Automatic control for commerical buildings HVAC

ENGINEERING MANUAL of AUTOMATIC CONTROL for COMMERCIAL BUILDINGS SI Edition Copyright 1989, 1995, 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: 97-77856 Home and Building Control Honeywell Inc Honeywell Plaza P.O Box 524 Minneapolis MN 55408-0524 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 Honeywell Europe S.A Avenue du Bourget 1140 Brussels Belgium Honeywell Asia Pacific Inc Room 3213-3225 Sun Hung Kai Centre No 30 Harbour Road Wanchai Hong Kong Printed in USA ii ENGINEERING MANUAL OF AUTOMATIC CONTROL 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 and use the International System of Units (SI) 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 third SI 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 December, 1997 KEVIN GILLIGAN President, H&BC Solutions and Services ENGINEERING MANUAL OF AUTOMATIC CONTROL iii iv ENGINEERING MANUAL OF AUTOMATIC CONTROL 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 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 v vi ENGINEERING MANUAL OF AUTOMATIC CONTROL ENGINEERING MANUAL of AUTOMATIC CONTROL CONTENTS Foreward iii Preface v Control System Fundamentals Control Fundamentals Introduction Definitions HVAC System Characteristics Control System Characteristics Control System Components Characteristics and Attributes of Control Methods 5 15 30 35 Psychrometric Chart Fundamentals Introduction Definitions Description of the Psychrometric Chart The Abridged Psychrometric Chart Examples of Air Mixing Process Air Conditioning Processes Humidifying Process Process Summary ASHRAE Psychrometric Charts 37 38 38 39 40 42 43 44 53 53 Pneumatic Control Fundamentals Introduction Definitions Abbreviations Symbols Basic Pneumatic Control System Air Supply Equipment Thermostats Controllers Sensor-Controller Systems Actuators and Final Control Elements Relays and Switches Pneumatic Control Combinations Pneumatic Centralization Pneumatic Control System Example 57 59 59 60 61 61 65 69 70 72 74 77 84 89 90 Electric Control Fundamentals Introduction Definitions How Electric Control Circuits are Classified Series 40 Control Circuits Series 80 Control Circuits Series 60 Two-Position Control Circuits Series 60 Floating Control Circuits Series 90 Control Circuits Motor Control Circuits 95 97 97 99 100 102 103 106 107 114 ENGINEERING MANUAL OF AUTOMATIC CONTROL vii Electronic Control Fundamentals Introduction Definitions Typical System Components Electronic Controller Fundamentals Typical System Application 119 120 120 122 122 129 130 Microprocessor-Based/DDC Fundamentals Introduction Definitions Background Advantages Controller Configuration Types of Controllers Controller Software Controller Programming Typical Applications 131 133 133 134 134 135 136 137 142 145 Indoor Air Quality Fundamentals Introduction Definitions Abbreviations Indoor Air Quality Concerns Indoor Air Quality Control Applications Bibliography 149 151 151 153 154 164 170 Smoke Management Fundamentals Introduction Definitions Objectives Design Considerations Design Priniples Control Applications Acceptance Testing Leakage Rated Dampers Bibliography 171 172 172 173 173 175 178 181 181 182 Building Management System Fundamentals Introduction Definitions Background System Configurations System Functions Integration of Other Systems 183 184 184 185 186 189 196 viii ENGINEERING MANUAL OF AUTOMATIC CONTROL Control System Applications 199 Air Handling System Control Applications Introduction Abbreviations Requirements for Effective Control Applications-General Valve and Damper Selection Symbols Ventilation Control Processes Fixed Quantity of Outdoor Air Control Heating Control Processes Preheat Control Processes Humidification Control Process Cooling Control Processes Dehumidification Control Processes Heating System Control Process