The rapid advancement of digital electronics and the resulting improvement in the operation of all HVAC systems has necessitated the production of this second edition. The HVAC industry has responded to the increases in the cost of energy by developing higher efficiencies in operating equipment such as condensing boilers and improvements in overall chiller plant energy consumption.

The central theme of this book on HVAC pumps and water systems is energy conservation. Much has been accomplished since 1996, and the continued use of advanced digital electronics such as adaptive control can only result in future lower energy consumptions. Also, almost total automation of HVAC water systems is now an achievable goal. This has produced simplified design of piping systems and the elimination of manual devices such as balancing valves that were used for manual control of water systems. Therefore this edition is about moving from manual to automatic operation and from complexity to simplicity in water systems. The result is a pronounced reduction in the energy required to operate all of the HVAC water systems, including condenser, chilled, hot, and ice water systems.

Following are some specific applications of energy conservation in HVAC water systems that will be reviewed in this edition.

• 1. The continued work of American Society of Heating and Air-Conditioning Engineers (ASHRAE) in testing steel and plastic pipe fittings has enabled design engineers to better calculate the friction losses of water systems. Chapter 3, Piping System Friction, includes data on plastic and copper pipe as well as the latest data on pipe fitting losses that are a result of research by ASHRAE.
• 2. A clearer understanding of the losses in centrifugal pumps will encourage design engineers to specify control that will operate a pump nearer to the pump’s best efficiency curve (BEP). Chapters 4 and 5 include new information on the design of centrifugal pumps.

• 3. Improved pump construction has resulted in higher pump efficiencies now available to the designer of water systems. Chapter 6 provides the latest information on the improvement of pump performance.
• 4. Variable frequency drives have been improved in efficiency and reduced first cost so that almost all variable flow water systems can now afford variable speed operation. Chapter 8 offers information on the much improved drives that are now available for the larger motors operating on medium voltages of 2,400 and 4,160 volt power.
• 5. Improved use of water in HVAC systems is highlighted in Chapters 8 and 9.
• 6. Continued improvement in the application of pumps to HVAC water systems has resulted in higher operating efficiencies and reduction in radial thrust and pump maintenance. New procedures are kW input control and constant flow-variable head systems.
• 7. Chapter 19 includes new information on the simpler control of HVAC pumps by using kW input in lieu of wire-to-water efficiency.
• 8. Chapter 11 has been expanded to include information on variable speed condenser pumps.
• 9. The development of digital control for chillers has resulted in the ability to control the leaving water temperature with variable flow in the evaporator. This has resulted in the development of variable primary flow that eliminates the need for the more complicated primary/ secondary pumping. This information is included in Chapter 14.
• 10. Chilled water distribution systems have been simplified, resulting in greater efficiency of water use in HVAC. This is highlighted in Chapter 15 as well as new information on actual distribution efficiency or coefficient of performance.
• 11. Additional information on high efficiency, condensing boilers is provided in Chapter 19.
• 12. New information on the use of lower temperature water for some heating systems and reheat is provided in Chapter 20.
• 13. The advent of reheat systems including reheat type chillers will be included in Chapters 9 and 20.
• 14. Digital control has eliminated the need for PID loops (proportional-integral-derivative) with their accompanying balancing problems. Various new energy saving techniques are now available, such as cooling tower/chiller kW input control of condenser water, and automatic adjustment of set points through the use of adaptive control. Chapter 23, Instrumentation, has been renamed to Instrumentation and Control to provide information on the many new control procedures that have been developed using adaptive control.

These are some of the new topics included in this second edition. Others include various forms of water system retrofit and geothermal heating and cooling. The result is a contemporary book on HVAC water pump and system design that provides the latest information on energy conservation in these systems. Use of this book in designing new HVAC water systems and the retrofit of existing systems will result in higher levels of efficiency in the distribution of water in HVAC systems.

Several people have been courageous in applying new technology to HVAC water systems. The included work on heat recovery has resulted from efforts by Tom Durkin, PE and Benny Kincaid of Indianapolis, Indiana.