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Modern Hydronic Heating, 2nd Edition

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Author: John Siegenthaler, P.E.
Copyright 2003
ISBN 0-7668-1637-0

Cost:
$132.00 for each book (1-9 copies) + shipping
for 10 copies or more please e-mail request to support@hydronicpros.com

When Modern Hydronic Heating was first published in 1995, it received many accolades for filling a major gap in the HVAC field; how to design modern hydronic heating systems for smaller buildings. Since its release, tens of thousands of copies of the text have been sold worldwide.

The second edition delivers even more information on state-of-the-art hydronic heating technology. It has been expanded by over 60 percent, and includes extensively updated graphics showing the latest techniques and hardware options.

This text covers both the fundamentals of hydronic heating as well as advanced topics that helps you design and install optimal systems.

Topics that have been extensively updated and expanded include:

- Radiant Panel Heating (including wall and ceiling heating)
- Primary/Secondary Piping
- Homerun Distribution Systems
- Injection Mixing
- Control Theory, Methods, and Hardware
- Variable Speed Pumping
- Buffer Tank Applications
- Multiple Boiler Systems
- Hydronic Snowmelting Systems
- Multi-load/Multi-load Systems
- Minitube Distribution Systems

Every copy of the second edition also includes a CD-ROM with the Hydronics Design Studio software (Academic Version). This software includes tools for performing heat loss estimates, piping system analysis, expansion tank sizing, and simulating the performance of baseboard heating systems, and more.

If you design or install hydronic heating systems you'll find this text indispensable. Even if you have the first edition, you'll want to own the second edition. It offers information not available anywhere else.

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TABLE OF CONTENTS

CHAPTER 1 FUNDAMENTAL CONCEPTS

Objectives 1
1.1 What Is A Hydronic Heating System? 1
1.2 Advantages of Hydronic Heating 1
1.3 Heat and Heat Transfer 5
1.4 Four Basic Hydronic Subsystems 8
1.5 The Importance of System Design 13
Summary 14
Key Terms 14
Chapter 1 Questions and Exercises 15

CHAPTER 2 HEATING LOAD ESTIMATES

Objectives 17
2.1 Introduction 17
2.2 Definition of Design Heating Load 17
2.3 Conduction Heat Losses 18
2.4 Foundation Heat Loss 22
2.5 Infiltration Heat Losses 25
2.6 Putting It All Together 27
2.7 Example of A Complete Heating Load Estimate 27
2.8 Computer-Aided Heating Load Calculations 33
2.9 Estimating Annual Heating Energy Usage 34
Summary 37
Key Terms 38
Chapter 2 Questions and Exercises 38

CHAPTER 3 HYDRONIC HEAT SOURCES

Objectives 41
3.1 Introduction 41
3.2 Classification of Hydronic Heat Sources 41
3.3 Gas- and Oil-Fired Boiler Designs 42
3.4 Conventional Versus Condensing Boilers 47
3.5 Domestic Hot Water Tanks As Hydronic Heat Sources 50
3.6 Power Venting Exhaust Systems 52
3.7 Combustion Air Requirements 54
3.8 Boiler Heating Capacity 55
3.9 Efficiency of Gas and Oil-Fired Boilers 57
3.10 Multiple Boiler Systems 60
3.11 Electric Boilers 63
3.12 Electric Thermal Storage(ETS) Systems 64
3.12 Hydronic Heat Pumps 66
3.14 System Design Considerations for Hydronic Heat Pumps 71
3.15 Renewable Energy Heat Sources 72
3.16 Active Solar Energy Systems 73
3.17 Wood-Fired Boilers 76
Summary 81
Key Terms 81
Chapter 3 Questions and Exercises 82
For Further Reading 82

CHAPTER 4 PROPERTIES OF WATER

Objectives 83
4.1 Introduction 83
4.2 Specific Heat and Heat Capacity 83
4.3 Sensible Heat Versus Latent Heat 84
4.4 Density 84
4.5 Sensible Heat Quantity Equation 85
4.6 Sensible Heat Rate Equation 86
4.7 Vapor Pressure and Boiling Point 87
4.8 Viscosity 88
4.9 Dissolved Air In Water 89
4.10 Incompressibility 90
Summary 90
Key Terms 90
Chapter 4 Questions and Exercises 90

