iWorx® PSU1
505-012, Effective: August 10, 2012 3
© 2012 Taco Electronic Solutions, Inc.
PSU1
The PSU1 pump sequencing unit is a stand-alone microprocessor-based controller for radiant heating or cooling appli-
cations.
Overview
The PSU1 is a compact, microcontroller-based controller for support of radiant applications with pump sequencing
needs. It controls the pump sequences, rotates and stages the pumps according to the programmed mode, maintains
desired differential temperature (Delta T), and generates flow alarms if no flow is detected.
The controller is based on LONWORKS
®
networking technology. The controller can be networked to a higher-level control
system for monitoring and control applications.
Features
• Control of two primary pumps with four control modes
• Standby pump operation with manually selectable lead pump
• Equal runtime operation with adjustable run time
• Two-stage digital control or single-stage modulated control (with digital enable) based on an adjustable primary
loop temperature differential
• Automatic configuration with a Local Control Interface (LCI) touchscreen
• Alarm/Event reporting
• LONWORKS® interface to building automation systems
PURPOSE OF THIS GUIDE
The iWorx® PSU1 Application Guide provides application information for the PSU1 Controller.
The reader should understand basic HVAC concepts, intelligent environmental control automation, and basic LON-
WORKS networking and communications. This application manual is written for:
• Users who engineer control logic
• Users who set up hardware configuration
• Users who change hardware or control logic
• Technicians and field engineers
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 responsi-
bility 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 pur-
poses. For example, iWorx® products are not intended for use to support fire suppression systems, life support sys-
tems, 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, inade-
quate operating environment, repair, attempted repair, modification or alteration, or other abuse. For further informa-
tion, 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.
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