any/all of the available diagnostics.

Binary Input - the single binary input can initiate or terminate the Demand Limit mode of operation, via a field supplied switch or contact closure.

Level

Chilled Water Coil - Freeze Stat

A low limit thermostat, mounted on the entering air side of the coil, is used to help prevent the chilled water coil from freezing during periods of low ambient temperature. If the temperature falls below a predetermined value the low limit

thermostat will trip, the hydronic valve will be fully opened, the supply fan will shut off, and the fresh air dampers will close.

Steam and Hot Water Coil Freeze Avoidance

Freeze Avoidance is a feature which helps prevent freezing of steam or hot water heat coils during periods of unit inactivity and low ambient temperatures. Whenever the unit supply fan is off, the outdoor air temperature is monitored. If the temperature falls below a predetermined value, the heating valve is opened to a position selected at the unit mounted Human Interface to allow a minimum amount of steam or hot water to flow through the coil and avoid freezing conditions.

Applications with Chilled Water Coil

Occupied/Unoccupied Switching

Description - 3 ways to switch Occupied/Unoccupied:

1. Night Setback (NSB) Panel

2. Field-supplied contact closure (hard wired binary input to RTM)

3. TRACER (or 3rd Party BAS with LCI module)

Night Setback Sensors

Trane's night setback sensors are programmable with a time clock function that provides communication to the air handler unit through a 2-wire communications link. The desired transition times are programmed at the night setback sensor and communicated to the air handler.

Night setback (unoccupied mode) is operated through the time clock provided in the sensors with night setback. When the time clock switches to night setback operation, the outdoor air dampers close and heating/cooling can be enabled or disabled depending on setup parameters.

As the building load changes, the night setback sensor energizes the air handler heating/cooling (if enabled)

RT-PRC031-EN 19

Controls VAV and CV

function and the supply fan. The air handler unit will cycle through the evening as heating/cooling (if enabled) is required in the space. When the time clock switches from night setback to occupied mode, all heating/cooling functions begin normal operation.

When using the night setback options with a VAV heating/cooling air handler, airflow must be maintained through the air handler unit. This can be accomplished by electrically tying the VAV boxes to the VAV Box output relay contacts on the Rooftop Module (RTM) or by using changeover thermostats. Either of these methods will assure adequate airflow through the unit and satisfactory temperature control of the building.

Occupied/Unoccupied input on the RTM

This input accepts a field supplied switch or contacts closure such as a time clock.

Trane Tracer™ or BAS System

The Trane Tracer System or a 3rd party BAS (with LCI module) can control the Occupied/Unoccupied status of the air handler.

Timed Override Activation ICS

This function is operational when the RTM is selected as the Zone Temperature Sensor source at the Human Interface Panel. When this function is initiated by the push of a override button on the ICS sensor, the Tracer will switch the unit to the Occupied mode. Unit operation (Occupied mode) during timed override is terminated by a signal from Tracer.

Timed Override Activation Non-ICS

This function is active whenever the RTM is selected as the Zone Temperature Sensor source at the Human Interface Panel. When this function is initiated by the push of an override button on the zone sensor, the unit will switch to the Occupied mode. Automatic Cancellation of the Timed Override Mode occurs after three hours of operation.

Comparative Enthalpy Control of Economizer

An optional Comparative Enthalpy system is used to control the operation of the economizer, and measures the temperature and humidity of both return air and outside air to determine which source has lower enthalpy. This system allows true comparison of outdoor air and return air enthalpy by measurement of outdoor air and return air temperatures and humidities.

Reference Enthalpy Control of Economizer

The optional reference enthalpy compares outdoor air temperature and humidity to the economizer enthalpy control setpoint. If outdoor air temperature and humidity are below the economizer enthalpy control setpoint, the economizer will operate freely. This system provides more sophisticated control where outdoor air humidity levels may not be acceptable for building comfort and indoor air quality.

Dry Bulb Temperature Control of Economizer

The optional dry bulb system measures outdoor temperature comparing it to the economizer control temperature setpoint. If the outdoor temperature is below the economizer dry bulb temperature control setpoint, the economizer will operate freely. This system is best suited for arid regions where the humidity levels of fresh air would not be detrimental to building comfort and indoor air quality.

Emergency Stop Input

A binary input is provided on the Rooftop Module (RTM) for installation of field provided switch or contacts for immediate shutdown of all unit functions.

High Duct Temp Thermostat

Two manual reset, high temperature limit thermostats are provided. One is located in the discharge section of the unit set at 240ºF and the other in the return air section of the unit set at

135ºF. If either setpoint is reached, the air handler unit is shut down.

CO2 Control - Demand Control Ventilation (DCV)

A ventilation reset function that provides the necessary ventilation for occupants and reduces energy consumption by minimizing the outdoor air damper position (or the OA flow setpoint with TRAQs) below the Building Design Minimum, while still meeting the ASHRAE Std 62.12004 ventilation requirements.