CHAPTER 5 PIPING, FITTINGS, AND VALVES

Objectives 93
5.1 Introduction 93
5.2 Piping Materials 93
5.3 Common Pipe Fittings 104
5.4 Specialized Fittings 107
5.5 Thermal Expansion of Piping 110
5.6 Common Valves 110
5.7 Specialty Valves for Hydronic Applications 116
5.9 Schematic Symbols for Piping Components 135
5.10 Tips On Piping Installation 136
5.11 Summary 138
Key Terms: 138
Chapter 5 Questions and Exercises 139

CHAPTER 6 FLUID FLOW IN PIPING

Objectives: 141
6.1 Introduction 141
6.2 Basic Concepts of Fluid Mechanics 141
6.3 Analyzing Fluid Flow In Smooth Pipes 150
6.4 Hydraulic Resistance of Fittings, Valves, and Other Devices 156
6.5 The System Resistance Curve 157
6.6 Piping Components Represented As Series Resistors 158
6.7 Parallel Hydraulic Resistances 163
6.8 Reducing Complex Piping Systems 167
6.9 Software-Based Circuit Analysis 170
6.10 Pipe Sizing Considerations 170
Summary 173
Key Terms 173
Chapter 6 Questions and Exercises 174

CHAPTER 7 CIRCULATING PUMPS

Objectives 177
7.1 Introduction 177
7.2 Pumps for Hydronic Systems 177
7.3 Placement of The Circulator Within The System 182
7.4 Pump Performance 185
7.5 Analytical Methods for Pump Performance 192
7.6 Circulator Efficiency 195
7.7 Pump Cavitation 198
7.8 Variable Speed Circulators 202
7.9 Specialty Circulators 206
7.10 Selecting A Circulator 207
Summary 209
Key Terms 209
Chapter 7 Questions and Exercises 210

CHAPTER 8 HEAT EMITTERS

Objectives 213
8.1 Introduction 213
8.2 Classification of Heat Emitters 213
8.3 Finned-Tube Baseboard Convectors 213
8.4 Thermal Ratings and Performance of Finned-Tube Baseboard 218
8.5 Sizing Finned-Tube Baseboard 220
8.6 Hydronic Fan-Coils 224
8.7 Thermal Performance of Fan-Coils 228
8.8 Panel Radiators 232
8.9 Radiant Baseboard 239
8.10 Head Loss of Heat Emitters 241
8.11 Heat Loss From Copper Tubing 242
8.12 System Operating Temperature 244
Summary 245
Key Terms 246
Chapter 8 Questions and Exercises 246

CHAPTER 9 CONTROL STRATEGIES, COMPONENTS, AND SYSTEMS

Objectives 247
9.1 Introduction 247
9.2 Closed-Loop Control System Fundamentals 248
9.3 Controlling the Output of Heat Sources 253
9.4 Controlling the Output of Heat Emitters 257
9.5 Switches, Relays, and Ladder Diagrams 268
9.6 Basic Hydronic System Control Hardware 278
9.7 Basic Boiler Control Hardware 289
9.8 Mixing Strategies and Hardware 295
9.9 Control System Design Principles 313
9.10 Example of a Modern Control System 314
9.11 Future of Hydronic Heating Controls 317
Key Terms 319
Chapter 9 Questions and Exercises 321

