Trane Intellipak 2 Service Manual

							General Information
RT-SVX24K-EN11
modules, sensors, remote panels, and customer binary
contacts to satisfy the applicable request for economizing,
mechanical cooling, heating, and ventilation. Refer to the
following discussion for an explanation of each module
function.
Rooftop Module (RTM - Standard on all units)
The rooftop Module (RTM) responds to cooling, heating,
and ventilation requests by energizing the proper unit
components based on information received from other
unit modules, sensors,
remote panels, and customer supplied binary inputs. It
initiates supply fan, exhaust fan, exhaust damper
positioning or variable frequency drive output, and
economizer operation based on
that information.
Compressor Module (MCM - standard on all
units)
The Compressor module, upon receiving a request formechanical cooling, energizes the appropriate
compressors and condenser fans. It monitors the
compressor operation through feedback information it
receives from various protection devices.
Human Interface Module (HI - standard on all
units)
The Human Interface module enables the operator toadjust the operating parameters for the unit using a 16 key
keypad. The 2 line, 40 character LCD screen provides
status information for the various unit functions as well as
menus for the operator to set or modify the operating
parameters.
Heat Module (used on heating units)
The Heat module, upon receiving a request for Heating,energizes the appropriate heating stages or strokes the
Modulating Heating valve as required.
Ventilation Override Module (VOM - Optional)
The Ventilation Override module initiates specifiedfunctions such as; space pressurization, exhaust, purge,
purge with duct pressure control, and unit off when any
one of the five (5) binary inputs to the module are
activated. The compressors and condenser fans are
disabled during the ventilation operation. If more than one
ventilation sequence is activated, the one with the highest
priority is initiated.
Interprocessor Communications Board (IPCB -
Optional used with the Optional Remote
Human Interface)
The Interprocessor Communication Board expandscommunications from the rooftop unit UCM network to a
Remote Human Interface Panel. DIP switch settings on the
IPCB module for this application should be; Switches 1 and
2“Off” , Switch 3 “On”.
Lontalk®/BACnet® Communication Interface
Module (LCI/BCI - Optional - used on units
with Trane ICS™ or 3rd party Building
Automation Systems)
The LonTalk/BACnet Communication Interface modules
expand communications from the unit UCM network to a
TraneTracer Summit™ or a 3rd party building automation system and allow external setpoint and configuration
adjustment and monitoring of status and diagnostics.
Exhaust/Comparative Enthalpy Module
(ECEM - Optional used on units with Statitrac
and/or comparative enthalpy options)
The Exhaust/Comparative Enthalpy module receivesinformation from the return air humidity sensor, the
Table 1. Resistance input vs. setpoint temperature
RTM cooling or 
heating setpoint 
input used as the 
source for a ZONE 
temp setpoint (°F) RTM cooling 
setpoint input 
used as the source  for SUPPLY AIR temp setpoint  cooling (°F) Resistance (Ohms) 
Max. 
Tolerance 5%
40 401084
45 45992
50 50899
55 55796
60 60695
65 65597
70 70500
75 75403
80 80305
n/a 85208
n/a 90111
Table 2. RTM resistance value vs. system operating
mode
Resistance applied to 
RTM MODE input 
Terminals (Ohms) 
Max. Tolerance 5% Constant Volume Units
Fan Mode System Mode
2320 AutoOff
4870 AutoCool
7680 AutoAuto
10770 OnOff
13320 OnCool
16130 OnAuto
19480 AutoHeat
27930 OnHeat 
						

							General Information
12RT-SVX24K-EN
outside air humidity sensor, and the return air temperature
sensor to utilize the lowest possible humidity level when
considering economizer operation. In addition, it receives
space pressure information which is used to maintain the
space pressure to within the setpoint control band. Refer
toFigure 1 for the Humidity vs. Voltage input values.
Multi Purpose Module MPM (Optional - used
with Return Fan Control, Energy Recovery, and
Evaporative Condensers)
The MPM supports three optional features. The first of
which is return plenum pressure control by receiving
analog voltage information for measuring return plenum
pressure, calibrating that reading, and providing an output
to control the return fan speed (if variable speed
configured) in response to control algorithm requests.