If the space CO or equal to the CO the outdoor air damper will open to the Design Min Outdoor Air Damper (or OA Flow) Setpoint. If there is a call for economizer cooling, the outdoor air damper may be opened further to satisfy the cooling request.

If the space CO equal to the CO the outdoor air damper will close to the DCV Minimum Outdoor Air Damper (or OA Flow) Setpoint.

level is greater than

Design Setpoint,

level is less than or

Minimum Setpoint,

20 RT-PRC031-EN

er Minimum

OA Dam

Design

Min OA Damper Setpoint

DCV Min

Damper Setpoint

CO2 Min Setpoint

Controls VAV and CV

Space CO

CO2 Level

Level

CO2 Design

Setpoint

Min OA Damper Position

Target

Twinning requires an LCI module installed in each unit and is accomplished by binding variables between unit communication modules, communicating common setpoints and conditions (temperatures, pressures, fan speeds, damper positions, occupancy, states, etc.) and allowing each unit to run independent algorithms.

Twinned units must share a common supply and return duct network.

Twinned units operate:

a. as part of a Trane ICS™

installation, with Tracer Summit

b. on an interoperable project

with a 3rd party LonTalk

c. as an independent group

(bound via Rover® or 3rd party tool).

Figure 14. CO

If there is a call for economizer cooling, the outdoor air damper may

Control

other cases the return fan is turned

on or off with the supply fan. be opened further to satisfy the cooling request.

If the space CO2 level is greater than the CO than the CO

Minimum Setpoint and less

Design Setpoint, the

outdoor air damper position is (or OA flow) modulated proportionally to the Space CO between the CO the CO

level relative to a point

Design Setpoint. If there is a

Min Setpoint and

call for economizer cooling, the outdoor air damper may be opened further to satisfy the cooling request. See Figure 14, p. 21

LonTalk® Building

Automation System

The LonTalk Communication

Interface for IntelliPak II (LCI-I)

controller expands communications

from the unit UCM network to a

Trane Tracer Summit or a 3rd party

building automation system, utilizing

LonTalk, and allows external setpoint

and configuration adjustment and

monitoring of status and diagnostics.

The LCI-I utilizes an FTT-10A Free

Topology transceiver, which supports

non-polarity sensitive, free topology

Humidification Control

A relay output is provided to control an externally connected, field supplied humidifier. Logic is provided for Occupied and Unoccupied humidification control with safeguards to prevent cycling between humidification and dehumidification

Return Fan Control

A return fan reduces the load on the supply fan motor or can allow a unit to operate at a higher static pressure.

The return fan VFD is modulated independently to maintain desired

wiring, which allows the system

installer to utilize star, bus, and loop

architectures.This controller works in

standalone mode, peer-to-peer with

one or more other units, or when

connected to a Trane Tracer Summit

or a 3rd party building automation

system that supports LonTalk. The

LCI-I controller is available as a

factory or field-installed kit.

Twinning

Twinning is a Master Unit and one, or

more, similarly configured Slave

Unit(s) operating cooperatively, as a

group, to provide higher capacity

and/or redundancy at partial capacity. return air plenum pressure. In all

RT-PRC031-EN 21

Applications Considerations

Exhaust/Return Fan Options

When is it necessary to provide building exhaust? Whenever an outdoor air economizer is used, a building generally requires an exhaust system. The purpose of the exhaust system is to exhaust the proper amount of air to prevent over or under-pressurization of the building.

The goal is to exhaust approximately 10 percent less air than the amount of outside air going into the building. This maintains a slightly positive building pressure.

The reason for applying either a return, or exhaust fan is to control building pressure. The Trane 100 percent modulating exhaust system with Statitrac is an excellent choice for controlling building pressure in the majority of applications.

For more demanding applications, Trane's 100 percent modulating return fan system with Statitrac is an excellent choice for systems with high return static pressure losses, or duct returns. Both systems employ direct digital control technology to maintain building pressure. Either return or exhaust fan systems with Statitrac may be used on any air handler application that has an outdoor air economizer.

A building may have all or part of its exhaust system in the air handler unit. Often, a building provides exhaust external to the air handling equipment. This external exhaust must be considered when selecting the air handler exhaust system.

With an exhaust fan system, the supply fan motor and drives must be sized to overcome the total system static pressure, including return losses, and pull return air back to the unit during non-economizer operation.

However, a supply fan can typically overcome return duct losses more efficiently than a return air fan system.

Essentially, one large fan by itself is normally more efficient than two fans in series because of only one drive loss, not two as with return fan systems.

In a return fan system, the return fan is in series with the supply fan, and operates continuously whenever the supply fan is operating to maintain return air volume. The supply fan motor and drives are sized to deliver the design CFM based on internal and discharge static pressure losses only.