CHAPTER 10 HYDRONIC RADIANT PANEL HEATING

Objectives 323
10.1 Introduction 323
10.2 What Is Radiant Heating? 323
10.3 What Is A Hydronic Radiant Panel? 324
10.4 The History of Radiant Panel Heating 324
10.5 Benefits of Radiant Panel Heating 325
10.6 Physiology of Radiant Panel Heating 326
10.7 Methods of Hydronic Radiant Panel Heating 328
10.8 Slab-on-Grade Radiant Floors 329
10.9 Concrete Thin-Slab Radiant Floors 336
10.10 Poured Gypsum Thin-Slab Radiant Floors 340
10.11 Above-Floor Tube and Plate Systems 344
10.12 Below-Floor Tube and Plate Systems 348
10.13 Suspended Tube Systems 351
10.14 Plateless Staple-Up Systems 354
10.15 Prefab Subfloor/Underlayment Panels 355
10.16 Radiant Wall Panels 357
10.17 Radiant Ceiling Panels 361
10.18 Tube Placement Considerations (Floor Panels) 364
10.19 Radiant Panel Circuit Sizing Procedure 373
10.20 System Piping and Temperature Control Options 381
Summary 401
Key Terms 401
Chapter 10 Questions and Exercises 405

CHAPTER 11 DISTRIBUTION PIPING SYSTEMS

Objectives 407
11.1 Introduction 407
11.2 Zoning Considerations 407
11.3 System Equilibrium 409
11.4 The Concept of Iterative Design 411
11.5 Single Series Circuits 412
11.6 Single Circuit/Multizone (One-Pipe) Systems 414
11.7 Multizone/Multicirculator Systems 418
11.8 Multizone Systems Using Zone Valves 424
11.9 Parallel Direct-Return Systems 429
11.10 Parallel Reverse-Return Systems 433
11.11 Home Run Distribution Systems 436
11.12 Primary/Secondary Systems 439
11.13 Hybrid Distribution Systems 450
Summary 455
Key Terms 455
Chapter 11 Questions and Exercises 455

CHAPTER 12 EXPANSION TANKS

Objectives 459
12.1 Introduction 459
12.2 Standard Expansion Tanks 459
12.3 Diaphragm-Type Expansion Tanks 462
12.5 The Expansion Tank Sizer Software Module 468
12.6 Point of No Pressure Change 468
Summary 472
Key Terms 472
Chapter 12 Questions and Exercises 472

CHAPTER 13 AIR REMOVAL, FILLING, AND PURGING

Objectives 475
13.1 Introduction 475
13.2 Problems Created by Entrapped Air 475
13.3 Types of Entrapped Air 476
13.4 Air Removal Devices 478
13.5 Correcting Chronic Air Problems 482
13.6 Filling and Purging a System 483
13.7 Make-Up Water Systems 489
Summary 491
Key Terms 491
Chapter 13 Questions and Exercises 491

CHAPTER 14 AUXILIARY LOADS AND SPECIALIZED APPLICATIONS

Objectives 493
14.1 Introduction 493
14.2 Heat Exchangers 493
14.2 Domestic Water Heating 497
14.4 Intermittent Garage Heating 504
14.5 Spa and Hot Tub Heating 506
14.6 Pool Heating 508
14.7 Hydronic Snowmelting 510
14.8 Buffer Tanks 522
14.9 Minitube Distribution Systems 526
Summary 530
Key Terms 530
Chapter 14 Questions and Exercises 531

APPENDICES

APPENDIX A SCHEMATIC SYMBOLS 533
APPENDIX B R-VALUES OF COMMON BUILDING MATERIALS 535
APPENDIX C USEFUL CONVERSION FACTORS AND DATA 537
GLOSSARY 539
INDEX 559

