2. Copyright Materials
This educational activity is protected by U.S. and International copyright laws. Reproduction, distribution, display, and use of the educational activity without written permission of the presenter is prohibited.
© AMCA International

3. Learning Objectives Definition of System Effect
How to calculate System Effect
System Effect’s effect on power consumption
The difference between inlet and outlet System Effect
How to avoid System Effect

4. Fan Efficiency
Efficiency, η
Results of a fan air performance test are plotted on a curve similar to this.
Air Flow, Q

5. Regulation 3 – 5 % 76 million ton2 of coal
Efficiency, η
Results of a fan air performance test are plotted on a curve similar to this.
Air Flow, Q

6. What we can do
Efficiency, η
Results of a fan air performance test are plotted on a curve similar to this.
Air Flow, Q

7. What we can do %
Efficiency, η
Results of a fan air performance test are plotted on a curve similar to this.
Air Flow, Q

8. Fan Testing for Air Performance
These are pictures of the AMCA Lab.
Fans come in to the lab. They’re tested. They get installed. And the performance of the system falls short. What happened?

9. AMCA Standard 210 Test Fan Auxiliary Fan Nozzles Fan Airflow
Piezometer Ring
Fan Static Pressure
This is a typical fan test setup at AMCA.
We measure fan static pressure with a Piezometer ring
We measure airflow with nozzles, using Bernoulli’s equation and pressure drop across the nozzles
We calculate Fan Total Pressure by adding the Velocity Pressure at the fan outlet to Fan Static Pressure, so fan total pressure is strictly a convention.
The auxiliary fan on the right overcomes the pressure loss in the chamber so that we can determine fan performance near free delivery
PS = PT – PV
PT = PT2 – PT1
PS = PT2 – PT1 – PV
PT2 = PS2 + PV2
PS = PS2 + PV2 – PT1 – PV
PV = PV2
PS = PS2 + PV2 – PT1 – PV2
PS = PS2 – PT1
PT1 open to atmosphere
PS = PS2
PS = PS7

10. Nozzle Wall These are pictures of the AMCA Lab.
Fans come in to the lab. They’re tested. They get installed. And the performance of the system falls short. What happened?

11. AMCA 210 Test Results
800
2.5
700 2
600
500
1.5
Pressure, P
400
Power, H 1
300
Results of a fan air performance test are plotted on a curve similar to this.
200
0.5
100 2 4 6 8 10 12
Air Flow, Q

12. AMCA Standards 500-D & -L Piezometer Ring Damper Pressure Drop Nozzles
Test Damper
Auxiliary Fan
Nozzles
Damper Airflow
Piezometer Ring
Damper Pressure Drop
This figure illustrates a pressure drop test of an air system component.
This figure shows a damper under test, but there are similar tests for louvers, silencers and other components

13. Fan Operating Point AMCA 500-D Test Results Operating Point 700 600
400
Pressure, P
Results of a pressure drop test are plotted on a graph similar to this
What this graph actually shows is a system curve for a typical air system where the system resistance follows a parabolic curve
For simple systems, resistance is calculated by adding the pressure drops of the system’s components
It’s understood that a fan system curve is not strictly parabolic, but it’s shown here as a parabolic curve as this estimation is close enough to reality for this presentation’s purposes.
AFTER SECOND CLICK
The fan operating point, or the system’s operating point is at the intersection of the system curve and fan curve
300
200
100 2 4 6 8 10 12
Air Flow, Q

14. Speed Change New Operating Point New speed Operating Point 800 700 600
500
New speed
Operating Point
400
Pressure, P
300
A change in speed of the fan will create a new a new fan curve with a new intersecting point somewhere on the system curve
200
100 2 4 6 8 10 12 14
Air Flow, Q

15. Damper Opening Operating Point New Operating Point New System
700
600
500
Operating Point
400
New Operating Point
Pressure, P
300
Changing the system will create a new system curve with a new intersecting point somewhere on the fan curve
New System
200
100 2 4 6 8 10 12
Air Flow, Q

16. System Effect 1ST Definition
Installed duct configuration does not match tested duct configuration

17. Installation Type D —Ducted Inlet / Ducted Outlet
Auxiliary Fan
Nozzles
Fan Airflow
Piezometer Ring
Fan Static Pressure
Test Fan
Plenum
This is a typical fan test setup at AMCA.
What’s important to note here are the ducts on the inlet and outlet. These model a ducted inlet/ducted outlet configuration or Installation Type D.
Why is this important? Because if the fan is installed on a plenum without ducts, the fan will not perform as well as when it was tested in the lab. It’s important to match as closely as possible the tested duct configuration to the actual duct configuration where the fan will be installed.
(Note to presenter: 2nd click removes chamber, moves fan and ducts to the center)
Installed Fan

18. AMCA Catalog Ratings “Performance certified is for installation type:
A: Free inlet, Free outlet”
B: Free inlet, Ducted outlet”
C: Ducted inlet, Free outlet”
D: Ducted inlet, Ducted outlet”
These ratings are found in catalogs of certified products.
For certified products it is mandatory to include these statements so the use knows how the fan was tested, and whether or not it matches how the fan will be installed.

