The VPU2 is a self-contained microprocessor-based controller for one Variable Air Volume (VAV) package unit. Applications include VAV package units with up to four stages of cooling, or a floating point control valve or a modulated output (valve or variable speed circulator) two stages of heating, or a floating point control valve or a modulated output
(valve or variable speed circulator) an economizer, and a variable speed fan. The VPU2 is designed for integrated networked operation with the iWorx® Local Control Interface (LCI) and up to 56 VAV terminal unit controllers.
Overview
Digital inputs are provided for fan status, mixed air low limit indication, smoke detector, and filter status. Analog inputs
are provided for mixed air temperature, return air humidity, supply air temperature and supply duct static pressure. An
indoor air quality (IAQ) input can be configured for analog or digital operation.
The VPU2 incorporates digital outputs in the form of triacs for fan start/stop, four cooling stages, two heating stages
and a two-position economizer. In addition, two analog outputs are provided to control a modulated economizer and
variable speed fan drive.
The controller is based on the LONWORKS® networking technology. The controller can be networked to a higher-level
control system for monitoring and control applications.
Features
• Four stages of cooling, or floating point valve control or a modulated output (valve or variable speed circulator)
• Two stages of heating, or floating-point valve control or a modulated output (valve or variable speed circulator)
• Dehumidification
• Modulated fan speed
• Digital or modulated economizer
• Economizer enabled based on enthalpy calculations or dry bulb
• Minimum cycle timers for stages
• Runtime accumulation for heating, cooling and fan
• Local backup schedule
• Maximum of 56 zones (VAV boxes)
• Supply air temperature safety limits
• Time proportioned control of the staged outputs to reduce cycling
• Proportional + Integral control of the modulated economizer, modulated heating, modulated cooling, and static
pressure
• Mixed air low limit protection, filter status, fan proof, freeze stat, and smoke detection inputs
• IAQ compensation based on IAQ alarm input or zone controller alarm
• Outside Air Temperature cutoffs
• Automatic morning warm-up sequence
•LONWORKS interface to building automation systems
• Automatic configuration with the LCI
• Alarm/Event reporting
PURPOSE OF THIS GUIDE
The iWorx® VPU2 Application Guide provides application information for the VPU2 Controller.
The reader should understand basic HVAC concepts, intelligent environmental control automation, and basic LON-
WORKS networking and communications. This Application Guide is written for:
• Technicians and field engineers of Taco Electronic Solutions, Inc.
REPRESENTATIONS AND WARRANTIES
This Document is subject to change from time to time at the sole discretion of Taco Electronic Solutions, Inc. All
updates to the Document are available at www.taco-hvac.com. When installing this product, it is the reader’s responsibility to ensure that the latest version of the Document is being used.
iWorx® products shall only be used for the applications identified in the product specifications and for no other purposes. For example, iWorx® products are not intended for use to support fire suppression systems, life support systems, critical care applications, commercial aviation, nuclear facilities or any other applications where product failure
could lead to injury to person, loss of life, or catastrophic property damage and should not be used for such purposes.
Taco Electronic Solutions, Inc. will not be responsible for any product or part not installed or operated in conformity with
the Document and instructions or which has been subject to accident, disaster, neglect, misuse, misapplication, inadequate operating environment, repair, attempted repair, modification or alteration, or other abuse. For further information, please refer to the last page of this Document for the company’s Limited Warranty Statement, which is also issued
with the product or available at www.taco-hvac.com.
APPLICABLE DOCUMENTATION
See the table below for additional documentation that may be applicable to this controller.
– Application Engineers
– Installers
– Service Personnel
– Start-up Technicians
– End user
– Application Engineers
– Installers
– Service Personnel
– Start-up Technicians
– End user
– Application Engineers
– Installers
– Service Personnel
– Start-up Technicians
– End user
– Wholesalers
– Contractors
LonWorks FTT-10A Free Topology Transceiver User’s Guide, published by Echelon Corporation. It provides specifications and user instructions for the FTT-10A Free Topology Transceiver. See also: www.echelon.com/support/documentation/manuals/transceivers.