PREFACE

This book, like its predecessor, is about the state of the artin hydronic (water-based) heating systems for residential and light commercial buildings. It was written to provide comprehensive, up-to-date, and unbiased information for heating technology students as well as heating professionals. It is aimed at those willing to work with their heads as well as their hands. During my 25 years working as an HVAC engineer, it has become apparent that an information gap exists for those interested in upgrading their knowledge of designing and installing high quality hydronic heating systems for smaller buildings. I believe that residential and small commercial buildings deserve better heating systems than they often get. After all, even small heating systems affect the comfort and well being of numerous people over many years. Much of what has been written on hydronics is aimed at engineers, and intended for use in larger commercial or institutional buildings. It is often impractical to scale such large system designs for use in smaller buildings. Manufacturers' information, while often well done, seldom takes the heating professional through the entire design process. Since most heating systems for smaller buildings are non-engineered, the installing contractor often has sole responsibility for ensuring that the components are properly matched, sized, andinstalled. In the absence of proper training, this can lead to the same mistakes being repeated over and over. It also leadsto design stagnation, where installers are only willing to deal with a certain type of equipment or system design, regardless of the situation with which they are faced. Many overlook the profitable opportunities offered through creative useof modern hydronic heating hardware and design methods. Since the first edition of this text was released in 1995, growth in the hydronic heating market for residential and light commercial buildings has been phenomenal. The hydronic radiant panel heating market, in particular, has grown by over 1000 percent during the last decade. With this growth has come a variety of new products and design methods. The second edition has been extensively updated and expanded to include the latest information on both hardware and design procedures.

ORGANIZATION

The first chapters of the book acquaint the reader with the fundamental physical processes involved in hydronic heating. Topics such as basic heat transfer, heating load calculations, and properties of fluids are discussed. A good understanding of these basics enhances the technician's design and troubleshooting skills. Later chapters use the fundamental principles for overall system design. The reader is referred back to relevant sections of earlier chapters during the design process to reinforce the importance of the basics. Case studies at the end of some of the later chapters show complete system piping and control wiring diagrams.

Chapter 1 provides an overview of hydronic heating, and the basic concepts involved. It emphasizes comfort as the ultimate goal of the heating professional. It encourages an attitude of craftsmanship and professionalism.

Chapter 2 discusses heating load calculations. Experience indicates that such calculations can be a stumbling block for students, as well as for those in the trade who want to jump right into design and layout without first determining what the system needs to provide. Without proper load information, any type of heating system can fail to deliver the required comfort. A complete method for determining design heating loads is presented, including new worksheets. The second edition includes new information, allowing for quick comparisons of various fuel options.

Chapter 3 surveys a wide spectrum of hydronic heat sources. These include conventional gas and oil-fired boilers,as well as newer devices such as hydronic heat pumps, modulating/condensing boilers, thermal storage systems, and solar energy collectors. The second edition includes new material on the use of wood-fired heat sources. Emphasis is placed on matching the temperature and flow requirementsof the heat source with those of the distribution system.

Chapter 4 describes, in simple terms, the physical properties of water including specific heat, density, viscosity, and solubility of air. Two very important equations that relate heat and heat flow to water temperature and flow rate are introduced.

Chapter 5 is a "show and tell" chapter covering the proper use of tubing, fittings, and valves in hydronic systems. The use of copper tubing as well as materials such as PEX andPEX-AL-PEX is discussed. Common valves are illustratedand their proper use is emphasized. Several specialty fittings and valves are also discussed. The second edition provides additional application schematics for the hardware discussed.

Chapter 6 is the key analytical chapter of the text. It introduces a new method for calculating the head loss of a fluid as it flows through a piping system. This new concept, called hydraulic resistance, builds an analogy between fluid flow in piping circuits and the principles of current, voltage, and resistance in electrical circuits. A method is developed that allows the reader to analyze both simple and complex piping circuits. The material presented allows the reader to construct a system resistance curve for both simple and complex piping systems.

Chapter 7 presents both qualitative and quantitative informationon circulators for smaller hydronic systems. The pump curve is introduced and used to properly match a circulator to a piping system. The intersection of the pump curve of a candidate circulator and system resistance curve of the piping system reveals the operating flow rate of the circulator/piping system combination. Quantitative and graphical methods are shown for finding this point. The chapter also places strong emphasis on what circulator cavitationis, and how to avoid it. The second edition presents the latest information on specialty circulators with built-incheck valves as well as applications for variable speed circulators.

Chapter 8 surveys several types of hydronic heat emitters, including finned-tube baseboard convectors, fan-coils, panel radiators, and radiant baseboards. The advantages and disadvantages of each type are discussed. Performance and sizing information is also given.

