February 18, 2014, 4:59 pm

Is Duct Leakage Testing Really Just Smoke & Mirrors?

February 18_Duct Leakage Testing ImageOf the more than a million miles of duct work in U.S. homes, industry experts estimate that more than two-thirds of them have leaks. This can account for as much as 25 percent of a home’s total energy loss. Duct leakage can dramatically reduce the HVAC equipment’s capacity and performance, causing hot and cold spots and humidity problems. Leaky ducts can also significantly increase homeowners’ utility bills and, worse yet, create air quality problems by pulling pollutants and other health hazards directly into the home. All of this creates an uncomfortable living environment for homeowners and their families.

Keeping in mind the number of issues that can arise from leaky ducts, ACH&R News writer David Richardson investigates the current metrics used for residential duct leakage testing, a verification process put in place by the International Energy Conservation Code (IECC) to ensure that healthy, clean air is provided to homeowners. In his article, “Using Duct Surface for Leakage Testing?” Richardson informs us of his findings:

Current duct leakage testing involves pressurizing the duct system to the standard 25 pascals using a calibrated fan and comparing the airflow against the conditioned floor area (CFA) of a home. Depending on local codes, the total leakage allowed is limited anywhere from 12 cubic feet per minute (cfm) per 100 square feet of CFA to 4 cfm, per the 2009 and 2012 IECC codes, respectively.

The problem with these measurements comes two fold. First, as Richardson explains, duct leakage occurs at the surface area of the duct, not the CFA. Therefore the current formula for testing duct leakage does not test the actual area of concern. Secondly, the 25 pascals value that the industry has deemed the standard operating pressure is simply outdated. Richardson writes that you rarely find duct systems running at that pressure in the field nowadays and in fact, pressures are usually elevated due to undersized duct systems.

No matter which way you cut it, Richardson’s examination shows that residential duct leakage testing can easily yield misleading or inaccurate results. So, as he asks, do we revise a formula that has been used for years or do we sacrifice some level of accuracy for convenience and simplicity?

What’s our answer? Go duct-free. Visit www.mitsubishipro.com to learn more on how you can avoid the smoke and mirrors of duct leakage testing by choosing ductless technology as the HVAC solution.

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