Fan Efficiency Grades and System Effect and Their Effects on HVAC Systems Matt Spink, P.E. Greenheck Fan Corporation
Learning Objectives Understanding Fan Efficiency Grades (FEG) Selection of fans within acceptable efficiency tolerances System Effect: Understanding their impact on performance/energy
Background US total energy consumption for 2010 98 Quadrillion BTUs! (1.0 quadrillion = 1,000,000,000,000,000 BTUs) According to the DOE US fans consume: 0.9 quads of electricity in industrial applications 1.6 quads of electricity in commercial applications (2.5 quads is about 2.5% of total) * Sources: DOE and LLNL
Background Savings Potential in HVAC Systems System Leakage System Effects Fan Efficiency Drive Efficiency Fan Selection Source: AMCA International
DOE suggests 65% fan efficiency. ASHRAE & AMCA collaborate on AMCA 205 Fan Efficiency Grades. Background AMCA begins certifying FEGs 2012 IgCC adopts FEG 71 DOE publishes intent to regulate fan energy efficiency 2007 2008 2009 2010 2011 2012 2013 AMCA 205-10 Fan Efficiency Classification For Fans ASHRAE 90.1 adopted FEG 67
Fan Energy Consumption Power Input (Electrical) Power Loss! Power Output (Flow and Pressure)
Fan Energy Consumption Fan Efficiency Electrical Power In Motor Loss (10%) Drive Loss (3% - 10%) Bearing Loss (3%) Aerodynamic Loss (10% to 20%) Fan Power Out
What is Fan Efficiency? Efficiency = Power Output Power Input Fan Efficiency = CFM x Pressure BHP
What is Fan Efficiency? CFM x Ps Static Efficiency = x 100% 6343.3 x BHP CFM x Pt Total Efficiency = x 100% 6343.3 x BHP P T = P S + P V
Fan Curves 6.0 Ps 5.0 4.0 3.0 Ps vs. CFM Surge Area BHP vs. CFM 10.0 8.0 6.0 BHP 2.0 4.0 1.0 2.0 0.0 0 2 4 6 8 10 12 CFM x 1000 0.0
Fan Curves 6.0 5.0 Ps vs. CFM 100 Ps 4.0 3.0 2.0 1.0 Static Efficiency vs. CFM Peak 75% 80 60 40 20 Efficiency 0.0 0 2 4 6 8 10 12 CFM x 1000 0
Fan Selection for Efficiency 6.0 Ps 5.0 4.0 3.0 Ps Surge Area High Efficiency, Low Sound BHP 10.0 8.0 6.0 BHP 2.0 4.0 1.0 0.0 Low Efficiency, High Sound 0 2 4 6 8 10 12 CFM x 1000 2.0 0.0
Fan Selection for Efficiency 18 20 22 Ps 24 27 30 Design Duty CFM
Fan Selection for Efficiency High Efficiency, Low Sound Static Efficiency % Ps Peak SE Actual Selections % CFM
Fan Efficiency Grades ANSI/AMCA Standard 205-10 Energy Efficiency Classifications for Fans ISO 12759:2010 Fans Efficiency Classification for Fans
Fan Efficiency Grades AMCA 205 85
Fan Efficiency Grades AMCA 205 Airfoil Centrifugal Backward Inclined Forward Curved
AMCA 205 AMCA 205, Annex A: In order to achieve the goals in energy savings by operating fans it is important that the fan is selected in the system close to the peak of the fan efficiency. The fan operating efficiency at all intended operating point(s) shall not be less than 15 percentage points below the fan peak total efficiency (see figure).
Fan Efficiency Grades 6.0 5.0 Ps vs. CFM 100 Ps 4.0 3.0 2.0 1.0 Total Efficiency vs. CFM Peak 75% 80 60 40 20 Efficiency 0.0 0 2 4 6 8 10 12 CFM x 1000 0
Fan Curves Ps 6.0 5.0 4.0 3.0 2.0 1.0 Ps vs. CFM Total Efficiency vs. CFM 60% Minimum within 15 points of peak efficiency 100 80 60 40 20 Efficiency 0.0 0 2 4 6 8 10 12 CFM x 1000 0
ASHRAE 90.1 Addendum u 6.5.3.1 Fan System Power and Efficiency Limitation 6.5.3.1.3 Fan Efficiency. Fans shall have a Fan Efficiency Grade (FEG) of 67 or higher based on manufacturers certified data, as defined by AMCA 205. The total efficiency of the fan at the design point of operation shall be within 15 percentage points of the maximum total efficiency of the fan. Exceptions: a. Single fans with a motor of 5 hp or less. b. Multiple fans in parallel or series that have a combined motor power of 5 hp or less and are operated as the functional equivalent of a single fan. c. Fans that are part of equipment listed under 6.4.1.1 Minimum Equipment Efficiencies Listed Equipment Standard Rating and Operating Conditions. d. Fans included in equipment bearing a third-party-certified seal for air or energy performance of the equipment package. e. Powered wall/roof ventilators (PRV) as defined by ANSI/AMCA-99-2010.