Chapter 9 is a major chapter dealing with control components and systems for hydronic heating. This area of hydronic heating has grown immensely since the first edition was published. The second edition has correspondingly expanded to present the latest hardware and design methods. It now delves deeper into the control theory as well as practical applications of the latest hardware. Control systems for multiload/multitemperature systems are discussed. Ladder diagrams are used as a framework on which to design such control systems. The chapter concludes with a look at the future of control systems for hydronic heating, including discussion of adaptive control, Internet accessible controls, and communication among various control devices.

Chapter 10 is devoted entirely to hydronic radiant panel heating. The second edition includes extensively revised installation graphics and design information for radiant floors as well as radiant walls and ceilings. The latest hardware options are discussed. A completely revised step-by-step design method is presented with new data for thin-slab as well as tube and plate systems. This chapter equips hydronic heating professionals to work within this rapidly expanding segment of the hydronic heating market.

Chapter 11 covers several types of distribution piping configurations, including series loop, one-pipe diverter tee, multizone, two-pipe reverse-return, and primary/secondarysystems. The second edition presents revised schematics of these piping systems. New material has been included on home run distribution systems using PEX or PEX-AL-PEXtubing, as well as the increasingly popular method of primary/secondary piping. The fundamental analytical methods presented in Chapters 6 and 7 are now called upon to design each type of piping system. The chapter concludes with examples of state-of-the-art distribution systems for multiload/multitemperature systems.

Chapters 12 and 13 deal with the specialized topics of expansion tanks and air removal. Both survey the latest typesof hardware, and show how to properly select it.

Chapter 14 covers several miscellaneous topics. Auxiliary loads such as indirect water heating, pool/spa heating, and intermittent garage heating are discussed.

New material has been included to assist in sizing indirect domestic waterheaters. Extensive material on the design and application of hydronic snow- and ice-melting (SIM) systems has also been added. Other new topics include buffer tanks and minitube distribution systems.

HYDRONICS DESIGN STUDIO
This second edition includes a CD-ROM with theAcademic Version of newly released software called the Hydronics Design Studio. This Windowsý-based software is built around the analytical methods presented in the text. It allows rapid simulation of flow in user-defined piping systems, including those with multiple parallel branch circuits. It also includes modules for room heat loss estimating, expansion tank sizing, and detailed simulation and sizing of series-loop baseboard systems. Several examples of how the software can be used to evaluate long numerical calculations are given. References to the software are marked with a disc icon in the margin of the text. A professional version of the Hydronics Design Studio with increased capabilities is also available. Visit the website www.hydronicpros.com for additional information.

OTHER FEATURES OF THE SECOND EDITION

- Hundreds of new and standardized schematic drawings for both piping and electrical control systems. These drawings are presented in a consistent format throughout the text rather than simply reprinted from several inconsistent sources. An appendix of the graphic symbols is provided for reference.

- Updated photographs and illustrations of the latest in hydronic heating hardware, as well as work in progressas hydronic systems are installed.

- A full description of all variables, along with the required units, is given whenever an equation is introduced. All inputs are expressed in the customary English units used in the trade.

- Many example calculations organized in the form of a situation statement, solution procedure, and discussion of the results.

Much of the material in this text has been classroom tested at Mohawk Valley Community College in Utica, NewYork. The text and software has formed the basis of a one semester course dedicated solely to hydronic heating.Student input has been helpful in determining the appropriate presentation level of the material, and in fine-tuning the software.

ACKNOWLEDGMENTS
My deepest gratitude goes to longtime associate MarioRestive of Mohawk Valley Community College who diligently worked to help create the Hydronics Design Studio. Without his skill, this crucial component of the text would not exist.

I would like to thank all members of the production team, especially John Fisher of Delmar, and Vince Potenza of SoundLightMind, for their diligence and patience as the second edition has taken form. It has been a long road, but I'm confident the reader will benefit immensely from the extensive revision efforts that are now complete.

John Siegenthaler, P.E.

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