need for duct leakage
TRANSCRIPT
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TESTINGFOR
DUCT
LEAKAGE
Engineered Air Balance Co., Inc.
Spring, Texas
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WhatShouldBeSpecifiedAssociatedAirBalance ASHRAE 2012DuctConstructionChapter
TypeofSystem Minimum
Test
Maximum
Allowable
System
Condition
TestPressure1,7
in.wc(Pa)
Allowabl
System
Pressure , Leakage Leakage
1.Fractionalhorsepowerfan
systems;fan
coils,
small
exhaust/supplyfans,andresidential
0.50WC
(125 pa)
2% Operating
System
Operating
Pressure
5%
systems
Construction
.
2.Smallsystems;splitDXsystems 1.00WC 2%
(940l/s),
and
residential
systems
1 Testpressureshouldnotexceedthepressureratingoftheduct.7Itisrecommendedthatthepressureratingoftheductbeequaltothefanshutoffpressureifthepossibility
o ans uo ex s se er n sys emsor nsys emsw smo e re ampercon ro .
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WhatShouldBeSpecified
AssociatedAirBalance ASHRAE 2012DuctConstructionChapterounc tan ar ystemsan qu pment an oo
TypeofSystem Minimum
TestPressure
Maximum
Allowable
System
Condition
TestPressure1,7,in.wc
Allowable
System1,7
Leakage (Pa) Leakage
3.VAVandCAVboxesand
associateddownstream
2
1.00WC
(250pa)
2% Operating
System
Not
Addressed
4.Singlezone,multizone,
returnducts,andexhaust
ducts stems
2.00WC
(500pa)
2% Operating
System
Operating
Pressure
5%
Durin 2.0 500 5%
Construction
1 Testpressureshouldnotexceedthepressureratingoftheduct.7Itisrecommendedthatthepressureratingoftheductbeequaltothefanshutoffpressureifthepossibilityoffanshutoff
.
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WhatShouldBeSpecified
AssociatedAirBalanceCouncilAABCStandard ASHRAE 2012DuctConstructionChapterSystemsandEquipmentHandbook
TypeofSystem Minimum
Test
Pressure
1,7
Maximum
Allowable
Leakage
System
Condition
TestPressure1,7,
in.wc(Pa)
Allowable
System
Leakage. cons an vo ume uc s
inchasesandconcealed
spaces,mainreturnducts
onVAV8 andCAV8 systems
.
(745pa)
pera ng
System
o resse
During
Construction
NotAddressed
1 Testpressureshouldnotexceedthepressureratingoftheduct.7Itisrecommendedthatthepressureratingoftheductbeequaltothefanshutoffpressureifthe
possibilityoffanshutoffexistseitherinVAVsystemsorinsystemswithsmoke/firedampercontrol.8
.
outlet,thentheboxshouldbeincludedintheupstreamleakagetesting.
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WhatShouldBeSpecifiedAssociatedAirBalanceCouncilAABCStandard ASHRAE 2012DuctConstructionChapterSystemsandEquipmentHandbook
Typeof
System Minimum
Test
Pressure1,7
Maximum
Allowable
Leaka e
System
Condition
TestPressure
1,7,
in.wc(Pa)
Allowable
System
Leaka e
6.SupplyductsforVAV8 and
CAV
8
systemsVAVandCAVterminal
4.00WC
(995
pa)
1% Operating
System
Operating
Pressure
5%
boxestestedwith
upstreamductwork
Construction
4.0 (1000)
Downstream
Box: 1.0(250)
estpressure
s ou
not
excee
t e
pressure
rat ng
o
t e
uct.7Itisrecommendedthatthepressureratingoftheductbeequaltothefanshutoffpressureifthe
possibilityoffanshutoffexistseitherinVAVsystemsorinsystemswithsmoke/firedampercontrol.8 Itisassumedthattheprimaryairdamperislocatedattheterminalboxinlet. Ifinsteadthisdamperis
att eterm na oxout et,t ent eterm na oxs ou e nc u e nt eupstream ea agetest ng.
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WhatShouldBeSpecified
AssociatedAirBalance ASHRAE 2012DuctConstructionChapterounc tan ar ystemsan qu pment an oo
TypeofSystem Minimum Maximum System TestPressure1,7, Allowable
Test
Pressure1,7Allowable
Leakage
Condition in.wc(Pa) System
Leakage
7.Dual
duct
systems,
both
6.00
WC 1% Operating
Operating
5%
o uc an co uc pa ys em ressure
During
Construction
6.0(1500) 5%
.
g
pressure
n u c on
system .