Year-Round System Control Processes ASHRAE Psychrometric Charts 201 203 203 204 206 207 208 209 211 223 228 235 236 243 246 248 261 Building Airflow System Control Applications Introduction Definitions Airflow Control Fundamentals Airflow Control Applications References 263 265 265 266 280 290 Chiller, Boiler, and Distribution System Control Applications Introduction Abbreviations Definitions Symbols Chiller System Control Boiler System Control Hot and Chilled Water Distribution Systems Control High Temperature Water Heating System Control District Heating Applications 291 295 295 295 296 297 327 335 374 380 Individual Room Control Applications Introduction Unitary Equipment Control Hot Water Plant Considerations 395 397 408 424 ENGINEERING MANUAL OF AUTOMATIC CONTROL ix Engineering Information 425 Valve Selection and Sizing Introduction Definitions Valve Selection Valve Sizing 427 428 428 432 437 Damper Selection and Sizing Introduction Definitions Damper Selection Damper Sizing Damper Pressure Drop Damper Applications 445 447 447 448 457 462 463 General Engineering Data Introduction Conversion Formulas and Tables Electrical Data Properties of Saturated Steam Data Airflow Data Moisture Content of Air Data 465 466 466 473 476 477 479 Index 483 x ENGINEERING MANUAL OF AUTOMATIC CONTROL INDEX District Heating 380 Booster Pump Station 383 Definitions 381 Distribution Network 380 Heat Distribution Network 382 Heat generation 382 Heat Sources 380 Hot Water Pipeline 383 Hot Water System Control 382 Mixing Station 383 Primary Network 381 Secondary Network 381 Substation 381 System Configuration 382 Diversity 295 Diverting Valve 436 Domestic Hot Water 381 Double bundle 295 Double-seated valve 431 Down-Blow Unit Heater 410 Droop 6, 19 Dry Air Requirement 66 Dry-Bulb Temperature 38 Dual Duct ATU 406 Constant Volume ATU 407 Dual Temperature Systems 365 Changeover Precautions 365 Multiple-Zone 365 Dynamic Display Data 184 Electronic Indicating Devices 129 Output Control 128 Output Devices 128 Power Supply 129 System Application 130 Transducer 129 Electronic Control 6, 120 Electronic Control Fundamentals 119 Electronic Control Systems 120 Electronic Controller 121, 129 Electronic-Pneumatic Transducer 83 Electrostatic air cleaner 152 Emission standard 152 EMS 184 Energy Management 184 Energy Management Software 138 Distributed Power Demand 142 Enthalpy 139 Load Reset 139 Night Cycle 138 Night Purge 139 Optimum Start 138 Optimum Stop 138 Zero Energy Band 141 Energy Management System 184 Energy/Work Conversion Multipliers 471 Enhanced proportional-integral-derivative (EPID) 6, 25 Enthalpy 39, 139 Enthalpy Controllers Electronic 128 EPID control 6, 26 Equal Percentage Valve 435 Ethylene Glycol Solutions 437 Expansion valve 297 E Economizer 215, 217, 218, 219, 220, 222, 248, 255 Effects of Humidity 160 Temperature 159 Electric Control 6, 120 Electric Control Circuits 97, 99 Electric Control Combinations Series 40 101 Series 60 Floating 106 Series 60 Two-Position 105 Series 80 103 Series 90 111 Electric Control Fundamentals 95 Electric Motors 475 Electric-Pneumatic Relay 82, 87 Electrical Conductors 475 Electrical Data 473 Electrical Distribution Systems 473 Single-Phase System 473 Three-Phase Delta System 474 Three-Phase Four-Wire Wye System 474 Three-Phase Three-Wire Wye System 474 F Facilities Management 185 Fahrenheit/Celsius Conversion Tables 469 Fan Duct system curve 273 Fan and duct system curve comparison 273 Horsepower 273 Laws 273 Performance terms 272 Types 272 Fan Coil Units 418 Four-Pipe Heating/Cooling Single Coil 420 Split Coil 420 Two-Pipe Heating/Cooling 419 Fan Interlock 117 Fan Ratings 477 Feed and Bleed System 63 Fiber Optic 188 Filtration 14 Final Control Element 6, 59 488 ENGINEERING MANUAL OF AUTOMATIC CONTROL INDEX Flame Safeguard Control 330 Instrumentation 331 Floating Control 20 Electric 