The return fan motor and drives are sized to pull the return CFM back to the unit based on return duct static. Therefore, with a return fan system, the supply fan ordinarily requires less horsepower than a system with an exhaust fan

IntelliPak™ II Rooftop Air Handler Unit Offers Four Types of Exhaust/Return Fan Systems:

100 percent modulating exhaust with Statitrac™ direct space sensing building pressurization control (with or without exhaust variable frequency drives)

100 percent modulating exhaust without Statitrac

100 percent modulating plenum return airfoil fan with Statitrac direct space sensing building pressurization control with variable frequency drive

100 percent modulating plenum return airfoil fan without Statitrac

Drivers for applying either return or exhaust fan systems range from economy, to building pressure control, to code requirements, to generally accepted engineering practices

Application Recommendations

100 Percent Modulating Exhaust with Statitrac Control, Constant Volume and VAV Units

For both CV and VAV air handlers, the 100 percent modulating exhaust discharge dampers (or VFD) are modulated in response to building pressure. A differential pressure control system, Statitrac, uses a differential pressure transducer to compare indoor building pressure to atmospheric pressure.

The FC exhaust fan is turned on when required to lower building static pressure to setpoint. The Statitrac control system then modulates the discharge dampers (or VFD) to control the building pressure to within the adjustable, specified deadband that is set at the Human Interface Panel.

Economizer and return air dampers are modulated independent of the exhaust dampers (or VFD) based on ventilation control and economizer cooling requests.

Advantages:

• The exhaust fan runs only when needed to lower building static pressure.

• Statitrac compensates for pressure variations within the building from remote exhaust fans and makeup air units.

• The exhaust fan discharges in a single direction resulting in more efficient fan operation compared to return fan systems.

• When discharge dampers are utilized to modulate the exhaust airflow, the exhaust fan may be running unloaded whenever the economizer dampers are less than 100 percent open.

22 RT-PRC031-EN

Applications Considerations

The Trane 100 percent modulating exhaust system with Statitrac provides efficient control of building pressure in most applications simply because 100 percent modulating exhaust discharge dampers (or VFD) are controlled directly from building pressure, rather than from an indirect indicator of building pressure, such as outdoor air damper position.

100 Percent Modulating Exhaust System without Statitrac, Constant Volume Units Only

This fan system has performance capabilities equal to the supply fan. The FC exhaust fans are started by the economizer's outdoor air damper position and the exhaust dampers track the economizer outdoor air damper position. The amount of air exhausted by this fan is controlled by modulating discharge dampers at the fan outlet. The discharge damper position is controlled by a signal that varies with the position of the economizer dampers. When the exhaust fans start, the modulating discharge dampers are fully closed, and exhaust airflow is 15 to 20 percent of total exhaust capabilities.

Advantages:

• The exhaust fan runs only when the economizer reaches the desired exhaust enable point.

• Exhaust dampers are modulated based on the economizer position.

• The exhaust fan discharges in a single direction resulting in more efficient fan operation compared to return fan systems.

• When discharge dampers are utilized to modulate the exhaust airflow, the exhaust fan may be running unloaded whenever the economizer dampers are less than 100 percent open.

The Trane 100 percent modulating exhaust system provides excellent linear control of building exhaust in most applications where maintaining building pressure is not important.

100 Percent Modulating Return Fan Systems with Statitrac™ Control, Constant Volume and VAV units

For both CV and VAV applications, the IntelliPak II air handler offers 100 percent modulating return fan systems. A differential pressure control system, Statitrac, uses a differential pressure transducer to compare indoor building pressure to atmospheric pressure. The return fan exhaust dampers are modulated, based on space pressure, to control the building pressure to within the adjustable, specified deadband that is set at the Human Interface Panel. A VFD modulates the return fan speed based on return duct static pressure. Economizer and return air dampers are modulated independent of the exhaust dampers based on ventilation control and economizer cooling requests.

Advantages:

• The return fan operates independently of the supply fan to provide proper balance throughout the airflow envelope.

• Statitrac compensates for pressure variations within the building from remote exhaust fans and makeup air units.

• The return fan acts as both exhaust and return fan based on operation requirements.

The Trane 100 percent modulating return system with Statitrac provides efficient control of building pressure in applications with higher return duct static pressure and applications requiring duct returns.

Exhaust discharge dampers are controlled directly from building pressure, return fan VFD is controlled from return static pressure, and return/economizer dampers are controlled based on ventilation control and economizer cooling requests. 100 Percent Modulating Return Fan without Statitrac™ Control, Constant Volume Units Only

The exhaust discharge dampers are modulated in response to building pressure. The return fan runs continuously while the supply fan is energized.

Economizer and return air dampers are modulated independent of the exhaust dampers based on ventilation control, and economizer cooling requests.

Advantages:

• The exhaust dampers are modulated as needed through a space pressure sensor input to maintain building pressure.

• The return fan discharges in two directions, thereby balancing exhaust and unit return air volumes.

Supply and Return Airflow Configurations

The typical air handler installation has both the supply and return air paths routed through the roof curb and building roof. However, many air handler installations require horizontal supply and/or return from the air handler because of a building's unique design or for acoustic considerations.