19. System Effect 2nd Definition
Even when the tested duct configuration matches the installed duct configuration, improper duct design can introduce adverse flow conditions

20. Elbow Example
One example of a System Effect cause would be elbows installed adjacent to the fan’s inlet and outlet.
Even if the friction loss of the elbow was properly accounted for, the proximity of the elbow to the inlet of the fan adversely affects the fan’s performance
The uneven velocity profile on the fan’s outlet, or the high velocity jets on the fan’s outlet, cause the actual pressure drop through the elbow to be much greater than that calculated assuming a fully developed flow profile.

37. AMCA Publication 201—Plenum Example
This is an example taken from Publication 201
It shows the difference in required Fan Static Pressure solely due to the change in location of a plenum

38. Plenum Example REQUIRED Fan PS 922 Pa
E-F duct friction at 5000CMH (Q) 747 Pa (duct design)
E contraction loss-plenum to duct 50 Pa (part of duct system)
E PS energy required to create velocity at E 125 Pa (part of duct system)
D PV loss (also PT loss) at D as result of air velocity decrease Pa
PS does not change from duct to plenum at D
C-D outlet duct on fan as tested Pa
REQUIRED Fan PS 922 Pa

39. Plenum Example Plenum This is an example taken from Publication 201
It shows the difference in required Fan Static Pressure solely due to the change in location of a plenum

40. Plenum Example
Note the new location of the plenum, and the new Fan Static Pressure requirement due to System Effect.
The next pages show how we arrived at a System Effect Factor of 150 Pa
D-E duct friction at 5000CMH (Q) 747 Pa (duct design)
D contraction loss-plenum to duct 50 Pa (part of duct system)
D PS energy required to create velocity at D 125 Pa (part of duct system)
B-C SEF 149 Pa
B-C PV loss (also PT loss) at C as result of air velocity decrease Pa
PS does not change from duct to plenum at C
REQUIRED Fan PS 1071 Pa

41. Plenum Example from AMCA 201
Assuming:
Use of the same fan for both systems
Can attain both operating points with a change in speed
Speed change ratio; (1071/922)0.5 = 1.08 2
PC = NC N ( ) P
1/2
N𝑐 N = PC P ( )

42. Plenum Example from AMCA 201
HC = NC N ( ) H 3
H, Fan Power
1.083 = 1.25 (Fan Law for Power)
The increased in power consumption to overcome System Effect is about 25%

43. 8% Speed Change 25% More H 8% More Q 800 2.5 700 2 600 500 1.5
Pressure, P
400
Power, H 1
300
SECOND CLICK ADDS CURVES FOR SPEED CHANGE
THIRD CLICK CALLS OUT 8% MORE AIR
FOURTH CLICK CALLS OUT 25% MORE POWER
This is illustrated now to demonstrate the penalty in power consumption when fan speed is increased to deliver more airflow
200
8% More Q
0.5
100 2 4 6 8 10 12 14
Air Flow, Q

44. Inlet System Effect SYSTEM EFFECT ACTUAL FAN CURVE WITH SYSTEM EFFECT
CATALOG PERFORMANCE CURVE
DESIGN RESISTANCE
AIRFLOW DEFICIENCY
DESIGN AIRFLOW

45. Outlet System Effect ACTUAL SYSTEM WITH SYSTEM EFFECT
CALCULATED SYSTEM WITH NO ALLOWANCE FOR SYSTEM EFFECT
SYSTEM EFFECT LOSS AT DESIGN AIRFLOW
CATALOG PERFORMANCE CURVE
DESIGN RESISTANCE
AIRFLOW DEFICIENCY
DESIGN AIRFLOW

46. Speed Changes Before Increasing Speed
Check with the manufacturer for max safe operating speed
Determine expected power increase
Motor size
Electric Service
Expect more noise

52. Rules of Thumb Minimum 2.5 duct diameters on Outlet
Minimum 3 to 5 duct diameters on Inlet
Avoid inlet swirl

53. Recommendations
Allow enough space in the building design to allow for appropriate fan connections to the system
Take into account the fact that the total cost for the building is the original capex cost plus the cost to operate it

54. Recommendations
Use allowances in the design calculations when space or other factors dictate less than optimum arrangement of the fan outlet and inlet connections

55. Recommendations
Include adequate allowance for the effect of all accessories and appurtenances on the performance of the system and the fan
Belt drive loss
VIVs
Belt guards

56. Questions? Mark Stevens Executive Director AMCA International