107 Flow (Gas/Air) Conversion Multipliers 470 (Liquid) Conversion Multipliers 470 Sensing element 32 Flow coefficient 429 Flow tracking 165, 166, 258, 285 Flue Gas Analysis 329 Flushout 152 Force Conversion Multipliers 472 Free Cooling-Tower Cooling 323 Fume hood control 287 Functions Operations-Level 189 Alarm Processing 190 Communications Software 189 Controller Support 191 Hardware 189 Reports 190 Security 190 Server 190 Software 189 Standard Software 189 System Graphics 190 System Text 190 System-Level Controller 189 Zone-Level Controller 189 Fundamentals Control Electronic Controller 129 Indoor Air Quality 152 Heat Recovery System 323 Heat Surface Factor 381 Heat Transfer Station 381 Heating Heating Anticipation 102 Heating coil 10 Heating control processes 223 Heating Process 43 Heating system control processes 246 HEPA filter 152 Hesitation Relay 82 Hierarchical Configuration 184 High Temperature Water Control Selection 375 Heating System Control 374 Safety 375 Space Heating Units 378 Steam Generators 379 Valve Flow Characteristics 376 Valve Selection 375 High Temperature Water (HTW) Heating 374 High-Limit Controller 101, 103, 111 High-Pressure Selector Relay 79 Hot and Chilled Water Distribution Systems Control 335 Hot Water Control Method Selection 364 Reset 361 Supply Temperature Control 361 Flow Control 361 Hot Water Systems Control 360 Modulating 360 HTW Coils 377 Control Selection 375 Space Heating Units 378 HTW Steam Generators 379 HTW Valve Selection 375 HTW Water Converters Multizone Space-Heating 378 Humidification 13 Humidification control processes 235 Humidifier Air Washer 49 Steam Jet 46 Vaporizing 50 Humidifying Process 44 Humidity See Relative Humidity Humidity Controller 71 Humidity Ratio 38 Hunting Hybrid Heat Transfer Substations 386 Hydronic Systems Corrosive Elements 432 Hysteresis 140 G Gas Burners 329 Gas- or Oil-Fired Unit Heater 411 General Engineering Data 465 Global Points 142 Globe Valve 431, 433 Glycol Solutions 437, 438 Graphic Control 195 Specifying 193 Graphic display 168 Graphic Penetration 195 H Hand-Off-Auto Start-Stop Circuit 115 Hardware Configuration 186 Heat anticipation 18 Heat Exchanger 381 Heat Exchanger Substation 381 Heat pump 11, 421 Operation 421 ENGINEERING MANUAL OF AUTOMATIC CONTROL 489 INDEX I Manual Switch Control 86 Materials safety data sheets 152 Measured variable Metric Prefixes 466 Microprocessor-based control Microprocessor-Based Controller 133, 135 Microprocessor-Based/DDC Fundamentals 131 Microprocessor-Based Systems 120 Mixed Air 60 Mixing Valve 436 Modulating 6, 60 Modulating Control Electric 107 Modulating Steam Coil Performance 371 Sensing element 32 Moisture Content 38 Moisture Content of Air Data 479 Moisture in Compressed Air 479 Momentary Fast-Slow-Off Start-Stop Circuit 116 Momentary Start-Stop Circuit 115 Motor Contactors and Relays 114 Control Circuits 114 Control Combinations 117 Starters 114 Hand-Off-Auto 115 Momentary Fast-Slow-Off 116 Momentary Push-Button 115 Motor Starter 128 Multiple Decoupled Chiller Control 313 Multizone Space-Heating HTW Water Converters 378 I/O Summary 193 In-Depth Integration 196 Indicating Device Electronic 129 Indirect Heat Transfer Substations 385 Individual Room Control Applications 395 Individual Room Control Automation 423 Indoor air quality Acceptance testing 163 Air contaminants 154 Codes and standards 162 Concerns 154 Control applications 164 Design considerations 158 Design procedures 160 Indoor air contaminant indicators 158 Indoor Air Quality Fundamentals 149 Induction VAV ATU 402 Infiltration 10 Infrared heater 10 Instantaneous Converter Control 376 Integral Action 121 Integration System 187 In-Depth 188 Surface 188 Isothermal Process 38 L Laboratory pressurization control 288 Lag 27 Latent Heat 38 Legionnaires disease 152 Length Conversion Multipliers 467 Limit Control 85 Limit