Duct Leakage Testing - NEBB
Duct Leakage TestingKen Helfers, TSI Inc. 2011, TSI Incorporated
Agenda Need for duct leakage testing Duct leakage testing standards and regulations Performing duct leakage testing 2011, TSI Incorporated
Why Test Ducts forL kLeakage? Conserve energy– 10-30% of heated/cooled air lost through ductwork– Leaky supply ducts don’t delivery air where needed– Leaky return ducts add load 2011, TSI Incorporated
Why Test Ducts forL kLeakage? Indoor Air Quality– Leaky returns can pull in air from uncontrolledspaces,pcausingg Humidity problems Contaminants 2011, TSI Incorporated
System Leakage IAQIAQ, Comfort,Comfort Energy issues caused byleakage from HVAC System System Leakage Duct Leakage Equipment Leakage Accessoryy Leakageg Scope of presentation Duct leakage– Does not include: Leakage through Equipment (See ASHRAE 193) Leakage through Accessories– Commercial & industrial systems Similar concepts for residential 2011, TSI Incorporated
Why Test Ducts forL kLeakage? RequirementsRit– US SMACNA HVAC Air Duct Leakageg Test manual,, First edition,, 1985ASHRAE 90.1 (Proposed)Project specificationsCalifornia Title 24 residential testing required if ahu/furnace ingarage or ducts in non-conditioned space (attic)– Europe BS EN 12237:2003 – Circular DuctworkBS EN 1507:2006 – Rectangular DuctworkDW/143 (HVAC—A practical guide to Ductwork leakage testing)Eurovent 2/2 (Air leakage rate in sheet metal air distribution systems) 2011, TSI Incorporated
Where Does Duct LeakageOOccur? Transverse Joint– Duct-to-duct, -branch,-tap, etc. LongitudinalgSeam– Joining of 2 edges indirection of airflow Penetration– Rod, wire, tubing, etc. Sealing not required:– Spiral seams– Screws & fasteners– Damper rods 2011, TSI Incorporated
Where Does Duct LeakageOOccur? Higher-pressure ductwork– ASHRAE 9090.11 recommends only testing ductwork rated 3 in H2O– Don’t test flex duct 2011, TSI Incorporated
How to Test Duct Leakage(B i )(Basic) Identify ductwork section to be tested– Calculated surface area Seal ductwork Pressurize ductwork to specified level Measure flow required to maintain ductpressure Compare to standards 2011, TSI Incorporated
Duct LeakageMeasurements % of Flow requirements– Problem: Disregards size of ductwork & static pressure– i.e. 1% of flow on 3900 cfm systemy 39 cfm.If 1300 ft2 duct area 3 cfm leakage / 100 ft2300 ft2 duct area 13 cfm leakage / 100 ft2 Test pressure requirements– Problem: Test pressure higher than duct design– i.e. testing system designed for 2 in H2O operation at 10 inH2 O NeedN d tto considerid– Surface area of ductwork Type of ductwork (round, rectangular)– Static pressure 2011, TSI Incorporated
US Duct Leakage TestingRRequirementsit - (SMACNA)Duct ClassSeal Class½-, 1-, 2-inwgC3-inwg4-, 6-, 10-inwgBATransversea sve seJoints,Jos, SeaSeamssS liSealingTTransverseJoints andand All WallApplicableJoints OnlySeamsPenetrationsLeakage Class (CL) – CFM Leakage per 100 ft2 @ 1 in H2ORectangular24126MetalRound Metal1263F CL* P0.65 F Max Leakage (cfm/100 ft2) CL Leakage Class (from table above) P Pressure (in H2O) 2011, TSI Incorporated
Prior to Field Testing 2011, TSI Incorporated
Prior to Field Testing1) Duct System Designer:Include on Design/Contract Drawing: SpecifySif DuctD tPPressure ClClassificationifi ti 2011, TSI Incorporated
US Duct Leakage TestingRRequirementsit - (SMACNA)Duct ClassSeal Class½-, 1-, 2-inwgC3-inwg4-, 6-, 10-inwgBATransversea sve seJoints,Jos, SeaSeamssS liSealingTTransverseJoints andand All WallApplicableJoints OnlySeamsPenetrationsLeakage Class (CL) – CFM Leakage per 100 ft2 @ 1 in H2ORectangular24126MetalRound Metal1263F CL* P0.65 F Max Leakage (cfm/100 ft2) CL Leakage Class (from table above) P Pressure (in H2O) 2011, TSI Incorporated