With IntelliPak II, there are several ways to accomplish horizontal supply, see Tab le 1, p. 2 4 and/or return, see Ta b le 2, p . 24 .

RT-PRC031-EN 23

Applications Considerations

Table 1 Supply Airflow Configuration

With Bag

Cabinet Configuration Supply Airflow Discharge Direction Type

Standard Length Downflow - Standard Option Cooling Only Yes No No No Standard Length Horizontal - Right Side - Standard Option Cooling Only Yes No No No Standard Length Horizontal - Left Side - Field Convertible Cooling Only Field

Standard Length Downflow - Standard Option Gas, Electric, Steam,

Standard Length Horizontal - Right Side - Standard Option Gas, Electric, Steam,

Standard Length Horizontal - Left Side - Field Convertible Gas, Electric, Steam,

Four Foot Blank Section Downflow - Standard Option Cooling Only Yes Yes Yes Yes Four Foot Blank Section Horizontal - Right Side - Standard Option Cooling Only Yes Yes Yes Yes Four Foot Blank Section Horizontal - Left Side - Field Convertible Cooling Only Field

Four Foot Blank Section Downflow - Standard Option Gas, Electric, Steam,

Four Foot Blank Section Horizontal - Right Side - Standard Option Gas, Electric, Steam,

Four Foot Blank Section Horizontal - Left Side - Field Convertible Gas, Electric, Steam,

Eight Foot Blank Section Downflow - Standard Option Cooling Only, Steam

Eight Foot Blank Section Horizontal - Right Side - Standard Option Cooling Only, Steam

Eight Foot Blank Section Horizontal - Left Side - Field Convertible Cooling Only, Steam

Eight Foot Blank Section Downflow - Standard Option Gas* or Electric Yes No High

Eight Foot Blank Section Horizontal - Right Side - Standard Option Gas* or Electric Yes No High

Eight Foot Blank Section Horizontal - Left Side - Field Convertible Gas* or Electric Field

Hot Water Heat

Heat, Hot Water Heat

Acceptable Application

Convert

Yes No No No

No No No No

Convert

No No No No

Yes Yes Yes Yes

Field

Convert

Final

Filters

No No No

Yes Yes Yes

No High

With

Cartridge

Final Filters

Temperature

With HEPA

Final Filters

High

Temperature

High

Temperature

High

Temperature

Table 2 Return Airflow Configuration

AirflowConfig

Vertical Yes Yes Yes Yes Hor izontal - Right Yes Yes Yes Yes Horizontal - Left No Field Convert No No Horizontal - End Yes Yes No No

Exhaust Fan VFD

Exhaust Fan

No VFD Return Fan VFD

24 RT-PRC031-EN

Return Fan

No VFD

Applications Considerations

When using an IntelliPak II Air Handler for horizontal supply and/or return, an additional pressure drop must be added to the supply external static to account for the 90 degree turn the air is making. This additional pressure drop depends on airflow and air handler size, but a range of

0.10 inches to 0.30 inches can be expected. The openings on the air handler all have a one inch lip around the perimeter to facilitate ductwork attachment.

Corrosive Atmospheres

Trane's IntelliPak II Air Handlers are designed and built to industrial standards and will perform to those standards for an extended period depending on the hours of use, the quality of maintenance performed, and the regularity of that maintenance. One factor that can have an adverse effect on unit life is its operation in a corrosive environment.

Because copper is more resistant to corrosion than aluminum, coil life expectancy is greatly increased.

Ventilation Override Sequences

One of the benefits of using an exhaust fan rather than a return fan, in addition to the benefits of lower energy usage and improved building pressurization control, is that the air handler can be used as part of a ventilation override system. Several types of sequences can be easily done when exhaust fans are a part of the air handling system.

What would initiate the ventilation override control sequence? Typically, a manual switch is used and located near the fire protection control panel. This enables the fire department access to the control for use during or after a fire. It is also possible to initiate the sequence from a fieldinstalled automatic smoke detector. In either case, a contact closure begins the ventilation override control sequence.

CAUTION!

The ventilation override system should not be used to signal the presence of smoke caused by a fire.

Trane can provide five (5) different ventilation override sequences on both CV and VAV IntelliPak II Air Handlers. For convenience, the sequences are factory preset but are fully field edited from the Human Interface Panel or Tracer™. Any or all five sequences may be “locked” in by the user at the Human Interface Panel.

The user can customize up to five (5) different override sequences for purposes such as smoke control. The following parameters within the unit can be defined for each of the five sequences:

• Supply Fan - on/off

• Inlet Guide Vanes - open/closed/ controlling

• Variable Frequency Drives - on (60 Hz)/off (0 Hz)/controlling

• Exhaust/Return Fan - on/off

• Exhaust Dampers - open/closed

• Economizer dampers - open/ closed

• Heat - off/controlling (output for) VAV Boxes - open/controlling

Factory preset sequences include unit Off, Exhaust, Purge, Purge with duct pressure control, and Pressurization. Any of the userdefined Ventilation Override sequences can be initiated by closing a field supplied switch or contacts connected to an input on the Ventilation Override Module. If more than one ventilation override sequence is being requested, the sequence with the highest priority is initiated. Refer to the Ventilation Override Module (VOM) page 17 in the Control section of this catalog for more details on each override sequence.