Controller 112 Limit Sensor 121 Line Voltage 99 Linear Valve 434 Load 6, 26 Load Analyzer Relay 79 Load Reset 135 Lockout Relay 78 Low Pressure Steam Distribution Systems 370 Low Voltage 99 Low-Limit Controller 102, 103, 111 Low-Pressure Selector Relay 79 N Natural Convection Units 408 Negative (Reverse) Reset 121 Night Cycle 138 Night purge control 285 Nozzle-Flapper Assembly 62 O Off gassing 152 Offset 6, 21, 22, 60, 121 Oil Burners 329 On/off control One-Pipe Steam Systems 370 Open-Closed Control 105 Operating Software 133, 137 Operation Series 40 101 Series 60 Floating 106 Series 60 Two-Position 104 Series 80 102 Series 90 108 Operations-Level Functions 189 Processor 184, 187 M Main Line 60 Main Sensor 121 Management-Level Processor 184, 187 Manipulated variable 6, 15, 60 Manual Minimum Positing of Outdoor Air Damper 113 Manual Positioning Switch 84 490 ENGINEERING MANUAL OF AUTOMATIC CONTROL INDEX Operator interface 167 Optimum Start 138 Optimum Stop 138 Output Control 128 Output Devices 128 Pressure Reducing Stations District Heating 383 Pressure Reducing Valve Station 68, 369 Pressure Reducing Valves 69 Pressure Sensor Electronic 127 Pressure sensors 277 Pressure-Dependent ATU 399 Pressure-Independent ATU 399 Primary Network 381 Process Processor Management-Level 184 Operations-Level 184 Programming Configuration 138 Custom Control 138 Data File 138 System Initialization 138 Sensing element 33 Properties of Saturated Steam Data 476 Proportional Band 6, 22, 60, 121 Proportional Control 6, 21, 121 Proportional-Integral 121 Proportional-integral (PI) control 7, 23 Proportional-Integral Controller 72 Proportional-integral-derivative (PID) control 7, 25 Propylene Glycol Solutions 438 Psi to kPa Conversion 466 Psychrometric Aspects Air Conditioning Process 43 Air Washer 49 Cooling and Dehumidification 51 Air Washer 51 Cooling Process 44 Dehumidification and Reheat 52 Heating Process 43 Humidifying Process 44 Mixed Air 42 Steam Jet Humidifier 46 Vaporizing Humidifier 50 Psychrometric Chart Fundamentals 37 Psychrometric Charts 39 ASHRAE 53 Psychrometric Processes 40 Pulse Width Modulation 128 Pump Affinity Laws 339 Efficiency 338 Performance 337 Performance Curves 338 Power Requirements 338 Pump Control Variable Speed 353 Decoupled 358 Minimum Flow 357 Pump Speed Valve Position Load Reset 355 P Parallel Fan ATU 404 Peer Communications Protocol 188 Phone Lines 188 PI PI control 23 PID PID control 25 Pilot Bleed System 62 Pilot-operated valve 431 Piping Arrangements Hot Water 359 Piping Systems Coupled Vs Decoupled 347 Direct Vs Reverse Return 346 Pitot tube sensors 277 Pneumatic Centralization 89 Control Combinations Changeover Control 87 Electric-Pneumatic Relay Control 87 Limit Control 85 Manual Switch Control 86 Pneumatic Recycling Control 88 Pneumatic-Electric Relay Control 88 Reset Control 87 Sequence Control 85 Control System 61, 90 Controller 72 Potentiometer 81 Recycling Control 88 Sensor 73 Switch 83 Pneumatic control Pneumatic Control Fundamentals 37 Pneumatic-Electric Relay 82, 88 Positive (Direct) Reset 121 Positive displacement compressor 295 Positive-Positioning Relay 80 Power Supply Electronic 129 Preheat control processes 228 Pressure Controller 71 Pressure Conversion Multipliers 466 Pressure drop 430 critical 430 Pressure Independent Constant Volume ATU Dual Duct 407 VAV ATU Dual Duct 406 ENGINEERING MANUAL OF AUTOMATIC CONTROL 491 INDEX Pumping Constant speed 295 Primary-Secondary 360 Variable speed 296 Pumps Applied to Open Systems 343 Centrifugal Hot and Chilled Water Systems 336 Matching to Water Distribution Systems 340 Multiple 343 Variable Speed 342 Reset from Outdoor air temperature 225 Hot deck temperature 226 Hot Water 361 Negative 121 Positive 121 Supply Air Temperature 221, 224, 225 Reset Authority 23, 120 Reset Changeover 59 Reset Control 7, 22, 60, 87, 121 Resistance