This module also provides inputs and outputs for control of all Energy Recovery feature devices including the
energy wheel, exhaust and outdoor air bypass dampers,
and recovery preheat. The liquid line pressure sensor
inputs for both refrigeration circuits are received through
the MPM in support of head pressure control on water-
cooled condenser units.
Variable Speed Module (VSM - Optional -Used with Fault Detection and Diagnostics
FDD)
The VSM is used with FDD. The VSM will accept a 0-10Vdc
actuator feedback position signal which will then be used
to determine the state of OutsideAir Damper system.
Modulating Dehumidification Module MDM
(Optional - used with Dehumidification
Control)
The MDM supports specific control inputs and outputs forModulating Dehumidification control including
modulating Reheat and Cooling valve control as well as
the Reheat Pumpout Coil Relay output. The Modulating
Dehumidification control algorithm provides control
requests to the MDM to accomplish proper
Dehumidification control.
Ventilation Control Module (VCM)
The Ventilation Control Module (VCM) is located in thefilter section of the unit and is linked to the unit UCM
network. Using a “velocity pressure” sensing ring located
in the outside air section allows the VCM to monitor and
control the quantity of outside air entering the unit to a
minimum airflow setpoint.
An optional temperature sensor can be connected to the
VCM which enables it to control a field installed outside air preheater. An optional CO
2sensor can be connected to the
VCM to control CO
2reset. The reset function adjusts the
minimum CFM upward as the CO
2concentrations
increase.
The maximum effective (reset) setpoint value for outside air entering the unit is limited to the systems operating
CFM. The following table lists the velocity pressure vs.
Input Voltage (see also Figure 6, p. 18.).
The velocity pressure transducer/solenoid assembly is illustrated below. Refer to the “Units withTRAQ™ Sensor,”
p. 103 for VCM operation.
Figure 1. Humidity vs. current
Table 3. Minimum outside air setpoint w/VCM and
TRAQ™ sensing
Unit Input Volts CFM
90-162 Tons 0.5 - 4.5 VDC  0 - 46000 
						

							General Information
RT-SVX24K-EN13
Generic Building Automation System Module
(GBAS - Optional used with
non-Trane building control systems)
The Generic Building Automation System (GBAS) module
allows a non-Trane building control system to
communicate with the rooftop unit and accepts external
setpoints in the form of analog inputs for cooling, heating,
supply air pressure, and a binary Input for demand limit. Refer to the “Field Installed Control Wiring” section for the
input wiring to the GBAS module and the various desired
setpoints with the corresponding DC voltage inputs for
both VAV, SZVAV, RR and CV applications.
Input Devices and System Functions
The descriptions of the following basic Input Devices used
within the UCM network are to acquaint the operator with
their function as they interface with the various modules.
Refer to the unit electrical schematic for the specific
module connections.
Constant Volume (CV) and
Variable Air Volume (VAV) Units
Supply Air Temperature Sensor
An analog input device used with CV and VAV applications
that monitors the supply air temperature for: supply air
temperature control (VAV), supply air temperature reset
(VAV), supply air temperature low limiting (CV), supply air
tempering (CV/VAV). It is mounted in the supply air
discharge section of the unit and is connected to the RTM.
Figure 2. Velocity pressure transducer/solenoid assembly
Figure 3. Outside air tubing schematic
Figure 4. Return air pressure tubing schematic 
						

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14RT-SVX24K-EN
Return Air Temperature Sensor
An analog input device used with a return humidity sensor
on CV and VAV applications when the comparative
enthalpy option is ordered. It monitors the return air
temperature and compares it to the outdoor temperature
to establish which temperature is best suited to maintain
the cooling requirements. It is mounted in the return air
section and is connected to the ECEM.
