Analysis and design of heating, ventilating, and air-conditioning systems

Analysis and Design of

Heating, Ventilating, and

Air-Conditioning Systems

Analysis and Design of

Heating, Ventilating, and

Air-Conditioning Systems

Second Edition

Herbert W. Stanford III and

Adam F. Spach

CRC Press

Taylor & Francis Group

6000 Broken Sound Parkway NW, Suite 300

Boca Raton, FL 33487-2742

© 2019 by Taylor & Francis Group, LLC

CRC Press is an imprint of Taylor & Francis Group, an Informa business

No claim to original U.S. Government works

Printed on acid-free paper

International Standard Book Number-13: 978-1-138-60241-0 (Hardback)

This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been

made to publish reliable data and information, but the author and publisher cannot assume responsibility for the

validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the

copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to

publish in this form has not been obtained. If any copyright material has not been acknowledged, please write and let

us know so we may rectify in any future reprint.

Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or

utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including

photocopying, microfilming, and recording, or in any information storage or retrieval system, without written

permission from the publishers.

For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://

www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA

01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users.

For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been

arranged.

Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for

identification and explanation without intent to infringe.

Visit the Taylor & Francis Web site at

http://www.taylorandfrancis.com

and the CRC Press Web site at

http://www.crcpress.com

v

Contents

Preface........................................................................................................................................... xiii

Authors ...........................................................................................................................................xv

Section I Basic Concepts

1. HVAC Basics ............................................................................................................................3

1.1 Overview of HVAC.......................................................................................................3

1.1.1 Definition of Air-Conditioning......................................................................3

1.1.2 Energy Impact of HVAC Systems..................................................................4

1.2 Buildings as Thermodynamic Systems .....................................................................5

1.2.1 Systems Concepts.............................................................................................5

1.2.2 Energy Gains and Losses in Building Spaces..............................................6

1.2.3 Building Envelope Design..............................................................................7

1.3 Common HVAC Elements ...........................................................................................9

1.3.1 Structural Support for HVAC Components .................................................9

1.3.2 Electrical Aspects of HVAC Systems ..........................................................12

1.4 Definitions of HVAC Terms.......................................................................................25

Bibliography ........................................................................................................................... 31

2. The Air-Conditioning Process...........................................................................................33

2.1 Introduction .................................................................................................................33

2.2 Air and Its Properties .................................................................................................34

2.2.1 Atmospheric Air ............................................................................................34

2.2.2 Water Vapor....................................................................................................35

2.2.3 Terminology....................................................................................................35

2.2.4 Basic Psychrometrics .....................................................................................36

2.3 Methods of Measurement and Analysis..................................................................36

2.3.1 Thermodynamic Wet-Bulb Temperature ...................................................36

2.3.2 The Psychrometer.......................................................................................... 37

2.3.3 The Psychrometric Chart..............................................................................38

2.4 Typical Air-Conditioning Processes ........................................................................ 41

2.4.1 Sensible Heating or Cooling......................................................................... 41

2.4.2 Combined Sensible and Latent Cooling (Dehumidification) ..................42

2.4.3 Heating and Humidification........................................................................43

2.4.4 Evaporative Cooling ......................................................................................44

2.4.5 Air Mixing ......................................................................................................45

2.5 Psychrometric Analysis of Complete Systems........................................................46

2.5.1 Space Heating and Cooling Loads ..............................................................46

2.5.2 Sensible Cooling Load...................................................................................47

2.5.3 Latent Cooling Loads ....................................................................................48

2.5.4 Psychrometric Chart Representation of Space Conditions......................49

2.5.5 The Coil Line ..................................................................................................50

2.5.6 Coil Contact and Bypass Factors ................................................................. 51

vi Contents

2.5.7 Psychrometric Analysis of Complete Systems .......................................... 52

Bibliography ........................................................................................................................... 52

3. HVAC Systems Concepts ....................................................................................................53

3.1 Introduction .................................................................................................................53

3.2 All-Air Systems ...........................................................................................................53

3.2.1 Single-Zone Systems......................................................................................56

3.2.2 VAV Systems ...................................................................................................58

3.2.3 Dual–Duct Systems .......................................................................................59

3.2.4 Multizone Systems......................................................................................... 62

3.2.5 VAV/Variable Temperature Systems ........................................................... 62

3.3 Air–Water Secondary Systems ..................................................................................65

3.3.1 Active and Passive Chilled Beam Systems.................................................65

3.3.2 FCUs and Unit Ventilators............................................................................ 67

3.4 Unitary Systems ..........................................................................................................68