Temperature Devices 122, 124 Restrictor 60, 62 Return Air 60 Reverse Acting 60 Reversing Relay 80 Rod and Tube 64 Rooftop unit 167 Run Time 142 Q Quick-Opening Valve 434 R Radiant Panels 409 Rangeability 296, 429 Ratings Valve 429 Ratio Relay 81 Reciprocating Compressor 295, 299 Reduced-Port valve 431 Refrigerant pressure 296 Refrigeration Absorption 299 Vapor-Compression 297 Relative Humidity 38, 481 Relative Humidity Controllers 128 Relative Humidity Sensor Electronic 125 Relay 99 Electronic 128 Pneumatic Averaging 80 Capacity 79 Electric-Pneumatic 82 Electronic-Pneumatic Transducer 83 Hesitation 82 High Pressure Selector 79 Load Analyzer 79 Lockout 78 Low-Pressure Selector 79 Pneumatic-Electric 82 Positive-Positioning 80 Ratio 81 Reversing 80 Snap Acting 78 Switching 77 Series 40 100 Relays and Switches 64, 77 Remote Setpoint 121 Requirements for effective control 204 S Saturation 38 Screw Compressor 295, 299 Secondary Network 381 Selection and sizing Damper 447 Sensible Heat 38 Sensing Element 7, 30, 31, 33 Averaging 64 Bimetal 63 Flow 32 Moisture 32 Pressure 31 Proof-of-operation 33 Rod and Tube 64 Temperature 30 Sensor 60 Electronic Pressure 127 Electronic Relative Humidity Capacitance 125 Quartz Crystal 126 Resistance 125 Electronic Temperature 122 BALCO 123 Platinum 124 Thermistor 124 Thermocouple 125 Sensor Span 60 Sensor-Controller Pneumatic 72 Velocity 73 Sequence Control 85 Sequencing fan control 285 Series 40 Controller 100 Operation 101 492 ENGINEERING MANUAL OF AUTOMATIC CONTROL INDEX Series 60 Actuators 103, 106 Controller 103 Floating Control Circuits 106 Floating Operation 106 Two-Position Control Circuits 103 Two-Position Operation 104 Series 80 Control Circuits 102 Controller 102 Operation 102 Series 90 Actuator 107 Bridge Circuit 108 Control Circuits 107 Controllers 107 Minimum Positioning 113 Operation 108 Switching Circuits 112 Transfer Circuits 112 Series Fan ATU 404 Setpoint 7, 15, 60, 121 Short cycling Shut-off 429 Sick building syndrome 153 Signal Amplifier 63 Single-Duct VAV ATU 400 Single-Pressure Reducing Valve 69 Single-seated valve 431 Sizing 437, 441 Sling Psychrometer 38 Smoke control 285 Smoke Management Fundamentals 171 Acceptance testing 181 Causes of smoke movement Buoyancy 174 Expansion 175 HVAC 177 Stack effect 175 Wind velocity 176 Control of malls, atria, and large areas 181 Control of smoke Airflow 178 Pressurization 177 Objectives 173 Codes and standards 174 General 173 Layout of system 174 Purging 178 Stairwell pressurization control 180 Zone pressurization control 179 Snap Acting Relay 78 Software Application 133, 137 Building Management 142 Direct Digital Control 137 Operating 133, 134 Solenoid Brake 97, 100, 101 Solenoid Valve 128 ENGINEERING MANUAL OF AUTOMATIC CONTROL Specific Volume 39 Spring Range 74 Stack effect 271 Starters 114 Steam Heating Devices 371 Pressure, Temperature, and Density 367 Properties 366 Quality 367 System Objectives 366 Steam Coil Low Temperature Protection 373 Performance Modulating 371 System Design Considerations 373 Steam Distribution Systems 368 Steam Distribution Systems and Control 366 Steam Jet Humidifier 46 Steam Piping Mains 368 Steam System Heat Characteristics 367 Steam Systems Advantages 366 Steam Traps 368 Steam Valve Control 105 Sizing 441 Step control Step controller 19 Electric 114 Storage Converters 378 Strain Gage 127 Substations Direct Heat Transfer 384 Hybrid Heat Transfer 386 Indirect Heat Transfer 385 Summer/Winter Changeover Control 105 Superheat 296, 297 Supply Air Air Leaving an Air Handling System 60 Supply and Return Main Pressures 373 Surface Integration 196 Surge 296 Switch Pneumatic Pneumatic Manual Positioning 84 Pneumatic Potentiometer 81 Pneumatic Switch 83 Switching Relay 77 Symbols 296 System Application Electronic 130 System Configurations 186 System Initialization Programming 143 