Leaving Evaporator Temperature Sensor
An analog input device used with CV and VAV applicationsthat monitors the refrigerant temperature inside the
evaporator coil to prevent coil freezing. It is attached to the
suction line near the evaporator coil and is connected to
the MCM. It is factory set for 30°F and has an adjustable
range of 25°F to 35°F.The compressors are staged “Off” as
necessary to prevent icing. After the last compressor stage
has been turned “Off”, the compressors will be allowed to
restart once the evaporator temperature rises 10°F above
the “coil frost cutout temperature” and the minimum three
minute “Off” time has elapsed.
Entering Evaporator Temperature Sensors
Analog input devices used with CV and VAV applications.
This device is used in conjunction with the Leaving Evaporator Temperature Sensor to prevent the unit from
running compressors with insufficient charge.
Filter Switch
A binary input device used on CV and VAV applicationsthat measures the pressure differential across the unit
filters. It is mounted in the filter section and is connected
to the RTM. A diagnostic SERVICE signal is sent to the
remote panel if the pressure differential across the filters
is at least 0.5 w.c. The contacts will automatically open
when the pressure differential across the filters decrease
to 0.4 w.c. The switch differential can be field adjusted
between 0.17 w.c. to 5.0 w.c. ± 0.05 w.c.
Leaving Recovery Exhaust Temp Sensor
Analog input device used on CV and VAV applications withEnergy Recovery option installed. It is used to monitor the
temperature of the leaving air on the Exhaust Fan side of
the energy recovery wheel. This temperature is used to
determine if the temperature of the wheel is too cold as
compared to the Recovery Frost Avoidance Setpoint. The
result is used to determine when to enable energy wheel
frost avoidance functions.
Supply, Exhaust and Return Fan Airflow
Proving Switches
Supply Airflow Proving Switch is a binary input device
used on CV and VAV applications to signal the RTM when
the supply fan is operating. It is located in the supply fan
section of the unit and is connected to the RTM. During a
request for fan operation, if the differential switch is
detected to be open for 40 consecutive seconds; compressor operation is turned “Off”, heat operation is
turned “Off”, the request for supply fan operation is turned
“Off” and locked out, exhaust dampers (if equipped) are
“closed”, economizer dampers (if equipped) are “closed”, and a manual reset diagnostic is initiated.
Exhaust/return Airflow Proving Switch is a binary input
device used on all rooftop units equipped with an exhaust
fan. It is located in the exhaust/return fan section of the unit
and is connected to the RTM. During a request for fan
operation, if the differential switch is detected to be open
for 40 consecutive seconds, the economizer is closed to
the minimum position setpoint, the request for exhaust
fan operation is turned “Off” and locked out, and a manual
reset diagnostic is initiated. The fan failure lockout can be
reset at the Human Interface located in the unit control
panel, by Tracer, or by cycling the control power to the
RTM Off/On.
Lead-Lag
A selectable mode of operation through the HumanInterface. It alternates the starting between the first
compressor of each refrigeration circuit. Only the
compressor banks will switch, not the order of the
compressors within a bank, providing the first compressor
in each circuit had been activated during the same request
for cooling.
Charge Isolation
During the OFF cycle, most of the charge is isolated
between the compressor (internal) discharge check valves
and liquid line solenoid valve. This reduces the OFF cycle
charge migration, and liquid feedback during subsequent
startup.The liquid line solenoid is energized (opened) with
the start of the circuit compressor.
Supply, Exhaust and Return Fan Circuit
Breakers
The supply fan and exhaust fan motors are protected by circuit breakers or fuses. They will trip and interrupt the
power supply to the motors if the current exceeds the
breakers “must trip” value. The rooftop module (RTM)
will shut all system functions “Off” when an open fan
proving switch is detected.
Low Pressure Control
Low Pressure Control is accomplished using a binary input
device on CV and VAV applications. LP cutouts are located
on the suction lines near the scroll compressors. The LPC
contacts are designed to close when the suction pressure
exceeds 41 ± 4 psig. If the LP control is open when a
compressor is requested to start, none of the compressors
on that circuit will be allowed to operate. They are locked
out and a manual reset diagnostic is initiated.
