Duct design quick introduction duct sizing tools and methods recommended duct velocities and noise effects. Starting with the original authors suggested thought process for analyzing typical problems, the reader is then exposed to a buzzword of our time. Fibrous glass insulated hvac duct systems 4 sheet metal ducts with exterior fibrous glass exterior insulation flexible blanket fibrous glass duct wrap insulation is designed for application to the exteriors of commercial and residential sheet metal heating, ventilating, and airconditioning ducts and plenums operating at temperatures between 40. Chapter 22, pipe design, has a new title and now incorporates the content of its sister chapter, pipes, tubes, and fittings, from hvac systems and equipment.
The duct design guide dr aft discusses these values, the lower end being used for high. More available in the ashrae handbook or smacna obtain other duct fittings pressure losses from manufacturers such as duct heaters, dampers, filters, grilles, coils, etc calculated by the following formula derived from bernoullis. Dougherty points out that typical values of friction loss per 100 ft are around 0. In this chapter, system design and the calculation of a systems frictional and dynamic resistance to airflow are considered. Design of flexibleduct junction boxes current standards ashrae 2012 hvac systems and equipment, box plenum systems using flexible duct constrains box width to 23x entrance width constrains box length to 2 x box width flat pressure loss 0. Book by sheet metal and air conditioning contractors national association, 2006. Why duct design is important the efficiency of air distribution systems has been found to be 6075% or less in many houses because of insufficient. In addition, the physical parameters of the duct, duct airflow, and uv installation have the potential to affect both the irradiance and the microorganisms response to it. Disclaimer of warranties a the sheet metal and air conditioning contractors national association smacna provides its product for informational. The air duct distribution network is an important component of hvac installations, helping to significantly reduce energy costs and reduce noise nuisance generated by the systems equipment.
American society of heating, refrigerating and air. This can provide significant savings in duct and fan motor costs. Corporation 1960 air duct design chapter in system design manual, part 2. Design considerations for commercial kitchen ventilation. Further considerations duct sizing methods there is no single duct sizing method that will inherently give the best duct design. Install duct systems in compliance with nfpa 90a installation of air conditioning and venting systems. Chapter 21, duct design, was reorganized for ease of use, and updated for data from the latest version of the ashrae duct fitting database. Energy estimating and modeling methods hvac design chapter 20. Ventilation and air distribution in indoor aquatic facilities. Smacna cad standard second edition v notice to users of this publication 1. This has included active participation in technical and standards committees for professional organizations that serve the hvac industry, such as ashrae, astm, amca, and smacna. Scribd is the worlds largest social reading and publishing site. Duct design fundamentals static pressure ps measure of the static energy of air flowing air which fills a balloon is a good example of static pressure equally exerted in all directions the atmospheric pressure of air is a static pressure 14.
There is a dearth of detailed advice in common hvac design handbooks describ. Chapter 16 of the 2000 ashrae handbooksystems and equipment examines duct construction and presents construction standards for. As is the case with upperroom uv installation design, the design parameters for uvc in in duct applications are not simple because of some uncertainty in. Residential cooling and heating load calculations 18. Highvelocity hv duct systems are characterized by air velocities in the range of 2500 to 3500 fpm. Publication 203 air movement and control association international, arlington heights, il ashrae 2001 energyefficient design of new lowrise residential buildings ashrae standard 90. Typical dryer manufacturers requirements where possible use a single exhaust duct per dryer sub title dryers are to run with a positive outlet pressure. This information should be consulted to ensure that the proper type and location of duct system is selected for the structure in question. Put your presentation title or confidentiality info here. Nonresidential cooling and heating load calculations 19. Clicking on a companys name will take you to their web site. Table 1 in accas manual j lists design con ditions for locations in the u. The latest edition of an ashrae standard may be purchased from the ashrae web site.
It does not present official positions of the society nor reflect society policy. Duct system design guide first edition 2003 mcgill airflow corporation mcgill airflow corporation one mission park groveport, ohio 43125 duct system design i notice. Duct design duct flow electromechanical engineering. No part of this work may be reproduced or used in any form or by any means graphic, electronic, or. The procedures of residential hvac design see figure 1 are covered in detail by a series of. This volume includes more than 1,000 pages and 40 chapters covering general engineering information, basic materials, climate data, load and energy calculations, duct and pipe design, plus reference tables for abbreviations and symbols, ip to. Duct design clicking on a companys name will take you to their web site. Ashrae fundamentals ip ch 21 duct design engineering360. Vav systems are the most common hvac system for commercial buildings, but. Pressure sensitive tape shall not be used as the primary sealant. Frigidaire dehumidifier manual 6 healthcare and operational issues in relation to mold problems bpkj 123710864 car park systems. Related commercial resources ashrae handbook fundamentals chapter.
Take the velocity of air in the main duct a as 8 ms for both the methods. The length of duct used for design purposes that includes the. The design process for a successful kitchen ventilation system starts when. A practical approach to design, implementation, connolly, t. More available in the ashrae handbook or smacna obtain other duct fittings pressure losses from manufacturers such as duct heaters, dampers, filters, grilles, coils, etc.
Ashrae american society of heating, refrigerating and airconditioning engineers. Fellow ashrae 0 f the three duct design procedures recommended by the 1997 ashrae handbookfundamentals, only the tmethod incorporates life. Related commercial resources chapter 35 duct design bernoulli equation. The fourth edition of hvac systems duct design presents the basic methods and procedures required to design hvac air distribution systems. Comply with ashrae fundamentals handbook and ashrae systems and equipment for design and fabrication of ductwork. As is the case with upperroom uv installation design, the design parameters for uvc in induct applications are not simple because of some uncertainty in. P total the total pressure loss across the duct fitting k. In addition to the basic engineering guidelines for the sizing of hvac ductwork systems, the. Deficiencies in duct design can result in systems that operate incorrectly or are expensive.
Lowvelocity ductwork design is very important for energy efficiency in air distribution systems. The fundamentals of duct system design mcgill airflow. I have seen that low of a value used in residential design but in the ashrae chapter on duct design, the friction chart shows a recommended shaded area from about 0. Ordinary heating, ventilating, and air conditioning duct systems read air pressures at 0. Design the duct system using a velocity method, and b equal friction method. Principle of duct design in hvac systems cedengineering. This manual provides the hvac system designer detailed information on duct design and u. Proper duct insulation eliminates the problem caused by excessive heat gain or loss. Ashrae 90571 design guide for air terminal units selection, application, control, and commissioning published by ashrae on january 1, 2018 preface air terminal units play an important role in the energy consumption of a building and ultimately the comfort of occupants, both acoustic and thermal. From ashrae fundamentals handbook, the following equations may be used to convert rectangular and flat oval ducts to and from round.
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