(1495pa) . pera ng
System pera ng
Pressure
During
Construction
6.0(1500) 5%
1 Testpressureshouldnotexceedthepressureratingoftheduct.
5 Largeinduction
systems
may
have
higher
pressure
requirements,
i.e.,
10
WC
(2490
pa)
7Itisrecommendedthatthepressureratingoftheductbeequaltothefanshutoffpressureifthe
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WhatShouldBeSpecifiedAssociatedAirBalance ASHRAE 2012DuctConstructionChapter
ounc an ar ys emsan qu pmen an ooTypeofSystem Minimum
Test
Maximum
Allowable
System
Condition
TestPressure1,7,
in.wc(Pa)
Allowable
System
Pressure1,7 Leakage Leakage
9.Manifoldedexhaustsystems
Exhaustsystems
for
labs
6.00WC6
(1495pa)
0.5% Operating
System
NotAddressed
During
Construction
NotA resse
10.Grease ductsystems 4.00WC
(995pa)
0% Operating
System
NotAddressed
DuringConstruction
NotAddressed
1 Testpressureshouldnotexceedthepressureratingoftheduct.6 Largemanifoldexhaustsystemsmayhavehigherpressurerequirements,i.e.,10WC(2490pa)7Itisrecommendedthatthepressureratingoftheductbeequaltothefanshutoffpressureifthe
possibilityof
fan
shut
off
exists
either
in
VAV
systems
or
in
systems
with
smoke/fire
damper
control.
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WhatShouldBeSpecifiedAssociatedAirBalance ASHRAE 2012DuctConstructionChapter
Typeof
System Minimum
Test
Pressure1,7
MaximumAllowable
Leakage
System
ConditionTest
Pressure
1,7,
in.WC(Pa)Allowable
System
Leakage
11.VAV8 andCAV8 return
systems
Not
Addressed
Operating
System
Operating
Pressure
5%
During
Downstream 5%
Construction box:3.0(750)
Upstreambox:
1.0(250)
1 Test ressureshouldnotexceedthe ressureratin oftheduct.
7Itis
recommended
that
the
pressure
rating
of
the
duct
be
equal
to
the
fan
shut
off
pressure
ifthe
possibilityoffanshutoffexistseitherinVAVsystemsorinsystemswithsmoke/firedampercontrol.8 Itisassumedthattheprimaryairdamperislocatedattheterminalboxinlet. Ifinsteadthisdamperis
attheterminalboxoutlet thentheterminalboxshouldbeincludedintheu streamleaka etestin .
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WhatShouldBeSpecified
AssociatedAirBalance ASHRAE 2012DuctConstructionChapterCouncilAABCStandard SystemsandEquipmentHandbook
TypeofSystem Minimum
Test
Maximum
Allowable
System
Condition
TestPressure1,7,in.WC
Allowabl
eSystem
Pressure1,7
Leakage (Pa) Leakage
12.
Chilled
beam
primary
su l
2.00 WC
(500 pa)
1% Operating
S stem
Operating
Pressure
5%
During
Construction
4.0(1000) 5%
1 .
7ItisrecommendedthatthepressureratingoftheductbeequaltothefanshutoffpressureifthepossibilityoffanshutoffexistseitherinVAVsystemsorinsystemswithsmoke/firedampercontrol.
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WhatShouldBeSpecified
ssoc a e r a anceCouncilAABCStandard
uc ons ruc on ap erSystemsandEquipmentHandbook
TypeofSystem Minimum
Test
Maximum
Allowable
System
Condition
TestPressure1,7,
in.wc(Pa)
Allowable
System
Pressure1,7 Leakage Leakage
Specified design
15.Airhandlingunits
.
(2500pa)
1%
Sitetest by
Manufacturer
pressure
Operating
Pressure
2.0(500)
1 .
7Itisrecommendedthatthepressureratingoftheductbeequaltothefanshutoffpressureifthe
possibility
of
fan
shut
off
exists
either
in
VAV
systems
or
in
systems
with
smoke/fire
damper
control.