The LP cutouts are designed to open if the suction pressure approaches 22 ± 4 psig. If the LP cutout opens
after a compressor has started, all compressors operating
on that circuit will be turned off immediately and will 
						

							General Information
RT-SVX24K-EN15
remain off for a minimum of three minutes. If the LP cutout
trips four consecutive times during the first three minutes
of operation, the compressors on that circuit will be locked
out and a manual reset diagnostic is initiated.
Saturated Condenser Temperature Sensors
Analog input devices used on CV and VAV applications
mounted inside a temperature well located on a
condenser tube bend. They monitor the saturated
refrigerant temperature inside the condenser coil and are
connected to the MCM. As the saturated refrigerant
temperature varies due to operating conditions, the
condenser fans are cycled “On” or “Off” as required to
maintain acceptable operating pressures.
Head Pressure Control
Accomplished using two saturated refrigeranttemperature sensors on CV and VAV applications. During
a request for compressor operation, when the condensing
temperature rises above the “lower limit” of the
controlband, the Compressor Module (MCM) starts
sequencing condenser fans “On”. If the operating fans can
not bring the condensing temperature to within the
controlband, more fans are turned on. As the saturated
condensing temperature approaches the lower limit of the
controlband, fans are sequenced “Off”.
The minimum “On/Off” time for condenser fan staging is 5.2 seconds. If the system is operating at a given fan stage
below 100% for 30 minutes and the saturated condensing
temperature is above the “efficiency check point” setting,
a fan stage will be added. If the saturated condensing
temperature falls below the “efficiency check point”
setting, the fan control will remain at the present operating
stage. If a fan stage cycles four times within a 10 minute
period, the control switches from controlling to the “lower
limit” to a temperature equal to the “lower limit” minus
the “temporary low limit suppression” setting. It will
utilize this new “low limit” temperature for one hour to
reduce condenser fan short cycling.
For evaporative condensing units, head pressure is
monitored with pressure transducers attached to the
saturated condensing line and converted to a temperature
by the MPM. This temperature is used to control the
variable speed fan and sump pump. When the
temperature rises above the upper limit (120°F) the sump
pump is energized. If the condensing temperature drops
below the lower limit (70°F) the sump pump is de-
energized.
High Pressure Limit Controls
High Pressure controls are located on the discharge lines
near the scroll compressors. They are designed to open
when the discharge pressure approaches 650 ± 10 psig.
The controls reset automatically when the discharge pressure decreases to approximately 550 ± 10 psig.
However, the compressors on that circuit are locked out
and a manual reset diagnostic is initiated after the fourth
occurrence of a high pressure condition.
Outdoor Air Humidity Sensor
An analog input device used on CV and VAV applicationswith 100% economizer. It monitors the outdoor humidity
levels for economizer operation. It is mounted in the
outside air intake section and is connected to the RTM.
Return Air Humidity Sensor
An analog input device used on CV and VAV applicationswith the comparative enthalpy option. It monitors the
return air humidity level and compares it to the outdoor
humidity level to establish which conditions are best
suited to maintain the cooling requirements. It is mounted
in the return air section and is connected to the ECEM.
Space Humidity Sensor
Analog input device used on CV and VAV applications withmodulating dehumidification option and/or
humidification field installed option. It is used to monitor
the humidity level in the space and compared to
dehumidification and humidification setpoints to maintain
space humidity requirements. It is field mounted in the
space and connected to the RTM.
Status/Annunciator Output
An internal function within the RTM module on CV and
VAV applications that provides:
c. diagnostic and mode status signals to the remotepanel (LEDs) and to the Human Interface
d. control of the binary Alarm output on the RTM
e. control of the binary outputs on the GBAS module to inform the customer of the operational status
and/or diagnostic conditions
Low Ambient Compressor Lockout
Utilizes an analog input device for CV and VAV
applications. When the system is configured for low
ambient compressor lockout, the compressors are not
allowed to operate if the temperature of the outside air
falls below the lockout setpoint. When the temperature
rises 5°F above the lockout setpoint, the compressors are
allowed to operate. The factory preset is 50°F.
These compressors come equipped with a protection module that monitors phase loss, phase sequencing and
motor temperature.
