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ENGINEERING MANUAL OF AUTOMATIC CONTROL i

HONEYWELL

ENGINEERING MANUAL of

AUTOMATIC

CONTROL for

COMMERCIAL BUILDINGS

ii ENGINEERING MANUAL OF AUTOMATIC CONTROL

Copyright 1934, 1940, 1953, 1988, 1991 and 1997 by Honeywell Inc.

All rights reserved. This manual or portions thereof may not be reporduced

in any form without permission of Honeywell Inc.

Library of Congress Catalog Card Number: 97-72971

Honeywell Europe S.A.

3 Avenue du Bourget

1140 Brussels

Belgium

Honeywell Asia Pacific Inc.

Room 3213-3225

Sun Hung Kai Centre

No. 30 Harbour Road

Wanchai

Hong Kong

Home and Building Control

Honeywell Limited-Honeywell Limitée

155 Gordon Baker Road

North York, Ontario

M2H 3N7

Honeywell Latin American Region

480 Sawgrass Corporate Parkway

Suite 200

Sunrise FL 33325

Home and Building Control

Honeywell Inc.

Honeywell Plaza

P.O. Box 524

Minneapolis MN 55408-0524

Printed in USA

ENGINEERING MANUAL OF AUTOMATIC CONTROL iii

FOREWORD

The Minneapolis Honeywell Regulator Company published the first edition of the Engineering Manual of

Automatic Control in l934. The manual quickly became the standard textbook for the commercial building

controls industry. Subsequent editions have enjoyed even greater success in colleges, universities, and contractor

and consulting engineering offices throughout the world.

Since the original 1934 edition, the building control industry has experienced dramatic change and made

tremendous advances in equipment, system design, and application. In this edition, microprocessor controls are

shown in most of the control applications rather than pneumatic, electric, or electronic to reflect the trends in

industry today. Consideration of configuration, functionality, and integration plays a significant role in the

design of building control systems.

Through the years Honeywell has been dedicated to assisting consulting engineers and architects in the

application of automatic controls to heating, ventilating, and air conditioning systems. This manual is an outgrowth

of that dedication. Our end user customers, the building owners and operators, will ultimately benefit from the

efficiently designed systems resulting from the contents of this manual.

All of this manual’s original sections have been updated and enhanced to include the latest developments in

control technology. A new section has been added on indoor air quality and information on district heating has

been added to the Chiller, Boiler, and Distribution System Control Applications Section.

This twenty-first edition of the Engineering Manual of Automatic Control is our contribution to ensure that

we continue to satisfy our customer’s requirements. The contributions and encouragement received from previous

users are gratefully acknowledged. Further suggestions will be most welcome.

Minneapolis, Minnesota

October, 1997

KEVIN GILLIGAN

President, H&BC Solutions and Services

iv ENGINEERING MANUAL OF AUTOMATIC CONTROL

ENGINEERING MANUAL OF AUTOMATIC CONTROL v

PREFACE

The purpose of this manual is to provide the reader with a fundamental understanding of controls and how

they are applied to the many parts of heating, ventilating, and air conditioning systems in commercial buildings.

Many aspects of control are presented including air handling units, terminal units, chillers, boilers, building

airflow, water and steam distribution systems, smoke management, and indoor air quality. Control fundamentals,

theory, and types of controls provide background for application of controls to heating, ventilating, and air

conditioning systems. Discussions of pneumatic, electric, electronic, and digital controls illustrate that applications

may use one or more of several different control methods. Engineering data such as equipment sizing, use of

psychrometric charts, and conversion formulas supplement and support the control information. To enhance

understanding, definitions of terms are provided within individual sections. For maximum usability, each section

of this manual is available as a separate, self-contained document.

Building management systems have evolved into a major consideration for the control engineer when evaluating

a total heating, ventilating, and air conditioning system design. In response to this consideration, the basics of

building management systems configuration are presented.

The control recommendations in this manual are general in nature and are not the basis for any specific job or

installation. Control systems are furnished according to the plans and specifications prepared by the control

engineer. In many instances there is more than one control solution. Professional expertise and judgment are

required for the design of a control system. This manual is not a substitute for such expertise and judgment.

Always consult a licensed engineer for advice on designing control systems.