Natural Gas Heating Considerations

Trane uses heavy gauge 304 L stainless steel throughout the construction of its natural gas drum and tube heat exchangers for the IntelliPak II product. These heat exchangers can be applied with confidence, particularly with full modulation control, when mixed air temperatures are below 50°F, and low ambient temperatures can cause condensation to form on the heat

exchanger. IntelliPak II natural gas heat exchangers are not recommended for applications with mixed air conditions entering the heat exchanger below 30°F to insure adequate leaving air heating temperature.

For airflow limitations and temperature rise across the heat exchanger information, see Tab l e 2 7,

p. 70.

Acoustical Considerations

The ideal time to make provisions to reduce sound transmission to the space is during the project design phase. Proper placement of air handler equipment is critical to reducing transmitted sound levels to the building. The most economical means of avoiding an acoustical problem is to place any air handler equipment away from acoustically critical areas. If possible, air handling equipment should not be located directly above areas such as: offices, conference rooms, executive office areas and classrooms. Ideal locations are above corridors, utility rooms, toilet facilities, or other areas where higher sound levels are acceptable.

Several basic guidelines for unit placement should be followed to minimize sound transmission through the building structure:

Locate the unit's center of gravity close to or over a column or main support beam to minimize roof deflection and vibratory noise.

If the roof structure is very light, roof joists should be replaced by a structural shape in the critical areas described above.

If several units are to be placed on one span, they should be staggered to reduce deflection over that span.

It is impossible to totally quantify the effect of building structure on sound transmission, since this depends on the response of the roof and building members to the sound and vibration of the unit components. However, the guidelines listed above are experience proven guidelines which

RT-PRC031-EN 25

Applications Considerations

will help reduce sound transmission. The ASHRAE publication "A Practical Guide to Noise and Vibration Control for HVAC Systems" also provides valuable information.

There are several other sources of unit sound, i.e., supply fan, exhaust/ return fans, and aerodynamic noise generated at the duct fittings. Refer to the ASHRAE Applications Handbook, Chapter 47, 2003 edition for guidelines for minimizing the generation of aerodynamic noise associated with duct fittings. A good source of information on general acoustical considerations for air handlers is the 2000 ASHRAE Journal article titled, "Controlling Noise from Large Rooftop Units".

The Trane Acoustic Program (TAP) allows complete modeling of air handler acoustical installation parameters. The software models airborne sound from supply and return ducts, as well as duct breakout and roof transmission sound, so that the designer can identify potential sound problems and make design alterations before equipment installation. Output of the program shows the resulting NC (or RC) level for any point in the occupied space. TAP is also capable of modeling the effect of outdoor sound on the surrounding area. This program is available from Trane's Customer Direct Service Network

(C.D.S.), ask your local Trane representative for additional information on this program.

Clearance Requirements

The recommended clearances identified in Figure 31, p. 85 should be maintained to assure adequate service capability, maximum capacity and peak operating efficiency. If the clearances shown are not possible on a particular job, consider the following:

• Do the clearances available allow

for major service work such as changing coils?

• Do the clearances available allow

for proper outside air intake and exhaust air removal?

• If screening around the unit is

being used, is there a possibility of air recirculation from the exhaust to the outside air intake?

Figure 15. Unit Placement

Outdoor

Air Intake

Outdoor

Air Intake

Exhaust Air

Outdoor

Air Intake

Actual clearances which appear inadequate should be reviewed with a local Trane sales engineer.

When two or more units are to be placed side by side, the distance between the units should be increased to 150 percent of the recommended single unit clearance. The units should also be staggered, see Figure 15, p. 26, for two reasons:

To reduce span deflection if more than one unit is placed on a single span. Reducing deflection discourages sound transmission.

To assure proper diffusion of exhaust air before contact with the outside air intake of adjacent unit.

Exhaust Air

Outdoor

Air Intake

26 RT-PRC031-EN

Applications Considerations

Duct Design

It is important to note that the rated capacities of the air handler can be met only if the air handler is properly installed in the field. A well-designed duct system is essential in meeting these capacities.

The satisfactory distribution of air throughout the system requires that there be an unrestricted and uniform airflow from the air handler discharge duct. This discharge section should be straight for at least several duct diameters to allow the conversion of fan energy from velocity pressure to static pressure.

However, when job conditions dictate elbows be installed near the air handler outlet, the loss of capacity and static pressure may be reduced through the use of guide vanes and proper direction of the bend in the elbow. The high velocity side of the air handler outlet should be directed at the outside radius of the elbow rather than the inside as illustrated in

Figure 16, p. 27.

