For example, in a variable air volume system, sheet metal ducts with fibrous glass duct liner may be used on the high pressure side if design static pressure exceeds the 2 in. Smacna cad standard sheet metal and air conditioning. Book by sheet metal and air conditioning contractors national association, 2006. Asterisks indicate wording that is taken directly and verbatim from the smacna hvac duct construction standards, 2nd ed. Design guide for heating, ventilating, and air conditioning systems. Dimensional stability shape deformation ashrae handbooks and the smacna hvac duct and strength. Lowvelocity design will lead to larger duct sizes, but it may be worth since, doubling of duct diameter. In addition to the basic engineering guidelines for the sizing of hvac ductwork systems, the manual also provides related information on economics of duct systems, duct system layout, pressure losses, fan selection, duct leakage, acoustic considerations, and testing, adjusting and balancing tab. The other two manuals making up this group are the hvac systems duct design manual and the hvac systems testing, adjusting and balancing manual. Starting with the basics, lets start at the most elementary level by identifying components of a duct system. This manual provides the duct system designer with the technical information required to design a complete air distribution system. Using a graphic interface, the user describes the building by manipulating objects that represent building components and assigning construction characteristics to them. Smacna hvac air duct leakagg,e test manual, first edition, 1985 ashrae 90. Pdf smacna commercial duct design vuong le academia.
Ansi smacna 0062006 hvac duct construction standards eli p. Installation of ductwork should comply with smacna hvac duct construction. It is recommended that this manual be used in conjunction with the. The appendix contains a sample hvac systems commissioning specification, complete from the planning to the final execution stage. Decisions are made about the types of systems to be used. The volumetric flow rate of air that will be conveyed through the duct in an air conditioning system is determined by the coolingheat load and the desired supply air.
When the designer has only required leakage tests to be conducted in accordance with the smacna hvac air duct leakage test manual for verification that the leakage classifications in table 1 have been met and has given no other criteria and scope, he is deemed to have not fulfilled the responsibilities outlined in section 2. Air leakage in ductwork rev 02 linx industries, inc. In comparing duct performance, two elements should be equal in the related designs. Presents the basic methods and procedures required to design hvac air distribution systems.
Repair leaks and repeat tests until total leakage is less than 1% of system design airflow when the system is pressurized to the design duct pressure class rating. A duct system is a network of round or rectangular tubesgenerally constructed of sheet metal, fiberglass board, or a flexible plasticand wire compositelocated within the walls, floors, and ceilings. The fourth edition of hvac systems duct design presents the basic methods and procedures required. The base sheet should be prepared chapter 11 as soon as the architects floor plan is received. A comprehensive duct layout indicating sizes, design airflows, pressure class, and routing of the duct system. The length of duct used for design purposes that includes the. The fourth edition of hvac systems duct design presents the basic methods and procedures required to design hvac air distribution systems. Howard, iii sheet metal and air conditioning contractors national association. Ansismacna 0062006 hvac duct construction standards. Hvac systems duct design the sheet metal and air conditioning contractors national association, inc. Seismic supports are not required for hvac ductwork with ip 1. Highvelocity hv duct systems are characterized by air velocities in the range of 2500 to 3500 fpm. Ductwork proudly sponsored by this information first appeared as the article basics of duct design by jjw bill siganto and appeared in ecolibrium magazine.
Smacna, in keeping with its policy of disseminating information and providing standards of design and construction, offers this comprehensive and fundamental hvac systemsduct design manual as part of the continuing effort to upgrade the. A thorough explanation of recommissioning leads one through the preliminary investigation, survey and documentation phase, the design and installation of system modifications, and the actual recommissioning test. Industrial duct is a broad classification of ductwork used in industry for many diverse applications. Hvac systems duct design by the sheet metal and air conditioning contractors national association, inc. 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. This manual is often referred to as one of three manuals that constitute smacna s approach to hvac systems. Smacna hvac systems duct design manual, fourth edition december 2006, table a. Balance a residential hvac system find th return air vent, cold air return, refrigeration. Disclaimer of warranties a the sheet metal and air conditioning contractors national association smacna provides its product for informational. The types of fittings to be used based on the designers calculations of fitting losses i. In addition to the basic engineering guidelines for the sizing of hvac ductwork systems, the manual also provides related information on economics of duct systems, duct system layout, pressure losses, fan selection, duct. Offers the hvac system designer and installer detailed information on duct design, materials and construction methods.