It is hoped that the scope of information in this manual will provide the readers with the tools to expand their

knowledge base and help develop sound approaches to automatic control.

vi ENGINEERING MANUAL OF AUTOMATIC CONTROL

ENGINEERING MANUAL OF AUTOMATIC CONTROL vii

CONTENTS

Foreward ............................................................................................................................................................. iii

Preface ................................................................................................................................................................ v

Control System Fundamentals ............................................................................................ 1

Control Fundamentals ....................................................................................................................................... 3

Introduction.......................................................................................... 5

Definitions............................................................................................ 5

HVAC System Characteristics ............................................................. 8

Control System Characteristics ........................................................... 15

Control System Components .............................................................. 30

Characteristics And Attributes Of Control Methods ............................. 35

Psychrometric Chart Fundamentals ................................................................................................................ 37

Introduction.......................................................................................... 38

Definitions............................................................................................ 38

Description of the Psychrometric Chart............................................... 39

The Abridged Psychrometric Chart ..................................................... 40

Examples of Air Mixing Process .......................................................... 42

Air Conditioning Processes ................................................................. 43

Humidifying Process............................................................................ 44

ASHRAE Psychrometric Chart ............................................................ 53

Pneumatic Control Fundamentals .................................................................................................................... 57

Introduction.......................................................................................... 59

Definitions............................................................................................ 59

Abbreviations ....................................................................................... 60

Symbols............................................................................................... 61

Basic Pneumatic Control System ........................................................ 61

Air Supply Equipment .......................................................................... 65

Thermostats ........................................................................................ 69

Controllers ........................................................................................... 70

Sensor-Controller Systems ................................................................. 72

Actuators and Final Control Elements ................................................. 74

Relays and Switches ........................................................................... 77

Pneumatic Control Combinations ........................................................ 84

Pneumatic Centeralization .................................................................. 89

Pneumatic Control System Example ................................................... 90

Electric Control Fundamentals ......................................................................................................................... 95

Introduction.......................................................................................... 97

Definitions............................................................................................ 97

How Electric Control Circuits Classified .............................................. 99

Series 40 Control Circuits.................................................................... 100

Series 80 Control Circuits.................................................................... 102

Series 60 Two-Position Control Circuits............................................... 103

Series 60 Floating Control Circuits ...................................................... 106

Series 90 Control Circuits.................................................................... 107

Motor Control Circuits.......................................................................... 114

ENGINEERING MANUAL of

AUTOMATIC

CONTROL

viii ENGINEERING MANUAL OF AUTOMATIC CONTROL

Electronic Control Fundamentals ..................................................................................................................... 119

Introduction.......................................................................................... 120

Definitions............................................................................................ 120

Typical System .................................................................................... 122

Components ........................................................................................ 122

Electtonic Controller Fundamentals .................................................... 129

Typical System Application .................................................................. 130

Microprocessor-Based/DDC Fundamentals .................................................................................................... 131

Introduction.......................................................................................... 133

Definitions............................................................................................ 133

Background ......................................................................................... 134

Advantages ......................................................................................... 134

Controller Configuration ...................................................................... 135

Types of Controllers............................................................................. 136

Controller Software.............................................................................. 137

Controller Programming ...................................................................... 142

Typical Applications ............................................................................. 145

Indoor Air Quality Fundamentals ..................................................................................................................... 149

Introduction.......................................................................................... 151

Definitions............................................................................................ 151

Abbreviations ....................................................................................... 153

Indoor Air Quality Concerns ................................................................ 154

Indoor Air Quality Control Applications................................................ 164

Bibliography ......................................................................................... 170

Smoke Management Fundamentals ................................................................................................................. 171

Introduction.......................................................................................... 172

Definitions............................................................................................ 172

Objectives ............................................................................................ 173

Design Considerations ........................................................................ 173

Design Principles ................................................................................ 175

Control Applications ............................................................................ 178

Acceptance Testing ............................................................................. 181

Leakage Rated Dampers .................................................................... 181

Bibliography ......................................................................................... 182

Building Management System Fundamentals................................................................................................. 183

Introduction.......................................................................................... 184

Definitions............................................................................................ 184

Background ......................................................................................... 185

System Configurations ........................................................................ 186

System Functions ................................................................................ 189

Integration of Other Systems............................................................... 197

ENGINEERING MANUAL OF AUTOMATIC CONTROL ix

Control System Applications ............................................................................................... 199

Air Handling System Control Applications...................................................................................................... 201

Introduction.......................................................................................... 203

Abbreviations ....................................................................................... 203

Requirements For Effective Control .................................................... 204

Applications-General ........................................................................... 206