Space Pressure Transducer
An analog input device used on CV and VAV applicationswith the Statitrac option. It modulates the exhaust
dampers to keep the space pressure within the building to
a customer designated controlband. It is mounted on the
bottom support below the return damper blade assembly
and is connected to the ECEM. Field supplied pneumatic
tubing must be connected between the space being
controlled and the transducer assembly. 
						

							General Information
16RT-SVX24K-EN
Morning Warm-Up—Zone Heat
When a system changes from an unoccupied to an
occupied mode, or switches from STOPPED to AUTO, or
power is applied to a unit with the MWU option, the heater
in the unit or external heat will be brought on if the space
temperature is below the MWU setpoint. The heat will
remain on until the temperature reaches the MWU
setpoint.
If the unit is VAV, then the VAV box/unocc relay will
continue to stay in the unoccupied position and the VFD
output will stay at 100% during the MWU mode. When the
MWU setpoint is reached and the heat mode is terminated,
then the VAV box/unocc relay will switch to the occupied
mode and the VFD output will be controlled by the duct
static pressure. During Full Capacity MWU the economizer
damper is held closed for as long as it takes to reach
setpoint. During Cycling Capacity MWU the economizer
damper is allowed to go to minimum position after one
hour of operation if setpoint has not been reached.
Compressor Motor Winding Thermostats
A thermostat is embedded in the motor windings of eachScroll compressor. Each thermostat is designed to open if
the motor windings exceed approximately 221°F. The
thermostat will reset automatically when the winding
temperature decreases to approximately 181°F.
Rapid cycling, loss of charge, abnormally high suction
temperatures, or the compressor running backwards
could cause the thermostat to open. During a request for
compressor operation, if the Compressor Module detects
a problem outside of normal parameters, it turns any
operating compressor(s) on that circuit “Off”, locks out all
compressor operation for that circuit, and initiates a
manual reset diagnostic (compressor trip).
These compressors come equipped with a protection module that monitors phase loss, phase sequencing and
motor temperature.
Supply Air Temperature Low Limit
Uses the supply air temperature sensor input to modulate
the economizer damper to minimum position in the event
the supply air temperature falls below the occupied
heating setpoint temperature.
Discharge Line Thermostat for Evaporative
Condensers
The first compressor on each circuit is equipped with aDischarge Line Thermostat. If the temperature of the line
exceeds 210°F the thermostat interrupts the 115V circuit for
the compressors and both of the compressors on that circuit will be de-energized. Once the temperature drops
below 170°F the thermostat will close and allow the
compressor to be energized.
Freezestat
A binary input device used on CV and VAV units with
Hydronic Heat. It is mounted in the heat section and
connected to the Heat Module. If the temperature of the air
leaving the heating coil falls to 40°F, the normally open
contacts on the freezestat closes signalling the Heat
Module and the Rooftop Module (RTM) to:
f. drive the Hydronic Heat Actuator to the full openposition
Figure 5. Transducer voltage output vs. pressure input for supply, return and building pressure
-0.75 to 9.0 Iwc Pressure Transducer Voltage Output vs. Pressure Input
0.00 0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
-0. 75
-0. 25
0.2
5
0. 7
5
1. 2
5
1. 7
5
2. 2
5
2. 7
5
3. 2
5
3. 7
5
4. 2
5
4. 7
5
5. 2
5
5. 7
5
6. 2
5
6. 7
5
7. 2
5
7. 7
5
8. 2
5
8. 7
5Pressure (inches w.c.)
Volts 
						

							General Information
RT-SVX24K-EN17
g. turn the supply fan “Off”
h. closes the outside air damper
i. turns “On” the SERVICE light at the Remote Panel
j. initiates a “Low Temp Limit” diagnostic to the
Human Interface
Compressor Circuit Breakers
The Scroll Compressors are protected by circuit breakerswhich interrupt the power supply to the compressors if the
current exceeds the breakers “must trip” value. During a
request for compressor operation, if the Compressor
Module detects a problem outside normal parameters, it
turns any operating compressor(s) on that circuit “Off”,
locks out all compressor operation for that circuit, and
initiates a manual reset diagnostic (compressor trip).
