Understanding basic residential ductwork design please note. From ashrae fundamentals handbook, the following equations may be used to convert rectangular and flat oval ducts to and from round. For mechanical system designers language selection. Sdc engineering has the capability and experience to assist in the design of your system and ducting. All ductwork shall be of a clamptogether design using a dieformed, rolled edge in which is then joined together by a single lever clamp of similar material. As a first step the parameters that define comfort need to be identified temperature, humidity, air. A manual of recommended practice for design and have designed many successfully balanced ducting. From the building layout and the location of the supply fan, the length of each duct run is known. Designing a duct system is important but there are a few critical steps that come first. When applied to airflow in ducts, the flow work or static energy is represented by the static pressure of the air, and the velocity pressure of the air represents the. Engineering cookbook a handbook for the mechanical designer third edition this handy pocket reference is a token of loren cook companys appreciation to the many fine mechanical designers in our industry. Compliance to the design manual, which promulgates minimum performance design standards for va owned and leased. The purpose of the duct design is to select suitable dimensions of duct for each run and then to select a. Principle of duct design in hvac systems cedengineering.
Two duct design experts, jjw bill siganto and murray mason provide a wealth of information on the topic. Design of flexibleduct junction boxes us department of. 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. The basic fluid flow equations are not included here, but may be found in the ashrae handbook. 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. Lowvelocity design will lead to larger duct sizes, but it may be worth since, doubling of duct. Duct design quick introduction duct sizing tools and methods. Duct systems are designed to properly distribute air throughout a building. All information provided in this document is to be used as a guideline only. No matter how much money you spend on a highquality hvac system. In cases where dust or high concentrations of solids might accumulate, such accumulation within the duct system may be prevented by providing water spray.
The fundamentals of duct system design mcgill airflow. The designation of a pressure class pertains to straight duct and duct. If clean air return duct is required, duct resistance should also. Small hvac system design guide overview 1 overview this design guide focuses on packaged heating, ventilation and air conditioning hvac syst ems up to 10 tons per unitthe most common hvac. Duct size manufacturing costs duct systems pressure losses operation cost. Number one is the heating and cooling load calculation using a protocol like accas manual j or the ashrae handbook. This information should be consulted to ensure that the proper type and location of duct system is selected for the structure in question. Lowvelocity ductwork design is very important for energy efficiency in air distribution systems.
This 2017 va hvac design manual for the department of veterans affairs va healthcare facilities is the only detailed design requirements manual for va. Smacna cad standard second edition v notice to users of this publication 1. Ducting system design has many con straints such as low acoustic noise lev. The ashraefundamentals handbook contains hvac design criteria for most countries around the world. This manual is intended as a guide for electrical engineers and designers hereafter referred as. The ashraefundamentals handbook contains hvac design. Ductwork should be designed in accordance with the provisions of the ashrae handbook of fundamentals, or the sheet. Ceiling plenums, duct chases, and obstructions such as walls and beams often dictate that a certain size duct. Liquid pools and residue buildup that can result from condensation may create a hazardous condition if allowed to collect.
Choosing the rightsized duct is critical to maintain proper air flow in the system. Highvelocity hv duct systems are characterized by air velocities in the range of 2500 to 3500 fpm. Hvac design combining comfort with efficiency when defining an hvac installation,comfort is the most obvious primary consideration,as it is invariably the main reason for installing an hvac system in the first place. Nordfab quickfit ducting is manufactured in thomasville, nc and sparks, nv. Duct system design guide first edition 2003 mcgill airflow corporation mcgill airflow corporation one mission park groveport, ohio 43125 duct system design i notice. Introduction to design of industrial ventilation systems. Ducting handbook 4th ed final free download as pdf file. 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. System and ducting design scientific dust collectors. 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. The estimated heating and cooling loads are those required to meet the inside design conditions on the design load day. Put your presentation title or confidentiality info here. Three configurations to limit variation 2, 3 or 4 outlets outlets with 10, 150 or 250 cfm ducts sized to 0.
The ducting and clamps are made of similar materials. Nordfab duct is a clamptogether design using a rolled edge design with a single lever clamp. All of our engineers are well versed on the acgih industrial ventilation. Small hvac system design guide new buildings institute. No part of this work may be reproduced or used in any form or by any means graphic, electronic, or mechanical, including photocopying.
Clicking on a companys name will take you to their web site. The basic principles of duct design, part 1 energy vanguard. In principle, required amount of air can be conveyed through the air conditioning ducts by a number of combinations. Our manual d calculation service, is a complete custom duct design for your residential project. 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. Chapter 8 duct design and sealing state of louisiana. Ansismacna 0062006 hvac duct construction standards. 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. Developed by the innovation and energy technology sectors canmetenergy housing researchers and leep local energy efficiency partnerships team. Leaktight laser welded seams, instead of lockform or spiral duct which badly leaks. Document handbook of air conditioning system design.