Provides instructions for setting up and using
the iWorx® VPU2 controller.
Provides instructions for setting up and using
the iWorx® Local Control Interface.
Provides instructions for setting up and using
the iWorx® VAV Series controller.
An on-line configuration and submittal package
generator based on user input. Automatically
generates bill of materials, sequence of operations, flow diagrams, wiring diagrams, points
and specifications.
CAUTION: This symbol is intended to alert the user to the presence of important installation and mainte-
nance (servicing) instructions in the literature accompanying the equipment.
CAUTION: Risk of explosion if battery is replaced by an incorrect type. Contains lithium type battery; dispose of properly.
WARNING: Electrical shock hazard. Disconnect ALL power sources when installing or servicing this
equipment to prevent electrical shock or equipment damage.
Make all wiring connections in accordance with these instructions and in accordance with pertinent national and local
electrical codes. Use only copper conductors that are suitable for 167 °F (75 °C).
Static Electricity
Static charges produce voltages that can damage this equipment. Follow these static electricity precautions when handling this equipment.
• Work in a static free area.
• Touch a known, securely grounded object to discharge any charge you may have accumulated.
• Use a wrist strap when handling printed circuit boards. The strap must be secured to earth ground.
FCC Compliance
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of
the FCC rules. These limits are designed to provide reasonable protection against harmful interference. This equipment can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause
harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be
determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or
more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and the receiver.
• Connect the equipment to a power source different from that to which the receiver is connected.
• Consult the equipment supplier or an experienced radio/TV technician for help.
You are cautioned that any changes or modifications to this equipment not expressly approved in these instructions
could void your authority to operate this equipment in the United States.
BEFORE INSTALLING
About this Document
The instructions in this manual are for the VPU2 controller, which supporst one Variable Air Volume package unit.
Inspecting the Equipment
Inspect the shipping carton for damage. If damaged, notify the carrier immediately. Inspect the equipment for damage.
Return damaged equipment to the supplier.
• A power source for the equipment electronics and peripheral devices.
• Tools necessary to install, troubleshoot and service the equipment.
• The screws or DIN rail needed to mount the device.
• Peripheral devices, such as sensors, actuators, etc.
• Cabling, cabling raceway, and fittings necessary to connect this equipment to the power source, FTT-10A network
and peripheral devices.
Equipment Location
Abide by all warnings regarding equipment location provided earlier in this document.
Optimally, the equipment should be installed within a secure enclosure.
If the equipment is to be installed outdoors, it must be contained within a protective enclosure. The enclosure must
maintain internal temperature and humidity within the ranges specified for this equipment.
The equipment must be installed within 500 feet of all input peripherals (smoke detectors, sensors, etc.) that are connected to the equipment.
Selecting a Power Source
This equipment requires a UL recognized Class 2 external power source (not supplied) to operate. The controller
power input requires a voltage of 24 Volts AC.
To calculate power source current requirements, add the power consumption of all peripheral devices to that of the
controller.
The controller and sensor power supplies can use the same power source. If both are using the same power source,
the loads must have EMF protection. This protection can be integral to the load, or installed in the 24 VAC wiring across
the load’s coil.
To provide necessary RFI and transient protection, the controller’s ground (GND) pin (T40) must be connected to earth
ground or the earth ground of the packaged unit’s enclosure ground. Failure to properly ground the controller may
cause it to exceed FCC limits. Excessive noise could also produce inaccurate sensor data. The power source must be
capable of operating with this connection to ground.
INSTALLATION
Warning: Electrical shock hazard. To prevent electrical shock or equipment damage, disconnect ALL
power sources to controllers and loads before installing or servicing this equipment or modifying any wiring.
Mounting the Device
1.Select a mounting location. Enclosure mounting is recommended.
2.Hold the controller on the panel you wish to mount it on. With a marker or pencil mark the mounting locations on
the panel.