Constant Volume (CV) Units
Zone Temperature—Cooling
Relies on input from a sensor located directly in the space,
while a system is in the occupied “Cooling” mode. It
modulates the economizer (if equipped) and/or stages the
mechanical cooling “On and Off” as required to maintain
the zone temperature to within the cooling setpoint
deadband.
Zone Temperature—Heating
Relies on input from a sensor located directly in the space,
while a system is in the occupied “Heating” mode or an
unoccupied period, to stage the heat “on and off” or to
modulate the heating valve (hydronic heat only) as
required to maintain the zone temperature to within the
heating setpoint deadband. The supply fan will be
requested to operate any time there is a request for heat.
On gas heat units, the fan will continue to run for 60
seconds after the furnace is turned off.
Supply Air Tempering
On CV units equipped with staged gas heat, if the supply
air temperature falls 10°F below the occupied heating
setpoint temperature while the heater is “Off”, the first
stage of heat will be turned “On”.The heater is turned “Off”
when the supply air temperature reaches 10°F above the
occupied heating setpoint temperature.
Variable Air Volume (VAV) Units
Occupied Heating—Supply Air Temperature
When a VAV unit is equipped with “Modulating Heat”, andthe system is in an occupied mode, and the field supplied
changeover relay contacts have closed or per a BAS
command, the supply air temperature will be controlled to
the customer specified supply air heating setpoint. It will
remain in the heating status until the changeover relay
contacts are opened or BAS has released the heat
command.
Occupied Cooling—Supply Air Temperature
When a VAV unit is in the occupied mode, the supply airtemperature will be controlled to the customer specified
supply air cooling setpoint by modulating the economizer
and/or staging the mechanical cooling “On and Off” as
required.The changeover relay contacts must be open, or
BAS command set to auto or cool, for the cooling to
operate.
Daytime Warm-up
On VAV units equipped with heat, if the zone temperature
falls below the daytime warm-up initiate temperature
during the occupied mode, the system will switch to full
airflow. During this mode, the VAV box/unocc relay will be
energized (this is to signal the VAV boxes to go to 100%).
After the VAV box max stroke time has elapsed (factory set at 6 minutes), the VFD output will be set to 100%. The
airflow will be at 100% and the heat will be turned on to
control to the occupied heating setpoint.
When the zone temperature reaches the daytime warm-up termination setpoint, the heat will be turned off, the relay
will be de-energized, releasing the VAV boxes, the VFD
output will go back to duct static pressure control and the
unit will return to discharge air control. If the occ zone
heating setpoint is less than the DWU terminate setpoint,
the heat will turn off when the occ zone heat setpoint is
reached, but it will stay in DWU mode and cycle the heat
to maintain setpoint.
Unoccupied Heating—Zone Temperature
When a VAV unit is equipped with gas, electric, or hydronicheat and is in the unoccupied mode, the zone temperature
will be controlled to within the customer specified setpoint
deadband. During an unoccupied mode for a VAV unit, the
VAV box/unocc relay will be in the unoccupied position and the VFD output will be at 100%.This means that if there
is a call for heat (or cool) and the supply fan comes on, it
will be at full airflow and the VAV boxes in the space will
need to be 100% open as signaled by the VAV box/unocc
relay.
Supply Air Tempering
On VAV units equipped with “Modulating Heat” ,ifthe
supply air temperature falls 10°F below the supply air
temperature setpoint, the heat will modulate to maintain
the supply air temperature to within the low end of the
setpoint deadband.
Supply Duct Static Pressure Control
(Occupied)
The RTM relies on input from the duct pressure transducer when a unit is equipped with a Variable Frequency Drive to
set the supply fan speed to maintain the supply duct static
pressure to within the static pressure setpoint deadband.
The transducer compares supply duct pressure to ambient pressure. Refer to Figure 43, p. 67. 
