Vpu2; Overview; Features; Purpose Of This Guide - Taco iWorx UCP-1 Application Manual

VPU2

The VPU2 is a self-contained microprocessor-based controller for one Variable Air Volume (VAV) package unit. Appli-
cations include VAV package units with up to four stages of cooling, or a floating point control valve or a modulated out-
put (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 net-
worked 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 L
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
• L W interface to building automation systems
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• 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 L
W networking and communications. This Application Guide is written for:
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• Users who engineer control logic
505-010-2, Effective: April 29, 2014
© 2014 Taco Electronic Solutions, Inc.
®
W networking technology. The controller can be networked to a higher-level
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iWorx® VPU2
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