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Duct Leakage Testing
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Duct Leakage Testing
Agenda
- Need for duct leakage testing
- Duct leakage testing standards and regulations
- Performing duct leakage testing
Why Test Ducts for Leakage?
Conserve energy
- 10-30°/o of heated/cooled air lost through ductwork
- Leaky supply ducts don’t delivery air where needed
- Leaky return ducts add load
Indoor Air Quality
Leaky returns can pull in air from uncontrolled spaces,causing
- Humidity problems
- Contaminants
IAQ, Comfort, Energy issues caused by leakage from HVAC System
System Leakage = Duct Leakage + Equipment Leakage + Accessory Leakage
Scope of presentation = Duct leakage
Requirements
US
- SMACNA HVAC Air Duct Leakage Test manual, First edition, 1985
- ASHRAE 90.1 (Proposed)
- Project specifications
- California Title 24 -7 residential testing required if ahu/furnace in garage or ducts in non-conditioned space (attic)
Europe
- BS EN 12237:2003 – Circular Ductwork
- BS EN 1507:2006 – Rectangular Ductwork
- DW/143 (HVAC-A practical guide to Ductwork leakage testing)
- Eurovent 2/2 (Air leakage rate in sheet metal air distribution systems)
Transverse Joint
- Duct-to-duct, -branch,-tap, etc.
Longitudinal Seam
- Joining of 2 edges in direction of airflow
Penetration
- Rod, wire, tubing, etc.
Sealing not required
- Spiral seams
- Screws & fasteners
- Damper rods
How to Test Duct Leakage (Basic)
- Identify ductwork section to be tested – Calculated surface area
- Seal ductwork
- Pressurize ductwork to specified level
- Measure flow required to maintain duct pressure
- Compare to standards
Duct Leakage Measurements
0/o of Flow requirements
- Problem: Disregards size of ductwork & static pressure
- i.e. 1°/o of flow on 3900 cfm system = 39 cfm. If 1300 ft2 duct area = 3 cfm leakage I 100 ft2 300 ft2 duct area = 13 cfm leakage I 100 ft2
Test pressure requirements
- Problem: Test pressure higher than duct design
- i.e. testing system designed for 2 in H20 operation at 10 in H20
Need to consider
- Surface area of ductwork
Type of ductwork (round, rectangular)
- Static pressure
