Trane TRG-TRC013-EN User Manual

Air ConditioningClinicAir Conditioning FansOne of the Equipment SeriesTRG-TRC013-EN85667_Cvr.fm Page 1 Friday, October 8, 1999 10:05 AM

TRG-TRC013-EN 3period oneFan PerformancenotesWhen the pressure within the ductwork is positive, that is, greater than atmospheric, the water column is

4 TRG-TRC013-ENnotesperiod oneFan PerformanceSince some of the pressures observed in air conditioning systems are very small, the U-tube has been modi

TRG-TRC013-EN 5period oneFan PerformancenotesThe total amount of pressure generated by a fan has two components: velocity pressure and static pressur

6 TRG-TRC013-ENnotesperiod oneFan PerformanceWith the fan operating and the damper fully open, air moves through the duct unimpeded. The impact of the

TRG-TRC013-EN 7period oneFan PerformancenotesThis build-up of static pressure results in reduced air velocity (velocity pressure) and therefore a redu

8 TRG-TRC013-ENnotesperiod oneFan PerformanceAnother probe can be placed in the duct with its open end facing into the air stream. This probe senses t

TRG-TRC013-EN 9period oneFan PerformancenotesThe characteristics of a fan’s performance under various duct pressure conditions is tested by an apparat

10 TRG-TRC013-ENnotesperiod oneFan PerformanceNext, the measured velocity pressure is used to calculate the airflow delivered by the fan. The manomete

TRG-TRC013-EN 11period oneFan PerformancenotesFan Performance CurvesThis point can then be plotted on a chart that has static pressure on the vertical

12 TRG-TRC013-ENnotesperiod oneFan PerformanceWhen a series of points is plotted, a curve can be drawn. The resulting curve graphically illustrates th

NO POSTAGENECESSARYIF MAILEDIN THEUNITED STATESBUSINESS REPLY MAILFIRST-CLASS MAILPERMIT NO. 11LA CROSSE, WIPOSTAGE WILL BE PAID BY ADDRESSEETHE TRANE

TRG-TRC013-EN 13period oneFan PerformancenotesNext, the fan laws are used to calculate the performance characteristics of this same fan at other rotat

14 TRG-TRC013-ENnotesperiod oneFan PerformanceFinally, using the measurements from the dynamometer and the fan laws, curves can be calculated and plot

TRG-TRC013-EN 15period oneFan PerformancenotesA surge line is established during the fan test procedure to indicate the area on a fan performance curv

16 TRG-TRC013-ENnotesperiod oneFan PerformanceFan manufacturers may present their performance data in graphical and/or tabular form. Similar to using

TRG-TRC013-EN 17period oneFan PerformancenotesSystem Resistance CurveNow that a typical fan performance curve has been developed, let’s see how the fa

18 TRG-TRC013-ENnotesperiod oneFan PerformanceAssuming the system does not change, the static-pressure loss due to the system varies with the square o

TRG-TRC013-EN 19period oneFan PerformancenotesBy plotting several such points, a curve can be established. This system resistance curve represents the

20 TRG-TRC013-ENnotesperiod oneFan PerformanceConsider a case where the air resistance through the system is greater than predicted. Instead of the de

TRG-TRC013-EN 21period oneFan PerformancenotesReducing the fan speed causes the system resistance and fan performance curves to intersect at E. The fa

22 TRG-TRC013-ENnotesperiod oneFan PerformanceLet’s assume that the fan from the previous example, delivering 3,500 cfm[1.65 m3/s] at 2.0 in. H2O [491

Perforation 5.625” from topPerforation 3.25” from left edgeComment CardWe want to ensure that our educational materials meet your ever-changing resour

TRG-TRC013-EN 23period oneFan PerformancenotesIn a constant-volume system, where the fan is always delivering the same airflow, the fan is generally s

24 TRG-TRC013-ENnotesperiod oneFan PerformanceThe fan performance curves discussed so far are typical of both the centrifugal and fixed-pitch vaneaxia