System Integration 196 System-Level Controller 133, 136, 146, 185 Controller Functions 185 493 INDEX T U Temperature Dew-Point 38 Dry-Bulb 38 Wet-Bulb 39 Temperature Controller 71 Temperature Controllers Electronic 128 Temperature Sensor Electronic 122 Terminal Units Control 365 Thermal Storage Control 315 Control Modes 315 Thermistor 124 Thermocouple 125 Thermostat Pneumatic 60 Dual Temperature 69 Dual-Acting 69 High Capacity, Single Temperature 69 Low-Capacity, Single Temperature 69 Three-way Valve 431, 436 Throttling Range 7, 22, 60, 121 Adjustment 64 Throttling VAV ATU 400 Time and Event Programs 142 Time constant Time Proportioning 19, 102 Timed two-position control 18 Torque Conversion Multipliers 472 Total and static pressure sensors 278 Total Heat 39 Tower Free Cooling, Dual Chillers 325 Toxicity 153 Transducer 33 Electronic 121, 125, 128, 129 Electronic-to-Pneumatic 129 Transformer 99 Transmission Transmitter Electronic 121, 125, 127 Turndown 429 Twisted Copper Pair 188 Two-Pipe Steam Systems 370 Two-Position Control 7, 17, 105 Electric 107 Two-Pressure Reducing Valve 69 Two-Way Valve 431, 434 Unbalanced loading 295 Unit Heater 10, 409 Control 101, 410 Modulating 410 Two-Position 410 Down-Blow 410 Gas Fired 411 Oil Fired 411 Unit Ventilator 10, 411 ASHRAE Control Cycles 412 Control 412 Day/Night Setback 414 Digital 415 Draw-through 412 Unitary Equipment Control 408 Universal Controllers Electronic 128 V Valve 75 Ball 430, 433 Body rating 430 Butterfly 431, 433 Components 428 Diverting 436 Double-seated 431 Equal Percentage 435 Expansion 297 Globe 431, 433 Linear 434 Material and Media 431 Maximum Pressure 430 Temperature 430 Mixing 436 Pilot-operated 431 Quick-Opening 434 Ratings 429 Reduced-Port 431 Selection 432 Single-seated 431 Sizing 437, 441 Steam Sizing 441 Three-way 431 Two-way 431, 434 Types 430 Water Sizing 437 Valve Control Coil 348 494 ENGINEERING MANUAL OF AUTOMATIC CONTROL INDEX W Valve Flow Characteristics 376, 428 Terms 429 Valve Selection and Sizing 427 Vapor-Compression Cycle 297 Refrigeration 297 Vaporizing Humidifier 50 Variable Air Volume 267, 280 Relief fan control 283 Return air damper control 283 Return fan control 281 Supply fan control 280 Variable Air Volume ATU 399, 401, 402 Variable speed pumping (VSP) 296 Variable Vacuum Return Systems 371 Velocity Conversion Multipliers 470 Velocity Pressure 478 Velocity Sensor-Controller 73 Ventilation 10, 13 Ventilation control processes 209 Volatile organic compound 153 Voltage Conversion 475 Volume Conversion Multipliers 468 ENGINEERING MANUAL OF AUTOMATIC CONTROL Warmup control 285 Water Valves Sizing 437 Weight/Mass Conversion Multipliers 467 Wet-Bulb Temperature 39 Wind pressure effect 271 Work/Energy Conversion Multipliers 471 Y Year-round system control processes 248 Z Zero Energy Band 7, 141 Zone-Level Controller 133, 145, 185, 186 Functions 189 Zoning 495 INDEX NOTES 496 ENGINEERING MANUAL OF AUTOMATIC CONTROL INDEX NOTES ENGINEERING MANUAL OF AUTOMATIC CONTROL 497 INDEX NOTES 498 ENGINEERING MANUAL OF AUTOMATIC CONTROL INDEX NOTES ENGINEERING MANUAL OF AUTOMATIC CONTROL 499 INDEX NOTES 500 ENGINEERING MANUAL OF AUTOMATIC CONTROL INDEX NOTES ENGINEERING MANUAL OF AUTOMATIC CONTROL 501 INDEX NOTES 502 ENGINEERING MANUAL OF AUTOMATIC CONTROL ... sound approaches to automatic control ENGINEERING MANUAL OF AUTOMATIC CONTROL v vi ENGINEERING MANUAL OF AUTOMATIC CONTROL ENGINEERING MANUAL of AUTOMATIC CONTROL CONTENTS Foreward ... perform limited, predetermined control functions and sequences Microprocessor-based controllers use digital control for a wide variety of control sequences 16 ENGINEERING MANUAL OF AUTOMATIC CONTROL. .. ENGINEERING MANUAL OF AUTOMATIC CONTROL CONTROL FUNDAMENTALS INTRODUCTION Automatic controls can optimize HVAC system operation They can adjust temperatures and pressures automatically to reduce