3.4.1 Incremental Units ..........................................................................................68

3.4.2 Packaged Units...............................................................................................69

3.4.3 Split Systems ...................................................................................................69

3.4.4 Variable Refrigerant Flow Systems.............................................................. 70

3.5 Heat Pumps..................................................................................................................72

3.5.1 The Heat Pump Concept...............................................................................72

3.5.2 Air-Source Heat Pumps ................................................................................ 74

3.5.3 Water-Source Heat Pumps............................................................................ 76

3.5.3.1 Closed Circuit Heat Pump Systems............................................. 76

3.5.3.2 Closed Circuit Geothermal Heat Pump Systems ......................77

3.5.3.3 Open Circuit Geothermal Heat Pump Systems.........................80

3.5.3.4 Gas-Fired Engine-Driven Heat Pumps .......................................80

3.5.3.5 Heat Recovery Chiller/Heat Pump System................................80

3.5.4 Advanced Technology Heat Pumps............................................................ 81

Bibliography ...........................................................................................................................82

Section II The Design Method

4. HVAC Systems Design........................................................................................................85

4.1 Introduction .................................................................................................................85

4.2 Criteria for HVAC Design..........................................................................................87

4.3 Compliance with Building Codes and Standards..................................................88

4.3.1 International Mechanical Code ...................................................................88

4.3.2 International Energy Conservation Code ..................................................88

4.3.3 NFPA Standards and Guidelines ................................................................90

4.3.4 ASHRAE Standards and Guidelines ..........................................................90

4.4 Designing for Maintainability .................................................................................. 91

4.4.1 HVAC Equipment Location and Access .....................................................92

4.4.2 Mechanical Equipment Rooms for Air-Handling Equipment................93

4.4.3 Mechanical Equipment Rooms for Boilers and Chillers..........................93

4.4.4 Ceiling Cavity Space......................................................................................94

4.5 Designing for Energy Conservation ........................................................................95

Contents vii

4.5.1 Introduction to ASHRAE Standard 90.1.....................................................95

4.5.2 Simplified Energy Analysis..........................................................................96

4.5.3 Building Energy Modeling...........................................................................97

4.5.4 Exhaust Air Heat Recovery ..........................................................................99

4.5.5 Internal Source Heat Recovery .................................................................. 102

4.5.6 Thermal Energy Storage ............................................................................. 103

4.6 Designing for Sustainability ................................................................................... 105

4.6.1 High-Performance Building Elements...................................................... 105

4.6.2 Introduction to ASHRAE Standard 189.1 ................................................. 108

4.6.3 Net Zero/Sum Zero-Energy Buildings..................................................... 108

4.7 Construction Documents Quality Control............................................................ 110

Bibliography ......................................................................................................................... 112

5. Heating/Cooling Load Calculation................................................................................. 113

5.1 Introduction ............................................................................................................... 113

5.1.1 Building Thermal Balance.......................................................................... 113

5.1.2 Purpose of Load Calculations.................................................................... 113

5.2 Mechanics of Building Heat Loss and Gain.......................................................... 113

5.2.1 Design Conditions ....................................................................................... 114

5.2.2 Heat Transfer through Walls and Roofs................................................... 115

5.2.3 Heat Transfer through Fenestration.......................................................... 118

5.2.4 Heat Loss through Floors and Basements................................................122

5.2.5 Internal Heat Gains ..................................................................................... 124

5.2.6 Infiltration Loads .........................................................................................125

5.3 Load Computation Methodologies......................................................................... 128

5.3.1 Heat Balance and Radiant Time Series..................................................... 128

5.3.2 Total Equivalent Temperature Difference with Time Averaging ......... 130

5.3.3 Transfer Function......................................................................................... 131

5.3.4 Computer-Based Calculation Tools........................................................... 131

5.5 Benchmark Heating/Cooling Loads ...................................................................... 132

Bibliography ......................................................................................................................... 134

6. Air Tempering and Distribution..................................................................................... 135