Protecting Hydronic Coils From Freezing

Taking in outdoor air to satisfy Standard 62’s ventilation requirement increases the likelihood of air stratification. If a layer of air below freezing moves through the air handler, it can damage unprotected hydronic cooling and heating coils.

When a dangerously low air temperature is detected by the lowlimit thermostat on the entering-air side of the coil, it will trip. That triggers the water valve to fully open, the supply fan to stop, the outdoor air damper to close and ultimately degrades the building’s indoor air quality.

Two options that can be implemented to continue taking in outdoor air and avoid coil damage or tripping the low-limit thermostat include:

• Draining the coils

• Adding glycol to the cooling system water to lower its freezing point

External Piping Enclosure

Space inside the piping enclosure limits the ability to house control valves and actuators along with coil supply and return piping.

PROPER

IMPROPER

Figure 16. Duct Design

RT-PRC031-EN 27

Selection Procedure

This section outlines a step-by-step procedure that may be used to select a Trane air handler. The sample selection is based on the following conditions:

Summer Design:

• Summer outdoor design conditions - 95 DB/76 WB ambient temperature

• Summer room design conditions -78 DB/65 WB

• Total cooling load - 980 MBH (81.6 tons)

• Sensible cooling load - 735 MBH (61.25 tons)

• Outdoor air ventilation load -

154.0 MBH (12.8 tons)

• Return air temperature 78 DB/65 WB

Winter Design:

• Winter outdoor design condition is 0°F.

• Total return air temperature is 70°F.

• Total heating load - 720 MBH

• Winter outdoor air ventilation load - 288.6 MBH

• Total winter heating load -

1008.6 MBH

Air Delivery Data:

• Supply fan CFM - 36000 CFM

• Supply duct static pressure - 1.86

2.2 in wg

• Minimum outdoor air ventilation

- 3600 CFM

• Exhaust fan CFM - 36000 CFM

• Return air duct negative static pressure - 0.3 in wg

Electrical Characteristics:

• Voltage/cycle/phase - 460/60/3

Unit Accessories:

• Gas fired heat exchanger - High Heat

• Downflow supply and upflow return

• High Efficiency Throwaway filters

• Economizer

• Modulating 100 percent exhaust

Cooling Capacity Selection:

Step 1 - Coil and Fan Selection

A summation of the peak cooling load and the outside air ventilation load shows: 980 MBH + 154.0 MBH =

1134.0 MBH required unit capacity.

The supply fan air flow requirement is 36,000 cfm.

From Ta b le 10 , p . 3 9, a 4 row W coil with 144 fpf (fins per foot) and no turbulators at 80 DB/67 WB and 36000 supply air cfm has a total cooling capacity of 1336 MBH and sensible cooling capacity of 969 MBH. With chilled water coil capacity data at 80 DB/67 WB only, TOPSS is required for an accurate selection at other conditions. TOPSS is also required to select the correct water control valve for proper flow control, in this case a 2 ½ "or 3" valve.

Ta b le 3 , p . 3 4 - General Data shows

that air handler "C" can provide 36000 total supply CFM.

Thus air handler "C" with a 4 row 144 fpf W coil having no turbulators at 45°F entering water and a 10°F rise with a 2 ½" valve is selected. The coil water flow rate is 266 GPM and water side pressure drop is 13.7 ft of water.

Step 2 - Cooling Coil Entering Conditions

Mixed air dry bulb temperature determination:

Using the minimum percent of OA (3600 CFM ÷ 36000 CFM = 10 percent), determine the mixture dry bulb to the cooling coil.

RADB + % OA (OADB - RADB) = 78 + (0.10) (95 - 78) = 78 + 1.5 = 79.5°F

Approximate wet bulb mixture temperature:

RAWB + % OA (OAWB - RAWB) = 65 + (0.10) (76 - 65) = 65 + 1.1 = 66.1°F

Step 3 - Determine Supply Fan Motor Heat Gain

Having selected air handler casing "C" with a 4 row 144 fpf W coil and no turbulators, the supply fan BHP can be calculated.

The supply fan motor heat gain must be considered in final determination of unit capacity.

Supply Air Fan

Determine unit total static pressure at design supply CFM:

Supply Duct Static Pressure 2.2" Chilled Water Coil Table 33, p. 72 0.64" Return Duct Negative Static

Pressure Heat Exchanger Table 34, p. 72 0.03" Throwaway Filter Table 35, p. 73 0.26" Return Damper Table 34, p. 72 0.34" Economizer Damper

p. 72

Unit Total Static Pressure 4.0"

(i)

Add either the economizer damper value or return damper value, depending on which static pressure is greate r. (Do not us e both.)

(i)

Table 34,

0.30"

0.57"

Using total of 36000 CFM and total static pressure of 4.0 inches, enter

Tab l e 17, p. 4 8 . The table shows 40.4

BHP with 1097 rpm required for the 36" supply fan.

