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6.7.4. What about pinholes or other leaks in the flex?
One question we get a lot is about leaking flex duct that connects the ducTester to the return. I just tested
the most ripped up flex I could find on optional low flow Range 7; I had way bigger than pinholes and it
measured 0.68 CFM at 25 Pa. When you measure a typical leakage of 100 CFM at 25 Pa or more, this is
not even 1% so it is not worth spending money on replacing.
You can create your own inexpensive version of Range 7 by covering the front of your DucTester with grill
mask and putting a quarter inch square hole in it. Set your DucTester to Range 7 on Device 340, seal off
the end of your flex and measure the leakage. If you get more than 3 CFM you might start to worry about
it. Range 7 is available on the Model 340 but this test should show you don't need it.
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