Decisions are made about the types of systems to be used, building zoning, equipment locations, and routing of ductwork. The ashrae 2009 handbookfundamentals ashrae 2009a describes the procedures to evaluate. Duct design clicking on a companys name will take you to their web site. For air quantities greater than 4500 ls size duct at 10ms. Duct airflow velocities hvac design my engineering notes. Lowvelocity design will lead to larger duct sizes, but it may be worth since, doubling of duct diameter. Highvelocity hv duct systems are characterized by air velocities in the range of 2500 to 3500 fpm.
Mcgill airflow corporation is the nations foremost producer of sheet metal duct and fitting components for air handling systems. Duct design manual is intended to be used in conjunction with the american society of heating, refrigerating and air conditioning engineers, inc. Clicking on a companys name will take you to their web site. Duct fitting pressure loss various duct fitting pressure losses airah da3 or the airah technical handbook 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. More available in the ashrae handbook or smacna obtain other duct fittings pressure losses. Find out how to improve your air conditioning with better duct. Design the duct system using a velocity method, and b equal friction method. Document handbook of air conditioning system design.
Enter friction loss per 100 of duct inches of water, duct airflow cfm, duct length and the number of bends. This course will discuss the basic fundamentals and principles of air conditioning duct design and layout. Duct system design vi introduction foreword these reference manuals have been compiled and written by engineers and consultants employed by united mcgill corporation and its. This document is not a procedural stepbystep set of instructions on how to create a duct design. Sep, 2012 after air discharge grilles and the air handler, which consists of a heat exchanger and blower, have been located, it is advisable to make a singleline drawing showing the duct layout and the air quantities each branch and line must be able to carry. 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. Ductwork diy heating and cooling product sales for the doityourself home owner. Duct system design basics duct systems are designed to properly distribute air throughout a building.
The basic principles of duct design, part 1 energy vanguard. This method requires many computations, which makes noncost optimizing techniques more attractive to designers. Consequently, the total pressure or total energy of. Choosing the rightsized duct is critical to maintain proper air flow in the system. This course will discuss the basic fundamentals and. Paul guyer is a registered civil engineer, mechanical engineer, fire protection engineer, and architect with over 35 years experience in the design of buildings and. Find out how to improve your air conditioning with better duct design, and why you need hvac experts involved early in your renovation process. Ducts that are not well designed result in discomfort, high energy costs, bad air quality, and increased noise levels. Designing a duct system is important, but there are a few critical steps that come first.
Apr 23, 2014 air balancing dampers should be installed in branch ducts as close as possible to the main trunk duct. This report assists structural engineers in performing the structural analysis and design of ductwork. One of the design parameters that define the sizing of ductwork is the maximum allowable air velocity. Duct systems are designed to properly distribute air throughout a building. Consequently, the total pressure or total energy of air. Ductwork should be designed in accordance with the provisions of the ashrae handbook of fundamentals, or the sheet. We saw a need to present the evergrowing content of our product catalog in a. Air balancing dampers should be installed in branch ducts as close as possible to the main trunk duct. This report assists structural engineers in performing the structural analysis and design of.
The general guidelines state that if the winter design temperature for the location of the structure is above 35f, then both perimeter floor and ceiling distribu. The external face of the duct is faced with a robust reinforced aluminium foil which acts as a vapour barrier and confers air tightness on the duct. Handbook of heating, ventilation and air conditioning. Our manual d calculation service, is a complete custom duct design for your residential project. Air duct calculator flexible duct friction loss calculator. The ashraefundamentals handbook contains hvac design criteria for most countries around the world. Fellow ashrae 0 f the three duct design procedures recommended by the 1997 ashrae handbookfundamentals, only the. The secret to moving air efficiently through your duct. Of the methods of duct design in use, the equalfriction method is the most practical. Ductsize also has an option for specifying duct height and width constraints to control sizes. The application of its contents for the design of an air distribution system lies exclusively at the discretion of the system designer.
Air flow problems have plagued the hvac industry for years. All information provided in this document is to be used as a guideline only. Consequently, the total pressure or total energy of air flowing in a duct system is generally equal to the sum of the static pressure and the velocity pressure. Below is a simple model for determining duct sizes.