6.1 Heating and Cooling Coils ...................................................................................... 135

6.1.1 Direct Expansion Refrigerant Cooling Coils ........................................... 138

6.1.2 Chilled Water Cooling Coils ...................................................................... 140

6.1.3 Hot Water Heating Coils............................................................................. 141

6.1.4 Steam Heating Coils .................................................................................... 141

6.1.5 Electric Resistance Heating Coils .............................................................. 141

6.1.6 Preheating and Precooling Coils ............................................................... 143

6.1.7 Desiccant Cooling and Dehumidification................................................ 146

6.2 Air Distribution Design ........................................................................................... 147

6.2.1 Room Air Diffusion..................................................................................... 147

6.2.2 Typical Air Distribution Patterns .............................................................. 148

6.2.3 Large Space Air Distribution ..................................................................... 154

6.2.4 Displacement Ventilation Air Distribution.............................................. 155

6.3 Terminal Units........................................................................................................... 157

6.3.1 VAV Single-Duct TUs .................................................................................. 157

viii Contents

6.3.2 VAV Single-Duct Fan-Powered TUs .......................................................... 160

6.3.3 VAV Dual Duct TUs..................................................................................... 160

Bibliography ......................................................................................................................... 161

7. Duct Design ......................................................................................................................... 163

7.1 Introduction ............................................................................................................... 163

7.1.1 Steps in Duct System Design...................................................................... 163

7.1.2 Duct Air Balancing Rationale .................................................................... 164

7.2 Energy and Pressure Relationships........................................................................ 164

7.3 Friction Losses ........................................................................................................... 166

7.3.1 Calculation of Friction Losses in Ducts.................................................... 166

7.3.2 Calculation of Friction Losses in Fittings................................................. 170

7.4 Methods of Duct Design .......................................................................................... 171

7.4.1 Constant Velocity Method.......................................................................... 171

7.4.2 Velocity Reduction Method........................................................................ 171

7.4.3 Static Regain Method .................................................................................. 171

7.4.4 Equal Friction Method ................................................................................ 172

7.4.5 Duct Construction Criteria......................................................................... 173

7.4.6 Duct Design Guidelines.............................................................................. 174

7.5 Special Exhaust Systems Design............................................................................. 176

7.5.1 Laboratory Exhaust Systems ...................................................................... 176

7.5.2 Industrial Exhaust Systems ........................................................................ 179

7.6 Duct Insulation.......................................................................................................... 181

7.7 Fire and Smoke Control in Duct Systems.............................................................. 182

Bibliography ......................................................................................................................... 183

8. Piping Design...................................................................................................................... 185

8.1 Introduction ............................................................................................................... 185

8.1.1 Viscosity ........................................................................................................ 185

8.1.2 Weight Density, Specific Volume, and Specific Gravity ......................... 185

8.1.3 Mean Velocity of Flow................................................................................. 186

8.1.4 Piping Basics................................................................................................. 187

8.2 Hydronic Piping........................................................................................................ 191

8.2.1 Pipe Routing and Sizing ............................................................................. 192

8.2.2 Pressure Loss Calculation .......................................................................... 196

8.2.3 Expansion and Air Removal ...................................................................... 198

8.2.4 Freeze Protection.......................................................................................... 201

8.3 Steam and Condensate Piping ................................................................................ 202

8.3.1 Pipe Routing and Sizing .............................................................................203

8.3.2 Steam Trap Application and Sizing...........................................................206

8.3.3 Control of Steam Piping Expansion ..........................................................209

8.4 Refrigerant Piping..................................................................................................... 210

8.4.1 Design Considerations ................................................................................ 210

8.4.2 Suction Lines ................................................................................................ 213

8.4.3 Liquid Lines.................................................................................................. 215

8.5 Piping Insulation....................................................................................................... 215

8.5.1 Hot Piping Insulation.................................................................................. 215

8.5.2 Cold Piping Insulation ................................................................................ 215

Bibliography ......................................................................................................................... 218

Contents ix

Section III Systems and Components

9. Pumps and Fans .................................................................................................................. 221

9.1 Introduction ............................................................................................................... 221

9.2 Pumps and Applications.......................................................................................... 221

9.2.1 Pump Types and Characteristics............................................................... 221

9.2.2 Pump Arrangements...................................................................................225

9.2.3 Water Flow Volume Control.......................................................................230

9.3 Fans ............................................................................................................................. 231

9.3.1 Fan Energy Relations................................................................................... 231

9.3.2 Fan Types and Characteristics ...................................................................233

9.3.3 Fan and System Characteristics ................................................................. 237

9.3.4 System Effects...............................................................................................238

9.3.5 Variable Air Volume Fan Control.............................................................. 242

9.4 Pump and Fan Affinity Laws.................................................................................. 243

Bibliography ......................................................................................................................... 243

