Understanding and Combating System EffectsMark STEVENS, AMCA International, Inc.Alain GUEDEL, CETIAT

Learning Objectives• Basic air systems• What’s System Effect?• Inlet versus outlet System Effect• System Effect’s effect on power consumption• Is System Effect a common occurrence?• Rules of thumb

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Basic Air Systems

Fan Air Performance Testing

AMCA Standard 210

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Test Fan

Auxiliary Fan

NozzlesFan Airflow

Piezometer Ring Fan Static Pressure

Nozzle Wall

9

AMCA 210 Test Results

10

0

100

200

300

400

500

600

700

800

0 2 4 6 8 10 12Air Flow, Q

Pres

sure

, P

0

0.5

1

1.5

2

2.5

Power, H

AMCA Standards 500-D & -L

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Test Damper

Auxiliary Fan

NozzlesDamper Airflow

Piezometer Ring Damper Pressure Drop

Fan Operating Point

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Operating Point

0

100

200

300

400

500

600

700

0 2 4 6 8 10 12

Air Flow, Q

Pres

sure

, P

AMCA 500-D Test Results

Speed Change

New Operating PointNew speed

0

100

200

300

400

500

600

700

800

0 2 4 6 8 10 12 14

Air Flow, Q

Pres

sure

, P Operating Point

13

Damper Opening

New System

New Operating Point

0

100

200

300

400

500

600

700

0 2 4 6 8 10 12

Air Flow, Q

Pres

sure

, P

Operating Point

14

What’s System Effect?

Test Fan

Installation ≠ Test Setup

16

Auxiliary Fan

NozzlesFan Airflow

Piezometer Ring Fan Static Pressure

Installed Fan

PlenumPlenum

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”

17

Duct Setups Match, But…

19

Inlet Versus OutletSystem Effect

Outlet System Effect

Outlet System Effect

42

ACTUAL SYSTEM WITH SYSTEM EFFECT

CALCULATED SYSTEM WITH NO ALLOWANCE FOR SYSTEM EFFECT

SYSTEM EFFECT LOSS AT DESIGN AIRFLOW

AIRFLOW DEFICIENCY

DES

IGN

RES

ISTA

NC

E

DESIGN AIRFLOW

Outlet System EffectSE = pc + SEoWhere:• pc = Conventional pressure loss• SEo = Additional pressure loss due to non-uniform

flow• SEo = C x pfd2

Inlet System Effect

41

FAN PERFORMANCE CURVE WITH SYSTEM EFFECT

FAN PERFORMANCE CURVE

AIRFLOW DEFICIENCY, ΔqV1

SYST

EM R

ESIS

TAN

CE

DESIGN AIRFLOW

Inlet System Effect

fsV pq /1=ξ

“Nearly” constant

System Effect CalculationAMCA Publication 201

AMCA Publication 201Plenum Example

34

Plenum

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 0 Pa

PS does not change from duct to plenum at D C-D outlet duct on fan as tested 0 Pa

--------------------

REQUIRED Fan PS 922 Pa

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Plenum

36

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 PaB-C PV loss (also PT loss) at C as result of air velocity decrease 0 Pa

PS does not change from duct to plenum at C ------------------

REQUIRED Fan PS 1071 Pa

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AMCA 201 ExampleAssuming:Use of the same fan for both systemsCan attain both operating points with a

change in speed

Speed change ratio; (1071/922)0.5 = 1.08

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2

PC = NCN( ) P

AMCA 201 Example

1.083 = 1.25 The increased in power consumption to

overcome System Effect is about 25%

29

HC =NCN( ) H

3

Is System Effect a Common Occurrence?

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41

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43

44

45

46

47

48

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Rules of Thumb

Minimum 2.5 duct diameters on outlet

Minimum 3 to 5 duct diameters on inlet

Avoid inlet swirl

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RecommendationsAllow enough space in the building design to

allow for appropriate fan connections to the systemUse allowances in the design calculations

when space or other factors dictate less than optimum arrangement of the fan outlet and inlet connections Include adequate allowance for the effect of

all accessories and appurtenances on the performance of the system and the fan

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Recommendations• Be aware of ISO TR 16219• Make liberal use of AMCA’s Fan Application

Manual• AMCA 201 (under review)• AMCA 202• AMCA 203• AMCA 205

Questions?

Mark StevensExecutive Director

AMCA Internationalmstevens@amca.org

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Understanding and Combating System EffectsLearning ObjectivesBasic Air SystemsFan Air Performance TestingAMCA Standard 210Nozzle WallAMCA 210 Test ResultsAMCA Standards 500-D & -LFan Operating PointSpeed ChangeDamper OpeningWhat’s System Effect?Installation ≠ Test SetupAMCA Catalog RatingsDuct Setups Match, But…Slide Number 16Inlet Versus Outlet�System EffectOutlet System EffectOutlet System EffectOutlet System EffectInlet System EffectInlet System EffectSystem Effect Calculation�AMCA Publication 201AMCA Publication 201�Plenum ExampleSlide Number 25Slide Number 26Slide Number 27AMCA 201 ExampleAMCA 201 ExampleIs System Effect a �Common Occurrence?Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Rules of ThumbRecommendationsRecommendationsQuestions?