Below is a simple model for determining duct sizes. Duct design clicking on a companys name will take you to their web site. For full stepbystep instructions on ducting system design, download the pdf below. Air flow problems have plagued the hvac industry for years. Developed by the innovation and energy technology sectors canmetenergy housing researchers and leep local. Consider our improved automobile construction methods, home appliances, and the like as examples. A comprehensive duct layout indicating sizes, design airflows, pressure class, and routing of the duct system. Heat conduction and thermal resistance for steady state conditions and one dimensional heat transfer, the heat q conducted through a plane wall is given by. All clamp together ducting shall be of continuous laser welded construction along the longitudinal seam of the rolled form duct with the exception of the 3 which is lock formed.
The length of duct used for design purposes that includes the. No matter how much money you spend on a highquality hvac system, the equipment wont work at it s best without properly designed and installed ductwork. Design guide for heating, ventilating, and air conditioning systems. The initial duct sizing, pressure augmentation and size augmentation ips method has the potential to reduce ducting system lifecycle costs and the time it takes to design them. Chapter 8 duct design and sealing 143 chapter 8 duct design and sealing duct materials the three most common types of duct material used in home construction are metal, rigid fiberglass duct board, and flex duct. 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. The types of fittings to be used based on the designers calculations of fitting losses i.
A manual of recommended practice for design and have designed many successfully balanced ducting systems. Table 1 in accas manual j lists design con ditions for locations in the u. This should be selfevident, for if emissions are not efficiently captured at the. Heat conduction and thermal resistance for steady state conditions and one dimensional heat transfer, the heat q. Fundamentals distribution systems 2 space availability the sizing criteria will often be defined by the space available to run the ductwork figure 1. It delivers an schematic drawing of the duct system including locations and sizes of trunklines, branch ducts, outlet registers, an inlet grilles.
It provides access to frequently needed information. Fellow ashrae 0 f the three duct design procedures recommended by the 1997 ashrae handbook fundamentals, only the tmethod. Slope all horizontal ducting down towards the fume hood recommended guideline. The designation of a pressure class pertains to straight duct and duct fittings except for equipment and special components inserted into the ductwork. Youve got to know how much heating and cooling you need for each room in btuhr. The fourth edition of hvac systems duct design presents the basic methods and procedures required to design hvac air distribution systems. Duct design fundamentals pressure losses friction reynolds number f d h re f 2. Further considerations duct sizing methods there is no single duct sizing method that will inherently give the best duct design. Design information designing your dust collection system. The purpose of residential ductwork design is to properly distribute the airflow, produced by your heatingcooling system, to your house. Purpose of duct design from load and psychrometric calculations the required supply airflow rates to each conditioned space are known.
Designer selection of duct construction pressure class is acknowledgment of acceptable design velocity level and pressure level including any overpressure or underpressure conditions that may occur during normal and special modes of operation. Ashrae 2009 handbookfundamentals, chapter 20, space air diffusion. Duct design manual is intended to be used in conjunction with the american society of heating, refrigerating and air conditioning engineers, inc. Handbook of heating, ventilation and air conditioning.
Number one is the heating and cooling load calculation using a protocol like accas manual j or the ashrae handbook of fundamentals. Air handling design guide air handling systems dust. When diffusers, registers, and grilles are mounted to supply, return, and exhaust ducts, velocities should not exceed 1500 fpm or noise will result. Paul guyer is a registered civil engineer, mechanical engineer, fire protection engineer, and architect with over 35 years experience in the design. More available in the ashrae handbook or smacna obtain other duct fittings pressure losses from manufacturers. If you purchase the ductwork the drawings are free. The purpose of residential ductwork design is to properly distribute. Ducting handbook 4th ed final duct flow thermal insulation. Consequently, the total pressure or total energy of air flowing in a duct. Lowvelocity design will lead to larger duct sizes, but it may be worth since, doubling of duct diameter. Design of flexible duct junction boxes what did we look at. Click here to view more information about the acs ducting design service. Disclaimer of warranties a the sheet metal and air conditioning contractors national association smacna.
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. Procedures for hvac system design and installation criteria for a quality hvac system an hvac system should. Ducts that are not well designed result in discomfort, high energy costs, bad air quality, and increased noise levels. Leaktight laser welded seams, instead of lockform or spiral duct. Be properly sized to provide correct air flow, and meet roomby.902 1567 594 165 1550 1327 111 433 221 1127 613 252 1587 270 1386 128 622 121 1191 228 605 1504 1047 1189 1028 1398 1610 233 1554 1290 205 212 36 644 773 1338 1257 629 178 631 296