TRG-TRC013-EN 25period oneFan PerformancenotesUnlike the previous fan performance curves, those of the VPVA fan are plotted on the basis of airflow, a

26 TRG-TRC013-ENnotesperiod oneFan PerformanceSimilar to both the centrifugal and fixed-pitch vaneaxial fans, the intersection of the system resistanc

TRG-TRC013-EN 27notesThe most common types of fans used in air conditioning applications are the centrifugal and axial designs.In a centrifugal fan th

28 TRG-TRC013-ENnotesperiod twoFan TypesForward Curved (FC) FansThe first of these centrifugal fan wheels to be considered has blades that are curved

TRG-TRC013-EN 29period twoFan TypesnotesThe static pressure produced by a fan is a function of the forward motion of the air at the blade tip. The FC

30 TRG-TRC013-ENnotesperiod twoFan TypesNotice how the fan input-power lines cross the FC fan performance curves. If the system resistance were to dro

TRG-TRC013-EN 31period twoFan TypesnotesThe angle of the backward inclined blade causes the air leaving the wheel to bend back against the direction o

32 TRG-TRC013-ENnotesperiod twoFan TypesThe application range of the BI fan is from approximately 40 to 85 percentwide-open airflow. As before, an ope

Air Conditioning FansOne of the Equipment SeriesA publication ofThe Trane Company—Worldwide Applied Systems Group

TRG-TRC013-EN 33period twoFan TypesnotesA variation of this type of fan, called the backward curved (BC) fan, uses a slight curve in the fan blades, a

34 TRG-TRC013-ENnotesperiod twoFan TypesThe application range of the airfoil fan is from approximately 50 to 85 percent wide-open airflow. This is a n

TRG-TRC013-EN 35period twoFan TypesnotesVaneaxial FansIn an axial fan, the airflow passes straight through the fan, parallel to the shaft. There are t

36 TRG-TRC013-ENnotesperiod twoFan TypesThe application range of the vaneaxial fan is from approximately 60 to90 percent wide-open airflow. Similar to

TRG-TRC013-EN 37period twoFan TypesnotesThe VPVA fan is selected so that the operating point is within the most efficient area of the performance curv

38 TRG-TRC013-ENnotesperiod twoFan TypesThe selection of the type of fan to be used in a particular application is based on the system size and space

TRG-TRC013-EN 39notesperiod threeFan Capacity ControlThe previous discussions assumed that the fan would perform at a single operating point, located

40 TRG-TRC013-ENnotesperiod threeFan Capacity ControlThis modulation causes the actual system resistance curve to shift.In a VAV system, therefore, th

TRG-TRC013-EN 41period threeFan Capacity ControlnotesThis method of fan modulation can be used with any type of fan. It is most effective, however, wh

42 TRG-TRC013-ENnotesperiod threeFan Capacity ControlBecause of this issue, and since many VAV systems are large with high static pressures, some form

Preface© 1999 American Standard Inc. All rights reservedTRG-TRC013-ENiiThe Trane Company believes that it is incumbent on manufacturers to serve the i

TRG-TRC013-EN 43period threeFan Capacity ControlnotesAn exaggerated example is used to illustrate this system operation. Assume that the load on the s

44 TRG-TRC013-ENnotesperiod threeFan Capacity ControlThere are four methods used to actively control the capacity of a fan. They are discharge dampers

TRG-TRC013-EN 45period threeFan Capacity ControlnotesAs the VAV terminal units modulate shut, the system resistance curve shifts upward. The fan begin

46 TRG-TRC013-ENnotesperiod threeFan Capacity ControlInlet VanesThe next method of capacity control, inlet vanes, modulates a fan’s capacity by “presw

TRG-TRC013-EN 47period threeFan Capacity ControlnotesAs the VAV terminal units modulate shut, the system resistance curve shifts upward. The fan begin

48 TRG-TRC013-ENnotesperiod threeFan Capacity ControlFan-Speed ControlThe third method of capacity control, fan-speed control, modulates fan capacity

TRG-TRC013-EN 49period threeFan Capacity Controlnotesalong the VAV system modulation curve and the fan satisfies the systemstatic-pressure controller.

