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TSC Services:
Sealed Crawl Spaces | Blower Door Testing | Home Energy Audits | Duct Blaster® Testing
Measuring Duct Leakage
A duct leakage performance test involves pressurizing the duct system with a calibrated fan and simultaneously measuring the air flow through the fan and its effect on the pressure within the duct system. The tighter the duct system, the less air you need from the fan to create a change in duct system pressure. Testing procedures can be set up to measure only duct leaks which are connected to the outside, or to measure total duct leakage (i.e. leaks connected to the outside and inside of the house). Duct leakage measurements are used to diagnose and demonstrate leakage problems, estimate efficiency losses from duct leakage, and certify the quality of duct system installation.
Two different types of performance testing systems are used to measure duct leakage; a Duct Blaster® and a Blower Door.
Duct Blaster®
- A Duct Blaster is used to directly pressure test the duct system for air leaks, much the same way a plumber pressure tests water pipes for leaks.
- The Duct Blaster fan is first connected to the duct system at the air handler cabinet, or a return grille. After temporarily sealing all remaining registers and grills, the Duct Blaster fan is turned on to force air through all holes and cracks in the ductwork.
- The fan speed is increased until a standard test pressure is achieved in the duct system. A precise leakage measurement is then made using an airflow and pressure gauge connected to the Duct Blaster system.
- Estimates of efficiency losses from duct leakage can then be made from the leakage measurements.
- A theatrical fog machine can be used along with the Duct Blaster to inject a non-toxic fog into the duct system to visually demonstrate the location and extent of leakage in the ductwork.
Blower Door
- The Blower Door is a whole house testing system which indirectly measures duct leakage by pressurizing the entire house to a standard testing pressure.
- By comparing the whole house test before and after all registers are temporarily sealed, the Blower Door provides you with an estimate of duct leakage to the outside.
- With the Blower Door running, duct leaks can be pinpointed using a hand-held smoke puffer, or a leak detection tool called a pressure pan.
- In addition to diagnosing duct leakage problems, the Blower Door can identify building envelope improvements that will reduce energy use and increase comfort.
- Blower Door airtightness measurements can also be used in HVAC equipment design and sizing decisions, and to help estimate the need for mechanical ventilation.
Click Here to Learn About the Duct Blaster® Test