AABC TAB Journal 2000 Summer

TAB j o u r n a l S U M M E R 2 0 0 0 Serving the HVAC Test and Balance and Engineering Industries Duct Leakage Testing AABC Associated Air Balance Council New Easy-to-Use Software that Generates Customized Test & Balance Specifications! Introducing AABC’s SPECwriter The Associated Air Balance Council has developed a new, easy-to-use software program that brings efficiency and uniformity to your TAB specification writing. SPECwriter is an efficient and simple software created especially for
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  AABC  Associated Air Balance Council  TAB  journal TAB  journal Serving the HVAC Test andBalance and Engineering Industries SUMMER 2000 Duct LeakageTesting  The Associated Air Balance Council hasdeveloped a new, easy-to-use softwareprogram that brings efficiency anduniformity to your TAB specificationwriting. SPEC writer  is an efficient andsimple software created especiallyfor architects and engineers. With SPEC writer  , you can create a specificationthat meets the specific scope of yourproject. A completed specification canbe written and printed in just minutes!The program does all the work!  Easy to install and easy to learn.  Through its innovative approach, SPEC writer  delivers customizedspecifications that meet the precise needs of your projects.  Now your projects can be bid based on complete and precisedetails of the work required!  SPEC writer  also becomes a valuable log, allowing easy access andretrieval of all your project specifications at any time.  In addition, SPEC writer  adds a level of professionalism to all yourTAB specifications. SPECIAL INTRODUCTORY PRICE  $49.95!  Order your copy today! To order SPECwriter call or write:  1518 K Street NW, Suite 503  Washington, DC 20005  (202) 737-0202 AABC  Associated Air Balance Council  IBM/PC Compatible. For use with Windows 3.1 or higher. 4 MBytes of memory, 1 MByteof available hard disk space, a mouse and a printer. AABC’s SPEC writer   Introducing  S  P  E C  w r i t e r  g i v e s y o u  c u s t o m  T A B S p e c s  i n  j u s t m i n u t e s !  New Easy-to-Use Software that GeneratesCustomized Test & Balance Specifications!  11 Understanding Temperature and Altitude Corrections .. . . . . . . . . . . 2  Ron Schilling AirBasics - ForDesign Intent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  Jerry Lavender and Mike Van Weichen Parallel Pumping System Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8  Mario L. Perez Preliminary Testing Before Remodeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11  Bob Severin Static Pressure Set Points forVAVSystems . . . . . . . . . . . . . . . . . . . . 12  Derek R. Shupe Circuit SetterProblems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13  Richard Miller  AComparison of SMACNANew Duct Leakage Test Criteria . . . . . . . . 14  Laszlo A. Lukacs Fresh Airand Why it May Not be so Good forYou .. . . . . . . . . . . . . 15  James P. Bragg Proportional Balancing AirHandling Systems . . . . . . . . . . . . . . . . . . 17  Mike Nix Smoke Dampers - The Pressure Drop Dilemma . . . . . . . . . . . . . . . . 21  Albert L. Englehart  CONTENTS Associated AirBalance CouncilBoard of Directors and OfficersPresident William A. Derse Professional System Analysis, Inc . Executive Vice President Patrick H. Kelly  American Testing Inc. Secretary/Treasurer Robert A. Conboy  American Air Balance Co., Inc. Vice President/Eastern Zone-1 Joseph E. Baumgartner, III, P.E.  Baltimore Air Balance Company Vice President/Central Zone-2 Mike Young Test and Balance Corp. Vice President/Western Zone-3 Michael Renovich  RS Analysis, Inc. Immediate Past President William K. Thomas, Sr. P.E. Thomas-Young Associates, Inc. Director, Canadian Chapter Ed St. Laurent  A.H.S. Testing and Balancing, Ltd. Executive Director Kenneth M. Sufka TAB Journal Editor Brian G. Hutchings Editorial Office 1518 K Street, N.W., Suite 503Washington, D.C. 20005(202) 737-0202FAX: (202) 638-4833E-mail: TAB Journal is published quarterly bythe Associated Air Balance Council. It isdistributed free to AABC members andby subscription to non-members at $24per year. TAB Journal is an open forum for thefree expression of opinions andinformation. The views expressed arenot necessarily those of AABC, itsofficers, directors, or staff.Letters, manuscripts, and other submis-sions are welcome. However, TAB Journal accepts no responsibility forunsolicited material.All rights reserved. Copyright ©2000by the Associated Air Balance Council. TAB   j o u r n a l  From the Publisher Though not a required test, the Associated Air Balance Council Building recommends that all ductsystems, including low-pressure systems, be sealed and tested in accordance with its NationalStandards. In fact, AABC’s new 2000 National Standards (scheduled for release later this year)will feature an updated and revised chapter dedicated to Duct Leakage. Though most buildingcodes normally