From Figure 17, p. 30 supply fan motor heat gain = 109.0 MBH, or

109.0 MBH x 1000 ÷ ( 36000 CFM x

1.085 ) = 2.8°F supply fan motor heat

Step 4 - Determine Total Required Cooling Capacity

Required capacity = Total peak load + OA load + supply air fan motor heat

Required capacity = 980.0 + 154.0 +

109.0 = 1243.0 MBH

Step 5 - Determine Unit Capacity

The coil entering air conditions of

79.5 DB/66.1 WB are close to the capacity data table at 80 DB/67 WB used for the original selection. The unit capacity with the 4 row 144 fpf W coil with no turbulators at 45°F entering water a 10°F rise, 36000 cfm supply air flow and 10% outside air

28 RT-PRC031-EN

Selection Procedure

at 95°F is approximatly 1336 MBH total cooling and 969 MBH sensible cooling capacity.

Step 6 - Determine Leaving Air Temperature

Unit sensible heat capacity corrected for supply air fan motor heat = 969 MBH Sensible - 109.0 MBH Motor

Heat = 860 MBH.

Supply air dry bulb temperature difference =

Sensible MBH X 1000/1.085 x Supply CFM

Sensible Btu = 860 MBH x 1000 ÷ (1.085 x 36000 CFM) = 22°F

Supply air dry bulb = 79.5 DB - 22 =

57.5°F Leaving the cooling coil

Supply air wet bulb temperature difference = (need in RTU catalog too)

Total MBH x 1000 ÷ 4.5 x Supply CFM =

Unit enthalpy difference = 1336 MBH x 1000 ÷ (4.5 x 36000 CFM) = 8.25 Btu/lb.

Leaving enthalpy = h (ent WB) - h (diff). From Tab l e 6 , p . 3 7, p. 40 h (ent WB) =

30.9 Btu/lb.

Leaving enthalpy = 30.9 Btu/lb. - 8.25

Btu/lb. = 22.65 Btu/lb.

Supply air wet bulb = 54.0 Leaving the cooling coil.

Leaving air temperature = 57.5 DB/

54.0 WB

Heating Capacity Selection

Step 1 - Determine Air Temperature Entering Heating Module

Mixed air temperature = RADB + % OA (OADB - RADB) = 70 + (0.10) (0 - 70) = 63°F

Supply air fan motor heat temperature rise = 109000 Btu ÷ (1.085 x 36000 CFM) = 2.8°F

Air temperature entering heating module = 63.0 + 2.8 = 65.8°F

Step 2 - Determine Total Winter Heating Load

Total winter heating load = peak heating load + ventilation load supply fan motor heat = 720 + 288.6 -

109.0 = 899.6 MBH

Electric Heating System

Unit operating on 460/60/3 power supply.

From Table 29, p. 70, kw may be selected for a nominal 105 ton air handler "C" unit operating at 460-volt power. The 265 kw heat module (904.4 MBH) will satisfy the winter heating load of 899.6 MBH.

Table 28, p. 70 shows an air

temperature rise of 23.2°F for 36000 CFM through the 265 kw heat module.

Unit supply temperature at design heating conditions = mixed air temperature + air temperature rise =

65.8°F + 23.2°F = 89.0°F.

Gas Heating System (Natural Gas)

From Ta b le 27, p. 7 0 select the high heat module (1440 MBH output) to satisfy winter heating load of 899.6 MBH at unit CFM.

Ta b le 2 7, p . 70 also shows an air

temperature rise of 37.0°F for 36000 CFM through the heating module.

Unit supply temperature at design heating conditions = mixed air temperature + air temperature rise =

65.8°F + 37.0°F = 102.8°F.

Hot Water Heating System

Using a hot water supply temperature of 190°F and an entering

coil temperature of 65.8°F.

Subtract the mixed air temperature from the hot water temperature to determine the ITD (initial temperature difference).

ITD = 190°F - 65.8°F = 124.2°F. Divide the winter heating load by ITD = 1008.6 MBH ÷ 124.2°F = 8.12 Q/ ITD.

From Table 30, p. 71, select the low heat module. By interpolation, a Q/ ITD of 8.12 can be obtained at a gpm of 41. Water pressure drop at 41 gpm is 0.34 ft. of water.

Heat module temperature rise is determined by:

Total Btu = 1.085 x CFM x Air temperature rise, °F 1008600 / 1.085 / 36000 = 25.8°F

Unit supply air temperature = mixed air temperature + air temperature rise = 65. 8 + 25.8 = 91.6°F.

Steam Heating System

Using a 15 psig steam supply. From

Table 31, p. 71, the saturated

temperature steam is 250°F. Subtract mixed air temperature from the steam temperature to determine ITD.

ITD = 250°F - 65.8°F = 184.2°F.