10. Terminal Systems and Components............................................................................... 245

10.1 Systems Types and Applications ............................................................................ 245

10.1.1 Selecting the Right System for the Application....................................... 245

10.1.2 Space Needs and Other Requirements for Terminal Systems .............. 245

10.2 AHUs and Components........................................................................................... 249

10.2.1 AHUs ............................................................................................................. 249

10.2.2 Particulate Air Filtration.............................................................................253

10.2.3 Gas-Phase Filtration ....................................................................................255

10.2.4 Ultraviolet Air and Surface Treatment .....................................................256

10.2.5 Airside Economizer Cycle .......................................................................... 257

10.2.6 Cooling Coils Condensate Drainage......................................................... 261

10.3 Humidification .......................................................................................................... 262

10.4 Ventilation and Building Pressurization...............................................................264

10.4.1 Outdoor Air Intakes ....................................................................................265

10.4.2 Understanding and Applying ASHRAE Standard 62.1......................... 267

10.4.3 Demand Control Ventilation...................................................................... 271

10.4.4 Dedicated Outdoor Air Systems................................................................ 274

Bibliography ......................................................................................................................... 275

11. Refrigeration Systems and Components .......................................................................277

11.1 Refrigeration Basics ..................................................................................................277

11.1.1 Refrigerant Issues.........................................................................................277

11.1.2 Vapor Compression Refrigeration Cycle .................................................. 278

11.1.3 Vapor Absorption Refrigeration Cycle ..................................................... 282

11.2 Direct Expansion Refrigeration Systems ...............................................................285

11.3 Chilled Water Refrigeration Systems .....................................................................288

11.3.1 Determining Chilled Water Supply Temperature ..................................289

11.3.2 Establishing Chilled Water Temperature Range.....................................289

11.3.3 Vapor Compression Cycle Water Chillers ................................................290

11.3.4 Scroll Compressor Water Chillers ............................................................. 292

11.3.5 Rotary Screw Compressor Water Chillers ............................................... 297

11.3.6 Centrifugal Compressor Water Chillers................................................... 297

x Contents

11.3.7 Absorption Water Chillers..........................................................................299

11.3.8 Chilled Water System Configurations ......................................................300

11.3.9 Chilled Water Buffer Tanks........................................................................307

11.4 Condensers and Cooling Towers............................................................................308

11.4.1 Air-Cooled Condensers ..............................................................................308

11.4.2 Cooling Tower Fundamentals....................................................................309

11.4.3 Tower Configuration and Application...................................................... 314

11.4.4 Closed Circuit Evaporative Cooler............................................................ 319

11.5 Evaporative Air Cooling .......................................................................................... 320

11.6 Waterside Economizer Cycle ................................................................................... 320

Bibliography ......................................................................................................................... 323

12. Heating Systems and Components ................................................................................. 325

12.1 Firing Fossil Fuels ..................................................................................................... 325

12.1.1 Oil-Fired Systems......................................................................................... 325

12.1.2 Gas-Fired Systems........................................................................................ 328

12.2 Furnaces ..................................................................................................................... 329

12.3 Boilers .........................................................................................................................330

12.3.1 Boiler Types, Ratings, and Efficiency........................................................330

12.3.2 Application Considerations........................................................................ 331

12.3.3 Boiler/Furnace Venting............................................................................... 332

12.4 Hydronic Heating Systems ......................................................................................333

12.5 Steam Heating Systems ............................................................................................335

12.5.1 Steam Quality...............................................................................................335

12.5.2 Steam Heat Transfer....................................................................................338

12.5.3 Steam-to-Water Heat Exchangers ..............................................................338

12.5.4 Feedwater System ........................................................................................339

12.5.5 Steam Pressure Reducing Valves...............................................................339

12.5.6 Steam Condensate Receivers and Pumps.................................................343

Bibliography .........................................................................................................................344

13. HVAC Controls ...................................................................................................................345

13.1 DDC Fundamentals ..................................................................................................346

13.2 DDC Input/Output Points ....................................................................................... 351

13.2.1 Input/Output Basics .................................................................................... 351

13.2.2 DI Devices ..................................................................................................... 352

13.2.3 AI Devices .....................................................................................................353