require that ducts be sufficiently airtight to ensure energy conservation and controlof the air movement, humidity, and temperature in the space, problems with excessive duct leakageare widespread.This issue of  TAB Journal , entitled Duct Leakage Testing , contains several articles focusing on thistopic. In the articles, we see how duct leakage is affected by static pressure, openings in the duct(through joints, seams, access doors, rod penetrations, etc), and workmanship, and how duct testingcan save money and improve indoor air quality. Among these, Laszlo Lukacs with AerodynamicsInspecting Company compares the differences between SMACNA’s New Duct Leakage TestCriteria against their old one and reports that newer may not always be better. Albert Englehart,Mechanical Testing, Inc., presents an informative case study on problems with static pressure dropsacross smoke dampers, and the drawbacks of using smoke dampers in small ducts. And finally, JerryLavender and Mike Van Weichen of AIRWASO, show the importance of duct leakage testing andhow testing for duct leakage can save the owner considerable expense over the long run.In the Forum section, James Bragg’s humorously titled article, “Fresh Air and Why it May Not beso Good For You,” addresses the serious issue how adding too much outside air can actually lead topoor indoor air quality. In other articles, Mike Nix, of Delta-T, Inc., takes a look at the benefits of proportional balancing air handling systems, and Mario Perez, Precisionaire of Texas, explains whyit is important to perform a thorough analysis of each parallel pumping system application. Thisissue of  TAB Journal also includes a new edition of AABC’s technical newsletter TechTips , and areport by the Department of Energy revealing that most commercial HVAC auxiliary equipment isnot energy efficient.We thank all of the authors for their contributions, and for helping to make this another informativeand educational issue of  TAB Journal . We welcome reader input at TAB Journal and encourageyou to provide us with your comments, letters, and articles.  2 TAB Journal FAN PERFORMANCE Understanding Temperatureand Altitude Corrections Ron Schilling Greenheck Fan Company T he most common influences on airdensity are the effects of temperatureother than 70°F and barometric pressuresother than 29.92 caused by elevationsabove sea level.Ratings found in fan performance tablesand curves are based on standard air,which is defined as clean, dry air with adensity of .075 pounds per cubic foot,with the barometric pressure at sea levelof 29.92 inches of mercury and a tempera-ture of 70°F. Selecting a fan to operate atconditions other than standard airrequires adjustment to both static pres-sure and brake horsepower. The volumeof air will not be effected in a givensystem because a fan will move the sameamount of air regardless of the air den-sity. In other words, if a fan will move3,000 CFM at 70°F, it will also move3,000 CFM at 250ºF. Because 250°F airweighs only 34% of 70°F air, the fan willrequire less bhp, but it will also createless pressure than specified.When a fan is specified for given CFMand static pressure (Ps) at conditions otherthan standard, the correction factors (shown in table) must be applied to selectthe proper size fan, fan speed and bhp tomeet the new condition. The best way tounderstand how the correction factors areused is to work out several examples.Let’s look at an example using a specifica-tion for a fan to operate at 600°F at sealevel. This example will clearly show thatthe fan must be selected to handle a muchgreater static pressure than specified. Example #1 A20 centrifugal fan (20 BISW) isrequired to deliver 5,000 CFM at 3.0 inchesstatic pressure. Elevation is 0 (sea level).Temperature is 600°F.1.Using the chart, the correction factoris 2.00.2.Multiply the specified operating staticpressure by the correction factor todetermine the standard air densityequivalent static pressure. (Correctedstatic pressure = 3.0 x 2.00 = 6 . Thefan must be selected for 6 in. of staticpressure.)3.Based upon our performance table for a20 BISWfan at 5,000 CFM at 6 inwg. 2,018 frpm is needed to producethe required performance. (This nowrequires a Class II fan. Before the cor-rection was made it would haveappeared to be a Class I selection.)4.The bhp from the performance chart is6.76.5.What is the operating bhp at 600°F?Since the horsepower shown in the perform-ance chart refers to standard air density, thisshould be corrected to reflect actual bhp at thelighter operating air. Operating bhp = standardbhp  2.00 or 6.76  2.00 = 3.38 bhp.  Important: We now know the operatingbhp. However, what motor horsepower should be specified for this fan? Figure 1:  It is acceptable to interpolate when exact temperatures or elevations are not shown in chart. AirTemp.°F 00.870.961. Air Density Correction Factors Elevation [ feet above sea level ]
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