Duct Leakage EquationF CLWhereduct.65P2F Leakage [CFM] / 100 ftCL Duct Leakage ClassificationP Duct Static Pressure [[“ww.g.]g] 2011, TSI Incorporated
2011, TSI Incorporated
Prior to Field Testing1) Duct System Designer:Include on Design/Contract Drawing: Test (or not) as installed? Depends on designintent/requirements If Test: Specify on Dwgs Portion of ductwork, or whole system?Positive Pressure? Negative?P id methodProvideth d ddetailst il 2011, TSI Incorporated
Prior to Field TestingQuote from HVAC AIR DUCT LEAKAGE TESTMANUAL (SMACNA):“WHERE NO SPECIFIC DUCT PRESSURECLASS DESIGNATIONS ARE PROVIDED BYTHE DESIGNER THE 1” WATER GAGEPRESSURE CLASS IS THE BASIS OFCOMPLIANCE 2011, TSI Incorporated
Prior to Field Testing EXCEPT WHEN THE DUCT IS VARIABLEVOLUME: ALL VARIABLE VOLUME DUCTUPSTREAM OF VAV BOXES HAS A 2” W.G.BASIS OF COMPLIANCE WHEN THEDESIGNER DOES NOT GIVE A PRESSURECLASS.”– from SMACNA HVAC AIR DUCT LEAKAGETEST MANUAL, 1985 2011, TSI Incorporated
Prior to Field Testing2) Testing Agency: Prepare paperwork Test plan TestT t reportt formf 2011, TSI Incorporated
Prior to Field Testing3) Testing Agency: Prepare the site Plan/Coordinate with construction/installationcontractors Blanking materials Equipment Select according to Test Requirements Consider System Flowrate Leakage Classification Flow Capacity of Test System 2011, TSI Incorporated
Prior to Field Testing Equipment Details:– Must use instruments that have been calibratedwithin the ppast 12 months– Calibration certificates traceable to NIST– ConsiderCTest SSystem capabilities: Ability to Log data and download with Time/Date stampvs using liquid-inclined and U-tube manometersvs. 2011, TSI Incorporated
Prior to Field Testing Contingency planning(Designer: Put plans in contract drawing/specs)– If duct leak test FAILS – then what?REMEDIATE! 2011, TSI Incorporated
Prior to Field Testing REMEDIATION Plan– Seal the leaks– Wait for seals to cure– Re-testRe test Re-test failed section only?gg need to test more sections? Does section failure triggerSPECIFY! 2011, TSI Incorporated
Test Procedure1) Select Duct Section for Testing2) Measure and Calculate Duct Surface Area3)) Seal All Openingspg ((exceptp one)) 2011, TSI Incorporated
2011, TSI Incorporated
Test ApparatusDuct Leakage Test System consists of:1) Blower with speed control (VFD) togeneraterange of pressure/flow2) Flow measuring devices- Flow Grid/Flow Station (High Flow)- Orifice Plate (Low Flow)3) PPressure iinstrumentstt ((manometers)t )4) Accessories to attach to duct system5) Optional item (smoke generator) 2011, TSI Incorporated
Test System:CConsiderationsidi Maximize:Flow Range– Limits duct section size/Leakage Rate Maximize: Pressure Range– High Pressure Blower to cover duct classes ½” to 10” w.g.g Maximize: Instrument Measurement Accuracy– Flow: 2.5% of reading– Pressure: 1% of reading 2011, TSI Incorporated
Test System Considerations Instrumentation:– Traceable to National Standards (NIST)– Logging capability – SIMPLIFY! Time/Date Stamp on each data setCalculates FlowsCalculates Leakage rate based on duct ft2 inputIndicates PASS/FAIL status according to selectabledefined leakage classifications Report generation and validation 2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
2011, TSI Incorporated
Summary Leaky ductwork is costly There are Standards and Test Procedures Designer: Be Specific with specs andi t tiinstructions ChooseChththe righti ht TTestt EEquipmentit 2011, TSI Incorporated
Contacts Ken Helfers, TSI Inc. Ken.helfers@tsi.com502-897-0945897 0945 502 Siva Iyer, TSI Inc. siva.iyer@tsi.com651-765-3721765 3721 651 2011, TSI Incorporated
Appendix 2011, TSI Incorporated