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WhatShouldBeSpecified
AssociatedAirBalanceCouncilAABCStandard ASHRAE 2012DuctConstructionChapterSystemsandEquipmentHandbook
Test
Pressure1,7Allowable
Leakage
Condition
1,7,in.wc(Pa)
System
Leakage
16.Multizone
supply
Item
4
2% Operating
Operating
5%
systems;Multizone
returnsystems;
Multizoneexhaust
above
2.00WC
(500Pa)
System Pressure
During
Construction
2.0(500) 5%
1 Testpressureshouldnotexceedthepressureratingoftheduct.7Itisrecommendedthatthepressureratingoftheductbeequaltothefanshutoffpressureif
the ossibilit offanshutoffexistseitherinVAVs stemsorins stemswithsmoke firedam er
control.
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WhatShouldBeSpecified
ForAir
Handling
Units
(AHU)with
total
static
pressures
(TSP)
below
4WCIwouldsuggestthetestrequirementbe2xTSPnottoexceed
10 WC.Suggestpane e ection eteste uring t eAHU
pressuretest.
Instrumentationused
to
measure
the
pressure
across
the
orifice
tubemusthave.01WCresolution.
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DeflectionTesting
Deflectionlimit
of
L/250
shall
be
demonstrated.
Measurements
shallbetakenatmidpointofLusingdialindicatorsreadingin
1 1000t s. Mountingo ia in icatorss a ein epen ento t e
unitcasing. Multiplemeasurementsshallbemade. Dialindicator
shallbe
mounted
at
mid
point
of
L
on
the
seams.
L
is
defined
as
theheightofthelargestpanelonthesidesoftheAHU,widthofthe
largestpanelacrossthetopoftheAHU,andthesmallerofwidthor
heightofthelargestpanelfortheendsoftheAHU. Theseare
knownas
the
governing
panels.
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IssuesofSealingDucttoaLeakageClassandSealClass
Case1:PriortoSMACNAHVACAirDuctLeakageTestManual,1985two
ent ca p aseso aresearc u ngwere u t y erentcontractors.
TheAHUsystemsweredualduct.Phase1bycontractorArequired
increasingthe
RPM
and
loading
the
125HP
motors
(156
amps)to
maintain
.
requireddecreasingtheRPMwhichloweredtheampdraw(92amps)to
maintainthestaticpressureattheendofthesystem.
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IssuesofSealingDucttoaLeakageClassandSealClass
Case2:
Two
identical
ten
story
office
buildings
were
built
by
the
same
contractors.Theoutsideair(OSA)andtoiletexhaustductrisersinthe
.
identicalsizesandhadthesamerateddesignairflow.Thespecification
requiredapressuretestof3.0andleakagetonotexceed2%.BuildingA
.
ductsealingbyteamBfailedmanytimesandfinallypassedafter3weeks
ofextrasealing.
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IssuesofSealingDucttoaLeakageClassandSealClass
Case3:
A
96
x96
main
exhaust
duct
was
designed
for
180,000
CFM.
The
sealclasswasAandtheleakageclasswas6.Thespecificationsrequired
.
andfoundtheleakagetobebetween8%to15%.Theductwasinstalledin
aninterstitialspace andthetopoftheductranbetweenthebeams.An
andnotthetopandbottom.
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IssuesofSealingDucttoaLeakageClassandSealClass
Case4:
Connection
of
plenum
boxes
to
diffusers.
On
ahard
ducted
systemthediffuserswereconnectedtoplenumboxes.Thediffusers
wereinsta e wit zipscrewsoneac si e.Ourtesting oun 15%
leakage.Theplenumboxeshadtobedisconnectedfromthebranch
ductand
the
diffuser
and
plenum
removed
to
properly
seal
the
connection.Afterthediffusersandplenumboxeswerereinstalled
noleakagewasdetected.
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ReportingDuctLeakage Job Number
Job
Name DescriptionofDuctTested
er orme yan nesses
Equipmenttagordesignationoftheprimarymover
DesignCFM
of
Test
Section
TestEquipmentOrificeSizeandCalibrationDate
RequiredSP ActualSP
AllowableLeaka einCFMDeterminedb %ofDuctBein Tested
ActualLeakage
CFM
Pass/Fail
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AnticipatedCost
Thesecostsarebasedontheassumptionthatbuildingsare
designedontheaverageof1CFM/Ft2 andthecostisapproximately$2.00/ Ft2
ShouldbeSpecifiedAbove CFM Cost/Year=Leak %
xCFMx$2.00
Construction ChapterCost/Year=Leak %xCFMx$2.00
1.&2.SmallSystems
(multiples)
2000 $80 $200
3.TerminalBox Downstream
Ductwork(multiples)1570 $62.80 $157.00
. , ,
VAV,CAV
. .