Valve and Damper Selection ............................................................... 207

Symbols............................................................................................... 208

Ventilation Control Processes ............................................................. 209

Fixed Quantity of Outdoor Air Control ................................................. 211

Heating Control Processes.................................................................. 223

Preheat Control Processes ................................................................. 228

Humidification Control Process ........................................................... 235

Cooling Control Processes .................................................................. 236

Dehumidification Control Processes ................................................... 243

Heating System Control process ......................................................... 246

Year-Round System Control processes .............................................. 248

ASHRAE Psychrometric Charts .......................................................... 261

Building Airflow System Control Applications ............................................................................................... 263

Introduction.......................................................................................... 265

Definitions............................................................................................ 265

Airflow Control Fundamentals ............................................................. 267

Airflow Control Applications ................................................................. 281

References .......................................................................................... 292

Chiller, Boiler, and Distribution System Control Applications ....................................................................... 293

Introduction.......................................................................................... 297

Abbreviations....................................................................................... 297

Definitions............................................................................................ 297

Symbols............................................................................................... 298

Chiller System Control......................................................................... 299

Boiler System Control.......................................................................... 329

Hot And Chilled Water Distribution Systems Control ........................... 337

High Temperature Water Heating System Control .............................. 376

District Heating Applications ................................................................ 382

Individual Room Control Applications ............................................................................................................ 399

Introduction.......................................................................................... 401

Unitary Equipment Control .................................................................. 412

Hot Water Plant Considerations .......................................................... 428

x ENGINEERING MANUAL OF AUTOMATIC CONTROL

Engineering Information....................................................................................................... 429

Valve Selection and Sizing ................................................................................................................................ 431

Introduction.......................................................................................... 432

Definitions............................................................................................ 432

Valve Selection .................................................................................... 436

Valve Sizing ......................................................................................... 441

Damper Selection and Sizing ............................................................................................................................ 451

Introduction.......................................................................................... 453

Definitions............................................................................................ 453

Damper Selection ................................................................................ 454

Damper Sizing ..................................................................................... 463

Damper Pressure Drop ....................................................................... 468

Damper Applications ........................................................................... 469

General Engineering Data ................................................................................................................................. 471

Introduction.......................................................................................... 472

Weather Data ...................................................................................... 472

Conversion Formulas And Tables........................................................ 475

Electrical Data ..................................................................................... 482

Properties Of Saturated Steam Data................................................... 488

Airflow Data ......................................................................................... 489

Moisture Content Of Air Data .............................................................. 491

Index ....................................................................................................................................... 494

ENGINEERING MANUAL OF AUTOMATIC CONTROL

CONTROL FUNDAMENTALS

1

CONTROL

SYSTEMS

FUNDMENTALS

Contents

Introduction ............................................................................................................ 5

Definitions ............................................................................................................ 5

HVAC System Characteristics ............................................................................................................ 8

General................................................................................................ 8

Heating ................................................................................................ 9

General................................................................................................ 9

Heating Equipment .............................................................................. 10

Cooling ................................................................................................ 11

General................................................................................................ 11

Cooling Equipment .............................................................................. 12

Dehumidification .................................................................................. 12

Humidification ...................................................................................... 13

Ventilation ............................................................................................ 13

Filtration............................................................................................... 14

Control System Characteristics ............................................................................................................ 15

Controlled Variables ............................................................................ 15

Control Loop ........................................................................................ 15

Control Methods .................................................................................. 16

General ........................................................................................... 16

Analog And Digital Control .............................................................. 16

Control Modes ..................................................................................... 17

Two-Position Control ....................................................................... 17

General ....................................................................................... 17

Basic Two-Position Control ......................................................... 17

Timed Two-Position Control ........................................................ 18

Step Control .................................................................................... 19

Floating Control............................................................................... 20

Proportional Control ........................................................................ 21

General ....................................................................................... 21

Compensation Control ................................................................ 22

Proportional-Integral (Pi) Control .................................................... 23

Proportional-Integral-Derivative (Pid) Control ................................. 25

Enhanced Proportional-Integral-Derivative (epid) Control .............. 25

Adaptive Control ............................................................................. 26

Process Characteristics....................................................................... 26

Control

Fundamentals

ENGINEERING MANUAL OF AUTOMATIC CONTROL

CONTROL FUNDAMENTALS

4

Load ................................................................................................ 26

Lag .................................................................................................. 27

General ........................................................................................... 27