						

							General Information
18RT-SVX24K-EN
Space Temperature Averaging
Space temperature averaging for Constant Volume
applications is accomplished by wiring a number of
remote sensors in a series/parallel circuit.
The fewest number of sensors required to accomplish space temperature averaging is four. The Space
Temperature Averaging with Multiple Sensors figure illustrates a single sensor circuit (Single Zone), four
sensors wired in a series/parallel circuit (Four Zone), nine
sensors wired in a series/parallel circuit (Nine Zone). Any
number squared, is the number of remote sensors
required.
Wiring termination will depend on the type of remote panel or control configuration for the system. Refer to the
wiring diagrams that shipped with the unit.
Figure 6. Transducer voltage output vs. pressure input
with VCM and TRAQ™ sensing
Transducer Voltage Output vs.   Pre ssure  Input
0. 0 0. 5
1. 0 1. 5 2. 0
2. 5 3. 0 3. 5 4. 0
-0.5 0. 0 0.5 1. 0 1. 5 2.0 2.5 3. 0 3.5 4. 0 4. 5 5.0 P r e ssu r e  ( i n c h e s w . c . )
Volts
Figure 7. Unit component layout and “ship with” locations
Return/
Exhaust Fan Outside Air
Dampers
Supply Fan Condenser
Fans
Compressor Section
Heating
Section
Exhaust Damper Hood
Evap Coil Evap Coil
Controls
Variable
Frquency
Drive (VFD)
Filter Section
Reheat Coil Option
Outside Air Dampers
Return Air Dampers
Flue Vent  Access
Variable
Frquency
Drive (VFD)
Hot Water/Steam 
Hydronic ConnectionOutside Air 
Static Kit and sensors 
						

							General Information
RT-SVX24K-EN19
Unit Control Modules
Unit control modules are microelectronic circuit boards
designed to perform specific unit functions. The control
modules, through proportional/integral control
algorithms, provide the best possible comfort level for the
customer. They are mounted in the control panel and are
factory wired to their respective internal components.
The control modules receive and interpret information from other unit modules, sensors, remote panels, and
customer binary contacts to satisfy the applicable request
for economizing, mechanical cooling, heating, and
ventilation. Figure 9illustrates the typical location of each
designated module. Figure 8. Space temperature averaging with multiple sensors 
						

							General Information
20RT-SVX24K-EN
Single Zone Variable Air Volume
(SZVAV) Only
The IntelliPak controls platform will support Single Zone
VAV as an optional unit control type in order to meetASHRAE 90.1. The basic control will be a hybrid VAV/CV configured unit that provides discharge temperature
control to a varying discharge air temperature target
setpoint based on the space temperature and/or humidity
conditions. Concurrently, the unit will control and optimize
the supply fan speed to maintain the zone temperature to
a zone temperature setpoint.
Supply Fan Output Control
Units configured for Single Zone VAV control will utilize
the same supply fan output control scheme as on
traditional VAV units except the VFD signal will be based
on zone heating and cooling demand instead of the supply
air pressure.
VFD Control
Single Zone VAV units will be equipped with a VFD-
controlled supply fan which will be controlled via a 0-
10VDC signal from the Rooftop Module (RTM). With the
RTM supply fan output energized and the RTM VFD output at 0VDC, the fan speed output is 37% (22Hz) from the VFD
by default; and at 10VDC the fan speed output is 100%
(60Hz). The control scales the 0-10VDC VFD output from
the RTM linearly to control between the 37-100% range.
The VFD will modulate the supply fan motor speed, accelerating or decelerating as required to maintain the
zone temperature to the zone temperature 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.
Ventilation Control
Units configured for Single Zone VAV control will require
special handling of the OA Damper Minimum Position
control in order to compensate for the non-linearity of
airflow associated with the variable supply fan speed and
damper combinations. Units configured for TRAQ with or
without DCV will operate identically to traditional units
with no control changes.
Space Pressure Control
For units configured with Space Pressure Control with or
without Statitrac, the new schemes implemented for
economizer minimum position handling require changes
to the existing Space Pressure Control scheme in order to
Figure 9. Control module locations
BCI