The 2004 ASHRAE Handbook—HVAC Systems and Equipment discusses various common systems and the equipment (components or assemblies) that comprise them, and describes features and differences. This information helps system designers and operators in selecting and using equipment. A new chapter (47), Mechanical Dehumidifiers and Heat Pipes, has been added. ASHRAE Technical Committees have updated chapters for current technology, clarified existing information, deleted obsolete material, and reorganized some chapters. Some of the revisions are as follows:

• Chapter 1, HVAC System Analysis and Selection, has expanded lists and discussion of system selection criteria.
• Chapter 2, Building Air Distribution, has added information on mixing plenums and static air mixers.
• Chapter 3, In-Room Terminal Systems, contains more information on both humidity control and fan-coils.
• Chapter 4, Central Cooling and Heating, has been rewritten to include more information on central systems’ advantages and disadvantages; controls; and considerations for plant location, including noise and vibration.
• Chapter 5, Decentralized Cooling and Heating, has been updated throughout, with additional discussion on advantages and disadvantages of various systems.
• Chapter 6, Panel Heating and Cooling, extensively revised, now has panel performance rating equations and information on hybrid (load-sharing) systems using panels.
• Chapter 7, Cogeneration Systems and Engine and Turbine Drives, now contains content previously published in the 2000 volume’s Chapter 47, Engine-Driven Heating and Cooling Equipment, plus new information on electrical system interface, fuel cells, and microturbines.
• Chapter 8, Applied Heat Pump and Heat Recovery Systems, has added the results of two ASHRAE research projects that (1) provided guidelines for evaluating the environmental benefits of using heat recovery heat pumps, and (2) evaluated computer models for water loop heat pumps and heat recovery chillers.
• Chapter 9, Design of Small Forced-Air Heating and Cooling Systems, has expanded discussions on commercial systems and on air distribution design considerations, especially duct location, leakage, and insulation.
• Chapter 16, Duct Construction, has been updated for research on sealing of duct/terminal connections, and has new sections on antimicrobial and fabric ducts.
• Chapter 17, Room Air Distribution Equipment, has been updated throughout and included new sections on supply nozzles and variable-geometry diffusers.
• Chapter 18, Fans, contains new sections on calculating the temperature rise across fans and on fan vibration concerns.
• Chapter 21, Air Cooling and Dehumidifying Coils, has expanded coil construction descriptions and new maintenance recommendations.
• Chapter 22, Desiccant Dehumidification and Pressure-Drying Equipment, updated for new technology, also has new material on ventilation air applications, plus a description of an interactive desiccant wheel performance estimator available on the TC 8.12 homepage via the ASHRAE Web site.
• Chapter 23, Air-Heating Coils, has updated sections on steam coils and coil maintenance.
• Chapter 35, Condensers, has added a comparison of water-cooled versus air-cooled condensers and information on biological control, brazed condensers, pony motors, and purging noncondensables.
• Chapter 36, Cooling Towers, has more information on closed-circuit towers, capacity control (including variable-frequency drives), critical speeds, biological control, wet/dry towers, plume, and cold-weather operation.
• Chapter 37, Liquid Coolers, has expanded descriptions of cooler types, including a new table listing feed devices, capacity ranges, and commonly used refrigerants for each.
• Chapter 44, Air-to-Air Energy Recovery, extensively revised, has added examples, figures, and calculation procedures, plus new material on air leakage, performance ratings, fan power requirements, pressure drop, and membrane plate heat exchangers.
• Chapter 46, Room Air Conditioners and Packaged Terminal Air Conditioners, no longer has dehumidifier information (see new Chapter 47) but has added tables on energy efficiency standards for room air conditioners.
• Chapter 47, Mechanical Dehumidifiers and Heat Pipes, a new chapter, includes basic construction and operating practices on this equipment for high-dew-point applications, plus discussion of heat pipes and their use with mechanical dehumidifiers.

This Handbook volume is published, both as a bound print volume and in electronic format on a CD-ROM, in two editions: one using inch-pound (I-P) units of measurement, the other using the International System of Units (SI).

To make suggestions for improving a chapter or for information on how you can help revise a chapter, please comment using the form on the ASHRAE Web site; or e-mail mowen@ashrae.org; or write to Handbook Editor, ASHRAE, 1791 Tullie Circle, Atlanta, GA 30329; or fax 678-539-2187.

Mark S. Owen
Editor