3.Using a small drill bit pre-drill the mounting holes.
4.Using two #6 pan head screws, mount the controller to the panel.
5.Wire the controller (See Routing Cabling to the Device).
Cabling used to connect the power source and cabling used to connect the FTT-10A network must remain
separated within the control enclosure and wiring conduit.
Grounding the Device
The ground terminal (T40) must be securely connected to earth ground. Failure to properly ground this
equipment will result in improper operation. Improper grounding may also increase the risk of electrical
shock and may increase the possibility of interference with radio/TV reception.
For best performance, connect the power supply common terminal (T38) to the same external point as the
ground terminal (T40).
WARNING: Terminals 6, 9, 12, 15, and 18 are connected internally on all VPU2 controllers. Disconnect
ALL power sources when installing or servicing this equipment to prevent electrical shock or equipment
To connect the Return Air Humidity sensor to the unit, connect the positive wire from the sensor to RAH (T19) and the
other wire to the adjacent common (T18). The sensor must be of the 0-10 Volt type.
If global indoor air humidity readings are being provided over the network, it is not necessary to attach a return air
humidity sensor directly to the VPU2.
Mixed Air (MAT)
To connect the Mixed Air thermistor to the unit, attach one wire from the thermistor to MAT (T17) and the other wire to
the adjacent common (T18). The thermistor used must be 10K Precon Type III.
To connect the Supply Air thermistor to the unit, attach one wire from the thermistor to SAT (T16) and the other wire to
the adjacent common (T15). The thermistor used must be 10K Precon Type III.
Smoke Detector (SMK)
To connect the smoke detector switch to the digital input, attach one wire of the contact to SMK (T14) and the other
wire to the adjacent common (T15). This must be a dry contact normally open switch. This input is for indication only. A
separate smoke detector should be wired into a fire alarm system if the generation of a fire alarm is required.
Filter Status (FIL)
To connect the filter switch to the digital input, attach one wire of the contact to FIL (T13) and the other wire to the adjacent common (T12).
Mixed Air Low Limit (MLL)
This must be a dry contact normally open switch. To connect the low limit indication switch to the digital input, attach
one wire of the contact to MLL (T11) and the other wire to the adjacent common (T12). This must be a dry contact normally open switch.
Indoor Air Quality (IAQ)
This must be a dry contact normally-open switch. To connect the digital CO2 level sensor to the unit, attach one wire
from the sensor to IAQ (T10) and the other wire to the adjacent common (T9). For a digital sensor, this must be a dry
contact, normally closed switch. For an analog sensor, it must be of the 0-10V type.
Static Pressure (SPR)
To connect the static pressure sensor to the analog input, attach the positive wire from the sensor to SPR (T8) and the
other wire to the adjacent common (T9). The sensor must be analog, 0 to 10 volt type.
Return Air Temperature (RAT)
To connect the return air temperature thermistor to the analog input, attach one wire of the sensor to RAT (T7) and the
other wire to the adjacent common (T6).
Fan Proof (FNP)
To connect the fan proof switch to the digital input, attach one wire of the contact to FNP (T5) and the other wire to the
adjacent common (T6). This must be a dry contact, normally closed switch. If you are not providing a fan proof input, T5
and T6 must be shorted (jumpered) together.
Connecting Output Devices
Modulated Economizer (ECNM)
The modulated economizer output can be set to 0-10 V max through the control logic. Connect the positive wire from
the damper actuator to ECNM (T37) and the other wire to the adjacent common (T36). See preceding figures for
details.
Modulated Heating (HTGM)
The modulated heating output can be set to 0-10 V max through the control logic. Connect the positive wire from the
heating output to HTGM (T35) and the other wire to COM (T36). See preceding figures for details.
Modulated Cooling (CLGM)
The modulated cooling output can be set to 0-10 V max through the control logic. Connect the positive wire from the
cooling output to CLGM (T34) and the other wire to COM (T33). See preceding figures for details.