13.2.4 DO Devices ...................................................................................................363

13.2.5 AO Devices ...................................................................................................364

13.3 Final Control Elements.............................................................................................366

13.3.1 Control Valves ..............................................................................................366

13.3.2 Control Dampers..........................................................................................368

13.4 Direct Digital Controllers and Systems ................................................................. 370

13.4.1 DDC System Architecture .......................................................................... 370

13.4.2 Controllers and Control Loops .................................................................. 371

13.4.3 Networks and Communication ................................................................. 372

13.5 HVAC Sequences of Operation ............................................................................... 375

13.6 DDC System Security ...............................................................................................377

Contents xi

13.7 DDC System Design Checklist................................................................................ 379

Bibliography .........................................................................................................................380

Section IV Special Considerations

14. Special HVAC Design Considerations...........................................................................383

14.1 Indoor Air Quality....................................................................................................383

14.2 Antiterrorism Design for HVAC Systems..............................................................385

14.2.1 Introduction..................................................................................................385

14.2.2 Terror Threats against Buildings...............................................................386

14.2.3 HVAC Design to Minimize Explosive Threats........................................ 387

14.2.4 HVAC Design to Minimize CBR Threats .................................................388

14.3 HVAC Water Treatment............................................................................................390

14.3.1 Hot and Chilled Water Systems Chemical Treatment............................390

14.3.2 Evaporative Cooling Water Systems Chemical Treatment ....................390

14.3.3 Evaporative Cooling Water Systems Nonchemical Treatment.............. 394

14.3.4 Steam and Condensate Systems Chemical Treatment ........................... 396

14.3.5 Legionella Risk Management in HVAC Water Systems...........................399

14.4 Vibration and Noise Mitigation ..............................................................................400

14.4.1 Noise Definition and Design Criteria .......................................................400

14.4.2 Indoor Noise Control in HVAC Systems .................................................. 401

14.4.3 Outdoor Noise Issues in HVAC Systems..................................................404

14.5 HVAC Systems Start-Up and Commissioning......................................................407

14.5.1 HVAC Systems Operation Prior to Commissioning...............................407

14.5.2 The Commissioning Process......................................................................408

14.6 Correcting HVAC Performance for Altitude and Temperature ......................... 410

Bibliography ......................................................................................................................... 411

15. Engineering Economics and Design Decision-Making ............................................. 413

15.1 Introduction ............................................................................................................... 413

15.2 Defining HVAC Design Alternatives ..................................................................... 415

15.3 Estimating Capital Requirements........................................................................... 417

15.3.1 Capital Cost Estimating .............................................................................. 417

15.3.2 Time/Money Relationships........................................................................ 418

15.4 Recurring Costs Determination..............................................................................420

15.4.1 Utilities Costs................................................................................................420

15.4.2 Maintenance Costs....................................................................................... 421

15.5 Component Service Life and Replacement ...........................................................422

15.6 Comparing Alternatives and Dealing with Uncertainty .................................... 424

15.6.1 Alternatives with Different Economic Lives............................................427

15.6.2 Sensitivity Analysis .....................................................................................427

15.6.3 Selecting Alternatives within the Project Budget ...................................428

15.7 Overview of LCCA ...................................................................................................429

15.7.1 Basic Practices for LCCA.............................................................................429

15.7.2 Calculations and Analysis Tools ...............................................................429

Bibliography .........................................................................................................................430

xii Contents

16. Building Information Modeling ..................................................................................... 431

16.1 Introduction ............................................................................................................... 431

16.2 BIM Advantages ........................................................................................................ 432

16.3 Applying BIM............................................................................................................434

16.3.1 BIM Use by HVAC Designers.....................................................................435

16.3.2 BIM Use by Contractors/Subcontractors..................................................436

16.3.3 BIM Use by Owners.....................................................................................436

16.4 AIA Contracts............................................................................................................436

Bibliography .........................................................................................................................437

17. Construction Contract Administration..........................................................................439

17.1 Introduction ...............................................................................................................439

17.2 Design Period Considerations.................................................................................440

17.3 Preconstruction Procedures and Practices............................................................442

17.4 Construction Period Procedures and Practices ....................................................444

17.5 Completion and Closeout Procedures and Practices...........................................448

17.6 Avoiding Litigation Pitfalls......................................................................................449