50 TRG-TRC013-ENnotesperiod threeFan Capacity ControlThe performance and control of the direct-drive, variable-pitch vaneaxial (VPVA) fan is similar t

TRG-TRC013-EN 51period threeFan Capacity ControlnotesThese curves describe the performance characteristics of various methods of fan capacity control,

52 TRG-TRC013-ENnotesperiod fourApplication ConsiderationsSeveral considerations must be addressed when applying fans in air conditioning systems, inc

TRG-TRC013-EN iiiContentsIntroduction ... 1period one Fan Performance ...

TRG-TRC013-EN 53period fourApplication ConsiderationsnotesSystem Static-Pressure ControlFan capacity control requires a signal from a controller, whic

54 TRG-TRC013-ENnotesperiod fourApplication ConsiderationsAnother method of static-pressure control, the optimized static-pressure control method, pos

TRG-TRC013-EN 55period fourApplication ConsiderationsnotesSystem EffectAt the end of Period One, we discussed the effect of the air resistance through

56 TRG-TRC013-ENnotesperiod fourApplication Considerationsthe fan outlet, this system effect should be accounted for in the fan selection. If an elbow

TRG-TRC013-EN 57period fourApplication ConsiderationsnotesAn HVAC system can be made quieter by reducing the source (fan) sound level and/or increasin

58 TRG-TRC013-ENnotesperiod fourApplication ConsiderationsEffect of Actual (Nonstandard) ConditionsMost fan performance data is published at standard

TRG-TRC013-EN 59period fourApplication ConsiderationsnotesEquipment Certification StandardsThe Air Movement and Control Association (AMCA) establishes

60 TRG-TRC013-ENnotesLet’s review the main concepts that were covered in this clinic on air conditioning fans.Period One introduced the method of dete

TRG-TRC013-EN 61period fiveReviewnotesPeriod Two introduced the various fan types, including forward curved (FC), backward inclined (BI), airfoil (AF)

62 TRG-TRC013-ENnotesperiod fiveReviewPeriod Four covered several considerations in the application of fans in air conditioning systems, including sys

iv TRG-TRC013-EN

TRG-TRC013-EN 63period fiveReviewnotesFor more information, refer to the following references: Fans and their Application in Air Conditioning (Trane l

64 TRG-TRC013-ENQuestions for Period 11 The total pressure generated by the fan is made up of two components, __________ pressure and __________ press

TRG-TRC013-EN 65Quiz6 Between the forward curved (FC) and backward inclined (BI) fans, which one can handle higher static-pressure applications?7 Expl

66 TRG-TRC013-EN1 velocity pressure and static pressure2aPv = 0.5 in. H2O [125 Pa]b V = 2,832 fpm [14.4 m/s]c Airflow = 4,248 cfm [2 m3/s]3aairflowb s

TRG-TRC013-EN 67adjustable-frequency drive (AFD)See variable-speed drive.airfoil (AF) A type of centrifugal fan that is similar to the backward inclin

68 TRG-TRC013-ENGlossaryfan-speed control A method of controlling fan capacity by varying its speed of rotation—commonly accomplished using a variable

TRG-TRC013-EN 69Glossarynotestotal efficiency The percentage of input power that is realized as useful work in terms of total energy (pressure).total

The Trane CompanyWorldwide Applied Systems Group3600 Pammel Creek RoadLa Crosse, WI 54601-7599www.trane.comAn American Standard CompanyLiterature Ord

TRG-TRC013-EN 1notesIntroductionEfficient distribution of conditioned air needed to heat, cool, and ventilate a building requires the service of a pro

2 TRG-TRC013-ENnotesperiod oneFan PerformanceCompared to compressors, the pressures generated by these air-moving devices within the ductwork of HVAC