International Green Construction CHAPTER 6 Code 2012 IgCC 607.2.2.3 Minimum fan efficiency. Stand-alone supply, return and exhaust fans designed for operating with motors over 750 watts (1hp) shall have an energy efficiency classification of not less than FEG71 as defined in AMCA 205. The total efficiency of the fan at the design point of operation shall be within 10 percentage points of either the maximum total efficiency of the fan or the static efficiency of the fan.
Things are not always as they seem; the first appearance deceives many. - Phaedrus (Roman Poet)
Fan Types 40,000 CFM at 0.25 Ps Model Impeller Dia BHP FEG $ Cost Sidewall Prop 54 7.11 56 1.0 Tube Axial 54 8.30 67 1.7 Vane Axial 54 6.87 75 4.4 Housed Centrifugal 49 13.4 90 3.8 Housed Centrifugal 60 6.8 90 6.1
Fan Types Adhering to codes that require minimum Fan Efficiency Grades will result in replacing this: 28
With this: Fan Types 29
Fan Selections 15,000 CFM at 4 Ps SW Airfoil Centrifugal Fan Class Oper BHP Static Eff Total Eff Peak Static Eff Peak Total Eff FEG 22 III 24.5 38% 55% 75% 79% 85 24 III 19.0 50% 64% 74% 79% 85 27 II 16.2 58% 70% 74% 79% 85 30 II 13.6 70% 79% 78% 83% 85 33 I 12.5 75% 82% 78% 83% 85 36 I 12.0 78% 83% 78% 83% 85
Summary New standards are going to require Fan Efficiency Grades FEGs are an indicator of Peak Total Efficiency, not of Fan input power For fan comparison and selection, use the actual Fan BHP Future standards will likely start to look at installed systems, not just individual components
System Effects 3
Design Airflow Ps 6.0 5.0 4.0 3.0 2.0 1.0 0.0 Design System Curve Catalog Fan Curve 0 2 4 6 8 10 12 14 CFM x 1000
Fan Curves Show how a fan will operate in any system (installation) Based on standardized tests AMCA 210 Tested under ideal conditions
System Effects Defined: Anything you place in close proximity before or after the fan that effects the cataloged performance. 3
System Effects
Actual Airflow 6.0 Ps 5.0 4.0 3.0 2.0 1.0 0.0 System Curve Catalog Fan Curve Actual Fan 0 Curve 2 4 6 8 10 12 14 CFM x 1000
Why System Effect is Important Can decrease performance Can cause excess vibration Can cause excess noise Can require more energy (HP) to achieve rated performance Takes time to determine and understand 4
Three most common causes of deficient performance of a fan/system are: Improper outlet connections Non-uniform inlet flow Swirl at the inlet 4
Fan Outlet Velocity Profiles Blast Area Cut off Outlet Area Discharge Duct 25% Centrifugal Fan 50% 75% 100% Effective Duct Length Axial Fan Adapted from AMCA Publication 201-202, Fans and Systems. 4
Effective Duct Length Effective Duct Length = 2.5 Duct Diameters for 2,500 FPM or less Add 1 duct diameter for each additional 1,000 FPM For rectangular ducts, the equivalent duct diameter is (4 x width x length / 3.14) ^ 0.5 4
System Effect Curve 1 3 Adapted from AMCA Publication 201-202, Fans and Systems. 2 4
System Effect Curves for Outlet Ducts - Centrifugal Fans B l a s t A r e a C u t o f f N o D u c t O u t l e t A r e a 1 0 0 % E f f e c t i v e D u c t L e n g t h 1 2 % E f f e c t i v e D u c t 2 5 % E f f e c t i v e D u c t D i s c h a r g e D u c t 5 0 % E f f e c t i v e D u c t 1 0 0 % E f f e c t i v e D u c t B l a s t A r e a O u t l e t A r e a S y s t e m E f f e c t C u r v e 0. 4 P R - S U W -- 0. 5 P R - S U W -- 0. 6 R - S S - T U - V W - X -- 0. 7 S U W - X -- -- 0. 8 T - U V W X -- -- 0. 9 W - W W - X -- -- -- 1. 0 -- -- -- -- -- Adapted from AMCA Publication 201-202, Fans and Systems. 4
System Effect Curve 1 +0.45 in w.g. 3 Adapted from AMCA Publication 201-202, Fans and Systems. 2 4
Thank you for your time. Questions? 49
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