17.7 Construction Administration Checklist................................................................ 452

17.7.1 Construction Administration Practices and Procedures Checklist .....453

Index ................................................... 457

xiii

Preface

The first edition of this book came about as the outgrowth of a conversation between a

group of practicing heating, ventilating, and air-conditioning (HVAC) design engineers

in 1983 concerning their dissatisfaction with both the textbooks used in HVAC college

courses (what few there were) and the design handbooks then available. Thus, I set out

to write a text that I would have liked to have had as a student and one that I would have

retained as a practicing engineer. I feel that the first edition had some success in meeting

the following objectives:

1. To build a text around a strong “systems” point of view with emphasis on the

energy consumption ramifications of design decisions

2. To primarily address HVAC applications for institutional, commercial, and indus￾trial buildings

3. To make this text valuable as a resource tool for the practicing engineer

4. To use the methodologies of the American Society of Heating, Refrigerating, and

Air-Conditioning Engineers (ASHRAE) Handbook as the primary reference source.

These objectives continue to apply in this second edition.

Another major impetus to the writing of this book was the fact that for many years

I made a very good living investigating and solving HVAC system operating problems in

buildings, many of which were the result of inadequate or incorrect design. Even now, a

recent survey conducted by one major industry magazine indicates that the majority of all

building owners queried responded that there were problems and ongoing dissatisfaction

with the HVAC systems in their buildings. These experiences indicate that HVAC design

engineers are still too often doing a less-than-adequate job in the delivery of the final

product: an HVAC system that “satisfies.”

The “science” of HVAC design is well developed. One has only to read the ASHRAE

Handbook and other texts currently in use in the academic environment to realize that the

basics of psychometrics, heat gain/loss calculations, fluid flow, fan and pump operations,

and so on are well defined and readily available to the practicing engineer. Thus, while

this text also addresses these fundamental topics, it is, rather, the “art” of successful HVAC

design, including proper system and component application, which was incorporated into

the first edition and significantly expanded in this second edition.

Design goes beyond load calculations and duct and pipe sizing. In fact, these are the

smallest parts of the design effort. It is more important for the design engineer to have a

proper grasp of systems applications, controls, and the basics of “fitting the right solution to

solve the problem.” In this text, significant emphasis is placed on “systems” considerations

of each basic topic.

A word about units: In 1981, ASHRAE published their Handbook-Fundamentals in which

the primary unit designations were in accordance with the Système International (SI). The

result was a handbook that was useless to the practicing professional in the United States,

and there subsequently was a “revolt” within the membership of ASHRAE between the

academic and practicing sides of the organization. The compromise was the publishing of

xiv Preface

the 1985 Handbook-Fundamentals (and all subsequent volumes) in two separate editions, one

using the inch-pound (IP) system and the other using SI.

The first edition of this book, published in 1988, utilized only IP units. Since then, though,

the HVAC market has become more global in nature and now ASHRAE requires dual unit

publications. Thus, this edition uses IP units and equations as primary, with SI units and

equations as secondary, in accordance with the SI Guide for HVAC&R, American Society of

Heating, Refrigerating, and Air-Conditioning Engineers, Inc., Atlanta, Georgia, 2013.

Now, 30 years since the first edition of this book was published, a number of HVAC

topics have changed: heating/cooling load calculation methodologies, indoor air-quality

considerations, control systems and sequences of operation, increased emphasis on

energy efficiency and sustainability, etc. Since my semiretirement in 1998, I have written

and taught on a number of these developing issues in HVAC design and this new text

incorporates much of that material.

However, the HVAC design business has also changed over the last 30 years…

production methods (the transition from hand drafting to computer-aided drafting to

building information modeling), the general reduction in contractor skills and capabilities

(resulting in a need for the detail and coordination within design documents), the impact

of greatly expanded building codes and industry standards, etc., are all markedly different

that they were in 1988.

This created the need for a coauthor who had the expertise and experience to address

these areas in this edition. Therefore, I asked Adam F. Spach, P.E., a friend and colleague

with whom I’ve worked over the last 15 years and consider to be one of the brightest

younger engineers I’ve ever met, to join me in the writing of this new edition.

Finally, I rededicate this book to Guy Hammer Cheek, P.E. (1927–1987), my friend, my

mentor, and the man who introduced me to the idea of “HVAC systems concepts” and who

diligently encouraged me to pick the right one(s) for each application.

Herbert W. Stanford III, P.E.

North Carolina

2019