Ashrae welcomes your comments on the handbook or a specific handbook chapter. The objective of the handbook of hvac design is to provide a practical guide and a reliable reference for designing and operating hvac systems. For air quantities greater than 180 ls, but less than 4500 ls. Heat conduction and thermal resistance for steady state conditions and one dimensional heat. The fourth edition of hvac systems duct design presents the basic methods and procedures required to design hvac air distribution systems. The most common design trunk line layout is provided in the illustration below. The structural design of air and gas ducts for power. It delivers an schematic drawing of the duct system including locations and sizes of trunklines, branch ducts, outlet registers, an inlet grilles. Prepared by the air and gas duct structural design committee of the energy division of asce.
There is a dearth of detailed advice in common hvac design handbooks describing how to design ductwork for. The objective of the handbook of hvac design is to provide a. To this point in our little series on duct design, weve been calculating intermediate quantitites. Number one is the load calculation using a protocol like accas manual j or the ashrae handbook of fundamentals.
Lowvelocity ductwork design is very important for energy. Ceiling plenums, duct chases, and obstructions such as walls and beams often dictate that a certain size duct be used, regardless of whether or not it is the best size from a. Air handling design guide air handling systems dust. Take the velocity of air in the main duct a as 8 ms for. Compliance to the design manual, which promulgates minimum performance design standards for va owned and leased. Mar 04, 2020 you probably didnt realize that your hvac system and its air duct system is something you need to be thinking about even before the architect has completed the plans. Ductsize is based on the design procedures given in the ashrae handbook of fundamentals and the smacna hvac systems duct design manual. The fundamentals of duct system design mcgill airflow. This manual provides the hvac system designer detailed information on duct design and u. The requirements for exhaust air and outdoor supply air for each zone must be established prior to calculating cooling and heating. It details the necessary steps for planning, design, equipment selection, operation and maintenance. The purpose of residential ductwork design is to properly distribute the airflow, produced by your heatingcooling system, to your house.
This feature is also useful for analyzing problems in existing systems where the duct sizes are already specified. Take the velocity of air in the main duct a as 8 ms for both the methods. Design guide for heating, ventilating, and air conditioning systems. The internal face of the duct has either an aluminium coating, a glass mat or fabric layer, depending on the properties required of the duct. Fellow ashrae 0 f the three duct design procedures recommended by the 1997 ashrae handbook fundamentals, only the tmethod incorporates lifecycle cost. Number one is the load calculation using a protocol like accas.
To submit a comment about any aspect or part of the handbook series, you can use the handbook comment form. Hvac systems duct design sheet metal and air conditioning. Youve got to know how much heating and cooling you need for each room. For air quantities less than 180 ls, size duct at 4. Lowvelocity ductwork design is very important for energy efficiency in air distribution systems. Air and gas ducts for fossil fuel power stations and industrial boiler applications are unique structures, yet structural analysis and design of ductwork are not currently referenced or governed by any national code or design standard. One typical misconception about mixing box design is the idea that cold air introduced high will drop due.
At installation, ductwork spans should be mechanically fastened together. Number one is the heating and cooling load calculation using a protocol like accas manual j or the ashrae handbook of fundamentals. Jan, 2019 one of the design parameters that define the sizing of ductwork is the maximum allowable air velocity. The basic fluid flow equations are not included here, but may be found in the ashrae handbook. The air duct distribution network is an important component of hvac installations. Ductsize hvac duct sizing and analysis elite software. Youve got to know how much heating and cooling you need for each room in btuhr. Purchase any of the current handbook volumes in print or individual chapter pdfs through the ashrae bookstore, or pdfs of the entire 2018. 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.
Duct system design vi introduction foreword these reference manuals have been compiled and written by engineers and consultants employed by united mcgill corporation and its subsidiary, mcgill airflow corporation. After air discharge grilles and the air handler, which consists of a heat exchanger and blower, have been located, it is advisable to make a singleline drawing showing the duct. The fundamentals of rigid duct design greenbuildingadvisor. Introduction to design of industrial ventilation systems. Price has long been innovative in the presentation of technical content and product information. For professional advice on good ductwork design in the savannah area, contact byrd heating and air conditioning. Fundamentals distribution systems 2 space availability the sizing criteria will often be defined by the space available to run the ductwork figure 1. The structural design of air and gas ducts for power stations. Dont kill your air flow with this flex duct disease. Principle of duct design in hvac systems cedengineering.
Tasks of the hvac design, an outline the following outline follows the organization of the chapters in this book. At installation, ductwork spans should be mechanically fastened together with sheet metal screws and each joint sealed with mastic. Designing a duct system is important but there are a few critical steps that come first. Related commercial resources ashrae handbook fundamentals chapter. Understanding basic residential ductwork design please note.
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