Duct Leakage: How Much

January/February 2001
A version of this article appears in the January/February 2001 issue of Home Energy Magazine.
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January 01, 2001
Q:Is there a standard for energy-efficient ducts? I was called to a home built in 1955 that is under a warranty from a recent sale. The customer wanted us to “fix the ducts.” I didn’t see anything wrong with the ducts, but they claimed PG&E (the local utility) tested them and they were too leaky. Is there a standard and how do you test for it? A: There are a number of state and federal standards that limit duct leakage based on different leakage test results. In the most common test, the registers are temporarily sealed and a fan is used to pressurize the ducts and measure the leaks.         To understand the test differences, you should know these duct leakage terms:         Total duct leakage. This refers to all the air that escapes from the duct other than through registers. A total duct leakage test measures all leaks, whether the air ends up inside or outside the house. This is the simplest and most widely used leakage measurement.         Leakage at 25 Pascals (Pa). When the ducts are tested, ...

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