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ENGINEERING MANUAL OF AUTOMATIC CONTROL i HONEYWELL ENGINEERING MANUAL of AUTOMATIC CONTROL for COMMERCIAL BUILDINGS ENGINEERING MANUAL OF AUTOMATIC CONTROL ii 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 ENGINEERING MANUAL OF AUTOMATIC CONTROL iv 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. ENGINEERING MANUAL OF AUTOMATIC CONTROL vi 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 ENGINEERING MANUAL OF AUTOMATIC CONTROL viii 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 ENGINEERING MANUAL OF AUTOMATIC CONTROL x 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 [...]... 13 13 14 Control System Characteristics Controlled Variables Control Loop Control Methods General Analog And Digital Control Control Modes Two-Position Control General Basic Two-Position Control Timed Two-Position Control Step Control Floating Control Proportional Control. .. OF AUTOMATIC CONTROL The basic control loops in a central air handling system can be classified as shown in Table 1 Depending on the system, other controls may be required for optimum performance Local or zone controls depend on the type of terminal units used 8 CONTROL FUNDAMENTALS Table 1 Functions of Central HVAC Control Loops Control Loop Classification Ventilation Description Basic Better Controls... the differential gap The controlled variable fluctuates between the two temperatures CLOSED Basic two-position control works well for many applications For close temperature control, however, the cycling must be accelerated or timed ANALOG CONTROL SIGNAL OPEN TIME BASIC TWO-POSITION CONTROL DIGITAL CONTROL SIGNAL In basic two-position control, the controller and the final control element interact without... microprocessor controlled Pneumatic control systems use varying air pressure from the sensor as input to a controller, which in turn produces a pneumatic output signal to a final control element Pneumatic, electromechanical, and electronic systems perform limited, predetermined control functions and sequences Microprocessor-based controllers use digital control for a wide variety of control sequences... Attributes Of Control Methods 35 Control System Components ENGINEERING MANUAL OF AUTOMATIC CONTROL 4 CONTROL FUNDAMENTALS INTRODUCTION 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... by a heat anticipator in electric controls and by a timer in electronic and digital controls 72 71 CONTROL POINT 70 69 68 TIME C2089 Fig 23 Comparison of Basic Two-Position and Timed Two-Position Control In timed two-position control, the basic interaction between the controller and the final control element is the same as for basic two-position control However, the controller responds to gradual changes... sensors The controller often furnishes flexible DDC and energy management control routines Digital control: A control loop in which a microprocessorbased controller directly controls equipment based on sensor inputs and setpoint parameters The programmed control sequence determines the output to the equipment Droop: A sustained deviation between the control point and the setpoint in a two-position control. .. applications Automatic control requires a system in which a controllable variable exists An automatic control system controls the variable by manipulating a second variable The second variable, called the manipulated variable, causes the necessary changes in the controlled variable In a room heated by air moving through a hot water coil, for example, the thermostat measures the temperature (controlled... The controller reconverts the output value to a signal to operate an actuator The controller samples digital data at set time intervals, rather than reading it continually The sampling method is called discrete control signaling If the sampling interval for the digital controller is chosen properly, discrete output changes provide even and uninterrupted control performance CONTROL METHODS GENERAL An automatic. .. including the control algorithm, and sends a signal to an actuator In many of the larger commercial control systems, an electronic-pneumatic transducer converts the electric output to a variable pressure output for pneumatic actuation of the final control element The most common forms of energy for automatic control systems are electricity and compressed air Systems may comprise one or both forms of energy . ENGINEERING MANUAL OF AUTOMATIC CONTROL i HONEYWELL ENGINEERING MANUAL of AUTOMATIC CONTROL for COMMERCIAL BUILDINGS ENGINEERING MANUAL OF AUTOMATIC CONTROL ii Copyright. approaches to automatic control. ENGINEERING MANUAL OF AUTOMATIC CONTROL vi ENGINEERING MANUAL OF AUTOMATIC CONTROL vii CONTENTS Foreward iii Preface v Control