European Duct LeakageRRequirementsit - RoundRd DuctsD tStatic Pressure Limit MaximumDuct Pressure Positive Negative Air VelocityClassPaPam/sLow pressure50050010– Class AMediumpressure –100075020Class BHigh pressure200075040– ClassCl C Pt test pressure 2011, TSI IncorporatedAir .003pt0.65
European Duct LeakageRequirements - RectangularDuctsAir TightnessClassLow pressure –Class AMedium pressure– Class BHigh pressure –Class CStatic Pressure Limit (ps) PaPositive at 040010002000 Pt test pressure 2011, TSI *pt0.650 003*p0.003pt0.65
Comparison of SMACNA & EUL kLeakageRequirementsRit 2011, TSI Incorporated
ComparisonStandard / ActualConversionsEU StandardsSMACNA StandardRequiredSuggested if: Air Temp 40 F or 100 F ElevationElti 1500 ffeett Duct static -20 in H2Oor 20 in H2O 2011, TSI Incorporated
ComparisonReport RequirementsEU StandardsSMACNA StandardSpecified in Standards Site details Date LocationLti Test equipment Personnel &witnesses Ductwork installer &manufacturer Duct designoperating pressure Required AirTightness ClassDefers to projectspecifications. Suggests: Site Details DateD t Location Personnel &witnesses Duct section tested 2011, TSI Incorporated
ComparisonReport RequirementsEU StandardsSMACNA StandardSpecified in Standards Measurements Duct surface area TestT t pressure Leakage rate Pressurizing time Calculated Leakage factor Air Leakage Limit Pass/fail resultDefers to projectspecifications. Suggests: Measurements DuctD t surfacefarea Test pressure Leakage rate Calculated Max Air Leakageallowed Pass/fail result 2011, TSI Incorporated
– ASHRAE 90.1 recommends only testing ductwork rated 3 in H 2 – Don’t test flex duct. How to Test Duct Leakage (B i )(Basic) Identify ductwork section to be testedIdentify ductwork section to be tested – Calculated surface area Seal ductworkSeal ductwork
ducts, existing data bases of duct leakage area meas U f'.m nts, the impacts of duct leakage on space-con d1t1oning energy consumption and peak demand and he ventilation impacts of duct leakage. The pape; also includes a brief discussion of techniques for sealing duct systems in the field. The results derived from duct leakage area and .
Variability of duct leakage is high. About 10% of homes showed little leakage; 10% showed severe leakage. Duct leakage added about 10% to house leakiness, measured by fan pressurization (4 Pa ELA and 50 Pa air exchange). Flow hood tests showed return duct leakage about twice that of supply ducts during normal furnace fan operation. This typically
Restricted duct access or external insulation Few constraints to the Aeroseal process Labor drives retrofit duct sealing costs Blocking ducts for pressurization and sealant delivery Measuring duct leakage costs nearly as much as sealing duct leakage Verification of sealed leakage is built into the process
method of duct fabrication, method of sealing, workmanship, and static pressure differential. An equation that describes leakage as a function of leakage class and static pressure is presented in the "Duct Design" chapter of the 1993 ASHRAE Handbook. This equation is used to calculate the leakage rate through a unit of duct surface for constant .
This is the test pressure. This is the duct leakage Figure 3: The gauge will also display 4 CFM per 100 square feet when the floor area of 2,000 square feet is entered. This is the Duct Leakage per 100 square feet Figure 1: The gauge displays the test pressure of -25 Pa and duct leakage of 80 CFM Figure 2 Duct Tester connections
ANSI/SMACNA HVAC Air Duct Leakage Test Manual. . leakage class for duct, not a percent. 90.1 class 4 all duct IECC class 4 all duct IAPMO GPMCS class 4 all duct. Why not use a % to fan flow? ASHRAE RP 1292. Active Tests vs Static Tests Active test –test performed on a File Size: 1MBPage Count: 59
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