Measurement Lag ........................................................................... 27

Capacitance .................................................................................... 28

Resistance ...................................................................................... 29

Dead Time....................................................................................... 29

Control Application Guidelines ............................................................ 29

Control System Components ............................................................................................................ 30

Sensing Elements ............................................................................... 30

Temperature Sensing Elements ...................................................... 30

Pressure Sensing Elements............................................................ 31

Moisture Sensing Elements ............................................................ 32

Flow Sensors .................................................................................. 32

Proof-Of-Operation Sensors ........................................................... 33

Transducers ........................................................................................ 33

Controllers ........................................................................................... 33

Actuators ............................................................................................. 33

Auxiliary Equipment............................................................................. 34

Characteristics And Attributes Of Control Methods .............................................................................................. 35

ENGINEERING MANUAL OF AUTOMATIC CONTROL

CONTROL FUNDAMENTALS

5

INTRODUCTION

This section describes heating, ventilating, and air

conditioning (HVAC) systems and discusses characteristics and

components of automatic control systems. Cross-references

are made to sections that provide more detailed information.

A correctly designed HVAC control system can provide a

comfortable environment for occupants, optimize energy cost

and consumption, improve employee productivity, facilitate

efficient manufacturing, control smoke in the event of a fire,

and support the operation of computer and telecommunications

equipment. Controls are essential to the proper operation of

the system and should be considered as early in the design

process as possible.

Properly applied automatic controls ensure that a correctly

designed HVAC system will maintain a comfortable

environment and perform economically under a wide range of

operating conditions. Automatic controls regulate HVAC

system output in response to varying indoor and outdoor

conditions to maintain general comfort conditions in office

areas and provide narrow temperature and humidity limits

where required in production areas for product quality.

Automatic controls can optimize HVAC system operation.

They can adjust temperatures and pressures automatically to

reduce demand when spaces are unoccupied and regulate

heating and cooling to provide comfort conditions while

limiting energy usage. Limit controls ensure safe operation of

HVAC system equipment and prevent injury to personnel and

damage to the system. Examples of limit controls are low￾limit temperature controllers which help prevent water coils

or heat exchangers from freezing and flow sensors for safe

operation of some equipment (e.g., chillers). In the event of a

fire, controlled air distribution can provide smoke-free

evacuation passages, and smoke detection in ducts can close

dampers to prevent the spread of smoke and toxic gases.

HVAC control systems can also be integrated with security

access control systems, fire alarm systems, lighting control

systems, and building and facility management systems to

further optimize building comfort, safety, and efficiency.

DEFINITIONS

The following terms are used in this manual. Figure 1 at the

end of this list illustrates a typical control loop with the

components identified using terms from this list.

Analog: Continuously variable (e.g., a faucet controlling water

from off to full flow).

Automatic control system: A system that reacts to a change

or imbalance in the variable it controls by adjusting

other variables to restore the system to the desired

balance.

Algorithm: A calculation method that produces a control

output by operating on an error signal or a time series

of error signals.

Compensation control: A process of automatically adjusting

the setpoint of a given controller to compensate for

changes in a second measured variable (e.g., outdoor

air temperature). For example, the hot deck setpoint

is normally reset upward as the outdoor air

temperature decreases. Also called “reset control”.

Control agent: The medium in which the manipulated variable

exists. In a steam heating system, the control agent is

the steam and the manipulated variable is the flow of

the steam.

Control point: The actual value of the controlled variable

(setpoint plus or minus offset).

Controlled medium: The medium in which the controlled

variable exists. In a space temperature control system,

the controlled variable is the space temperature and

the controlled medium is the air within the space.

Controlled Variable: The quantity or condition that is

measured and controlled.

Controller: A device that senses changes in the controlled

variable (or receives input from a remote sensor) and

derives the proper correction output.

Corrective action: Control action that results in a change of

the manipulated variable. Initiated when the

controlled variable deviates from setpoint.

Cycle: One complete execution of a repeatable process. In

basic heating operation, a cycle comprises one on

period and one off period in a two-position control

system.

Cycling: A periodic change in the controlled variable from

one value to another. Out-of-control analog cycling

is called “hunting”. Too frequent on-off cycling is

called “short cycling”. Short cycling can harm electric

motors, fans, and compressors.

Cycling rate: The number of cycles completed per time unit,

typically cycles per hour for a heating or cooling

system. The inverse of the length of the period of the

cycle.