The modulated static pressure fan output can be set to 0-10 V max through the control logic. Connect the positive wire
from the fan output to SPF (T32) and the other wire to COM (T33). See preceding figures for details.
Cooling Stage 1 or Cooling Floating Point Valve Open (C1)
The cooling stage output must be connected to a 24 VAC pilot relay if the load is greater than 1 Amp. See preceding
figures for details. If the load is less than 1 Amp, connect cooling stage 1 to C1 (T31) and TC12 (T30). For control of a
floating point valve, connect C1 as the valve open signal.
Cooling Stage 2 or Cooling Floating Point Valve Close (C2)
The cooling stage output must be connected to a 24 VAC pilot relay if the load is greater than 1 Amp. See preceding
figures for details. If the load is less than 1 Amp, connect cooling stage 2 to C2 (T29) and TC12 (T30). For control of a
floating point valve, connect C2 as the valve close signal.
Cooling Stage 3 (C3)
The cooling stage output must be connected to a 24 VAC pilot relay if the load is greater than 1 Amp. See preceding
figures for details. If the load is less than 1 Amp, connect to C3 (T28) and TC34 (T27).
Cooling Stage 4 (C4)
The cooling stage output must be connected to a 24 VAC pilot relay if the load is greater than 1 Amp. See preceding
figures for details. If the load is less than 1 Amp, connect to C4 (T26) and TC34 (T27).
Heating Stage 1 or Heating Floating Point Valve Open (H1)
The heating stage output must be connected to a 24 VAC pilot relay if the load is greater than 1 Amp. See preceding
figures for details. If the load is less than 1 Amp, connect heating stage 1 to H1 (T25) and TC56 (T24). For control of a
floating point heating valve, connect H1 (T25) as the valve open signal. TC56 (T24) is the common.
Heating Stage 2 or Heating Floating Point Valve Close (H2)
The heating stage output must be connected to a 24 VAC pilot relay if the load is greater than 1 Amp. See preceding
figures for details. If the load is less than 1 Amp, connect heating stage 2 to H2 (T23) and TC56 (T24). For control of a
floating point heating valve, connect H2 (T23) as the valve close signal. TC56 (T24) is the common.
Fan (FAN)
The fan output must be connected to a 24 VAC pilot relay if the load is greater than 1 Amp. See preceding figures for
details. If the load is less than 1 Amp, connect the fan to FAN (T22) and TC78 (T21).
Two Position Economizer (ECD)
The two-position economizer output must be connected to a 24 VAC pilot relay if the load is greater than 1 Amp. See
preceding figures for details. If the load is less than 1 Amp, connect the economizer to ECD (T20) and TC78 (T21).
Other Connections
Network (LON)
Network wiring must be twisted pair. One network wire must be connected to terminal NETA (T1) and the other network
wire must be connected to terminal NETB (T2). Polarity is not an issue since an FTT-10A network is used for communications.
Power (PWR)
Connect one output wire from a 24 VAC power supply to PWR (T39) and the other output wire from the power supply to
the adjacent common terminal (T38). T38 must be connected to earth ground.
Terminal GND (T40) must be connected to earth ground. Failure to properly ground this equipment will
result in improper operation. Improper grounding may also increase the risk of electrical shock, and may
increase the possibility of interference with radio and TV reception.
Protocol
The VPU2 is based on the LONWORKS® networking technology and can be networked to a higher-level control system
for monitoring and control applications. For additional information on the Protocol reference the LonWorks FTT-10A Free Topology Transceiver User's Guide, published by the Echelon Corporation.
• Cabling: Maximum node-to-node distance: 1312 feet (400 meters)
• Maximum total distance: 1640 feet (500 meters)
Cable TypePairsDetailsTaco Catalog No.
Level 4 22AWG (0.65mm)1Unshielded, Plenum, U.L. Type CMPWIR-022
For detailed specifications, refer to the FTT-10A Free-Topology Transceiver User’s Guide published by Echelon Corporation (www.echelon.com/support/documentation/manuals/transceivers).