A duct system is a network of round or rectangular tubesgenerally constructed of sheet. California contractors skills tested in dramatic academy. The mechanical skills of a smacna contractor, control air north inc. This text has been extensively revised and updated, and now includes key portions of the previously separate duct design home course study material. Rules of duct design acca manual d residential duct systems. Identify code requirements regarding sizing, design, and selection of hvac equipment and ducts explain how the acca manual j, s and d load calculation standards are used to determine appropriate sizing and design of ducts and hvac equipment describe the role the hvac system plays in moisture control and the effect.
Ansismacna 0062006 hvac duct construction standards eli p. Hvac ducts are suspended from hangers 12 inches 305 mm or less in length with hangers detailed to avoid. The return air duct shall be sized based on peak ahu supply air. Insuring that the design documents convey to the hvac contractor what the designer wants by clarifying. Lowvelocity ductwork design is very important for energy efficiency in air distribution systems. This manual provides not only the basic engineering guides for the sizing of. The noise level in a duct system does not progressively decrease away from the fan until it reaches zero. Duct construction, including sheet metal thicknesses, seam and joint construction, reinforcements, and hangers and supports, shall comply with smacnas hvac duct construction standards metal and flexible and performance requirements and design criteria indicated in duct schedule article. There is a lower limit caused by selfgenerated noise. Smacna hvac systems duct design manual bni building news. Principle of duct design in hvac systems cedengineering.
The colebrook equation value of f must be solved for iteratively. Creating the drawings, schedules, and specifications that fully and accurately describe the hvac design. Systems duct design manual, there are many other smacna publications available that relate to the design and installation of hvac sys hvac systems duct design fourth edition related smacna publications xvi hvac systems duct design fourth edition. Sheet metal and air conditioning contractors national association smacna states in its hvac systems duct design 2006, 4th edition, section 2. The structural components of a typical hvac duct system include the sheet metal ducts, stiffeners for the ducts, duct supports, and other inline components such as duct heaters, dampers, etc. Any duct system over 3000 ls must be tested at minimum 10% of.
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. Where area change, direction change, divided flow, or united flow fittings other than those illustrated here are shown on the contract drawings, are not of proprietary manufacture, and are defined with friction loss coefficients in either the smacna hvac duct system design manual or the ashrae fundamentals handbook chapter on duct design, such. The ashrae fundamentals handbook chapter on duct design and the smacna hvac duct systems design manual contain additional information on. Smacna table 12 duct sealing requirements seal class class sealing required static pressure construction class a. Download hvac duct construction tables according to smacna. Pressure in ducts near room air terminals is nearly always below 12 w. Product detail sheet metal and air conditioning contractors. Art hvac system in california biological sciences building 3. The level 2 duct design tdp will present many areas of design enhancement, such as smacna duct construction standards, duct design code requirements, fitting selection using loss coefficients, avoiding acoustic issues, unique vav system duct features, and using life cycle cost analysis as a design criteria. The hvac duct system designer is faced with many considerations once load calculations are completed and the type of distribution system to be used has been determined. Rightsizing of a heating, ventilation, and airconditioning hvac system is the selection of. There is another area of concern with the extended plenum systembecause of the higher velocities in the plenum, it is possible that the branches closest to the indoor blower may not feed the desired amount of air cfm.
Air flow problems have plagued the hvac industry for years. California contractors skills tested in dramatic academy of science museum project aerial photo showcases the living roof with the seven hills of san francisco and bms operable windowsportals for natural ventilation and light. Armed with knowledge from real job examples, you can make informed decisions on product selection and scope resulting in more efficient, less expensive duct systems. Duct design quick introduction duct sizing tools and methods recommended duct velocities and noise effects duct fitting pressure losses do and donts of duct design duct applications as 4254. Smacna hvac system duct design manual is a guide to designing commercial and light industrial heating, ventilating and air conditioning systems. While ventilating duct in industry is often specified within the range of low pressure and high pressure standards, as described in smacna manuals for these criteria, we usually refer to industrial duct as that which conveys air or gas. This manual provides the hvac system designer detailed information on duct design and u. Applications 2015 or approved latest edition, and in the smacna hvac system sound. Duct sizing and construction tables according to smacna pdf. Smacna cad standard second edition v notice to users of this publication 1.
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