Divide winter heating load by ITD =

1008.6 MBH ÷ 184.2°F = 5.48 Q/ITD.

Table 31, p. 71, select the low heat

module. The low heat module at 36000 cfm has a Q/ITD = 7.44

Heat module capacity, Q = ITD x Q/ ITD = 185°F x 7.44Q/ITD = 1376 MBH

Heat module air temperature rise is determined by:

Total Btu = 1.085 x CFM x Air temperature rise, °F 1376000 / 1.085 / 36000 = 35.2°F

Unit supply temperature at design conditions = mixed air temperature + air temperature rise = 65.8°F + 35.2°F = 100.1°F.

Air Delivery Procedure

Supply fan performance tables include internal resistance of air handler.

For total static pressure determination, system external static must be added to appropriate component static pressure drop cooling coil, filters, optional economizer, optional exhaust fan, optional heating system, optional cooling only extended casing).

Supply Fan Motor Sizing

The supply fan motor selected in the cooling capacity determination was

40.4 BHP and 1097 RPM. Thus, a 40 HP supply fan motor is selected.

Enter Table 39, p. 77 to select the proper drive. For anair handler "C" with 40 HP motor, a drive letter A 1100 RPM is selected.

RT-PRC031-EN 29

Selection Procedure

Exhaust Fan Motor Sizing

The exhaust/return fan is selected based on total return system negative static pressure and exhaust fan CFM. Return system negative static includes return duct static, and any other job site applicable static pressure drop.

Return duct static pressure = 0.30 inches.

Total return system negative static pressure = 0.30 inches.

Exhaust fan CFM = 36000 CFM

From Table 39, p. 77 the required BHP is 21.44 BHP at 400 RPM. Thus, the exhaust fan motor selected is 25 HP.

To select a drive, enter Ta bl e 3 7, p . 75 for a 25 HP motor and air handler "C". Drive selection number 4 - 400 RPM.

Return Fan Motor Sizing

The same static pressure and CFM considerations must be taken for return fan size, horsepower, and drive selection as are required for exhaust fan sizing. However, since the return fan runs continuously the sensible heat generated by the return fan motor must be included in the entering evaporator coil mixed air temperature equation.

In this selection, if the return motor BHP is equal to the exhaust motor BHP, 21.44 BHP = 58.1 MBH x 1000÷ (1.085 x 36000 Return CFM) = 1.5°F added to the return air temperature. Where altitudes are significantly above sea level, use Table 6, p. 37,

Table 7, p. 37 and Tab l e 8, p . 3 7 for

applicable correction factors.

Unit Electrical Requirements

Selection procedures for electrical requirements for wire sizing amps, maximum fuse sizing, and dual element fuses are given in the electrical service section of this catalog.

an air density correction is needed to project accurate unit performance.

Figure 18, p. 37 shows the air density

ratio at various temperatures and elevations.

The procedure to use when selecting a supply or exhaust/return fan at elevations and

temperatures other than standard is as follows:

1. First, determine the air density ratio using Figure 18, p. 37.

2. Divide the static pressure at the nonstandard condition by the air density ratio to obtain the corrected static pressure.

3. Use the actual CFM and the corrected static pressure to determine the fan RPM and BHP from the performance tables or curves.

4. The fan RPM is correct as selected.

5. BHP must be multiplied by the air density ratio to obtain the actual operating BHP.

FAN MOTOR HEAT

300

250

Std Motor

200

150

100

Hi Efficiency Motor

In order to better illustrate this procedure, the following example is used:

Consider an air handler"C" that is to deliver 32000 actual CFM at 3-inches total static pressure (tsp), 55°F leaving air temperature, at an elevation of 5000 ft.

1. F rom Figure 18, p. 37, the air density ratio is 0.86.

2. Tsp = 3.0-inches / 0.86 = 3.49 inches tsp.

3. From fan performance Ta bl e 17,

p. 48 air handler"C" (without inlet

vanes) will deliver 32000 CFM at

3.49 inches TSP at 997 RPM and

30.27 BHP.

4. The RPM is correct as selected 997 RPM.

5. BHP = 30.27 x 0.86 = 26.3 BHP actual.

Cooling coil MBH should be calculated at standard and then converted to actual using the correction factors in Tab l e 6, p . 3 7,

Table 7, p. 37, Tab l e 8 , p. 3 7 . Apply

these factors to the capacities selected at standard CFM so as to correct for the reduced mass flow rate across the condenser.

Heat selections other than gas heat will not be affected by altitude. Nominal gas capacity (output) should be multiplied by the factors given in

Ta b le 8 , p . 3 7 before calculating the

heating supply air temperature.

Altitude Corrections

Fan Motor Heat MBH

The air handler performance tables and curves of this catalog are based on standard air (.075 lbs/ft). If the airflow requirements are at other than standard conditions (sea level),

30 RT-PRC031-EN

Figure 17. Fan Motor Heat

0 102030405060708090100

Motor Brake Horse Power

PM1206

+ 78 hidden pages