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AnticipatedCost
TypeofSystemFromWhatShouldbeSpecifiedAbove MaximumCFM AABC StandardsCost/Year=Leak % x CFM x
ASHRAE2012DuctConstructionCha ter Cost Year =
$2.00
Leak %xCFMx$2.00
5.DuctsinChases 50000 $1000 $5000
6.VAVandCAVSupplyDucts 80000 $1600 $8000
7.DualDuctS stems 150000 $3000 $15000
8.High
Pressure
Induction 100000 $1000 $10000
9.ManifoldExhaustSystem 200000 $2000 $20000
. rease uc s o resse
11.VAV&CAVReturnSystems 100000 $1000used1% $10000
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AnticipatedCost
TypeofSystemFromWhatShouldbeSpecifiedAbove MaximumCFM AABCStandardCost/Year=Leak %x CFM x 2.00
ASHRAE2012DuctConstructionCha ter Cost Year=Leak %xCFMx$2.00
12.ChilledBeam 20000 $200used.5% $2000
13.Supply&Returnlocated
Outdoors
30000 $0used0% $3000
14.Exhaust
Ductwork 200000 $4000
used
1% $8000
15.AHUs 150000 $3000 $3000
16. Multizone S stems 25000 1000 used 2% 2500
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AnticipatedCost
The$2.00
per
CFM
came
from
an
estimated
value
when
TC
5.2
was
analyzingterminalboxleakage.ThesamecostperCFMwasfound
to etrueina7400 t o icewit 5roo topsing ezoneunits.
ResearchbuildingoperatorshavestatedtheircostperCFMranges
between$4.00
to
$8.00
per
CFM
depending
on
how
many
100%
OSAsystemsareservingthebuildingandhowmanyspaceshave
highairchangerates.
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WhatDoesASHRAEStandard90.1Addendumcq add
6.4.4.2Ductwork
and
Plenum
Leakage
6.4.4.2.1DuctSealing.Ductworkandallplenumswithpressureclass
ratingsshallbeconstructedtosealclassA,asrequiredtomeetthe
requirementsofsection6.4.4.2.2,andwasstandardindustry
practice(see
Informative
Appendix
E).
.....
All
connections
shall
be
sealed,includingbutnotlimitedtospinins,taps,otherbranch
connections,accessdoors,accesspanels,andductconnectionsto
equipment.Sealingthatwouldvoidproductlistingsisnotrequired.
Spirallock
seems
need
not
be
sealed.
All
duct
pressure
class
ratings
shallbedesignatedinthedesigndocuments.
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WhatDoesASHRAEStandard90.1Addendumcq add
6.4.4.2.2DuctLeakageTests.Ductworkthatisdesignedtooperateat
staticpressuresinexcessof3in.wcandallductworklocated
outdoorsshall
be
leak
tested
according
to
industry
accepted
test
rocedures seeInformativeA endixE .Re resentativesections
totalingnolessthan25%ofthetotalinstalledductareafor
designatedpressureclassshallbetested.Allsectionsshallbe
selected b the buildin owner or the desi nated re resentative of
thebuildingowner.Positivepressureleakagetestingisacceptable
fornegativepressureductwork.Themaximumpermittedduct
= 0.65 = max max
leakageCFM/100
ft2 duct
surface
area.
CL=for,ductleakageclass,
CFM/100ft2 ductsurfaceareaat1in.wc.P=testpressure,which
, .
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Summary
Ihaveseenonseveralprojects sampleleakagetestingofthe
ductworkspecifiedandthesealingofthesampleducttobebetter
thanthe
remaining
ductwork.
Iwould
suggest
that
100%
of
the
ductworkbetested.
TosaveenergyIwouldsuggestthatductworkabove3WCbe
testedattheductratedpressureandnotexceed1%leakage.
e uc ra e pressures ou ew a era e ansys ems u
offpressurewouldbeifadamperfailed.Thestaticpressuresetting
forthelimitswitchesmustbesetbelowthemaximum test
pressure
o
t e
uct. Tonotpressuretestductworkandassumethesealantwillbe
appliedproperlyhassavedmoneyonthefrontendbutcostthe
ownerdearlythroughoutthelifeofthesystem.
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QUESTIONS
IT COULD BE WORSE